@article { ISI:000293192100022, title = {Size- and shape-sensitive reactivity behavior of Al-n(n=2-5, 13, 30, and 100) clusters toward the N-2 molecule: a first-principles investigation}, journal = {Journal of Physical Chemistry C}, volume = {115}, number = {30}, year = {2011}, month = {AUG}, pages = {14615-14623}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Reactivity of aluminum clusters has been found to exhibit size-sensitive variations. N-2 reduction is a hard process, and its dissociation on the Al surface is one of the few chemical methods available under nonhazardous conditions. In this context, we attempt to understand the adsorption behavior of N-2 molecules as a function of varying size and shape of Al clusters using a Density Functional Theory (DFT) based method. During the complex formation, various N-2 adsorption modes are examined. The results clearly demonstrate that, while the interaction energy does not vary with respect to the cluster size, shape of the cluster is highly contributive toward the chemisorption (a prerequisite for the reactivity) of the N-2 molecule. The underlying electronic and structural factors influencing the adsorption of N-2 molecules on the Al clusters are analyzed with the help of the Electron Localization Function (ELF) and Frontier Molecular Orbitals. As an illustration, the activation barrier calculations on various Al-13 conformations are calculated, and results confirm the experimental propositions that high-energy structures (depending upon their geometrical and electronic orientation) are more favorable for N-2 reduction.

}, issn = {1932-7447}, doi = {10.1021/jp203452a}, author = {Kulkarni, Bhakti S. and Krishnamurty, Sailaja and Pal, Sourav} } @article {46665, title = {Surface functionalization: an efficient alternative for promoting the catalytic activity of closed shell gold clusters}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, year = {2020}, month = {OCT }, pages = {23351-23359}, type = {Article}, abstract = {

{Surface functionalization through adsorption of ligands or non-metal atoms is considered to be an interesting and viable approach for tuning the physicochemical properties of gold clusters. Highly stable and magic numbered electronic configurations of thiolate protected gold clusters such as Au-25(SR)(18), Au-38(SR)(24)etc. with intriguing properties are the direct manifestation of the rich chemistry of the Au-S interface. The present investigation discerns the CO oxidation activity of structurally well characterized sulphur functionalized gold cluster anions AumS4-

}, issn = {1463-9076}, doi = {10.1039/d0cp01918f}, author = {Joshi, Krati and Krishnamurty, Sailaja and Dar, Manzoor Ahmad} } @article {47661, title = {Substrate augmented catalytic activity towards NRR: a case study of Li doped Al clusters on defective graphene}, volume = {566}, year = {2021}, month = {NOV}, pages = {150586}, type = {Article}, abstract = {Density Functional Theory (DFT) based methods are applied to examine the potential of lithium doped aluminium clusters consisting of 3-13 atoms for dinitmgen molecule activation in terms of N N bond length, redshift in N N bond stretching frequency, nitrogen interaction energy and frontier molecular orbitals analysis. The present work highlights the role of monovacant C-3 defective graphene as a support in fine tuning the catalytic activity of Li doped Al clusters for reduction of N-2. Fundamental insights to synergic binding of clusters with defective graphene is brought out and its role in enhancing activation of dinitmgen molecule is explained. Supported Aln-1Li clusters with six or more atoms are noted to be more active towards N-2 molecule activation as compared to the clusters without support. Dinitrogen molecule undergoes a maximum bond elongation of 1.56 angstrom corresponding to redshift of 1690 cm(-1) on Al7Li@graphene and Al12Li@graphene. This is maximum value reported in context of activation for N-2 molecule till date.}, keywords = {Al clusters, Al12Li, C-3 defective graphene, DFT, Li Doping, N-2 activation, Red-shift}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2021.150586}, author = {Samal, Pragnya Paramita and Poonam and Krishnamurty, Sailaja} } @article {48368, title = {Structure-property insights into chiral thiophene copolymers by direct heteroarylation polymerization}, journal = {European Polymer Journal}, volume = {181}, year = {2022}, month = {DEC }, pages = {111676}, type = {Article}, abstract = {

