@article { ISI:000266061500016, title = {Dependence of Si-29 NMR chemical shielding properties of precursor silicate species, Q(0) on its local structure at the pre-nucleation stages of zeolite synthesis - a DFT based computational correlation}, journal = {Microporous and Mesoporous Materials}, volume = {122}, number = {1-3}, year = {2009}, month = {JUN}, pages = {105-113}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The exploration for new zeolite structures with tailored framework architectures for enhanced catalytic applications requires the knowledge about their nucleation and crystallization at molecular level. Nuclear magnetic resonance (NMR) is one of the most widely tried techniques to understand this. However, by NMR, it is difficult to accurately assign the molecular level precursor silicate structures at the pre-nucleation stages of zeolite synthesis. Hence, understanding the chemical shielding of such precursor molecules using quantum mechanical (QM) computations is extremely useful. Alkali is a fundamental component in the alkali based hydrothermal zeolite synthesis and its nature plays a major role. In the present report, we attempt to understand the differences in the local structure of the primary building block such as Si(OH)(4) (Q(0) silicate species) due to the associated alkali and their influence on NMR chemical shielding properties. Present work reports the calculation of Si-29 NMIR isotropic chemical shifts of T species with different cations such as Na, K and Ca using density functional theory (DFT). Results of natural bonding orbital (NBO) analysis, Perturbation theory energy analysis and electron density iso-surfaces were employed to obtain a deeper insight about their influence on the chemical shielding and on zeolite synthesis. (C) 2009 Elsevier Inc. All rights reserved.

}, keywords = {Ab initio method, Density Functional Theory (DFT), Electron density, NBO analysis, Perturbation theory, Q(0) silicate species, Si-29 NMR chemical shift, synthesis, zeolite}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2009.02.022}, author = {Selvaraj, Kaliaperumal and Kurian, Reshmi} } @article { ISI:000349902200001, title = {Computational investigation on the catalytic activity of Rh-6 and Rh4Ru2 clusters towards methanol activation}, journal = {Theoretical Chemistry Accounts }, volume = {134}, number = {1}, year = {2014}, month = {DEC}, pages = {1597}, publisher = {SPRINGER}, type = {Article}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Catalysis of molecular activation of small molecules through scission of strong chemical bonds is one of the major challenges faced by chemists. More specifically, activation of the strong C-H and O-H bonds of various alcohols, especially methanol, is one of the various important intermediate steps of key organic reactions. Our present work explores a suitable metal cluster catalyst towards methanol dissociation. In particular, we have examined the effect of ruthenium doping (Rh:Ru = 2:1) on the catalytic activity of Rh-6 cluster towards methanol dissociation. Density functional theory-based calculations illustrate two competitive pathways for methanol dissociation, which are via O-H and C-H bond breaking. Both the pathways are found to be energetically favourable in the presence of bimetallic and mono-metallic clusters. Importantly, energy barrier for O-H bond dissociation reduces considerably in doped cluster as compared to pure Rh-6 cluster and is smaller than the values reported for a number of other small metallic clusters.

}, keywords = {Bimetallic Clusters, Density Functional Theory (DFT), Doping, Methanol Activation, Rhodium Clusters}, issn = {1432-881X}, doi = {10.1007/s00214-014-1597-z}, author = {Ghatak, Kamalika and Sengupta, Turbasu and Krishnamurty, Sailaja and Pal, Sourav} } @article { ISI:000356520400003, title = {Computational strategies for understanding the nature of interaction in dioxin imprinted nanoporous trappers}, journal = {Journal of Molecular Recognition}, volume = {28}, number = {7}, year = {2015}, month = {JUL}, pages = {427-437}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

