@article{RODRIGUEZOLGUIN2021,

title = {Al2O3 Nanofibers Prepared from Aluminum Di(sec-butoxide)acetoacetic Ester Chelate Exhibits High Surface Area and Acidity},

author = {M. A. Rodriguez-Olguin and H. Atia and M. Bosco and A. Aguirre and R. Eckelt and E. D. Asuquo and M. Vandichel and J. G. E. Gardeniers and A. Susarrey-Arce},

url = {https://www.sciencedirect.com/science/article/pii/S0021951721004796},

doi = {https://doi.org/10.1016/j.jcat.2021.11.019},

issn = {0021-9517},

year  = {2021},

date = {2021-11-22},

urldate = {2021-01-01},

journal = {Journal of Catalysis},

abstract = {Alumina (Al2O3) is a widely used material for catalysis in the chemical industry. Besides a high specific surface area, acid sites on Al2O3 play a crucial role in the chemical transformation of adsorbed molecules, which ultimately react and desorb from the catalyst. This study introduces a synthetic method based on electrospinning to produce Al2O3 nanofibers (ANFs) with acidity and porosity tuned using different aluminum precursor formulations. After electrospinning and heat treatment, the nanofibers form a non-woven network with macropores (∼4 μm). Nanofibers produced from aluminum di(sec-butoxide)acetoacetic ester chelate (ASB) show the highest total acidity of ca. 0.70 µmol/m2 determined with temperature-programmed desorption of ammonia (NH3-TPD) and BET. The nature of the acid site in ASB ANFs is studied in detail with infrared (IR) spectroscopy. Pyridine is used as a molecular probe for the identification of acid sites in ASB. Pyridine showed the presence of Lewis acid sites prominently. Density-functional theory (DFT) is conducted to understand the desorption kinetics of the adsorbed chemical species, such as ammonia (NH3) on crystalline γ-Al2O3. For our analysis, we focused on a mobile approach for chemisorbed and physisorbed NH3. The computational results are compared with NH3-TPD experiments, ultimately utilized to estimate the desorption energy and kinetic desorption parameters. The experiments are found to pair up with our simulation results. We predict that these non-woven structures will find application as a dispersion medium of metallic particles in catalysis.},

keywords = {},

pubstate = {forthcoming},

tppubtype = {article}

}

@article{KUMAR20213085,

title = {Breaking the trade-off between selectivity and adsorption capacity for gas separation},

author = {Naveen Kumar and Soumya Mukherjee and Nathan C. Harvey-Reid and Andrey A. Bezrukov and Kui Tan and Vinicius Martins and Matthias Vandichel and Tony Pham and Lisa M. Wyk and Kolade Oyekan and Amrit Kumar and Katherine A. Forrest and Komal M. Patil and Leonard J. Barbour and Brian Space and Yining Huang and Paul E. Kruger and Michael J. Zaworotko},

url = {https://www.sciencedirect.com/science/article/pii/S2451929421003636},

doi = {https://doi.org/10.1016/j.chempr.2021.07.007},

issn = {2451-9294},

year  = {2021},

date = {2021-11-11},

urldate = {2021-01-01},

journal = {Chem},

volume = {7},

number = {11},

pages = {3085-3098},

abstract = {Summary The trade-off between selectivity and adsorption capacity with porous materials is a major roadblock to reducing the energy footprint of gas separation technologies. To address this matter, we report herein a systematic crystal engineering study of C2H2 removal from CO2 in a family of hybrid ultramicroporous materials (HUMs). The HUMs are composed of the same organic linker ligand, 4-(3,5-dimethyl-1H-pyrazol-4-yl)pyridine, pypz, three inorganic pillar ligands, and two metal cations, thereby affording six isostructural pcu topology HUMs. All six HUMs exhibited strong binding sites for C2H2 and weaker affinity for CO2. The tuning of pore size and chemistry enabled by crystal engineering resulted in benchmark C2H2/CO2 separation performance. Fixed-bed dynamic column breakthrough experiments for an equimolar (v/v = 1:1) C2H2/CO2 binary gas mixture revealed that one sorbent, SIFSIX-21-Ni, was the first C2H2 selective sorbent that combines exceptional separation selectivity (27.7) with high adsorption capacity (4 mmol·g−1).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ABDI202137774,

title = {The importance of identifying the true catalyst when using Randles-Sevcik equation to calculate turnover frequency},

author = {Zahra Abdi and Matthias Vandichel and Alla S. Sologubenko and Marc-Georg Willinger and Jian-Ren Shen and Suleyman I. Allakhverdiev and Mohammad Mahdi Najafpour},

url = {https://www.sciencedirect.com/science/article/pii/S0360319921035199},

doi = {https://doi.org/10.1016/j.ijhydene.2021.09.039},

issn = {0360-3199},

year  = {2021},

date = {2021-09-29},

urldate = {2021-01-01},

journal = {International Journal of Hydrogen Energy},

volume = {46},

number = {76},

pages = {37774-37781},

abstract = {Water splitting will become important to store excess renewable electrical energy into hydrogen. Although the oxygen-evolution reaction (OER) by water oxidation is a critical reaction for water splitting, further investigations are needed to find the details of the OER mechanism for various electrocatalysts. More in particular for homogeneous electrocatalysts, the Randles-Sevcik equation has been extensively applied to determine the turnover frequency (TOF). Herein, using vitamin B12 as a case study, we show that the dynamical deposition/dissolution of the heterogeneous catalyst during OER makes the Randles-Sevcik equation too complicated to be used for calculating the TOF. Indeed, the conventionally applied post-characterization methods do not provide sufficient accuracy to prove the homogeneity of OER mechanisms; thus, using the Randles-Sevcik equation to calculate the TOF is not necessarily correct.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{D1FD90057A,

title = {Theory and modelling: general discussion},

author = {Dmytro Äntypov and Vonika Ka-Man Au and Isabel Cooley and François-Xavier Coudert and Deanna M. D’Alessandro and Qiaowei Li and Martin Schroder and Mikhail Suyetin and Matthias Vandichel and Sihai Yang and Michael Zaworotko and Elena" Besley},

url = {http://dx.doi.org/10.1039/D1FD90057A},

doi = {10.1039/D1FD90057A},

year  = {2021},

date = {2021-09-29},

urldate = {2021-01-01},

journal = {Faraday Discuss.},

volume = {231},

pages = {258-265},

publisher = {The Royal Society of Chemistry},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acs.chemmater.1c01723,

title = {Efficient Capture of Trace Acetylene by an Ultramicroporous Metal–Organic Framework with Purine Binding Sites},

author = {Shivani Sharma and Soumya Mukherjee and Aamod V Desai and Matthias Vandichel and Gourab K Dam and Ashwini Jadhav and Gabriele Kociok-Köhn and Michael J Zaworotko and Sujit K Ghosh},

url = {https://doi.org/10.1021/acs.chemmater.1c01723},

doi = {10.1021/acs.chemmater.1c01723},

year  = {2021},

date = {2021-07-09},

urldate = {2021-07-09},

journal = {Chemistry of Materials},

volume = {33},

number = {14},

pages = {5800-5808},

abstract = {Efficient separation of acetylene (C2H2) from its byproducts, especially CO2, is difficult because of their similar physicochemical properties, including molecular dimensions and boiling point. Herein, we demonstrate trace C2H2 removal from C2H2/CO2 mixtures enabled by a new ultramicroporous metal–organic framework (MOF) adsorbent, IPM-101, which features an optimal pore size of 4 Å (close to the kinetic diameter of C2H2, 3.3 Å) and one-dimensional channels lined by Lewis basic purine groups. Single-component gas adsorption isotherms revealed a clear affinity toward C2H2 versus CO2 at low pressures with a substantial C2H2 uptake of 0.9 mmol g–1 at 3000 ppm and 298 K. Dynamic column breakthrough experiments revealed separation of C2H2 from 1:1 and 1:99 v/v C2H2/CO2 mixtures. IPM-101 exhibits one of the highest dynamic separation selectivity (αAC) values yet reported, 22.5 for 1:1 C2H2/CO2. Computational simulations indicated that the purine moiety was key to the strong C2H2 selectivity thanks to C2H2 selective N···HC≡CH interactions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acssuschemeng.1c03539,

title = {Understanding the Dynamics of Molecular Water Oxidation Catalysts with Liquid-Phase Transmission Electron Microscopy: The Case of Vitamin B12},

author = {Zahra Abdi and Esmael S Balaghi and Alla S Sologubenko and Marc-Georg Willinger and Matthias Vandichel and Jian-Ren Shen and Suleyman I Allakhverdiev and Greta R Patzke and Mohammad Mahdi Najafpour},

url = {https://doi.org/10.1021/acssuschemeng.1c03539},

doi = {10.1021/acssuschemeng.1c03539},

year  = {2021},

date = {2021-07-07},

journal = {ACS Sustainable Chemistry & Engineering},

volume = {9},

number = {28},

pages = {9494-9505},

abstract = {Cobalt compounds are intensely explored as efficient catalysts for the oxygen evolution reaction (OER). Since vitamin B12 is a soluble cobalt compound with high enzymatic activity, evaluating its OER activity is of relevance for biomimetic catalyst research. In this work, the temporal evolution of a homogenous vitamin B12 catalyst in the early stages of OER was investigated by an advanced combination of in situ electrochemical liquid transmission electron microscopy (EC-LTEM), in situ UV–vis spectroelectrochemistry, and extended X-ray absorption fine structure (EXAFS) methods. For the first time, we provided direct evidence of diffuse layer dynamics on the working electrode interface. The results suggested that the formation of cobalt oxyphosphate nanoparticles on the working electrode interface and in the presence of phosphate buffer is the initial stage of the catalytic pathway. Computational results confirmed that the ligand oxidation pathway could occur at potentials below the OER thermodynamic barrier (1.23 V vs reversible hydrogen electrode (RHE)), which leads to a Co ion leaching into the electrolyte. This study showed that investigation of the apparent molecular mechanisms of OER with metal complexes requires careful analyses. We illustrate the high precision and sensitivity of EC-LTEM under operational conditions to monitor heterogeneous catalysts generated during OER and to evaluate their actual roles in the catalytic process.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acsami.1c06241,

title = {High Working Capacity Acetylene Storage at Ambient Temperature Enabled by a Switching Adsorbent Layered Material},