Chiral thiophene copolymers with fluorene as co monomer are designed having N-Boc-L-glutamic acid-1-tert-butyl ester as a chiral substituent located either on the thiophene unit or the fluorene unit with varying spacer length. The atom-economic direct heteroarylation polymerization (DHAP) method is utilized for the polymerization. Gibb{\textquoteright}s free energy (delta G) for polymerization determined using DFT calculations indicate difficulty in achieving high molar mass when the bulky chiral substituents are attached through short spacer to the backbone. The experimental observations are in agreement with the theoretical calculations with no polymer-ization or very low molar mass sticky compounds obtained for reactions with predicted + \& UDelta;G values. Structure -property relationship are compared for two chiral polymers -P4 and P5 having the chiral substitution on thiophene and fluorene units respectively. No CD signal is observed in THF-a good solvent where the polymers are molecularly dissolved. Intense bisignated CD signal is observed for both polymers upon addition of methanol - a poor solvent, to their THF solution. The bisignate CD signal with maxima at lower wavelength and inflection point associated with the pi-pi* absorption band is characteristic of exciton coupling between polymer chains in a left handed helical orientation. Small differences are observed in the intensity of the CD signal for the polymers P4 and P5 highlighting the impact of steric hindrance of bulky pendant groups on polymer conformation. DHAP is an atom economic polymerization procedure that can be gainfully utilized for developing chiral conjugated polymers.

}, keywords = {chiral, DFT, Direct heteroarylation polymerization, Gibb?s free energy, Steric Hindrance}, issn = {0014-3057}, doi = {10.1016/j.eurpolymj.2022.111676}, author = {Nikam, Shrikant B. and Singh, Chandrodai Pratap and Krishnamurty, Sailaja and Asha, S. K.} } @article {48013, title = {Synergetic storage of ammonia over Al quantum dots embedded graphene sheets: a first principles perspective}, journal = {International Journal of Hydrogen Energy}, volume = {47}, year = {2022}, month = {OCT }, pages = {36873-36885}, type = {Article}, abstract = {

In view of the increasing energy demand and global warming, it is imperative to search for a renewable and environmental friendly fuel in lieu of non-renewable energy resources. Hydrogen stands out to be the best fuel as both, renewable and clean. Concerning the use of hydrogen as a fuel, its production as well as storage are current global challenges being worked on. In this article, a density functional theory based study is performed to identify the potential of supported Al cluster cages for ammonia storage. In this context, initially, stability of pristine and doped aluminum nanoclusters anchored on graphene sheet is evaluated following which thus supported stable nanoclusters are studied for the adsorption of NH3 to identify their storage capacity. For both, complexes and NH3 adsorbed complexes, Density of States (DOS), Charge Density Difference (CDD) and Bader charge analysis is done to understand their electronic properties.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

}, keywords = {Aluminum nanoclusters, Defective graphene, Endohedral doping, NH 3 adsorption}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2022.08.268}, author = {Singh, Chandrodai Pratap and Krishnamurty, Sailaja} } @article {49000, title = {Shape-controlled MoO3/MnO x nanocatalyst for the selective synthesis of 2-phenylquinoxaline drug motifs}, journal = {ACS Applied Nano Materials}, volume = {6}, year = {2023}, month = {DEC }, pages = {23442-23453}, type = {Article}, abstract = {

We have developed a highly effective shape-controlled MoO3/MnOx nanocatalyst for the selective synthesis of 2-phenylquinoxaline drug motifs at room temperature without any external oxidant. Electron microscopy images reveal that the MnOx material contains rod-shaped particles (length: 500-1000 nm and width: 150-200 nm) and the MoO3 species are uniformly dispersed in the MoO3/MnOx material. The MoO3/MnOx nanocatalyst calcined at 500 degrees C (MoO3/MnOx-5) contains abundant strong acid sites and an optimum ratio of Mn4+/Mn3+, which are responsible for the C-N cross-coupling reaction between 2-phenylethylamine and o-phenylenediamine, giving higher yields (\>96\%) of 2-phenylquinoxaline at mild conditions. The broad scope of this catalytic strategy at room temperature and without an external oxidant was confirmed by achieving \>90\% yields of functional 2-phenylquinoxalines from C-N cross-coupling of various o-phenylenediamines and 2-phenylethylamines. The outstanding reusability efficiency of the MoO3/MnOx-5 nanocatalyst up to five cycles without the need for a regeneration step as well as the effective scalability highlighted the practicability of the MoO3/MnOx-based catalytic protocol for carbon-heteroatom coupling reactions at room temperature and without an external oxidant. Using computational studies, the possible reasons for the selective synthesis of 2-phenylquinoxaline over the MoO3/MnOx-5 nanocatalyst were elucidated.

