@article {42748, title = {Large-bite bisphosphite, 1,3-C6H4{OPOC10H6(μ-S)C10H6O}2: synthesis, copper(I), and gold(I) complexes}, journal = {Journal of Organometallic Chemistry}, volume = {695}, year = {2010}, month = {NOV}, pages = {981{\textendash}986}, abstract = {

Large-bite bisphosphite ligand 1,3-C6H4{OPOC10H6(μ-S)C10H6O}2 (3), is obtained by reacting chlorophosphonite {OC10H6(μ-S)C10H6O}PCl (2) with resorcinol in the presence of triethylamine. Treatment of 3 with CuCl in 1:1 molar ratio produces a 1D-coordination polymer [CuCl{({\textendash}OC10H6(μ-S)C10H6O{\textendash})P({\textendash}OC6H4O{\textendash})P({\textendash}OC10H6(μ-S)C10H6O{\textendash})}-κP,κP]$\infty$ (4) in good yield. Similar reaction of 3 with two equivalents of AuCl(SMe2) affords a dinuclear complex, [Au2Cl2{({\textendash}OC10H6(μ-S)C10H6O{\textendash})P({\textendash}OC6H4O{\textendash})P({\textendash}OC10H6(μ-S)C10H6O{\textendash})}-κP,κP] (5). Single crystal X-ray structures of the ligand 3 and the complexes 4 and 5 are reported. The gold complex 5 shows dimeric structure supported by strong Au{\textperiodcentered}{\textperiodcentered}{\textperiodcentered}Au aurophilic interactions.

}, author = {Balakrishna, Maravanji S. and Kumar, Pawan and Punji, Benudhar and Mague, Joel T.} } @article { ISI:000369516100068, title = {Field emission properties of highly ordered low-aspect ratio carbon nanocup arrays}, journal = {RSC Advances}, volume = {6}, number = {12}, year = {2016}, month = {JAN}, pages = {9932-9939}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Herein, we design and develop a field emission device utilizing highly porous carbon nanocup (CNC) films. These three-dimensional (3D) low-aspect ratio CNC structures were fabricated by a combination of anodization and chemical vapor deposition techniques. The low turn-on fields of 2.30 V mu m(-1) were observed to draw an emission current density of 1 mu A cm(-2) and a maximum emission current density of similar to 1.802 mA cm(-2) drawn at an applied field of similar to 4.20 V mu m(-1). The enhanced field emission behavior observed from the CNC films is attributed to an excellent field enhancement factor of 1645. The observed field emission properties of CNC arrays are attributed to a synergistic combination of high aspect ratio, nano-sized radius of curvature, highly organized distribution of the emitters over the whole area of specimen and lower screening effect of the CNC arrays. These observations shed light on the effect of the stacking carbon layers of CNC on their electronic properties and open up possibilities to integrate new morphologies of graphitic carbon in nanotechnology applications. Thus, the low turn on field, high emission current density and better emission current stability enable CNC based future field emission applications.

}, issn = {2046-2069}, doi = {10.1039/c5ra25682h}, author = {Gupta, Bipin Kumar and Kedawat, Garima and Kumar, Pawan and Singh, Satbir and Suryawanshi, Sachin R. and Agrawal, Neetu and Gupta, Govind and Kim, Ah Ra and Gupta, R. K. and More, Mahendra A. and Late, Dattatray J. and Hahm, Myung Gwan} } @article {44233, title = {High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures}, journal = {AIP Advances}, volume = {8}, year = {2018}, month = {JAN}, pages = {015117}, type = {Article}, abstract = {

The vertical aligned carbon nanotubes (CNTs)-based pillar architectures were created on laminated silicon oxide/silicon (SiO2/Si) wafer substrate at 775 degrees C by using water-assisted chemical vapor deposition under low pressure process condition. The lamination was carried out by aluminum (Al, 10.0 nm thickness) as a barrier layer and iron (Fe, 1.5 nm thickness) as a catalyst precursor layer sequentially on a silicon wafer substrate. Scanning electron microscope (SEM) images show that synthesized CNTs are vertically aligned and uniformly distributed with a high density. The CNTs have approximately 2-30 walls with an inner diameter of 3-8 nm. Raman spectrum analysis shows G-band at 1580 cm(-1) and D-band at 1340 cm(-1). The G-band is higher than D-band, which indicates that CNTs are highly graphitized. The field emission analysis of the CNTs revealed high field emission current density (4mA/cm(2) at 1.2V/mu m), low turn-on field (0.6 V/mu m) and field enhancement factor (6917) with better stability and longer lifetime. Emitter morphology resulting in improved promising field emission performances, which is a crucial factor for the fabrication of pillared shaped vertical aligned CNTs bundles as practical electron sources. (c) 2018 Author(s).