author = {Shi-Qiang Wang and Xiao-Qing Meng and Matthias Vandichel and Shaza Darwish and Ze Chang and Xian-He Bu and Michael J Zaworotko},

url = {https://doi.org/10.1021/acsami.1c06241},

doi = {10.1021/acsami.1c06241},

year  = {2021},

date = {2021-05-13},

journal = {ACS Applied Materials & Interfaces},

volume = {13},

number = {20},

pages = {23877-23883},

abstract = {Unlike most gases, acetylene storage is a challenge because of its inherent pressure sensitivity. Herein, a square lattice (sql) coordination network [Cu(4,4′-bipyridine)2(BF4)2]n (sql-1-Cu-BF4) is investigated with respect to its C2H2 sorption behavior from 189 to 298 K. The C2H2 sorption studies revealed that sql-1-Cu-BF4 exhibits multistep isotherms that are temperature-dependent and consistent with the transformation from “closed” (nonporous) to four “open” (porous) phases induced by the C2H2 uptake. The Clausius–Clapeyron equation was used to calculate the performance of sql-1-Cu-BF4 for C2H2 storage at pressures >1 bar, which revealed that its volumetric working capacity at 288 K is slightly superior to acetone (174 vs 170 cm3 cm–3) over a safer pressure range (1–3.5 vs 1–15 bar). Molecular simulations provided insights into the observed switching phenomena, revealing that the layer expansion of sql-1-Cu-BF4 occurs via intercalation and inclusion of C2H2. These results indicate that switching adsorbent layered materials offer promise for utility in the context of C2H2 storage and delivery.},

note = {PMID: 33983706},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acs.inorgchem.0c03746b,

title = {Oxygen-Evolution Reaction by a Palladium Foil in the Presence of Iron},

author = {Nader Akbari and Ivan Kondov and Matthias Vandichel and Pavlo Aleshkevych and Mohammad Mahdi Najafpour},

url = {https://doi.org/10.1021/acs.inorgchem.0c03746},

doi = {10.1021/acs.inorgchem.0c03746},

year  = {2021},

date = {2021-04-07},

journal = {Inorganic Chemistry},

volume = {60},

number = {8},

pages = {5682–5693},

abstract = {Herein, we investigate the oxygen-evolution reaction (OER) and electrochemistry of a Pd foil in the presence of iron under alkaline conditions (pH ≈ 13). As a source of iron, K2FeO4 is employed, which is soluble under alkaline conditions in contrast to many other Fe salts. Immediately after reacting with the Pd foil, [FeO4]2– causes a significant increase in OER and changes in the electrochemistry of Pd. In the absence of this Fe source and under OER, Pd(IV) is stable, and hole accumulation occurs, while in the presence of Fe this accumulation of stored charges can be used for OER. A Density Functional Theory (DFT) based thermodynamic model suggests an oxygen bridge vacancy as an active site on the surface of PdO2 and an OER overpotential of 0.42 V. A substitution of Pd with Fe at this active site reduces the calculated OER overpotential to 0.35 V. The 70 mV decrease in overpotential is in good agreement with the experimentally measured decrease of 60 mV in the onset potential. In the presence of small amounts of Fe salt, our results point toward the Fe doping of PdO2 rather than extra framework FeOx (Fe(OH)3, FeO(OH), and KFeO2) species on top of PdO2 as the active OER sites.},

note = {PMID: 33826338},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Zhou2021,

title = {Synthesis of Colloidal WSe2 Nanocrystals: Polymorphism Control by Precursor-Ligand Chemistry},

author = {Pengshang Zhou, Pieter Schiettecatte, Matthias Vandichel, Anastasia Rousaki, Peter Vandenabeele, Zeger Hens, and Shalini Singh},

doi = {https://doi.org/10.1021/acs.cgd.0c01036},

year  = {2021},

date = {2021-01-29},

journal = {Crystal Growth & Design},

volume = {21},

number = {3},

pages = {1451-1460},

abstract = {Syntheses of transition-metal dichalcogenides (TMDs) using colloidal-chemistry approaches are gaining significant interest in recent years, as these methods enable the morphology and properties of the nanocrystals to be tuned for targeted applications. In this work, by only varying the ligand used during synthesis, we synthesized nanoflowers with oleic acid (OA) and 1T′ phase dominated WSe2 nanosheets with oleylamine (OLA). WSe2 nanocrystals show slower rate of formation for the metastable 1T′ phase. Surface chemistry analyses of the synthesized nanocrystals by solution NMR establish that neither of the ligands bind strongly to the surface of nanocrystals but are in a dynamic coordination with the WSe2 surface. A further examination of the coordination of tungsten hexacarbonyl (W(CO)6) with the respective ligands confirms that W(CO)6 decomposes in OA, losing its octahedral symmetry, which leads to fast reactivity in the flask. In contrast to this, W(CO)6 reacts with OLA to form a new complex, which leads to slower reactivity and crystallization of the synthesized nanocrystals in the octahedral 1T′ phase. These insights into the influence of precursor-ligand chemistry on reaction outcome and the peculiar surface chemistry of colloidal TMD nanocrystals will be instrumental in developing future colloidal TMD nanocrystals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000553709000001,

title = {Oxygen Evolution and Reduction on Fe-doped NiOOH: Influence of Solvent,  Dopant Position and Reaction Mechanism},

author = {Matthias Vandichel and Kari Laasonen and Ivan Kondov},

url = {https://doi.org/10.1007/s11244-020-01334-8},

doi = {10.1007/s11244-020-01334-8},

issn = {1022-5528},

year  = {2020},

date = {2020-07-29},

journal = {TOPICS IN CATALYSIS},

abstract = {The oxygen evolution reaction (OER) is the limiting factor in an 

 electrolyzer and the oxygen reduction reaction (ORR) the limiting factor 

 in a fuel cell. In OER, water is converted to O(2)and H+/e(-)pairs, 

 while in ORR the reverse process happens to form water. Both reactions 

 and their efficiency are important enablers of a hydrogen economy where 

 hydrogen will act as a fuel or energy storage medium. OER and ORR can 

 both be described assuming a four-step electrochemical mechanism with coupled H+/e(-)transfers between four intermediates (M-*},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000557552100001,

title = {Water Oxidation at Neutral pH using a Highly Active Copper-Based  Electrocatalyst},

author = {Hussein A Younus and Yan Zhang and Matthias Vandichel and Nazir Ahmad and Kari Laasonen and Francis Verpoort and Ce Zhang and Shiguo Zhang},

doi = {10.1002/cssc.202001444},

issn = {1864-5631},

year  = {2020},

date = {2020-07-15},

journal = {CHEMSUSCHEM},

abstract = {The sluggish kinetics of the oxygen evolution reaction (OER) at the 

 anode severely limit hydrogen production at the cathode in water 

 splitting systems. Although electrocatalytic systems based on cheap and 

 earth-abundant copper catalysts have shown promise for water oxidation 

 under basic conditions, only very few examples with high overpotential 

 can be operated under acidic or neutral conditions, even though hydrogen 

 evolution in the latter case is much easier. This work presents an 

 efficient and robust Cu-based molecular catalyst, which self-assembles 

 as a periodic film from its precursors under aqueous conditions on the 

 surface of a glassy carbon electrode. This film catalyzes the OER under 

 neutral conditions with impressively low overpotential. In controlled 

 potential electrolysis, a stable catalytic current of 1.0 mA cm(-2)can 

 be achieved at only 2.0 V (vs. RHE) and no significant decrease in the 

 catalytic current is observed even after prolonged bulk electrolysis. 

 The catalyst displays first-order kinetics and a single site mechanism 

 for water oxidation with a TOF (k(cat)) of 0.6 s(-1). DFT calculations 

 on of the periodic Cu(TCA)(2)(HTCA=1-mesityl-1H-1,2,3-triazole-4-carboxylic acid) film 

 reveal that TCA defects within the film create Cu(I)active sites that 

 provide a low overpotential route for OER, which involves Cu-I, Cu-II-OH},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000547455300015,

title = {Understanding Solid-Gas Reaction Mechanisms by Operando Soft X-Ray 

 Absorption Spectroscopy at Ambient Pressure},

author = {Luca Braglia and Martina Fracchia and Paolo Ghigna and Alessandro Minguzzi and Daniela Meroni and Raju Edla and Matthias Vandichel and Elisabet Ahlberg and Giuseppina Cerrato and Piero Torelli},

doi = {10.1021/acs.jpcc.0c02546},

issn = {1932-7447},

year  = {2020},

date = {2020-07-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY C},

volume = {124},

number = {26},

pages = {14202-14212},

abstract = {Ambient-pressure operando soft X-ray absorption spectroscopy (soft-XAS) 

 was applied to study the reactivity of hydroxylated SnO(2 )nanoparticles 

 toward reducing gases. H-2 was first used as a test case, showing that 

 the gas phase and surface states can be simultaneously probed: Soft-XAS 

 at the O K-edge gains sensitivity toward the gas phase, while at the Sn 

 M-4,M-5-edges, tin surface states are explicitly probed. Results 

 obtained by flowing hydrocarbons (CH4 and CH3CHCH2) unequivocally show 

 that these gases react with surface hydroxyl groups to produce water 

 without producing carbon oxides and release electrons that localize on 

 Sn to eventually form SnO. The partially reduced SnO2-x layer at the 

 surface of SnO2 is readily reoxidized to SnO2 by treating the sample 

 with O-2 at mild temperatures (>200 degrees C), revealing the nature of 

 ``electron sponge'' of tin oxide. The experiments, combined with DFT 

 calculations, allowed devising of a mechanism for dissociative 

 hydrocarbon adsorption on SnO2, involving direct reduction of Sn sites 

 at the surface via cleavage of C-H bonds and the formation of methoxy- 

 and/or methyl-tin species at the surface.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000526300600012,

title = {Reversible Switching between Nonporous and Porous Phases of a New SIFSIX 

 Coordination Network Induced by a Flexible Linker Ligand},

author = {Bai-Qiao Song and Qing-Yuan Yang and Shi-Qiang Wang and Matthias Vandichel and Amrit Kumar and Clare Crowley and Naveen Kumar and Cheng-Hua Deng and Victoria GasconPerez and Matteo Lusi and Hui Wu and Wei Zhou and Michael J Zaworotko},

doi = {10.1021/jacs.0c01314},

issn = {0002-7863},

year  = {2020},

date = {2020-04-01},

journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY},

volume = {142},

number = {15},

pages = {6896-6901},

abstract = {Closed-to-open structural transformations in flexible coordination 

 networks are of potential utility in gas storage and separation. Herein, 

 we report the first example of a flexible SiF62--pillared square grid material, [Cu(SiF6)(L)(2)](n) (L = 1,4-bis(1-imidazolyl)benzene), 