}, keywords = {cascade C-N cross-coupling, DFT studies, room temperature andopen air, shape-controlled MoO3/MnOx nanocatalyst, structure-activity correlation}, doi = {10.1021/acsanm.3c04820}, author = {Singh, Nittan and Putla, Suresh Babu and Pratap Singh, Chandrodai and Kalbande, Pavan Narayan and Choudhary, Priyanka and Krishnamurty, Sailaja and Krishnan, Venkata and Bhatte, Kushal and Sudarsanam, Putla} } @article {48941, title = {Steric and electronic effect in unsymmetrical squaraine dyes for dye-sensitized solar cells}, journal = {Journal of physical chemistry C }, volume = {127}, year = {2023}, month = {NOV}, pages = {22473-22488}, type = {Journal Article}, abstract = {

Functionalizing the light harvesting sensitizers with additional electron-donating or -withdrawing groups is a potential approach to modulate the photophysical and electrochemical properties which in-turn optimizes the driving force associated with the charge injection and dye-regeneration processes at the dye-TiO2/electrolyte interface and the photovoltaic device performance in dye-sensitized solar cells (DSSCs). Furthermore, modulated electronic levels of the dyes provide an opportunity to reduce the overpotential associated with the dye-regeneration process and make the dye-TiO2 interface compatible with various electrolytes. Furthermore, an in-built steric feature by means of introducing linear/branched alkyl groups in the sensitizer is important in controlling the aggregation of dyes on the TiO2 surface. Hence, to integrate both steric and electronic properties, a series of alkyl group-wrapped unsymmetrical squaraine dyes (SQ-X) with electron-donating and -withdrawing groups have been designed, synthesized, and utilized for DSSC device fabrication. These dyes are functionalized with alkyl groups at both sp(3)-C and N-atoms of the indoline donor moiety at the nonanchoring side to have a similar steric feature. Photophysical and electrochemical studies revealed that the HOMO and LUMO energy levels of the SQ-X series of dyes have been modulated systematically with sufficient driving forces for both charge injection and dye-regeneration processes with iodolyte (I-/I-3(-)) electrolyte. In the presence of electron-donating groups in SQ-X (where X = -NPh2 and -OMe), the HOMO energy levels are less positive than SQ-H, whereas the presence of electron-withdrawing groups such as -CO2Me, -CN, and -NO2 pushed the HOMO energy levels toward more positive potentials. Enhanced photovoltaic performances have been obtained for the dyes containing electron-donating groups, where the dye with the -NPh2 group showed a maximum of eta 7.03\% (V-OC 708 mV, J(SC) 13.16 mA cm(-2), and ff 78\%). The dye with the strong electron-withdrawing group -NO2 showed an efficiency of 1.49\% (V-OC = 634 mV, J(SC) = 3.13 mA cm(-2), and ff 75\%). As the dyes with the electron-withdrawing group possess deep positive HOMO energy levels, the DSSC device characterization has been investigated with the Cu+/2+ redox shuttle. The reduced device performance of electron-withdrawing-group-containing dyes is due to the unfavored charge distribution in the LUMO compared to the presence of electron-donating-group-containing dyes, and it was supported by the difference in the charge injection efficiency.

