@article { ISI:000311350000015, title = {First principle investigation on the thermal stability of a golden fullerene: a case study of Au-32}, journal = {Catalysis Today}, volume = {198}, number = {1, SI}, year = {2012}, month = {DEC}, pages = {106-109}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Structural and electronic properties of Au-32 cluster are analyzed using relativistic density functional theory (DFT) based methods. Further, DFT based molecular dynamical (MD) simulations are performed on Au-32 golden fullerene with an aim of understanding its thermal stability at various working temperatures. Various conformations being populated at different temperatures of a cluster are analyzed. The study shows that the ground state icosahedral conformation is stable only up to 300 K and structure remains in a hollow conformation only up to 400 K. This clearly explains the reasons for failure by experimentalists in trapping the unique fullerene conformation in spite of the theoretical predictions of it being a very stable one. The above MD study also indicates that the bare fullerene Au-32 cluster (without any stabilizing ligands) can be used for potential catalytic applications only around room temperatures. (C) 2012 Elsevier B. V. All rights reserved.

}, keywords = {Au-32 cluster, Born-Oppenheimer molecular dynamics, Density functional theory, Golden fullerenes, Relativistic effects}, issn = {0920-5861}, doi = {10.1016/j.cattod.2012.04.072}, author = {De, Himadri Sekhar and Krishnamurty, Sailaja and Pal, Sourav} } @article { ISI:000372756700003, title = {DFT based assay for tailor-made terpyridine ligand-metal complexation properties}, journal = {Molecular Simulations}, volume = {42}, number = {8}, year = {2016}, month = {MAY}, pages = {618-627}, publisher = {TAYLOR \& FRANCIS LTD}, type = {Article}, address = {4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}, abstract = {

Electron-rich terpyridine ligand and its metal complexes have a potential to grow as responsive surfaces by adapting their physicochemical properties as a function of environment. The responsiveness is brought about by judicious molecular level designing that is currently hindered due to lack of information and control on terpyridine (TPy)-metal (M) interactions at single molecule level. So far there is no organised understanding on the binding of different metals with TPy ligand and ways to modulate it. Being a large conjugated [GRAPHICS] system, TPy has a large scope to be functionalised with electron exchanging groups to alter its electronic structure and consequently its binding with metal atoms. In first report of such a kind, using density functional theory (DFT), we demonstrate that convenient modulation of TPy-M binding is possible through functionalisation of TPy for [GRAPHICS] , Ru, Fe, Mo and Au. Electron donating groups viz., CH [GRAPHICS] , OCH [GRAPHICS] , C [GRAPHICS] H [GRAPHICS] , NH [GRAPHICS] and electron withdrawing groups viz., CF [GRAPHICS] , COOH, CN and NO [GRAPHICS] are considered for functionalisation of TPy ligand. Significantly, the present work focuses on the functionalisation at 4 and 4 [GRAPHICS] positions of TPy molecule. The role of such a functionalisation in influencing the ligands structure-property correlation is missing in the literature to the best of our knowledge. The present investigation quantifies that by pertinent functionalisation of TPy, TPy-M binding energies can be modified up to [GRAPHICS] 60kcal/mol. Our results reveal that functionalisation leads to a considerable charge redistribution within the TPy-M complex with carbon atoms in pyridine rings functioning as major electron sink/source with a corresponding red/blue shift of [GRAPHICS] stretching frequency. This modifies the red-ox, optical and other chemical properties of TPy-M complexes. In brief, the present report illustrates a way to design ligands such as TPy for diverse applications through tailor-made functionalisation using electronic structure methodology.