 SIFSIX-23-Cu. SIFSIX-23-Cu exhibits reversible switching between 

 nonporous (beta 1) and several porous (alpha, gamma 1, gamma 2, and 

 gamma 3) phases triggered by exposure to N-2, CO2, or H2O. In addition, 

 heating beta 1 to 433 K resulted in irreversible transformation to a 

 closed polymorph, beta 2. Single-crystal X-ray diffraction studies 

 revealed that the phase transformations are enabled by rotation and 

 geometrical contortion of L. Density functional theory calculations 

 indicated that L exhibits a low barrier to rotation (as low as 8 

 kJmol(-1)) and a rather flat energy surface. In situ neutron powder 

 diffraction studies provided further insight into these sorbate-induced 

 phase changes. SIFSIX-23-Cu combines stability in water for over a year, 

 high CO2 uptake (ca. 216 cm(3)/g at 195 K), and good thermal stability.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000505822700001,

title = {Oxygen Evolution on Metal-oxy-hydroxides: Beneficial Role of Mixing Fe,  Co, Ni Explained via Bifunctional Edge/acceptor Route},

author = {Matthias Vandichel and Michael Busch and Kari Laasonen},

doi = {10.1002/cctc.201901951},

issn = {1867-3880},

year  = {2020},

date = {2020-03-01},

journal = {CHEMCATCHEM},

volume = {12},

number = {5},

pages = {1436-1442},

abstract = {Oxygen evolution reaction (OER) via mixed metal oxy hydroxides 

 [M(O)(OH)] may take place on a large variety of possible active sites 

 on the actual catalyst. A single site computational description assumes 

 a 4-step electrochemical mechanism with coupled H+/e(-) transfers between 4 intermediates (M-*, M-OH},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{YOUNUS2020100437,

title = {Engineering of a highly stable metal-organic Co-film for efficient electrocatalytic water oxidation in acidic media},

author = {H A Younus and M Vandichel and N Ahmad and E Ahlberg and M Busch and F Verpoort},

url = {http://www.sciencedirect.com/science/article/pii/S2468606920300563},

doi = {10.1016/j.mtener.2020.100437},

issn = {2468-6069},

year  = {2020},

date = {2020-01-01},

journal = {Materials Today Energy},

volume = {17},

pages = {100437},

abstract = {Water oxidation is traditionally performed over IrO2 and RuO2 owing to their high stability at low pH compared to molecular O2 evolution catalysts. The low stability of molecular complexes in acids limits their industrial exploitation as anodes in water-splitting devices, where high current densities and proton conductivity are required. Herein, an existing Co(1,10-phenanthroline)2 complex film is engineered to improve its pH-stability via extra OH substituents on the ligand, i.e. 1,10-phenanthroline-4,7-diol. This novel Co(1,10-phenanthroline-4,7-diol)2 complex film is active for water oxidation at low overpotentials and stable at low pH. Since the calculated water oxidation overpotentials of both complexes are similar, the difference in water oxidation activity is attributed to a smaller charge transfer resistance, which originates from a different anchoring style to the electrode via the OH groups of the ligand. This result is supported by electrochemical impedance measurements. The high pH-stability of the Co(1,10-phenanthroline-4,7-diol)2 film is computationally rationalized by a high crystal formation energy observed in DFT calculations. In summary, an acid-stable and active cobalt-based metal-organic film is reported that competes well with most reported earth-abundant catalysts for water oxidation under similar conditions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/cctc.202001284,

title = {Microwave-heated γ-Alumina Applied to the Reduction of Aldehydes to Alcohols},

author = {Bhausaheb Dhokale and Arturo Susarrey-Arce and Anna Pekkari and August Runemark and Kasper Moth-Poulsen and Christoph Langhammer and Hanna Härelind and Michael Busch and Matthias Vandichel and Henrik Sundén},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/cctc.202001284},

doi = {https://doi.org/10.1002/cctc.202001284},

year  = {2020},

date = {2020-01-01},

journal = {ChemCatChem},

volume = {12},

number = {24},

pages = {6344-6355},

abstract = {Abstract The development of cheap and robust heterogeneous catalysts for the Meerwein-Ponndorf-Verley (MPV) reduction is desirable due to the difficulties in product isolation and catalyst recovery associated with the traditional use of homogeneous catalysts for MPV. Herein, we show that microwave heated γ-Al2O3 can be used for the reduction of aldehydes to alcohols. The reaction is efficient and has a broad substrates scope (19 entries). The products can be isolated by simple filtration, and the catalyst can be regenerated. With the use of microwave heating, we can direct the heating to the catalyst rather than to the whole reaction medium. Furthermore, DFT was used to study the reaction mechanism, and we can conclude that a dual-site mechanism is operative where the aldehyde and 2-propoxide are situated on two adjacent Al sites during the reduction. Additionally, volcano plots were used to rationalize the reactivity of Al2O3 in comparison to other metal oxides.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/smm2.1008,

title = {A square lattice topology coordination network that exhibits highly selective C2H2/CO2 separation performance},

author = {Naveen Kumar and Soumya Mukherjee and Andrey A Bezrukov and Matthias Vandichel and Mohana Shivanna and Debobroto Sensharma and Alankriti Bajpai and Victoria Gascón and Ken-ichi Otake and Susumu Kitagawa and Michael J Zaworotko},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smm2.1008},

doi = {https://doi.org/10.1002/smm2.1008},

year  = {2020},

date = {2020-01-01},

journal = {SmartMat},

volume = {1},

number = {1},

pages = {e1008},

abstract = {Abstract C2H2/CO2 separation is an industrially important process that remains challenging because of the similar physicochemical properties of C2H2 and CO2. We herein report that the new square lattice (sql) coordination network [Cu(bipy-xylene)2(NO3)2]n, sql-16-Cu-NO3, 16 = bipy-xylene = 4,4′-(2,5-dimethyl-1,4-phenylene)dipyridine, exists in at least three forms, as-synthesised (α), activated (α′) and hydrated (β). The activated phase, sql-16-Cu-NO3-α′, is an ultramicroporous material that exhibits high selectivity towards C2H2 over CO2 as revealed by dynamic gas breakthrough experiments (1:1, C2H2/CO2) that afforded 99.87% pure CO2 in the effluent stream. The separation selectivity at 298 K and 1 bar, 78, is the third best value yet reported for C2H2 selective physisorbents whereas the mid-loading performance sets a new benchmark. The performance of sql-16-Cu-NO3-α′ is attributed to a new type of C2H2 binding site in which CH···ONO2 interactions enable moderately strong sorbent-sorbate binding (Qst (C2H2) = 38.6 kJ/mol) at low loading. Conversely, weak CO2 binding (Qst (CO2) = 25.6 kJ/mol) at low loading means that (ΔQst)AC [Qst (C2H2)–Qst (CO2)] is 13 kJ/mol at low coverage and 11.4 kJ/mol at mid-loading. Analysis of in situ powder X-ray diffraction and modelling experiments provide insight into the sorption properties and high C2H2/CO2 separation performance of sql-16-Cu-NO3-α′.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000498288300001,

title = {Viewpoint: Atomic-Scale Design Protocols toward Energy, Electronic, 

 Catalysis, and Sensing Applications},

author = {Florian Belviso and Victor E P Claerbout and Aleix Comas-Vives and Naresh S Dalal and Feng-Ren Fan and Alessio Filippetti and Vincenzo Fiorentini and Lucas Foppa and Cesare Franchini and Benjamin Geisler and Luca M Ghiringhelli and Axel Gross and Shunbo Hu and Jorge Iniguez and Steven Kaai Kauwe and Janice L Musfeldt and Paolo Nicolini and Rossitza Pentcheva and Tomas Polcar and Wei Ren and Fabio Ricci and Francesco Ricci and Huseyin Sener Sen and Jonathan Michael Skelton and Taylor D Sparks and Alessandro Stroppa and Andrea Urru and Matthias Vandichel and Paolo Vavassori and Hua Wu and Ke Yang and Hong Jian Zhao and Danilo Puggioni and Remedios Cortese and Antonio Cammarata},

doi = {10.1021/acs.inorgchem.9b01785},

issn = {0020-1669},

year  = {2019},

date = {2019-11-01},

journal = {INORGANIC CHEMISTRY},

volume = {58},

number = {22},

pages = {14939-14980},

abstract = {Nanostructured materials are essential building blocks for the 

 fabrication of new devices for energy harvesting/storage, sensing, 

 catalysis, magnetic, and optoelectronic applications. However, because 

 of the increase of technological needs, it is essential to identify new 

 functional materials and improve the properties of existing ones. The 

 objective of this Viewpoint is to examine the state of the art of 

 atomic-scale simulative and experimental protocols aimed to the design 

 of novel functional nanostructured materials, and to present new 

 perspectives in the relative fields. This is the result of the debates 

 of Symposium I ``Atomic-scale design protocols towards energy, 

 electronic, catalysis, and sensing applications'', which took place 

 within the 2018 European Materials Research Society fall meeting.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000474796600046,

title = {Initial Fe3O4(100) Formation on Fe(100)},

author = {Markus Soldemo and Matthias Vandichel and Henrik Gronbeck and Jonas Weissenrieder},

doi = {10.1021/acs.jpcc.9b04625},

issn = {1932-7447},

year  = {2019},

date = {2019-07-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY C},

volume = {123},

number = {26},

pages = {16317-16325},

abstract = {The initial oxidation of Fe(100) at 400 degrees C has been studied by 

 X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy 

 (STM), and low-energy electron diffraction, in combination with density 

 functional theory calculations. The first observed well-ordered surface 

 oxide is formed at a coverage of similar to 3 oxygen atoms per 

 unreconstructed surface Fe(100) atom. STM shows that this surface oxide 

 is terminated by straight atomic rows exhibiting a p(2 X 1) periodicity. 