}, keywords = {cobalt, Donor, Dynamics, Organic dyes}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.3c05222}, author = {Nawghare, Indrajeet S. and Singh, Ambarish Kumar and Maibam, Ashakiran and Krishnamurty, Sailaja and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj} } @article {48984, title = {Sulfonated zinc phthalocyanine coating as an efficient and ecofriendly corrosion inhibitor for copper surfaces: an in silico led design and its experimental validation}, journal = {Langmuir}, volume = {39}, year = {2023}, month = {NOV }, pages = {17295-17307}, type = {Article}, abstract = {

The current study highlights the successful integration of an in silico design with experimental validation to create a highly effective corrosion inhibitor for copper (Cu) surfaces. The synthesized sulfonated zinc phthalocyanine (Zn-Pc) is electrochemically characterized and demonstrates an impressive 97\% inhibition efficiency, comparable to the widely used industrial corrosion inhibitor, BTA, for Cu surfaces. The corrosion inhibition is comprehensively analyzed through potentiodynamic polarization and impedance spectroscopy techniques, supported by their respective equivalent circuits. Furthermore, the sample undergoes thorough characterization using scanning electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, contact angle measurements, and atomic force microscopy. Density functional theory calculations reveal that sulfonated Zn-Pc exhibits the highest interaction energy, underscoring its exceptional inhibition properties. These results open possibilities for utilizing computational methods to design and optimize corrosion inhibitors for protection of Cu surfaces.

}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.3c02393}, author = {Dekshinamoorthy, Amuthan and Samal, Pragnya Paramita and Krishnamurty, Sailaja and Khatri, Praveen K. and Jain, Suman Lata and Ray, Anjan and Vijayaraghavan, Saranyan} } @article {49238, title = {Scalable approach using a gC3N4 -covalent organic framework hybrid catalyst towards sustainable hydrogen production from seawater and wastewater}, journal = {CHEMICAL SCIENCE}, volume = {15}, year = {2024}, month = {AUG 22}, pages = {13381-13388}, type = {Journal Article}, issn = {2041-6520}, doi = {10.1039/d4sc01387e}, author = {Asokan, Kiran and Bhagyasree, T. M. and Devasia, George and Krishnamurty, Sailaja and Solim, Sabah and Rueda, Lina and Al-Mohannadi, Dhabia M. and Al-Hashimi, Mohammed and Kakosimos, Konstantinos and Santhosh Babu, Sukumaran} } @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} } @article {49424, title = {Synergistic combination of ZnCl2/Cu-BTC MOF for the photocatalytic oxidative deamination of benzylamines using CO2 under visible-light irradiation}, journal = {ACS Applied Engineering Materials}, volume = {2}, year = {2024}, month = {JUL}, pages = {2095{\textendash}2101}, type = {Article}, abstract = {

This paper demonstrates the first CO2-mediated oxidative deamination of benzylamines to benzaldehydes using a combination of ZnCl2\ and Cu-BTC MOF as photocatalysts in a carbon tetrachloride solvent under visible-light irradiation. Interestingly, the synergistic combination of ZnCl2\ and Cu-BTC afforded the targeted oxidation of benzylamine to benzaldehyde, wherein CO2\ acted as an oxidant. The individual components yielded the corresponding imine as the main product, resulting from the oxidative coupling of the benzylamine. DFT calculations and computational studies supported the proposed reaction pathways involving the formation of an intermediate imine from benzylamine via dehydrogenation followed by hydrolysis to produce benzaldehyde. This work, demonstrating the use of CO2\ as an oxidant, may open up new avenues for CO2\ utilization in chemical production by using sustainable light energy.

}, doi = {https://doi.org/10.1021/acsaenm.4c00251}, author = {Kumar, Amod and Bhatt, Sakshi and Samal, Pragnya Paramita and Krishnamurty, Sailaja and Jain, Suman L.} } @article {49340, title = {Synergistic effect of lactam and pyridine nitrogen on polysulfide chemisorption and electrocatalysis in lithium sulfur batteries}, journal = {ACS APPLIED MATERIALS \& INTERFACES}, volume = {16}, year = {2024}, month = {AUG }, pages = {42059-42068}, keywords = {Li-S battery, phenyl-diketopyrrolopyrrole, pyridine-diketopyrrolopyrrole}, issn = {1944-8244}, doi = {10.1021/acsami.4c05128}, author = {Javaregowda, Bharathkumar H. and Kargude, Radhakisan and Birajdar, Sarika and Shivankar, Bhavana and Krishnamurty, Sailaja and Jones, Lathe A. and Caruso, Rachel A. and Krishnamoorthy, Kothandam} } @article {49804, title = {syn-Selective hydrosilylation and hydroboration of alkynes at room temperature catalyzed by a phosphine-free (NNN)Fe(ii) complex}, journal = {Catalysis Science \& Technology}, volume = {15}, year = {2025}, month = {NOV}, pages = {6716-6725}, type = {Article}, abstract = {