}, keywords = {Binding energy, charge redistribution, Density functional theory, functionalisation, Metal organic complexes, metal-ligand interactions, terpyridine}, issn = {0892-7022}, doi = {10.1080/08927022.2015.1067368}, author = {Joshi, Krati and Krishnamurty, Sailaja and Singh, Iksha and Selvaraj, Kaliaperumal} } @article {46892, title = {Unravelling the distinct surface interactions of modified graphene nanostructures with methylene blue dye through experimental and computational approaches}, journal = {Journal of Hazardous Materials}, volume = {388}, year = {2020}, month = {APR}, pages = {121755}, type = {Article}, abstract = {

Nanoscopic modifications leading to multi-dimensional graphene structures are known to significantly influence their candidature for several applications including catalysis, energy storage, molecular sensing and most significantly adsorption and remediation of harmful materials such as dyes. The present work attempts to identify the key trajectories that connect the structural qualification with a chosen application, viz., the interactive forces in dye remediation. Various physico-chemically Modified Graphene Nanostructures (MGNs) such as 2 dimensional Graphite, Graphene Oxide (GO), reduced GO (rGO), holey rGO, and 3 dimensional GO hydrogel and Holey GO hydrogel are chosen and synthesised herein. These represent varieties of physicochemical features with respect to their dimensionality, surface features such as oxygen functionality, nanoscopic holes etc., that contribute to their characteristic overall surface interactions. Methylene Blue (MB), a popular industrial effluent posing major environmental concern is chosen to be a probe adsorbate in this case study. An exclusive real time in-situ UV visible spectral experiment provides the revealing reasons behind the outstanding performance of 2D GO sheets with an adsorption capacity of greater than 92 \% even at high MB concentrations (\>2000 ppm). A complex dependency of various factors such as surface oxygen, morphology, nanoporosity etc. on the unique overall interaction with an adsorbent such as MB by all these adsorbates is demonstrated using experimental and DFT based computational studies. Electrostatics and hydrogen bonding are understood to be the two dominant forces driving the MB adsorption on the best performing GO here.

}, keywords = {Density functional theory, In-situ UV-vis spectroscopy, Interactions, Methylene blue, Modified Graphene Nanostructures}, issn = {0304-3894}, doi = {10.1016/j.jhazmat.2019.121755}, author = {Manappadan, Zinoy and Kumar, Shubham and Joshi, Krati and Govindaraja, Thillai and Krishnamurty, Sailaja and Selvaraj, Kaliaperumal} } @article {47759, title = {Facile fabrication of nano silver phosphate on B-doped g-C3N4: an excellent p-n heterojunction photocatalyst towards water oxidation and Cr (VI) reduction}, journal = {Journal of Alloys and Compounds}, volume = {898}, year = {2022}, month = {MAR}, pages = {162853}, type = {Article}, abstract = {A photostable Ag3PO4/BCN type-II p-n heterojunction has been demonstrated by loading nano Ag3PO4 on B-doped g-C3N4 nanosheet (BCN). The photocatalysts were successfully characterized by various physicochemical techniques and their photocatalytic activities were tested towards the water oxidation reaction to produce oxygen and Cr (VI) reduction under visible light. The HRTEM confirms Ag3PO4 with a particle size of 15 nm has been deposited on BCN to construct a p-n heterojunction. The BCNS-50 absorbs more visible light in the solar spectrum as compared to other catalyst, demonstrating the ability to generate 587 mu mol h(-1)g(-1) O-2 and reduces 98\% of 20 ppm Cr (VI) solution in 1 h. The lower PL intensity as well as lower arc value in case of BCNS-50 suggests the maximum e-h separation and lower charge transfer resistance across the semiconductor/electrolyte interface. The BCN sheet provides a compact heterojunction where the oxidation peak of Ag3PO4 decreases gradually and disappear in case of BCNS-50 suggesting the enhance stability of Ag3PO4 in the heterojunction. BCNS-50 could able to produce -139 and 3087.5 mu A photocurrent both in cathodic and anodic direction which is approximately 7 and 2.4 folds higher as compared to nano Ag3PO4. The generation of photocurrent in both cathodic and anodic direction confirms the formation of p-n heterojunction which further supported by Mott-Schottky analysis. Furthermore the construction of the p-n heterojunction is verified via Mott-Schottky study. DFT calculation explains the contribution of various atomic orbital of Ag3PO4 and BCN towards the formation of hybrid orbital in the heterojunction and the path for charge delocalization between them. This work may provide a limelight and alternative pathway for enhanced photocatalytic performance on construction of the p-n heterojunction in a simple way. (C) 2021 Elsevier B.V. All rights reserved.}, keywords = {Cr (VI) reduction, Density functional theory, Interfacial zone, p-n heterojunction, Photocatalyst, Water oxidation}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2021.162853}, author = {Sahoo, Mitarani and Babu, Pradeepta and Singh, Chandrodai Pratap and Krishnamurty, Sailaja and Parida, Kulamani} } @article {48268, title = {Chemically modified graphene sheets as potential sensors for organophosphate compounds(pesticide): A DFT study}, journal = {Applied Surface Science}, volume = {619}, year = {2023}, month = {MAY}, pages = {156745}, type = {Article}, abstract = {