 However, already for oxide films with a coverage of similar to 4 oxygen 

 atoms (corresponding to one Fe3O4 unit cell thickness), wiggly atomic 

 rows appear similar to the c(2 X 2) reconstructed Fe3O4 (100)-surface 

 with the Fe3O4 unit vectors rotated 45 degrees to Fe(100). The wiggly 

 rows are a consequence of subsurface cation iron vacancies, which 

 previously have been observed for bulk surfaces. The formation of 

 subsurface vacancies is supported by the XPS O is signature, which is 

 modeled by considering the core-level shifts for all oxygen atoms in the 

 film. Throughout the oxidation series, the microscopy results reveal a 

 layer-by-layer (Frank-van der Merwe) growth.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000459731200013,

title = {A dimer path for CO dissociation on PtSn},

author = {Matthias Vandichel and Henrik Gronbeck},

doi = {10.1039/c8cy01989d},

issn = {2044-4753},

year  = {2019},

date = {2019-02-01},

journal = {CATALYSIS SCIENCE & TECHNOLOGY},

volume = {9},

number = {3},

pages = {695-701},

abstract = {Density functional theory calculations are used to investigate CO 

 adsorption, dissociation and SnOX formation on Pt3Sn. We find that 

 direct CO dissociation is prevented by high activation energies. An 

 energetically feasible path is instead CO dimer formation followed by 

 C-O bond cleavage. Dimers are formed in the presence of Sn adatoms which 

 effectively stabilize anionic OCCO- species. The presence of Sn adatoms 

 is crucial as dimers are unstable on Pt-only systems. The proposed 

 mechanism may explain recent experimental observations of SnOX and C-C 

 formation as PtxSn is exposed to CO.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000445805100009,

title = {CO Oxidation at SnO2/Pt3Sn(111) Interfaces},

author = {Matthias Vandichel and Henrik Gronbeck},

doi = {10.1007/s11244-018-1044-9},

issn = {1022-5528},

year  = {2018},

date = {2018-09-01},

journal = {TOPICS IN CATALYSIS},

volume = {61},

number = {14, SI},

pages = {1458-1464},

abstract = {Segregation induced formation of oxide/metal interfaces can 

 significantly influence the catalytic activity of alloy nanoparticles. 

 One example is Pt3Sn nanoparticles, which are known to segregate into 

 SnOX and an Sn deficient alloy phase during typical operating conditions 

 for CO oxidation. Here, we use density functional theory calculations to 

 investigate CO oxidation over Pt3Sn(111) supported SnO2 and (SnO2)(3), 

 representing the initial state of segregation. The results are compared 

 to CO oxidation at an interface between bulk-like SnO2 and Pt3Sn(111). 

 The barrier for CO oxidation via a Mars-van Krevelen mechanism is found 

 to be lower on SnO2 and (SnO2)(3) as compared to the bulk-like model. 

 However, the regeneration of the finite systems is associated with 

 higher barriers for O-2 dissociation which may become the rate limiting 

 step in the low temperature regime where the metal surface can be 

 assumed to be CO covered.},

note = {13th European Congress on Catalysis - A Bridge to the Future, Florence, 

 ITALY, AUG 27-31, 2017},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000442064100014,

title = {Favourable band edge alignment and increased visible light absorption in 

 beta-MoO3/alpha-MoO3 oxide heterojunction for enhanced 

 photoelectrochemical performance},

author = {Nisha Kodan and Aadesh P Singh and Matthias Vandichel and Bjorn Wickman and B R Mehta},

doi = {10.1016/j.ijhydene.2018.06.138},

issn = {0360-3199},

year  = {2018},

date = {2018-08-01},

journal = {INTERNATIONAL JOURNAL OF HYDROGEN ENERGY},

volume = {43},

number = {33},

pages = {15773-15783},

abstract = {Optimum band gap values, favourable band edge positions and stability in 

 the electrolyte are critical parameters required for a semiconductor to 

 have efficient photoelectrode properties. The present investigation 

 carried out on the phase pure alpha & beta MoO3 thin film shows that 

 the low bandgap beta-MoO3 possesses a mis-alignment with the water 

 oxidation potential, while a more suitable band alignment is observed 

 for the comparatively large bandgap alpha-MoO3. Both experimental and 

 DFT calculations show that the valence edge of the orthorhombic 

 (alpha-MoO3) phase is located at a higher energy (0.9 eV higher in 

 VB-XPS and 1 eV higher in the DOS plots) than the monoclinic (beta-MoO3) 

 phase, while the conduction edge value is roughly at the same energy 

 level (-2.5 eV) in both polymorphs. Based on the above investigations, 

 an all oxide heterojunction comprising of beta-MoO3/alpha-MoO3 is found 

 to be suitable for improved PEC performance due to favourable energy 

 band diagram and increased visible light absorption in beta-MoO3. 

 Significantly higher cathodic photocurrent is observed for the 

 beta-MoO3/alpha-MoO3 (1.6 mA/cm(2) at applied bias of -0.3V(RHE) under 

 simulated 1 sun irradiation) as compared to the very low anodic response 

 in beta-MoO3 (similar to 1.0 nA/cm(2)) and alpha-MoO3 (32 mu A/cm(2)). 

 (C) 2018 Published by Elsevier Ltd on behalf of Hydrogen Energy 

 Publications LLC.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000414724700006,

title = {Catalysis at the Rim: A Mechanism for Low Temperature CO Oxidation over 

 Pt3Sn},

author = {Matthias Vandichel and Alina Moscu and Henrik Gronbeck},

doi = {10.1021/acscatal.7b02094},

issn = {2155-5435},

year  = {2017},

date = {2017-11-01},

journal = {ACS CATALYSIS},

volume = {7},

number = {11},

pages = {7431-7441},

abstract = {Metal alloying is commonly used as a design strategy for catalyst 

 optimization. The mechanistic understanding of this class of systems is, 

 however, obscured by reaction induced segregation phenomena. Herein, the 

 case of CO oxidation over Pt3Sn is investigated using density functional 

 theory calculations combined with ab initio thermodynamics and 

 first-principles based microkinetic modeling. It is found that Pt3Sn 

 segregates under typical operating conditions into SnOx and an Sn 

 deficient metal phase. The segregation is driven both by the stability 

 of the metal oxide and the strong bonding of CO to Pt. The catalytic 

 consequences of a metal supported SnO2 phase are explored by comparing 

 CO oxidation at an SnOx/Pt interface with oxidation over Pt and Pt/Pt3Sn 

 skin models. The reaction is found to proceed with lower barriers at the 

 interface as compared to the metal-only systems and the cocatalytic role 

 of the SnOx rim is manifested by low temperature activity. The present 

 work highlights the effects of reaction-induced metaloxide/metal 

 interfaces and elucidates the role of Sn in PtSn alloys for CO oxidation 

 reactions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000398182300008,

title = {A Robust Molecular Catalyst Generated In Situ for Photoand 

 Electrochemical Water Oxidation},

author = {Hussein A Younus and Nazir Ahmad and Adeel H Chughtai and Matthias Vandichel and Michael Busch and Kristof Van Hecke and Mekhman Yusubov and Shaoxian Song and Francis Verpoort},

doi = {10.1002/cssc.201601477},

issn = {1864-5631},

year  = {2017},

date = {2017-03-01},

journal = {CHEMSUSCHEM},

volume = {10},

number = {5},

pages = {862-875},

abstract = {Water splitting is the key step towards artificial photosystems for 

 solar energy conversion and storage in the form of chemical bonding. The 

 oxidation of water is the bottle-neck of this process that hampers its 

 practical utility; hence, efficient, robust, and easy to make catalytic 

 systems based on cheap and earth-abundant materials are of exceptional 

 importance. Herein, an in situ generated cobalt catalyst, 

 [Co-II(TCA)(2)(H2O)(2)] (TCA=1-mesityl-1,2,3-1H-triazole-4-carboxylate), that efficiently 

 conducts photochemical water oxidation under near-neutral conditions is 

 presented. The catalyst showed high stability under photolytic 

 conditions for more than 3 h of photoirradiation. During electrochemical 

 water oxidation, the catalytic system assembled a catalyst film, which 

 proved not to be cobalt oxide/hydroxide as normally expected, but 

 instead, and for the first time, generated a molecular cobalt complex 

 that incorporated the organic ligand bound to cobalt ions. The catalyst 

 film exhibited a low overpotential for electrocatalytic water oxidation 

 (360 mV) and high oxygen evolution peak current densities of 9 and 2.7 

 mA cm(-2) on glassy carbon and indium-doped tin oxide electrodes, 

 respectively, at only 1.49 and 1.39 V ( versus a normal hydrogen 

 electrode), respectively, under neutral conditions. This finding, 

 exemplified on the in situ generated cobalt complex, might be applicable 

 to other molecular systems and suggests that the formation of a 

 catalytic film in electrochemical water oxidation experiments is not 

 always an indication of catalyst decomposition and the formation of 

 nanoparticles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000394359600017,

title = {Inserting CO2 into Terminal Alkynes via Bis-(NHC)-Metal Complexes},

author = {Heriberto Diaz Velazquez and Zhao-Xuan Wu and Matthias Vandichel and Francis Verpoort},

doi = {10.1007/s10562-016-1920-5},

issn = {1011-372X},

year  = {2017},

date = {2017-02-01},

journal = {CATALYSIS LETTERS},

volume = {147},

number = {2},

pages = {463-471},

abstract = {The direct interaction between CO2 and terminal alkynes in the presence 

 of bis-(NHC)-metal catalysts at ambient conditions was studied. Two Cu 

 and Ag-based bis-N-heterocyclic carbene Transition Metal catalysts were 

 synthesized. The (NHC)(2)-Ag complex showed a better catalytic 

 performance towards the carboxylation of terminal alkynes in comparison 

 with the copper analogue even for the conversion of acetylene gas. The 

 optimized conditions for the carboxylation are: the use of Cs2CO3 as 

 additive, one atmosphere CO2 and room temperature using 1% mol 

 catalyst. Mechanistic insight into the reaction mechanism is obtained by 

 means of state-of-the-art first principles calculations. 

