@article { ISI:000327467000009, title = {Exploring the effectiveness of different Lewis pair combinations in caged structures for the catalysis of ammonia borane dehydrogenation: a DFT study}, journal = {Physical Chemistry Chemical Physics}, volume = {15}, number = {48}, year = {2013}, month = {OCT}, pages = {20857-20867}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Zero dimensional cage structures containing four phenyl rings separated by imine linkers have recently been synthesized. In the current work, through a computational investigation using density functional theory (DFT), we demonstrate that modifying such cages by replacing the 2, 4, 6 carbon atoms in the phenyl rings to yield new rings, as well as replacing the imine moiety in the linker by other electronegative atoms, can yield interesting new cages that can be reactive in catalysing reactions such as the dehydrogenation of ammonia borane-an important reaction in hydrogen storage research. Specifically, it is predicted that phosphorus-nitrogen pairs (phosphorus in the 2, 4, 6 positions in the ring, nitrogen in the linker position), germanium-nitrogen and germanium-phosphorus pair combinations would lead to effective Lewis pairs that can work in tandem to dehydrogenate ammonia borane efficiently under room temperature conditions.

}, issn = {1463-9076}, doi = {10.1039/c3cp53557f}, author = {Pal, Amrita and Vanka, Kumar} } @article {43886, title = {Exploring the effect of hydroxylic and non-hydroxylic solvents on the reaction of [(VO)-O-IV(beta-diketonate)2] with 2-aminobenzoyl-hydrazide in aerobic and anaerobic conditions}, journal = {Dalton Transactions}, volume = {46}, year = {2017}, month = {SEP}, type = {Article}, abstract = {

Refluxing [(VO)-O-IV(beta-diketonate)(2)], namely [(VO)-O-IV(acetylacetonate)(2)] and [(VO)-O-IV(benzoylacetonate)(2)], separately with an equivalent or excess amount of 2-aminobenzoylhydrazide (ah) in laboratory grade (LG) CH3OH in aerobic conditions afforded non-oxidovanadium(IV) and oxidovanadium(V) complexes of the type [V-IV(L-1)(2)] (1), [(VO)-O-V(L-1)(OCH3)](2) (3) and [V-IV(L-2)(2)] (2), and [(VO)-O-V(L-2)(OCH3)] (4), respectively. (L-1)(2-) and (L-2)(2-) represent the dianionic forms of 2-aminobenzoylhydrazone of acetylacetone (H2L1) and benzoylacetone (H2L2), respectively, (general abbreviation, H2L), which was formed by the in situ condensation of ah with the respective coordinated [beta-diketonate] in medium-to-good yield. The yield of different resulting products was dependent upon the ratio of ah to [(VO)-O-IV(beta-diketonate)(2)]. For example, the yield of 1 and 2 complexes increased significantly associated with a decrease in the amount of 3 and 4 with an increase in the molar ratio of ah. Upon replacing CH3OH by a non-hydroxylic solvent, LG CHCl3, the above reaction yielded only oxidovanadium(V) complexes of the type [(VO)-O-V(L-1)(OH)](2) (5), [(VO)-O-V(L-2)(OH)] (6) and [(V2O3)-O-V(L)(2)] (7, 8) whereas, upon replacing CHCl3 by another non-hydroxylic solvent, namely LG CH3CN, only the respective [(V2O3)-O-V(L)(2)] (7, 8) complex was isolated in 72-78\% yield. However, upon performing the above reactions in the absence of air using dry CH3OH or dry CHCl3, only the respective [V-IV(L)(2)] complex was obtained, suggesting that aerial oxygen was the oxidising agent and the type of pentavalent product formed was dependent upon the nature of solvent used. Complexes 3 and 4 were converted, respectively, to 7 and 8 on refluxing in LG CHCl3 via the respective unstable complex 5 and 6. The DFT calculated change in internal energy (Delta E) for the reactions 2[(VO)-O-V(L-2)(OCH3)] + 2H(2)O -\> 2[(VO)-O-V(L-2)(OH)] + 2CH(3)OH and 2[(VO)-O-V (L-2)(OH)] -\> [(V2O3)-O-V(L-2)(2)] + H2O was, respectively, +3.61 and -7.42 kcal mol(-1), suggesting that the [(VO)-O-V(L-2) (OH)] species was unstable and readily transformed to the stable [(V2O3)-O-V(L-2)(2)] complex. Upon one-electron reduction at an appropriate potential, each of 7 and 8 generated mixed-valence [(L) (VO)-O-V-(mu-O)-OVIV(L)]species, which showed valence-delocalisation at room temperature and localisation at 77 K. Some of the complexes showed a wide range of toxicity in a dose-dependent manner against lung cancer cells comparable with that observed with cis-platin.

}, keywords = {Effective Core Potentials, Lung-cancer cells, Molecular-Orbital Methods, Non-oxido vanadium(iv), Non-Oxo, Oxovanadium(iv) Complexes, Tridentate ono ligand; Ray crystal-structure, Trigonal-prismatic Co-ordination, V-IV complex}, issn = {1477-9226}, doi = {10.1039/c7dt01776f}, author = {Biswas, Nirmalendu and Patra, Debashis and Mondal, Bipul and Bera, Sachinath and Acharyya, Swarnali and Biswas, Anup Kumar and Mukhopadhyay, Titas Kumar and Pal, Amrita and Drew, Michael G. B. and Ghosh, Tapas} }