A new computational model capable of understanding the nature of interactions in signature complexes formed between the template(2,3,7,8-tetrachlorodibenzo-p dioxin (TCDD)) and the functional monomers (methacrylic acid (MAA)) using density functional theory (DFT) has been designed. The polymer precursors were optimized for geometries in polymerization media, computing the interaction energies between template molecules and functional monomers of transient pre-polymerized complexes (PPC), and structural and vibrational properties reference to theoretical infrared spectra were computed using DFT of B3LYP/6 311+G(d,p) hybrid functional method. Atom in molecule theory was used to analyze the hydrogen-bonding characteristics of PPC of MAA-TCDD. Considering the theoretical titrations conducted in a virtual solvent box, it was found that the 1:4 molar ratio was required to form the most stable PPC in a given solvent system. The electron density plots indicate strong hydrogen bonding as shown by the 2pz dominant highest occupied molecular orbital (HOMO) character that could be the preferable sites of binding for target molecule, TCDD. Considering HOMO approach, the active adsorption sites in molecularly imprinted polymer was modeled to get insight on molecular recognition property for targeted molecule, TCDD. The proposed computational protocol is simple, accurate, and novel to design the polymer and is useful to predict the properties of polymer systems than the conventional theoretical analysis of template-monomer interactions. Copyright (c) 2015 John Wiley \& Sons, Ltd.

}, keywords = {carcinogenic pollutants, computer simulations, Density Functional Theory (DFT), intermolecular interactions, Molecularly Imprinted Polymers (MIP)}, issn = {0952-3499}, doi = {10.1002/jmr.2459}, author = {Khan, Muntazir S. and Pal, Sourav and Krupadam, Reddithota J.} } @article {48445, title = {Expounding lemonal terpenoids as corrosion inhibitors for copper using DFT based calculations}, journal = {Applied Surface Science}, volume = {614}, year = {2023}, month = {MAR}, pages = {156066}, type = {Article}, abstract = {

The most important bottleneck in identifying an innovative and yet viable corrosion inhibitor for copper surfaces is discerning the chemical interactions at the interface of adsorbate and adsorbent. The present work, primarily, discerns the interface chemistry of green corrosion inhibitors, viz., lemonal terpenoids, with the copper surfaces for the first time. The interface chemistry is evaluated for distinct facets of copper, modelled by periodic surfaces to finite sized aggregates, with two stereoisomers viz., citral and neral through density functional calculations. The adsorption/ interaction properties between the surface and the corrosion inhibiting molecule are analysed through the electronic properties such as density of states, charge density difference plots and Bader charges where in distinct bonding mechanisms are identified as a function of varying facets. Apart from the adsorption properties, molecular packing properties are of paramount importance towards the design of an efficient corrosion inhibitor for a surface. Hence, we also analyse the intermolecular stacking energies between the inhibitors when packed among themselves in vacuum and when adhered on to metal surfaces. The studies bring forth an understanding that lemon terpenoids are highly potential corrosion inhibitors for copper surfaces, particularly, for Cu (110) surfaces both in neutral and protonated form.

}, keywords = {Copper surface, Density Functional Theory (DFT), Green corrosion inhibitors, Interface chemistry, Lemonal terpenoids, Molecular stacking}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2022.156066}, author = {Samal, Pragnya Paramita and Singh, Chandrodai Pratap and Krishnamurty, Sailaja} } @article {49055, title = {Computational identification of most potent atom pair catalysts for electrocatalytic nitrogen reduction reaction over hydrogen evolution reaction}, journal = {Inter.}, volume = {58}, year = {2024}, month = {MAR }, pages = {1345-1358}, type = {Article}, abstract = {

Robust electrocatalytic atom pair compositions (APCs) where Nitrogen Reduction Reaction (NRR) is more enhanced over competing Hydrogen Evolution Reaction (HER) is searched for using computational studies based on Density Functional Theory based methods. Atomic pairs are anchored on mechanically and thermally stable graphene surfaces. A wide range of transition metal based atom pair compositions from 3d, 4d, and 5d groups are systematically investigated for reduction of dinitrogen molecule with lower reduction barrier as compared to HER. APR compositions of Ni-Rh with an overall limiting potential of -0.22 V, Fe-W with an overall limiting potential of -0.26 V and Co-Pt with an overall limiting potential of -0.28 V are identified as the most potent atomic pairs for enhanced nitrogen reduction reaction over the HER. Finally, the performance of most potent composition, viz., Ni-Rh is validated to be consistent with respect to their thermodynamic stability and performance within the solvent effects.