Owing to the extensive use of pesticides in agriculture and the threat posed to the environment and humankind, attention is drawn toward the need for its remediation from various sources, in particular from water. The adsorption characteristics of hydrophobic graphene and its BN doped counterparts are evaluated using DFT methodology, to assess their sensing potential towards notable pesticide molecules (Organophosphate pesticides (OPs) such as chlorpyriphos, parathion, methyl-parathion, and fenitrothion). To accomplish this, various elec-tronic properties such as band structure, DOS, Bader charge analysis, and CDD have been calculated. Interest-ingly, exothermic interactions (-0.1 eV to-2 eV) have been noted for all the OPs with NB doped single vacancy defect induced graphene surfaces. With an exception of FTN, all the other OPs showed significant changes in the electronic properties of surfaces as apparent from the change in band gap and nature of the band from indirect to direct. The appreciable adsorption energy, higher charge transfer, and notable variation in the band gap are the decisive factors behind the strong interaction exhibited by NB doped surfaces especially dg-(NB-2)2 (except FTN). These findings demonstrate the suitability of NB doped single vacancy defect induced graphene sheets for the detection of the studied OPs.

}, keywords = {Adsorption, BN doped graphene surfaces, Charge density difference, Density functional theory, Organophosphate pesticides}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2023.156745}, author = {Shivankar, Bhavana R. and Singh, Chandrodai Pratap and Krishnamurty, Sailaja} } @article {49362, title = {Indazole-5-amine (AIA) as competing corrosion coating to Benzotriazole (BTAH) at the interface of Cu: A DFT and BOMD case study}, journal = {Computational and Theoretical Chemistry}, volume = {1239}, year = {2024}, month = {SEP}, pages = {114762}, type = {Article}, abstract = {

This study compares three organic compounds-benzotriazole (BTAH), imidazole (IM), and indazole-5-amine (AIA)-as corrosion inhibitors for copper substrates. Using Density Functional Theory (DFT) and Born-Oppenheimer Molecular Dynamics (BOMD) calculations, it identifies AIA as a promising and cost-effective alternative to the toxic BTAH. The adsorption strength on Cu(1 0 0) surfaces is ranked AIA\>BTAH\>IM for both neutral and deprotonated forms. These findings are supported by electronic parameter studies, including Bader charge analysis, density of states (DOS), charge density differences (CDD), and frontier molecular orbital analysis. AIA shows the best adsorption in a parallel orientation at the top site. Packing studies reveal that hydrogen bonding stabilizes the interaction energies within self-assembled AIA aggregates. Organometallic complexation studies reveal that deprotonated BTAH exhibits higher interaction energy with a single Cu atom compared to AIA when bonded through the carbon end, consistent with the findings from BOMD studies. However, on periodic Cu surfaces, AIA outperforms BTAH molecules as seen from adsorption energies. This investigation highlights AIA{\textquoteright}s potential as a superior and more economical corrosion inhibitor for copper.