}, issn = {2158-3226}, doi = {10.1063/1.5004769}, author = {Gupta, Bipin Kumar and Kedawat, Garima and Gangwar, Amit Kumar and Nagpal, Kanika and Kashyap, Pradeep Kumar and Srivastava, Shubhda and Singh, Satbir and Kumar, Pawan and Suryawanshi, Sachin R. and Seo, Deok Min and Tripathi, Prashant and More, Mahendra A. and Srivastava, O. N. and Hahm, Myung Gwan and Late, Dattatray J.} } @article {46832, title = {Alpha-Angelica lactone catalyzed oxidation of benzylic sp(3) C-H bonds of isochromans and phthalans}, journal = {Organic \& Biomolecular Chemistry}, volume = {18}, year = {2020}, month = {JUN }, pages = {4046-4050}, type = {Article}, abstract = {

A metal-free organocatalytic system has been developed for highly efficient benzylic C-H oxygenations of cyclic ethers using oxygen as an oxidant. This oxidation reaction utilizes alpha-angelica lactone as a low cost/low molecular weight catalyst. The optimized reaction conditions allow the synthesis of valued isocoumarins and phthalides from readily available precursors in good yields. Mechanistic studies indicate that the reaction pathway likely involves a radical process via a peroxide intermediate.

}, issn = {1477-0520}, doi = {10.1039/d0ob00729c}, author = {Thatikonda, Thanusha and Deepake, Siddharth K. and Kumar, Pawan and Das, Utpal} } @article {47609, title = {Acid mediated sulfonylation of para-quinone methides with tosylmethyl isocyanides for the synthesis of diarylmethyl sulfones}, journal = {ChemistrySelect}, volume = {6}, year = {2021}, month = {JUL }, pages = {7158-7161}, type = {Article}, abstract = {An efficient, hydrochloric acid promoted reaction for the synthesis of diarylmethyl sulfones has been developed via unprecedented 1, 6-conjugate addition reaction of tosylmethyl isocyanide (TosMIC) with para-quinone methides.This catalyst free reaction provides various diarylmethyl sulfones in good to excellent yields in an operationally simple method under metal free conditions. Further transformations of the productsare also demonstrated.}, keywords = {1, 6-Conjugate addition, aromatization, Diarylmethylsulfone, para-Quinonemethide, TosMIC}, issn = {2365-6549}, doi = {10.1002/slct.202102272}, author = {Kumar, Pawan and Kale, Someshwar B. and Gonnade, Rajesh G. and Das, Utpal} } @article {47987, title = {Alpha-angelica lactone catalyzed oxidation of pyrrolidines to lactams}, journal = {European Journal of Organic Chemistry}, volume = {2022}, year = {2022}, month = {AUG}, pages = {e202200712}, type = {Article}, abstract = {

Herein, we report an efficient protocol for the synthesis of gamma-lactams from pyrrolidines and oxygen. The strategy follows a two-step process involving an initial generation alpha-amino alkyl radicals from pyrrolidines and oxygen in presence of 4-dimethylaminopyridine (DMAP) followed by trapping of the radical with oxygen species. This protocol demonstrates good functional group acceptance and provides a direct method to access gamma-lactams. The lactam derivatives were obtained in up to 98 \% yield.

}, keywords = {alpha-Amino alkyl radicals, alpha-Angelica lactone, lactams, Oxidation, Pyrrolidines}, issn = {1434-193X}, doi = {10.1002/ejoc.202200712}, author = {Deepake, Siddharth K. and Kumar, Manish and Kumar, Pawan and Das, Utpal} } @article {47899, title = {Mechanistically guided one pot synthesis of phosphine-phosphite and its implication in asymmetric hydrogenation}, journal = {European Journal of Organic Chemistry}, volume = {2022}, year = {2022}, month = {JAN}, pages = {e202101447}, type = {Article}, abstract = {

Although hybrid bidentate ligands are known to yield highly enantioselective products in asymmetric hydrogenation (AH), synthesis of these ligands is an arduous process. Herein, a one pot, atom-economic synthesis of a hybrid phosphine-phosphite (L1) is reported. After understanding the reactivity difference between an 0-nucleophile versus C-nucleophile, one pot synthesis of Senphos (L1) was achieved (72\%). When L1 was treated with [Rh], P-31 NMR revealed bidentate coordination to Rh. Senphos, in the presence of rhodium, catalyzes the AH of Methyl-2-acetamido-3-phenylacrylate and discloses an unprecedented turn over frequency of 2289, along with excellent enantio-selectivity (92\%). The generality is demonstrated by hydrogenating an array of alkenes. The AH operates under mild conditions of 1-2 bar H-2 pressure, at room temperature. The practical relevance of Ll is demonstrated by scaling-up the reaction to 1 g and by synthesizing DOPA, a drug widely employed for the treatment of Parkinson{\textquoteright}s disease. Computational insights indicate that the R isomer is preferred by 3.8 kcal/mol over the S isomer.