 [GRAPHICS] 

 .},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000378949800022,

title = {Biocompatible Zr-based nanoscale MOFs coated with modified poly 

 (epsilon-caprolactone) as anticancer drug carriers},

author = {Maria Filippousi and Stuart Turner and Karen Leus and Panoraia I Siafaka and Eirini D Tseligka and Matthias Vandichel and Stavroula G Nanaki and Ioannis S Vizirianakis and Dimitrios N Bikiaris and Pascal Van der Voort and Gustaaf Van Tendeloo},

doi = {10.1016/j.ijpharm.2016.05.048},

issn = {0378-5173},

year  = {2016},

date = {2016-07-01},

journal = {INTERNATIONAL JOURNAL OF PHARMACEUTICS},

volume = {509},

number = {1-2},

pages = {208-218},

abstract = {Nanoscale Zr-based metal organic frameworks (MOFs) UiO-66 and UiO-67 

 were studied as potential anticancer drug delivery vehicles. Two model 

 drugs were used, hydrophobic paclitaxel and hydrophilic cisplatin, and 

 were adsorbed onto/into the nano MOFs (NMOFs). The drug loaded MOFs were 

 further encapsulated inside a modified poly(epsilon-caprolactone) with 

 D-alpha-tocopheryl polyethylene glycol succinate polymeric matrix, in 

 the form of microparticles, in order to prepare sustained release 

 formulations and to reduce the drug toxicity. The drugs physical state 

 and release rate was studied at 37 degrees C using Simulated Body Fluid. 

 It was found that the drug release depends on the interaction between 

 the MOFs and the drugs while the controlled release rates can be 

 attributed to the microencapsulated formulations. The in vitro antitumor 

 activity was assessed using HSC-3 (human oral squamous carcinoma; head 

 and neck) and U-87 MG (human glioblastoma grade IV; astrocytoma) cancer 

 cells. Cytotoxicity studies for both cell lines showed that the polymer 

 coated, drug loaded MOFs exhibited better anticancer activity compared 

 to free paclitaxel and cisplatin solutions at different concentrations. 

 (C) 2016 Elsevier B.V. All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000384465500012,

title = {Water coordination and dehydration processes in defective UiO-66 type 

 metal organic frameworks},

author = {M Vandichel and J Hajek and A Ghysels and A De Vos and M Waroquier and V Van Speybroeck},

doi = {10.1039/c6ce01027j},

issn = {1466-8033},

year  = {2016},

date = {2016-01-01},

journal = {CRYSTENGCOMM},

volume = {18},

number = {37},

pages = {7056-7069},

abstract = {The UiO-66 metal organic framework is one of the most thermally and 

 chemically stable hybrid materials reported to date. However, it is also 

 accepted that the material contains structurally embedded defects, which 

 may be engineered to enhance properties towards specific applications 

 such as catalysis, sensing, etc. The synthesis conditions determine to a 

 large extent the level of perfection of the material and additionally 

 the catalytic activity may be enhanced by post-synthesis activation at 

 high temperature under vacuum, in which defect coordinating species 

 (H2O, HCl, monocarboxylic modulators, etc.) evaporate. The molecular 

 level characterization of defects is extremely challenging from both 

 theoretical and experimental points of view. Such experimental endeavor 

 was recently proposed via experimental SXRD measurements, also 

 unraveling the coordination of water on the Zr-O-Zr defect sites 

 [Angew. Chem., Int. Ed., 2015, 54, 11162-11167]. The present work 

 provides a theoretical understanding of defect structures in UiO-66(Zr) 

 by means of periodic density functional theory calculations and ab 

 initio molecular dynamics simulations. A range of defect structures are 

 generated with different numbers of missing linkers. For each of the 

 defects, the free energetic and mechanical stability is discussed and 

 the coordination of water and charge balancing hydroxide ions is 

 studied. For catalysis applications, the material is mostly pretreated 

 to remove water by dehydration reactions. For each of the proposed 

 defect structures, mechanistic pathways for dehydration reactions of the 

 Zr-bricks are determined employing nudged elastic band (NEB) 

 calculations. During the dehydroxylation trajectory, loose hydroxyl 

 groups and terephthalate decoordinations are observed. Furthermore, 

 dehydration reactions are lower activated if terephthalate linkers are 

 missing in the immediate environment of the inorganic brick. The 

 creation of defects and the dehydration processes have a large impact on 

 the mechanical properties of the material, which is evidenced by lower 

 bulk moduli and elastic constants for structures with more defects.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000371710500004,

title = {Origin of highly active metal-organic framework catalysts: defects? 

 Defects!},

author = {J Canivet and M Vandichel and D Farrusseng},

doi = {10.1039/c5dt03522h},

issn = {1477-9226},

year  = {2016},

date = {2016-01-01},

journal = {DALTON TRANSACTIONS},

volume = {45},

number = {10},

pages = {4090-4099},

abstract = {This article provides a comprehensive review of the nature of catalytic 

 sites in MOFs. In the last decade, a number of striking studies have 

 reported outstanding catalytic activities of MOFs. In all cases, the 

 authors were intrigued as it was unexpected from the ideal structure. We 

 demonstrate here that (surface) defects are at the origin of the 

 catalytic activities for the reported examples. The vacancy of ligands 

 or linkers systematically generates (surface) terminations which can 

 possibly show Lewis and/or Bronsted acido-basic features. The 

 engineering of catalytic sites at the nodes by the creation of defects 

 (on purpose) appears today as a rational approach for the design of 

 active MOFs. Similarly to zeolite post-treatments, post-modifications of 

 MOFs by linker or metal cation exchange appear to be methods of choice. 

 Despite the mild acidity of defective MOFs, we can account for very 

 active MOFs in a number of catalytic applications which show higher 

 performances than zeolites or benchmark catalysts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000364250800001,

title = {Mechanistic studies of aldol condensations in UiO-66 and UiO-66-NH2 

 metal organic frameworks},

author = {Julianna Hajek and Matthias Vandichel and Ben Van de Voorde and Bart Bueken and Dirk De Vos and Michel Waroquier and Veronique Van Speybroeck},

doi = {10.1016/j.jcat.2015.08.015},

issn = {0021-9517},

year  = {2015},

date = {2015-11-01},

journal = {JOURNAL OF CATALYSIS},

volume = {331},

pages = {1-12},

abstract = {A full mechanistic investigation is proposed for the industrially 

 important cross-aldol condensation reaction of heptanal with 

 benzaldehyde on the UiO-66 and the amino-functionalized UiO-66-NH2 

 metal-organic frameworks to form jasminaldehyde. Several experimental 

 studies indicate that the activity for the aldol condensation reaction 

 can be increased by proper functionalization of the material, e.g. by 

 introducing an additional basic amino site and thus creating a 

 bifunctional acid-base catalyst for the aldol condensation. The precise 

 molecular level origin for this behavior is to date unclear. Herein 

 state-of-the-art Density-Functional Theory (DFT) calculations have been 

 performed to unravel the mechanism of the cross- and self-aldol 

 condensations of benzaldehyde and propanal. To this end free energy 

 calculations have been performed on both extended cluster and periodic 

 models. It is found that the mechanism on both catalysts is essentially 

 the same, although a slightly stronger adsorption of the reactants and 

 slightly lower barriers were found on the amino functionalized material, 

 pointing toward higher initial activities. New experiments were 

 performed to confirm these observations. It is indeed found that the 

 initial activity toward cross-aldol condensation on the amino 

 functionalized material is higher, although after about 40 min of 

 reaction both materials become equally active. Our results furthermore 

 point out that the basic amino groups may promote side reactions such as 

 imine formation, which is induced by water. The study as presented can 

 assist to engineer materials at the molecular level toward the desired 

 products. (C) 2015 Elsevier Inc. All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000346173200024,

title = {Active site engineering in UiO-66 type metal-organic frameworks by 

 intentional creation of defects: a theoretical rationalization},

author = {Matthias Vandichel and Julianna Hajek and Frederik Vermoortele and Michel Waroquier and Dirk E De Vos and Veronique Van Speybroeck},

doi = {10.1039/c4ce01672f},

issn = {1466-8033},

year  = {2015},

date = {2015-01-01},

journal = {CRYSTENGCOMM},

volume = {17},

number = {2},

pages = {395-406},

abstract = {The catalytic activity of the Zr-benzenedicarboxylate (Zr-BDC) UiO-66 

 can be drastically increased if some BDC linkers are missing, as this 

 removes the full coordination of the framework metal ions. As a result, 

 metal centers become more accessible and thus more active for Lewis acid 

 catalysed reactions. Addition of modulators (MDL) to the synthesis 

 mixture can create more linker deficiencies (Vermoortele et al., J. Am. 

 Chem. Soc., 2013, 135, 11465) and leads to a significant increase in the 

 catalytic activity due to the creation of a larger number of open sites. 

 In this paper, we rationalize the function of the modulators under real 

 synthesis conditions by the construction of free energy diagrams. The 

 UiO-66 type materials form a very appropriate test case as the effect of 

 addition of modulators hydrochloric acid (HCl) and trifluoroacetate 

 (TFA) has been intensively investigated experimentally for the synthesis 

 process and post-synthetic thermal activation. Under synthesis 

 conditions, direct removal of BDC linkers requires a high free energy, 

 but replacement of such linker by one or more TFA species might occur 

 especially at high TFA : BDC ratios in the reaction mixture. 

 Post-synthesis activation procedures at higher temperatures lead to 

 substantial removal of the species coordinated to the Zr bricks, 

 creating open metal sites. A mechanistic pathway is presented for the 

 dehydroxylation process of the hexanuclear Zr cluster. For the 

 citronellal cyclization, we show that the presence of some residual TFA 

 in the structure may lead to faster reactions in complete agreement with 

 the experiment. Hirshfeld-e partial charges for the Zr ions have been 

 computed to investigate their sensitivity to substituent effects; a 

 strong correlation with the experimental Hammett parameters and with the 

 rates of the citronellal cyclization is found. The theoretical 

 rationalization may serve as a basis for detailed active site 

 engineering studies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000350643700005,

title = {Au@UiO-66: a base free oxidation catalyst},

author = {K Leus and P Concepcion and M Vandichel and M Meledina and A Grirrane and D Esquivel and S Turner and D Poelman and M Waroquier and V Van Speybroeck and G Van Tendeloo and H Garcia and P Van Der Voort},

doi = {10.1039/c4ra16800c},

issn = {2046-2069},

year  = {2015},

date = {2015-01-01},

journal = {RSC ADVANCES},

volume = {5},

number = {29},

pages = {22334-22342},

abstract = {We present the in situ synthesis of Au nanoparticles within the Zr based Metal Organic Framework, UiO-66. The resulting Au@UiO-66 materials were 

 characterized by means of N-2 sorption, XRPD, UV-Vis, XRF, XPS and TEM 

 analysis. The Au nanoparticles (NP) are homogeneously distributed along 

 the UiO-66 host matrix when using NaBH4 or H-2 as reducing agents. The Au@UiO-66 materials were evaluated as catalysts in the oxidation of benzyl alcohol and benzyl amine employing O-2 as oxidant. The Au@MOF 

 materials exhibit a very high selectivity towards the ketone (up to 

 100%). Regenerability and stability tests demonstrate that the Au@UiO-66 catalyst can be recycled with a negligible loss of Au species 

 and no loss of crystallinity. In situ IR measurements of UiO-66 and Au@UiO-66-NaBH4, before and after treatment with alcohol, showed an 

 increase in IR bands that can be assigned to a combination of 

 physisorbed and chemisorbed alcohol species. This was confirmed by 

 velocity power spectra obtained from the molecular dynamics simulations. 