}, keywords = {Atom pair catalysts, Density Functional Theory (DFT), Electrochemical nitrogen reduction reaction (eNRR), hydrogen evolution reaction (HER), IR stretching frequencies, N-N bond length}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.01.203}, author = {Verma, Tushar Singh and Dar, Afshana Hassan and Dar, Manzoor Ahmad and Selvaraj, Kaliaperumal and Krishnamurty, Sailaja} } @article {49352, title = {Size and morphology dependent activity of Cu clusters for CO2 activation and reduction: a first principles investigation}, journal = {ChemPhysChem}, volume = {25}, year = {2024}, month = {DEC}, type = {Article}, abstract = {

Various Cu-based materials in diverse forms have been investigated as efficient catalysts for electrochemical reduction of CO2; however, they suffer from issues such as higher over potential and poor selectivity. The activity and selectivity of CO2 electro reduction have been shown to change significantly when the surface morphology (steps, kinks, and edges) of these catalysts is altered. In light of this, size and morphology dependent activity of selected copper clusters, Cun (n=2-20) have been evaluated for the activation and reduction of CO2 molecule. The phase-space of these copper clusters is rich in conformations of distinct morphologies starting from planar, 2D geometries to prolate-shaped geometries and also high-symmetry structures. The binding efficiency and the activation of CO2 are highest for medium sized clusters (n=9-17) with prolate-morphologies as compared to small or larger sized CunCO(2) clusters that are existing mainly as planar (triangular, tetragonal etc.) or highly-symmetric geometries (icosahedron, capped-icosahedron etc.), respectively. The best performing (prolate-shaped) CunCO2 conformations are quite fluxional and also they are thermally stable, as demonstrated by the molecular dynamics simulations. Furthermore, on these CunCO(2) conformations, the step-by-step hydrogenation pathways of CO2 to produce value-added products like methanol, formic acid, and methane are exceptionally favorable and energy-efficient.

}, keywords = {CO2 activation, CO2 hydrogenation, Copper clusters, Density Functional Theory (DFT), molecular dynamics}, issn = {1439-4235}, doi = {10.1002/cphc.202400442}, author = {Amin, Seerat and Krishnamurty, Sailaja and Dar, Manzoor Ahmad and Joshi, Krati} } @article {49114, title = {Surface electronic properties-driven electrocatalytic nitrogen reduction on metal-conjugated porphyrin 2D-MOFs}, journal = {ACS Applied Materials and Interfaces}, volume = {16}, year = {2024}, month = {FEB }, pages = {8707-8716}, type = {Article}, abstract = {

Two-dimensional (2D) metal organic framework (MOF) or metalloporphyrin nanosheets with a stable metal-N-4 complex unit present the metal as a single-atom catalyst dispersed in the 2D porphyrin framework. First-principles calculations on the 3d-transition metals in M-TCPP are investigated in this study for their surface-dependent electronic properties including work function and d-band center. Crystal orbital Hamiltonian population (-pCOHP) analysis highlights a higher contribution of the bonding state in the M-N bond and antibonding state in the N-N bond to be essential for N-N bond activation. A linear relationship between Delta G(max) and surface electronic properties, N-N bond strength, and Bader charge has been found to influence the rate-determining potential for nitrogen reduction reaction (NRR) in M-TCPP MOFs. 2D Ti-TCPP MOF, with a kinetic energy barrier of 1.43 eV in the final protonation step of enzymatic NRR, shows exclusive NRR selectivity over competing hydrogen reduction (HER) and nitrogenous compounds (NO and NO2). Thus, Ti-TCPP MOF with an NRR limiting potential of -0.35 V in water solvent is proposed as an attractive candidate for electrocatalytic NRR.

}, keywords = {Density Functional Theory (DFT), electrocatalytic nitrogen reductionreaction, kinetic energy barrier, limitingpotential, Metalloporphyrin, NRR selectivity}, issn = {1944-8244}, doi = {10.1021/acsami.3c16406}, author = {Maibam, Ashakiran and Orhan, Ibrahim B. and Krishnamurty, Sailaja and Russo, Salvy P. and BabaRao, Ravichandar} }