}, keywords = {asymmetric hydrogenation, catalysis, DOPA synthesis, One pot synthesis, Phosphine-phosphite ligand}, issn = {1434-193X}, doi = {10.1002/ejoc.202101447}, author = {Sen, Anirban and Kumar, Rohit and Pandey, Swechchha and Raj, K. Vipin and Kumar, Pawan and Vanka, Kumar and Chikkali, Samir H.} } @article {48703, title = {Radical cascade cyclization of unactivated alkene-tethered indoles with aryldiazonium salt and sodium metabisulfite to access Azo- and Sulfonylated-2,3-Dihyro-1H-pyrrolo[1,2-a]indoles}, journal = {Journal of Organic Chemistry}, volume = {88}, year = {2023}, month = {JUN}, pages = {9123-9129}, type = {Article}, abstract = {

A method for the construction ofheterocyclic scaffold2,3-dihyro-1H-pyrrolo[1,2-a]indolesvia arylsulfonylradical-triggered cascade cyclization of unactivated alkene-tetheredindoles in the absence of any external photocatalyst has been developed.This protocol features easily accessible starting materials such assodium metabisulfite and aryldiazonium tetrafluoroborates at roomtemperature and offers good functional group compatibility, enablingthe introduction of various functionalized sulfonyl and azo groupsinto pyrrolo[1,2-a]indoles.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.3c00759}, author = {Kumar, Pawan and Rai, Archana and Kumar, Manish and Krishna, Gamidi Rama and Das, Utpal} } @article {49391, title = {Atmospheric-pressure continuous-flow methane oxidation to methanol and acetic acid using H2O2 over the Au-Fe catalyst}, journal = {ACS SUSTAINABLE CHEMISTRY \& ENGINEERING}, volume = {12}, year = {2024}, month = {MAY }, pages = {8958-8967}, type = {Journal Article}, keywords = {CO oxidation, HIGHLY SELECTIVE OXIDATION, metal-organic frameworks}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.4c02993}, author = {Jagtap, Anuradha V. and Kumar, Pawan and Gupta, Sharad and Nagendra, Abharana and Jha, Shambhu Nath and Bhattacharyya, D. and Ajithkumar, Thalasseril G. and Vinod, C. P.} } @article {49219, title = {Photocatalytic regeneration of reactive cofactors with inP quantum dots for the continuous chemical synthesis}, journal = {ACS Catalysis}, volume = {14}, year = {2024}, month = {APR}, pages = {6740-6748}, type = {Article}, abstract = {

The shuttling of redox-active nicotinamide cofactors between the light and dark cycles is the key to the continuous production of biomass in photosynthesis. The replication of such processes in artificial photosynthetic systems demands fast photoregeneration as well as simultaneous integration of these nicotinamide cofactors into the dark cycle. Here, we report the design of an artificial photosynthetic system for the continuous production of butanol via the constant photoregeneration and consumption of nicotinamide cofactors, powered by an indium phosphide quantum dot (InP QD) photocatalyst and alcohol dehydrogenase (ADH) enzyme, respectively. A strong electrostatic attraction between the oppositely charged InP QDs and electron mediators significantly enhanced the charge extraction and utilization processes, enabling a fast (similar to 30 min, with a turn over frequency of similar to 1333 h(-1)), quantitative (\>99\%), and selective photoregeneration of enzymatically active nicotinamide cofactors in the light cycle. These photoregenerated nicotinamide cofactors were further coupled in the dark cycle to trigger the ADH oxidoreductase enzyme for the production of butanol, via sequential as well as simultaneous light-dark cycles. The amount of butanol produced under simultaneous light-dark cycles was higher than the stoichiometric limit, proving the constant regeneration and consumption of nicotinamide cofactors in light and dark cycles, respectively. Thus, a proper design and integration of the InP QD-based photocatalytic cycle with the enzymatic cycle led to the effective electron shuttling between light and dark cycles, as seen in photosynthesis.