 Active peroxo and oxo species on Au could be visualized with Raman 

 analysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000351556800034,

title = {Au@UiO-66: a base free oxidation catalyst (vol 5, pg 22334, 2015)},

author = {K Leus and P Concepcion and M Vandichel and M Meledina and A Grirrane and D Esquivel and S Turner and D Poelman and M Waroquier and V Van Speybroeck and G Van Tendeloo and H Garcia and P Van der Voort},

doi = {10.1039/c5ra90022k},

issn = {2046-2069},

year  = {2015},

date = {2015-01-01},

journal = {RSC ADVANCES},

volume = {5},

number = {34},

pages = {26726},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000340508000016,

title = {Catalytic Performance of Vanadium MIL-47 and Linker-Substituted Variants 

 in the Oxidation of Cyclohexene: A Combined Theoretical and Experimental 

 Approach},

author = {Matthias Vandichel and Shyam Biswas and Karen Leus and Joachim Paier and Joachim Sauer and Toon Verstraelen and Pascal Van der Voort and Michel Waroquier and Veronique Van Speybroeck},

doi = {10.1002/cplu.201402007},

issn = {2192-6506},

year  = {2014},

date = {2014-08-01},

journal = {CHEMPLUSCHEM},

volume = {79},

number = {8},

pages = {1183-1197},

abstract = {The epoxidation of cyclohexene has been investigated on a metal-organic 

 framework MIL-47 containing saturated V+IV sites linked with functionalized terephthalate linkers (MIL-47-X},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000341473000001,

title = {Metal-dioxidoterephthalate MOFs of the MOF-74 type: Microporous basic 

 catalysts with well-defined active sites},

author = {Pieterjan Valvekens and Matthias Vandichel and Michel Waroquier and Veronique Van Speybroeck and Dirk De Vos},

doi = {10.1016/j.jcat.2014.06.006},

issn = {0021-9517},

year  = {2014},

date = {2014-08-01},

journal = {JOURNAL OF CATALYSIS},

volume = {317},

pages = {1-10},

abstract = {The hybrid frameworks M(2)dobdc (dobdc(4-) = 2,5-dioxidoterephthalate, M2+ = Mg2+, Co2+, Ni2+, Cu2+ and Zn2+), commonly known as CPO-27 or 

 MOF-74, are shown to be active catalysts in base-catalyzed reactions 

 such as Knoevenagel condensations or Michael additions. Rather than 

 utilizing N-functionalized linkers as a source of basicity, the 

 intrinsic basicity of these materials arises from the presence of the 

 phenolate oxygen atoms coordinated to the metal ions. The overall 

 activity is due to a complex interplay of the basic properties of these 

 structural phenolates and the reactant binding characteristics of the 

 coordinatively unsaturated sites. The nature of the active site and the 

 order of activity between the different M(2)dobdc materials were 

 rationalized via computational efforts; the most active material, both 

 in theory and in experiment, is the Ni-containing variant. The basicity 

 of Ni(2)dobdc was experimentally proven by chemisorption of pyrrole and 

 observation by IR spectroscopy. (C) 2014 Elsevier Inc. All rights 

 reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000343004300050,

title = {Base catalytic activity of alkaline earth MOFs: a (micro)spectroscopic 

 study of active site formation by the controlled transformation of 

 structural anions},

author = {P Valvekens and D Jonckheere and T De Baerdemaeker and A V Kubarev and M Vandichel and K Hemelsoet and M Waroquier and V Van Speybroeck and E Smolders and D Depla and M B J Roeffaers and D De Vos},

doi = {10.1039/c4sc01731e},

issn = {2041-6520},

year  = {2014},

date = {2014-01-01},

journal = {CHEMICAL SCIENCE},

volume = {5},

number = {11},

pages = {4517-4524},

abstract = {A new method has been developed for generating highly dispersed base 

 sites on metal-organic framework (MOF) lattices. The base catalytic activity of two alkaline earth MOFs, M-2(BTC)(NO3)(DMF) (M = Ba or Sr},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000342908200006,

title = {First principle chemical kinetics in zeolites: the methanol-to-olefin 

 process as a case study},

author = {Veronique Van Speybroeck and Kristof De Wispelaere and Jeroen Van der Mynsbrugge and Matthias Vandichel and Karen Hemelsoet and Michel Waroquier},

doi = {10.1039/c4cs00146j},

issn = {0306-0012},

year  = {2014},

date = {2014-01-01},

journal = {CHEMICAL SOCIETY REVIEWS},

volume = {43},

number = {21},

pages = {7326-7357},

abstract = {To optimally design next generation catalysts a thorough understanding 

 of the chemical phenomena at the molecular scale is a prerequisite. 

 Apart from qualitative knowledge on the reaction mechanism, it is also 

 essential to be able to predict accurate rate constants. Molecular 

 modeling has become a ubiquitous tool within the field of heterogeneous 

 catalysis. Herein, we review current computational procedures to 

 determine chemical kinetics from first principles, thus by using no 

 experimental input and by modeling the catalyst and reacting species at 

 the molecular level. Therefore, we use the methanol-to- olefin (MTO) 

 process as a case study to illustrate the various theoretical concepts. 

 This process is a showcase example where rational design of the catalyst 

 was for a long time performed on the basis of trial and error, due to 

 insufficient knowledge of the mechanism. For theoreticians the MTO 

 process is particularly challenging as the catalyst has an inherent 

 supramolecular nature, for which not only the Bronsted acidic site is 

 important but also organic species, trapped in the zeolite pores, must 

 be essentially present during active catalyst operation. All these 

 aspects give rise to specific challenges for theoretical modeling. It is 

 shown that present computational techniques have matured to a level 

 where accurate enthalpy barriers and rate constants can be predicted for 

 reactions occurring at a single active site. The comparison with 

 experimental data such as apparent kinetic data for well-defined 

 elementary reactions has become feasible as current computational 

 techniques also allow predicting adsorption enthalpies with reasonable 

 accuracy. Real catalysts are truly heterogeneous in a space-and 

 time-like manner. Future theory developments should focus on extending 

 our view towards phenomena occurring at longer length and time scales 

 and integrating information from various scales towards a unified 

 understanding of the catalyst. Within this respect molecular dynamics 

 methods complemented with additional techniques to simulate rare events 

 are now gradually making their entrance within zeolite catalysis. Recent 

 applications have already given a flavor of the benefit of such 

 techniques to simulate chemical reactions in complex molecular 

 environments.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000334832200006,

title = {Vanadium metal-organic frameworks: structures and applications},

author = {Pascal Van der Voort and Karen Leus and Ying-Ya Liu and Matthias Vandichel and Veronique Van Speybroeck and Michel Waroquier and Shyam Biswas},

doi = {10.1039/c3nj01130e},

issn = {1144-0546},

year  = {2014},

date = {2014-01-01},

journal = {NEW JOURNAL OF CHEMISTRY},

volume = {38},

number = {5},

pages = {1853-1867},

abstract = {This perspective review paper describes the V-containing metal-organic 

 frameworks that have been developed since the first systematic reports 

 on MOFs almost 15 years ago. These hybrid crystalline materials, 

 containing V(III) or V(IV) as metal nodes, show interesting behavior in 

 oxidation catalysis and gas sorption. A significant amount of papers has 

 appeared on the use of these structures in gas (hydrocarbon, CO2) 

 separation. Promising future research and development of V-MOFs is 

 suggested.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000344989700010,

title = {Water-soluble NHC-Cu catalysts: applications in click chemistry, 

 bioconjugation and mechanistic analysis},

author = {Heriberto Diaz Velazquez and Yara Ruiz Garcia and Matthias Vandichel and Annemieke Madder and Francis Verpoort},

doi = {10.1039/c4ob01350f},

issn = {1477-0520},

year  = {2014},

date = {2014-01-01},

journal = {ORGANIC & BIOMOLECULAR CHEMISTRY},

volume = {12},

number = {46},

pages = {9350-9356},

abstract = {Copper(I)-catalyzed 1,3-dipolar cycloaddition of azides and terminal 

 alkynes (CuAAC), better known as ``click'' reaction, has triggered the 

 use of 1,2,3-triazoles in bioconjugation, drug discovery, materials 

 science and combinatorial chemistry. Here we report a new series of 

 water-soluble catalysts based on N-heterocyclic carbene (NHC)-Cu 

 complexes which are additionally functionalized with a sulfonate group. 