Catalytic hydrofunctionalization of alkynes is the ideal and atom-economical route to synthesize vinylsilanes and vinylboronates, which are valuable organic building blocks. However, the process suffers from using expensive phosphine-ligated catalysts, sensitive organometallic activators, and elevated reaction temperatures. To overcome these challenges, herein, we developed a series of phosphine-free (NNN)-ligated iron complexes and demonstrated their potential as efficient catalysts for the hydrosilylation and hydroboration of both internal and terminal alkynes using NaOtBu as an activator. The reactions proceeded smoothly using 1.5 mol\% catalyst loading at room temperature and provided syn-selective vinylsilanes and vinylboronates. This hydrofunctionalization exclusively delivered mono-silylated and mono-borylated vinyls with tolerance of sensitive functionalities. At the same time, terminal alkynes provided excellent anti-Markovnikov selectivity with thermodynamically feasible beta-(E)-vinylsilanes and beta-(E)-vinylboronates. The presence of an N-H moiety in the ligand backbone is crucial in generating an Fe(ii) active catalyst and facilitating the catalytic process. Mechanistic investigations, including controlled reactions and external additive experiments, were performed to propose a redox-neutral reaction mechanism with iron maintaining its +2 oxidation state throughout the cycle. The DFT energy calculations unanimously support the proposed reaction mechanism.

}, issn = {2044-4753}, doi = {10.1039/d5cy00766f}, author = {Pradhan, Chandini and Dubey, Shivansh and Samal, Pragnya Paramita and Krishnamurty, Sailaja and Punji, Benudhar} } @article {49835, title = {Self-healing hydrogel electrolyte enabled by dynamic polar covalent and noncovalent interactions for high-performance rechargeable zinc-metal batteries: a leap toward sustainable energy storage}, journal = {Advanced Energy Materials}, volume = {16}, year = {2026}, month = {JAN}, type = {Article}, abstract = {

Hydrogel polymer electrolytes with superior multifunctional properties are promising alternatives to aqueous electrolytes for resolving interfacial issues in rechargeable zinc-metal batteries. In this study, an intrinsic self-healing hydrogel polymer electrolyte (PHBC-4) is synthesized, engineered through an integrated approach involving the polar covalent (B \& horbar;O bond), hydrogen-bond (polyvinyl alcohol-hydroxypropyl methylcellulose interface), and coordination-type (Zn \& horbar;O) interactions to enable self-healing functionality. The PHBC-4 has demonstrated high ionic conductivity (4.6 x 10-2 S cm-1), good oxidative stability (2.3 V vs Zn|Zn2+), a high cation transference number (0.89), superior tensile strength (0.32 MPa), and an impressive healing efficiency of 93\% achieved just within 5 min, confirming its robust self-healing capability. In Zn||Zn symmetric cells, it effectively suppresses dendrite growth, ensuring stable cycling for over 1032 h with an areal capacity of 1.0 mAh cm-2 at a current density of 1.0 mA cm-2. When paired with a Zn-doped MnO cathode in the rechargeable homemade pouch cell, the system delivers a high specific capacity of 160 mAh g-1 at 0.10 A g-1 and cycling stability up to 493 charge-discharge cycles at 2.0 A g-1. The self-healing ability of PHBC-4 HGPE is confirmed in a homemade pouch cell via OCV and charge-discharge tests, demonstrating stable performance. The DFT studies confirm molecular-level interactions within the hydrogel heterostructure.

}, keywords = {dendrite inhibition, flexible rechargeable zinc metal battery, high cation transference number, self-healing hydrogel polymer electrolyte}, issn = {1614-6832}, doi = {10.1002/aenm.202502883}, author = {Puthiyaveetil, Priyanka Pandinhare and Kurian, Rachna Maria and Samudre, Nikhil S. and Balasubramanian, Rajalakshmi and Torris, Arun and Pockil, Fayis Kanheeram and Bhat, Suresh and Ajithkumar, T. G. and Krishnamurty, Sailaja and Kurungot, Sreekumar} }