}, keywords = {artificial photosynthesis, biologicalcofactors, charge transfer, indiumphosphide, Photocatalysis, quantum dots}, issn = {2155-5435}, doi = {10.1021/acscatal.4c00817}, author = {Chakraborty, Indra Narayan and Jain, Vanshika and Roy, Pradyut and Kumar, Pawan and Vinod, Chathakudath P. and Pillai, Pramod P.} } @article {49914, title = {Exploring the electronic modulation in controlling the activity and selectivity of Ni-Au-In based catalyst in atmospheric pressure CO2 hydrogenation}, journal = {Chemical Engineering Journal}, volume = {520}, year = {2025}, month = {SEP }, pages = {165921}, type = {Article}, abstract = {

Nickel-based catalysts are widely used for the hydrogenation of CO2 but encounter stability challenges during prolonged reactions and at elevated temperatures. At atmospheric pressure, nickel primarily promotes methane formation in CO2 hydrogenation reactions. In this work, we demonstrate that the stability and activity of nickel can be significantly enhanced through gold (Au) modification. Furthermore, we achieve a near-complete selectivity switch from methane to CO by incorporating indium (In), mediated through the formation of Au-In alloy. This catalyst exhibits excellent CO2 conversion and CO selectivity at relatively lower temperatures (400 degrees C), addressing a major bottleneck in the Reverse Water-Gas Shifts (RWGS) reaction. XPS studies demonstrate an interesting electron transfer mechanism facilitated by gold, which involves the formation of electronrich Au species (Au delta-) and the development of Au-In alloys. This process improves the reducibility of nickel oxide while allowing a fraction of nickel to remain in its metallic form, managing a facile hydrogenation process and regulating the shift in selectivity from CH4 to CO.

}, keywords = {Alloy formation, Bimetallic catalyst, CO2 hydrogenation, RWGS, Selectivity switch, synergy, Trimetallic catalyst, XPS (X-ray photoelectron spectroscopy)}, issn = {1385-8947}, doi = {10.1016/j.cej.2025.165921}, author = {Bajpai, Jyotsna P. and Gupta, Sharad and Goud, Devender and Deka, Diku Raj and V. Jagtap, Anuradha and Kumar, Pawan and Ahamed, Momin and Peter, Sebastian C. and Vinod, C. P.} } @article {49623, title = {Photocatalytic oxidation of α-substituted amines to lactams/amides}, journal = {Advanced Synthesis \& Catalysis}, volume = {367}, year = {2025}, month = {FEB }, type = {Article}, abstract = {

We, herein, report a base free, photocatalytic decyanation of alpha-aminonitriles. A range of amides and lactams were obtained in 52-95\% yields. Control experiments indicate O2 as an amide/lactam oxygen source and the reaction (lactam formation) follows radical pathway via dioxetanimine species. This methodology also applied for alpha-ester/aldehyde substituted pyrrolidines in the presence of a base, probably via decarboxylation pathway.

}, keywords = {alpha-Aminonitriles, Decyanation, Dioxetanimine, Photocatalytic, pyrrolidine}, issn = {1615-4150}, doi = {10.1002/adsc.202400871}, author = {Kumar, Manish and Kumar, Pawan and Das, Utpal} } @article {49793, title = {Tunable, amine-functionalized porous silica catalyst for CO2 transformation into cyclic organic carbonates at atmospheric pressure}, journal = {Chemistry-A European Journal}, volume = {31}, year = {2025}, month = {AUG }, type = {Article}, abstract = {

A silica catalyst with characteristic features of broad pore size distribution, large pore width and tunable basic sites was synthesized by a one-step green co-condensation synthesis method analogous to SBA-15 synthesis. The surface chemical features of the above catalyst were explored by XPS, N-2 and CO2 adsorption and desorption experiments. The catalyst showed 90\% conversion of styrene oxide (SO) with nearly complete selectivity toward styrene carbonate (SC) in 7 hours under a solvent-free condition at a temperature of 120 degrees C with the aid of co-catalyst tetrabutylammonium bromide (TBAB). Moreover, the catalyst demonstrates versatility with various epoxide substrates, providing valuable insights into the cycloaddition reaction under ambient pressure conditions involving carbon dioxide. The mechanistic details of the catalytic conversion were investigated by the in-situ DRIFT studies and reported here.

}, keywords = {CO2 fixation, cyclic organic carbonates, heterogeneous catalysis, in-situ FTIR}, issn = {0947-6539}, doi = {10.1002/chem.202500873}, author = {Gorai, Twinkle and Thanasekar, Chandragopal and Kumar, Pawan and Babu, Athira and Kurungot, Sreekumar and Vinod, C. P.} }