 The complexes show superior activity towards CuAAC reactions and display 

 a high versatility, enabling the production of triazoles with different 

 substitution patterns. Additionally, successful application of these 

 complexes in bioconjugation using unprotected peptides acting as DNA 

 binding domains was achieved for the first time. Mechanistic insight 

 into the reaction mechanism is obtained by means of state-of-the-art 

 first principles calculations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000326845400037,

title = {New Functionalized Metal-Organic Frameworks MIL-47-X (X = -Cl, -Br, 

 -CH3, -CF3, -OH, -OCH3): Synthesis, Characterization, and CO2 Adsorption 

 Properties},

author = {Shyam Biswas and Danny E P Vanpoucke and Toon Verstraelen and Matthias Vandichel and Sarah Couck and Karen Leus and Ying-Ya Liu and Michel Waroquier and Veronique Van Speybroeck and Joeri F M Denayer and Pascal Van der Voort},

doi = {10.1021/jp406835n},

issn = {1932-7447},

year  = {2013},

date = {2013-11-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY C},

volume = {117},

number = {44},

pages = {22784-22796},

abstract = {Six new functionalized vanadium hydroxo terephthalates [V-III(OH)(BDC-X)]center dot n(guests) (MIL-47(V-III)-X-AS) (BDC = 1,4-benzenedicarboxylate; X = -Cl, -Br, -CH3, -CF3, -OH, -OCH3; AS = 

 as-synthesized) along with the parent MIL-47 were synthesized under 

 rapid microwave-assisted hydrothermal conditions (170 degrees C, 30 min, 

 150 W). The unreacted H2BDC-X and/or occluded solvent molecules can be 

 removed by thermal activation under vacuum, leading to the empty-pore 

 forms of the title compounds (MIL-47(V-IV)-X). Except pristine MIL-47 

 (+III oxidation state), the vanadium atoms in all the evacuated 

 functionalized solids stayed in the +IV oxidation state. The phase 

 purity of the compounds was ascertained by X-ray powder diffraction 

 (XRPD), diffuse reflectance infrared Fourier transform (DRIFT) 

 spectroscopy, Raman, thermogravimetric (TG), and elemental analysis. The 

 structural similarity of the filled and empty-pore forms of the 

 functionalized compounds with the respective forms of parent MIL-47 was 

 verified by cell parameter determination from XRPD data. TGA and 

 temperature-dependent XRPD (TDXRPD) experiments in an air atmosphere 

 indicate high thermal stability in the 330-385 degrees C range. All the 

 thermally activated compounds exhibit significant microporosity (S-BET 

 in the 305-897 m(2) g(-1) range), as verified by the N-2 and CO2 

 sorption analysis. Among the six functionalized compounds, 

 MIL-47(V-IV)-OCH3 shows the highest CO2 uptake, demonstrating the 

 determining role of functional groups on the CO2 sorption behavior. For 

 this compound and pristine MIL-47(V-IV), Widom particle insertion 

 simulations were performed based on ab initio calculated crystal 

 structures. The theoretical Henry coefficients show a good agreement 

 with the experimental values, and calculated isosurfaces for the local 

 excess chemical potential indicate the enhanced CO2 affinity is due to 

 two effects: (i) the interaction between the methoxy group and CO2 and 

 (ii) the collapse of the MIL-47(V-IV)-OCH3 framework.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000322501000013,

title = {Insight in the activity and diastereoselectivity of various Lewis acid 

 catalysts for the citronellal cyclization},

author = {Matthias Vandichel and Frederik Vermoortele and Stijn Cottenie and Dirk E De Vos and Michel Waroquier and Veronique Van Speybroeck},

doi = {10.1016/j.jcat.2013.04.017},

issn = {0021-9517},

year  = {2013},

date = {2013-09-01},

journal = {JOURNAL OF CATALYSIS},

volume = {305},

pages = {118-129},

abstract = {Industrial (-)-menthol production generally relies on the hydrogenation 

 of (-)-isopulegol, which is in turn produced with high selectivity by 

 cyclization of (+)-citronellal. This paper uses a combined theoretical 

 and experimental approach to study the activity and selectivity of three 

 Lewis acid catalysts for this reaction, namely ZnBr2, aluminum 

 tris(2,6-diphenylphenoxide) (ATPH), and the heterogeneous metal-organic framework Cu3BTC2 (BTC = benzene-1,3,5-tricarboxylate). ATPH is a strong 

 Lewis acid homogeneous catalyst with bulky ligands which provides very 

 high selectivities for the desired stereoisomer (>99%). The performance 

 of the catalysts was evaluated as a function of temperature, which 

 revealed that a higher catalyst activity allows working at lower 

 temperatures and improves the selectivity for isopulegol. The 

 selectivity distribution is kinetically driven for ZnBr2 and ATPH. The 

 theoretical selectivity distributions rely on the determination of an 

 extensive set of diastereomeric transition states, for which the 

 differences in free energy have been calculated using a complementary 

 set of ab initio techniques. Given the sensitivity of the selectivity to 

 small Gibbs free-energy differences, the agreement between experimental 

 and theoretical selectivities is satisfactory. On basis of the obtained 

 insights, rational design of new catalysts may be obtained. As proof of 

 concept, the hypothetical Cu-3(BTC-(NO2)(3))(2) Lewis catalyst - in 

 which each phenyl hydrogen of the BTC ligand is replaced by a nitro 

 group - is predicted to be very selective. (C) 2013 Elsevier Inc. All 

 rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000323019400014,

title = {Synthesis Modulation as a Tool To Increase the Catalytic Activity of 

 Metal-Organic Frameworks: The Unique Case of UiO-66(Zr)},

author = {Frederik Vermoortele and Bart Bueken and Gaelle Le Bars and Ben Van de Voorde and Matthias Vandichel and Kristof Houthoofd and Alexandre Vimont and Marco Daturi and Michel Waroquier and Veronique Van Speybroeck and Christine Kirschhock and Dirk E De Vos},

doi = {10.1021/ja405078u},

issn = {0002-7863},

year  = {2013},

date = {2013-08-01},

journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY},

volume = {135},

number = {31},

pages = {11465-11468},

abstract = {The catalytic activity of the zirconium terephthalate UiO-66(Zr) can be 

 drastically increased by using a modulation approach. The combined use 

 of trifluoroacetic acid and HCl during the synthesis results in a highly 

 crystalline material, with partial substitution of terephthalates by 

 trifluoroacetate. Thermal activation of the material leads not only to 

 dehydroxylation of the hexanuclear Zr cluster but also to post-synthetic 

 removal of the trifluoroacetate groups, resulting in a more open 

 framework with a large number of open sites. Consequently, the material 

 is a highly active catalyst for several Lewis acid catalyzed reactions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000320214800011,

title = {On the Thermodynamics of Framework Breathing: A Free Energy Model for 

 Gas Adsorption in MIL-53},

author = {An Ghysels and Louis Vanduyfhuys and Matthias Vandichel and Michel Waroquier and Veronique Van Speybroeck and Berend Smit},

doi = {10.1021/jp311601q},

issn = {1932-7447},

year  = {2013},

date = {2013-06-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY C},

volume = {117},

number = {22},

pages = {11540-11554},

abstract = {When adsorbing guest molecules, the porous metal-organic framework 

 MIL-53(Cr) may vary its cell parameters drastically while retaining its 

 crystallinity. A first approach to the thermodynamic analysis of this 

 ``framework breathing'' consists of comparing the osmotic potential in 

 two distinct shapes only (large-pore and narrow-pore). In this paper, we 

 propose a generic parametrized free energy model including three 

 contributions: host free energy, guest-guest interactions, and 

 host-guest interaction. Free energy landscapes may now be constructed 

 scanning all shapes and any adsorbed amount of guest molecules. This 

 allows us to determine which shapes are the most stable states for 

 arbitrary combinations of experimental control parameters, such as the 

 adsorbing gas chemical potential, the external pressure, and the 

 temperature. The new model correctly reproduces the structural 

 transitions along the CO2 and CH4 isotherms. Moreover, our model 

 successfully explains the adsorption versus desorption hysteresis as a 

 consequence of the creation, stabilization, destabilization, and 

 disappearance of a second free energy minimum under the assumptions of a 

 first-order phase transition and collective behavior. Our general 

 thermodynamic description allows us to decouple the gas chemical 

 potential mu and mechanical pressure P as two independent thermodynamic 

 variables and predict the complete (mu, P) phase diagram for CO2 

 adsorption in MIL-53(Cr). The free energy model proposed here is an 

 important step toward a general thermodynamics description of flexible 

 metal-organic frameworks.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000313220500016,

title = {New V-IV-Based Metal-Organic Framework Having Framework Flexibility and 

 High CO2 Adsorption Capacity},

author = {Ying-Ya Liu and Sarah Couck and Matthias Vandichel and Maciej Grzywa and Karen Leus and Shyam Biswas and Dirk Vollmer and Jorge Gascon and Freek Kapteijn and Joeri F M Denayer and Michel Waroquier and Veronique Van Speybroeck and Pascal Van der Voort},

doi = {10.1021/ic301338a},

issn = {0020-1669},

year  = {2013},

date = {2013-01-01},

journal = {INORGANIC CHEMISTRY},

volume = {52},

number = {1},

pages = {113-120},

abstract = {A vanadium based metal organic framework (MOF), VO(BPDC) (BPDC2- = 

 biphenyl-4,4'-dicarboxylate), adopting an expanded MIL-47 structure 

 type, has been synthesized via solvothermal and microwave methods. Its 

 structural and gas/vapor sorption properties have been studied. This 

 compound displays a distinct breathing effect toward certain adsorptives 

 at workable temperatures. The sorption isotherms of CO2 and CH4 indicate 

 a different sorption behavior at specific temperatures. In situ 

 synchrotron X-ray powder diffraction measurements and molecular 

 simulations have been utilized to characterize the structural 

 transition. The experimental measurements clearly suggest the existence 

 of both narrow pore and large pore forms. A free energy profile along 

 the pore angle was computationally determined for the empty host 

 framework. Apart from a regular large pore and a regular narrow pore 

 form, an overstretched narrow pore form has also been found. 

 Additionally, a variety of spectroscopic techniques combined with N-2 

 adsorption/desorption isotherms measured at 77 K demonstrate that the 

 existence of the mixed oxidation states V-III/V-IV in the titled MOF 

 structure compared to pure V-IV increases the difficulty in triggering 

 the flexibility of the framework.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000309314500001,

title = {Mechanistic insight into the cyclohexene epoxidation with VO(acac)(2) 

 and tert-butyl hydroperoxide},

author = {Matthias Vandichel and Karen Leus and Pascal Van der Voort and Michel Waroquier and Veronique Van Speybroeck},

doi = {10.1016/j.jcat.2012.06.002},

issn = {0021-9517},

year  = {2012},

date = {2012-10-01},

journal = {JOURNAL OF CATALYSIS},

volume = {294},

pages = {1-18},

abstract = {The epoxidation reaction of cyclohexene is investigated for the 

 catalytic system vanadyl acetylacetonate (VO(acac)(2)) with tert-butyl 

 hydroperoxide (TBHP) as oxidant with the aim to identify the most active 

 species for epoxidation and to retrieve insight into the most plausible 

 epoxidation mechanism. The reaction mixture is composed of various 

 inactive and active complexes in which vanadium may either have 

 oxidation state +IV or +V. Inactive species are activated with TBHP to 

 form active complexes. After reaction with cyclohexene, each active 

 species transforms back into an inactive complex that may be reactivated 

 again. The reaction mixture is quite complex containing hydroxyl, acetyl 

 acetonate, acetate, or a tert-butoxide anion as ligands, and thus, 

 various ligand exchange reactions may occur among active and inactive 

 complexes. Also, radical decomposition reactions allow transforming V+IV 

 to V+V species. To obtain insight into the most abundant active 

 complexes, each of previous transformation steps has been modeled 

 through thermodynamic equilibrium steps. To unravel the nature of the 

 most plausible epoxidation mechanism, first principle chemical kinetics 

 calculations have been performed on all proposed epoxidation pathways. 

