@article { ISI:000256765900007, title = {Electric field response of molecular reactivity descriptors: a case study}, journal = {Theoretical Chemistry Accounts}, volume = {120}, number = {4-6}, year = {2008}, month = {JUL}, pages = {375-383}, publisher = {SPRINGER}, type = {Article}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

In the present article, we study the influence of external electric field on the density-based global and local reactivity descriptors using examples of some planar nonlinear polyatomic molecules with C-2V point group symmetry. The study mainly involves the application of weak electric field in a direction along the principal axis and along its perpendicular direction. We also discuss the strength of the electric field studied in this work in terms of the strength of the molecular interaction. The work is expected to throw light on the effect of interactions within the above range on reactivity descriptors. Results are presented for a few prototype molecules.

}, keywords = {electric field, molecular interaction, planar nonlinear polyatomic molecules, Reactivity descriptors}, issn = {1432-881X}, doi = {10.1007/s00214-008-0437-4}, author = {Kar, Rahul and Pal, Sourav} } @article { ISI:000278112200007, title = {Effect of solvents having different dielectric constants on reactivity: a conceptual DFT approach}, journal = {International Journal of Quantum Chemistry}, volume = {110}, number = {9}, year = {2010}, month = {AUG}, pages = {1642-1647}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

Conceptual density functional theory is exploited to understand the reactivity in a medium of solvents with increasing dielectric constants. Aprotic as well as protic solvents are used for this study. It is found that the global parameters, such as chemical potential and hardness, decrease from gas phase to solvent phase with increasing dielectric constant. However, it is observed that the Fukui functions of the reactive atoms increase significantly with the dielectric constants of the aprotic solvents while for the protic solvents the variation of the reactivity indices is insignificant. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 110: 1642-1647, 2010

}, keywords = {COSMO, DFT, dielectric constant, Reactivity descriptors, solvent effect}, issn = {0020-7608}, doi = {10.1002/qua.22333}, author = {Kar, Rahul and Pal, Sourav} } @article { ISI:000281321000006, title = {Probing lewis acidity and reactivity of Sn- and Ti-beta zeolite using industrially important moieties: a periodic density functional study}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {329}, number = {1-2}, year = {2010}, month = {AUG}, pages = {36-43}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The Lewis acidic nature and reactivity of two industrially important catalysts, viz.. Sn and Ti substituted beta zeolite (T-BEA) are analyzed using a unique combination of structural parameters, energetics and reactivity descriptors. To achieve this purpose, we adsorb the industrially important moieties (L) namely NH(3), H(2)O, CH(3)OH, CH(3)CN on the active sites of T-BEA. The calculations were performed using a periodic density functional method where the valence electrons are described using a plane wave basis set in conjunction with pseudo-potentials for the core electrons. The analysis of the structural properties of these complexes reveals that TO(4) shows typical characteristic splitting 120 degrees/90 degrees, close to bipyramidal geometry as compared to tetrahedral symmetry observed in the bare T-BEA. This is associated with small variations in the framework bond lengths (\>= 0.08 angstrom) and a substantially large variation of bond angles (\<= 10 degrees) in all the ligand-zeolite complexes. Further in both cases of Sn and Ti substituted beta zeolite, ligand interacts at optimum inter-atomic bond distance. Our interaction energies show that adsorption of all ligand moieties is stronger at Sn center than that of Ti. In general, the order of stability of the different T-BEA adducts is NH(3) \> H(2)O \> CH(3)OH \> CH(3)CN. The ligand interaction is associated with the corresponding bond elongation and bond reduction of the adsorbed molecules on catalyst active site, which can be taken as measure of red or blue shifted frequencies. Finally, the global descriptors of reactivity justify the fact that soft acid, Sn-BEA, interacts strongly with soft bases following the Pearson{\textquoteright}s HSAB principle. However, hard acid, Ti-BEA interacts with soft bases to form a stable Lewis adduct. Furthermore, the HOMO-LUMO gap of all Sn-BEA-L adducts is lower than that of Ti-BEA-L adducts indicating to its higher Lewis acidic nature compared to Ti-BEA. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {Beta zeolite, Lewis acidity, Ligand-zeolite complex, Periodic-DFT, Reactivity descriptors}, issn = {1381-1169}, doi = {10.1016/j.molcata.2010.06.014}, author = {Kulkarni, Bhakti S. and Krishnamurty, Sailaja and Pal, Sourav} } @article { ISI:000326296800033, title = {Role of substituents on the reactivity and electron density profile of diimine ligands: a density functional theory based study}, journal = {Journal of Chemical Sciences}, volume = {125}, number = {5}, year = {2013}, month = {SEP}, pages = {1247-1258}, publisher = {INDIAN ACAD SCIENCES}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

In this paper, we study the reactivity of diimines like 2, 2({\textquoteright})-bipyridine, 1, l0-phenanthroline and 1, 2, 4-triazines using density-based reactivity descriptors. We discuss the enhancement or diminution in the reactivity of these ligands as a function of two substituent groups, namely methyl (-CH3) group and phenyl (-C6H5) group. The global reactivity descriptors explain the global affinity and philicity of these ligands, whereas the local softness depicts the particular site selectivity. The inter-molecular reactivity trends for the same systems are analysed through the philicity and group philicity indices. The sigma-donor character of these ligands is quantified with the help of electron density profile. In addition, the possible strength of interaction of these ligands with metal ions is supported with actual reaction energies of Ru-L complexes.

}, keywords = {2, 2 {\textquoteleft}-bipyridine, DFT, diimine, Reactivity descriptors, Ru-ligand interaction, substituent effects}, issn = {0974-3626}, doi = {10.1007/s12039-013-0469-8}, author = {Kulkarni, Bhakti S. and Mishra, Deepti and Pal, Sourav} }