}, keywords = {Adsorption, Born-Oppenheimer molecular dynamics, Corrosion inhibition, Density functional theory, Indazole derivatives}, issn = {2210-271X}, doi = {10.1016/j.comptc.2024.114762}, author = {Samal, Pragnya Paramita and Singh, Chandrodai Pratap and Tiwari, Shivani and Shah, Vaishali and Krishnamurty, Sailaja} } @article {49058, title = {Quasi-molecular hydrogen storage capacity of graphene quantum dots: A dispersion corrected DFT study}, journal = {Journal of Energy Storage}, volume = {84}, year = {2024}, month = {APR }, type = {Article}, abstract = {

Efficient storage of hydrogen, green fuel with the highest energy density, remains a pressing challenge. Among the several materials investigated for their potential hydrogen storage, 2D materials, like graphene, have advantages such as mechanical strength and large surface area but fail to store hydrogen reversibly. In this context, the present computational experiment demonstrates the potential of Graphene Quantum Dots (GQDs) with 24, 40 and 42 carbon atoms for their hydrogen storage capacity in quasi-molecular mode. Factors such as edge terminations, heteroatom doping, and anchoring of metal atoms are evaluated as a function of their storage capacity. The study clearly demonstrates an enhanced storage capacity of quantum dots, particularly, when a single Ti adatom is anchored on a 24 carbon atom GQD with a storage weight \% of 2.24 \% w/w. The storage weight \% is further noted to increase as a function of the number of Ti atoms anchored on the GQD with the highest hydrogen storage weight \% of 6.1 \% w/w. Importantly, the adsorption of hydrogen molecule on the Ti atom is through a quasi-molecular mode and is driven by Kubas interaction. This type of interactions makes GQDs as viable storage materials at room temperature. Secondly, the work demonstrates that GQDs offer higher storage capacities of hydrogen molecules as compared to their 2D counterparts viz., graphene sheets, making them attractive candidates to be explored experimentally.

}, keywords = {Density functional theory, graphene quantum dots, Hydrogen storage, Kubas interaction, Quasi -molecular adsorption, Ti adatom}, issn = {2352-152X}, doi = {10.1016/j.est.2024.110833}, author = {Khadilkar, Pranav and Samudre, Nikhil S. and Krishnamurty, Sailaja} } @article {49350, title = {Ultra-small Au nanoclusters with tailored photoluminescence properties using modified thiol ligands: a computational and experimental demonstration}, journal = {Particle \& Particle Systems Characterization}, volume = {41}, year = {2024}, month = {OCT}, type = {Article}, abstract = {

Au nanoclusters with tailored photoluminescence can be obtained through controlled nanoparticle ligand interface chemistry. The present work reports molecular gold nanoclusters with tuneable photoluminescence emission from 600 to 700 nm using N,N {\textquoteleft},N {\textquoteleft}{\textquoteright}-trialkyl (11-mercaptoundecyl)ammonium chloride ligands as capping-agents. The tunability within red spectral region is regulated through specific interface chemistry between gold nanoclusters of molecular range and functional groups of the quaternary ammonium head over N,N {\textquoteleft},N {\textquoteleft}{\textquoteright}-trialkyl(11-mercaptoundecyl)ammonium chloride. Combined understanding obtained from the spectroscopy, microscopy, and density functional theory studies demonstrate that the functional group specific electronic interactions at the interfaces steer the emission characteristics of {\textquoteleft}{\textquoteleft}molecular{\textquoteright}{\textquoteright} Au nanoparticles. The study clearly identifies that bulkier functional groups, i.e., triethyl, tripropyl, tributyl, and dimethyl benzene over N+ (of thiol ligand) through their steric effects minimize the particle size giving rise to tunable photoluminescence emission in red spectral region. However, the red shift seen in the emission Au nanoclusters with N-(11-mercaptoundecyl)-N,N {\textquoteleft}-dimethylbenzenammonium chloride ligand in contradiction to particle size effect is computationally proved to be due to the delocalization of electron density from benzene aromatic ring to N+ of ammonium head leading to a reduction in the HOMO-LUMO energy gap. Fluorescence properties of water dispersible Au nanoclusters are tuned by varying the ammonium head group. Density Functional Theory studies correlate the distinction in emission when head group is phenyl to charge transfer characteristics. image

}, keywords = {Density functional theory, photoluminescent Au nanoclusters, surface plasmon resonance, thiol ligand}, issn = {0934-0866}, doi = {10.1002/ppsc.202400011}, author = {Chahande, Anurag M. and Maibam, Ashakiran and Krishnamurty, Sailaja and Devi, R. Nandini} }