 Our results allow to conclude that the concerted Sharpless mechanism is 

 the preferred reaction mechanism and that alkylperoxo species 

 V+IVO(L)(OOtBu) and V+VO(L-1)(L-2)(OOtBu) species are most abundant. At 

 the onset of the catalytic cycle, vanadium +IV species may play an 

 active role, but as the reaction proceeds, reaction mechanisms that 

 involve vanadium +V species are preferred as the acetyl acetonate is 

 readily oxidized. Additionally, an experimental IR and kinetic study has 

 been performed to give a qualitative composition of the reaction mixture 

 and to obtain experimental kinetic data for comparison with our 

 theoretical values. The agreement between theory and experiment is 

 satisfactory. (C) 2012 Elsevier Inc. All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000308830700026,

title = {Ab Initio Parametrized Force Field for the Flexible Metal-Organic 

 Framework MIL-53(Al)},

author = {L Vanduyfhuys and T Verstraelen and M Vandichel and M Waroquier and V Van Speybroeck},

doi = {10.1021/ct300172m},

issn = {1549-9618},

year  = {2012},

date = {2012-09-01},

journal = {JOURNAL OF CHEMICAL THEORY AND COMPUTATION},

volume = {8},

number = {9},

pages = {3217-3231},

abstract = {A force field is proposed for the flexible metal-organic framework 

 MIL-53(Al), which is calibrated using density functional theory 

 calculations on nonperiodic clusters. The force field has three main 

 contributions: an electrostatic term based on atomic charges derived 

 with a modified Hirshfeld-I method, a van der Waals (vdW) term with 

 parameters taken from the MM3 model, and a valence force field whose 

 parameters were estimated with a new methodology that uses the gradients 

 and Hessian matrix elements retrieved from nonperiodic cluster 

 calculations. The new force field predicts geometries and cell 

 parameters that compare well with the experimental values both for the 

 large and narrow pore phases. The energy profile along the breathing 

 mode of the empty material reveals the existence of two minima, which 

 confirms the intrinsic bistable behavior of the MIL-53. Even without the 

 stimulus of external guest molecules, the material may transform from 

 the large pore (lp) to the narrow pore (np) phase [Liu et al. J. Am. 

 Chem. Soc. 2008, 120, 11813]. The relative stability of the two phases 

 critically depends on the vdW parameters, and the MM3 dispersion 

 interaction has the tendency to overstabilize the np phase.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000307274300002,

title = {Host-guest and guest-guest interactions between xylene isomers confined 

 in the MIL-47(V) pore system},

author = {An Ghysels and Matthias Vandichel and Toon Verstraelen and Monique A van der Veen and Dirk E De Vos and Michel Waroquier and Veronique Van Speybroeck},

doi = {10.1007/s00214-012-1234-7},

issn = {1432-881X},

year  = {2012},

date = {2012-07-01},

journal = {THEORETICAL CHEMISTRY ACCOUNTS},

volume = {131},

number = {7},

abstract = {The porous MIL-47 material shows a selective adsorption behavior for 

 para-, ortho-, and meta-isomers of xylenes, making the material a 

 serious candidate for separation applications. The origin of the 

 selectivity lies in the differences in interactions (energetic) and 

 confining (entropic). This paper investigates the xylene-framework 

 interactions and the xylene-xylene interactions with quantum mechanical 

 calculations, using a dispersion-corrected density functional and 

 periodic boundary conditions to describe the crystal. First, the 

 strength and geometrical characteristics of the optimal xylene-xylene 

 interactions are quantified by studying the pure and mixed pairs in gas 

 phase. An extended set of initial structures is created and optimized to 

 sample as many relative orientations and distances as possible. Next, 

 the pairs are brought in the pores of MIL-47. The interaction with the 

 terephthalic linkers and other xylenes increases the stacking energy in 

 gas phase (-31.7 kJ/mol per pair) by roughly a factor four in the fully 

 loaded state (-58.3 kJ/mol per xylene). Our decomposition of the 

 adsorption energy shows various trends in the contributing xylene-xylene 

 interactions. The absence of a significant difference in energetics 

 between the isomers indicates that entropic effects must be mainly 

 responsible for the separation behavior.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000301315700028,

title = {Efficient Approach for the Computational Study of Alcohol and Nitrile 

 Adsorption in H-ZSM-5},

author = {Jeroen Van der Mynsbrugge and Karen Hemelsoet and Matthias Vandichel and Michel Waroquier and Veronique Van Speybroeck},

doi = {10.1021/jp2123828},

issn = {1932-7447},

year  = {2012},

date = {2012-03-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY C},

volume = {116},

number = {9},

pages = {5499-5508},

abstract = {Since many industrially important processes start with the adsorption of 

 guest molecules inside the pores of an acidic zeolite catalyst, a proper 

 estimate of the adsorption enthalpy is of paramount importance. In this 

 contribution, we report ab initio calculations on the adsorption of 

 water, alcohols, and nitriles at the bridging Bronsted sites of H-ZSM-5, 

 using both cluster and periodic models to account for the zeolite 

 environment. Stabilization of the adsorption complexes results from 

 hydrogen bonding between the guest molecule and the framework, as well 

 as from embedding, i.e., van der Waals interactions with the pore walls. 

 Large-cluster calculations with different DFT methods, in particular 

 B3LYP(-D), PBE(-D), M062X(-D), and omega B97X-D, are tested for their 

 ability to reproduce the experimental heats of adsorption available in 

 the literature (J. Phys. Chem. B 1997, 101, 3811-3817). A proper account 

 of dispersion interactions is found to be crucial to describe the 

 experimental trend across a series of adsorbates of increasing size, 

 i.e., an increase in adsorption enthalpy by 10-15 kJ/mol for each 

 additional carbon atom. The extended-cluster model is shown to offer an 

 attractive alternative to periodic simulations on the entire H-ZSM-5 

 unit cell, resulting in virtually identical final adsorption enthalpies. 

 Comparing calculated stretch frequencies of the zeolite acid sites and 

 the adsorbate functional groups with experimental IR data additionally 

 confirms that the cluster approach provides an appropriate 

 representation of the adsorption complexes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000303925200019,

title = {Electronic Effects of Linker Substitution on Lewis Acid Catalysis with 

 Metal-Organic Frameworks},

author = {Frederik Vermoortele and Matthias Vandichel and Ben Van de Voorde and Rob Ameloot and Michel Waroquier and Veronique Van Speybroeck and Dirk E De Vos},

doi = {10.1002/anie.201108565},

issn = {1433-7851},

year  = {2012},

date = {2012-01-01},

journal = {ANGEWANDTE CHEMIE-INTERNATIONAL EDITION},

volume = {51},

number = {20},

pages = {4887-4890},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000300074300022,

title = {The coordinatively saturated vanadium MIL-47 as a low leaching 

 heterogeneous catalyst in the oxidation of cyclohexene},

author = {Karen Leus and Matthias Vandichel and Ying-Ya Liu and Ilke Muylaert and Jan Musschoot and Steven Pyl and Henk Vrielinck and Freddy Callens and Guy B Marin and Christophe Detavernier and Paul V Wiper and Yaroslav Z Khimyak and Michel Waroquier and Veronique Van Speybroeck and Pascal Van der Voort},

doi = {10.1016/j.jcat.2011.09.014},

issn = {0021-9517},

year  = {2012},

date = {2012-01-01},

journal = {JOURNAL OF CATALYSIS},

volume = {285},

number = {1},

pages = {196-207},

abstract = {A Metal Organic Framework, containing coordinatively saturated sites 

 linked together by terephthalic linkers (V-MIL-47), is evaluated as a 

 catalyst in the epoxidation of cyclohexene. Different solvents and 

 conditions are tested and compared. If the oxidant TBHP is dissolved in 

 water, a significant leaching of V-species into the solution is 

 observed, and also radical pathways are prominently operative leading to 

 the formation of an adduct between the peroxide and cyclohexene. If, 

 however, the oxidant is dissolved in decane, leaching is negligible and 

 the structural integrity of the V-MIL-47 is maintained during successive 

 runs. The selectivity toward the epoxide is very high in these 

 circumstances. Extensive computational modeling is performed to show 

 that several reaction cycles are possible. EPR and NMR measurements 

 confirm that at least two parallel catalytic cycles are co-existing: one 

 with V+IV sites and one with pre-oxidized V+V sites, and this is in 

 complete agreement with the theoretical predictions. (C) 2011 Elsevier 

 Inc. All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000310153300037,

title = {Synthesis, characterization and sorption properties of NH2-MIL-47},

author = {Karen Leus and Sarah Couck and Matthias Vandichel and Gauthier Vanhaelewyn and Ying-Ya Liu and Guy B Marin and Isabel Van Driessche and Diederik Depla and Michel Waroquier and Veronique Van Speybroeck and Joeri F M Denayer and Pascal Van Der Voort},

doi = {10.1039/c2cp42137b},

issn = {1463-9076},

year  = {2012},

date = {2012-01-01},

journal = {PHYSICAL CHEMISTRY CHEMICAL PHYSICS},

volume = {14},

number = {44},

pages = {15562-15570},

abstract = {An amino functionalized vanadium-containing Metal Organic Framework, 

 NH2-MIL-47, has been synthesized by a hydrothermal reaction in an 

 autoclave. Alternatively, a synthesis route via microwave enhanced 

 irradiation has been optimized to accelerate the synthesis. The 

 NH2-MIL-47 exhibits the same topology as MIL-47, in which the V center 

 is octahedrally coordinated. After an exchange procedure in DMF the 

 V+III center is oxidized to V+IV, which is confirmed by EPR and XPS 

 measurements. The CO2 and CH4 adsorption properties have been evaluated 

 and compared to MIL-47, showing that both MOFs have an almost similar 

 adsorption capacity and affinity for CO2. DFT-based molecular modeling 

 calculations were performed to obtain more insight into the adsorption 

 positions for CO2 in NH2-MIL-47. Furthermore our calculated adsorption 

 enthalpies agree well with the experimental values.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}