Chemistry - Research Publications

Permanent URI for this collectionhttps://kr.cup.edu.in/handle/32116/37

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Author: search.filters.author.Dhayal, Rajendra S.

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    Ag-S Type Quantum Dots versus Superatom Nanocatalyst: A Single Sulfur Atom Modulated Decarboxylative Radical Cascade Reaction
    (American Chemical Society, 2023-04-06T00:00:00) Meena, Sangeeta; Dastider, Saptarshi G.; Nishad, Chandra Shekhar; Jangid, Dilip Kumar; Kumar, Pankaj; Khirid, Samreet; Bose, Shubhankar Kumar; Mondal, Krishnakanta; Banerjee, Biplab; Dhayal, Rajendra S.
    The preparation of high-nuclearity silver nanoclusters in quantitative yield remains exclusive and their potential applications in the catalysis of organic reactions are still undeveloped. Here, we have synthesized a quantum dot (QD)-based catalyst, [Ag62S13(SBut)32](PF6)4 (denoted as Ag62S12-S) in excellent yield that enables the direct synthesis of pharmaceutically precious 3,4-dihydroquinolinone in 92% via a decarboxylative radical cascade reaction of cinnamamide with ?-oxocarboxylic acid under mild reaction conditions. In comparison, a superatom [Ag62S12(SBut)32](PF6)2 (denoted as Ag62S12) with identical surface anatomy and size, but without a central S2- atom in the core, gives an improved yield (95%) in a short time and exhibits higher reactivity. Multiple characterization techniques (single-crystal X-ray diffraction, nuclear magnetic resonance (1H and 31P), electrospray ionization mass spectrometry, energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis) confirm the formation of Ag62S12-S. The BET results expose the total active surface area in supporting a single e- transfer reaction mechanism. Density functional theory reveals that leaving the central S atom of Ag62S12-S leads to higher charge transfer from Ag62S12 to the reactant, accelerates the decarboxylation process, and correlates the catalytic properties with the structure of the nanocatalyst. � 2023 American Chemical Society.
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    Facile Fabrication of Ni9S8/Ag2S Intertwined Structures for Oxygen and Hydrogen Evolution Reactions
    (John Wiley and Sons Inc, 2022-12-21T00:00:00) Biswas, Rathindranath; Ahmed, Imtiaz; Manna, Priyanka; Mahata, Partha; Dhayal, Rajendra S.; Singh, Amol; Lahtinen, Jouko; Haldar, Krishna Kanta
    Here, we report the fabrication of the unique intertwined Ni9S8/Ag2S composite structure with hexagonal shape from their molecular precursors by one-pot thermal decomposition. Various spectroscopic and microscopic techniques were utilized to confirm the Ni9S8/Ag2S intertwined structure. Powder X-ray Powder Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis suggest that there is an enrichment of Ni9S8 phase in Ni9S8/Ag2S. The presence of Ag2S in Ni9S8/Ag2S improves the conductivity by reducing the interfacial energy and charge transfer resistance. When Ni9S8/Ag2S is employed as an electrocatalyst for electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity, it requires a low overpotential of 152 mV for HER and 277 mV for OER to obtain the geometrical current density of 10 mA cm?2, which is definitely superior to that of its components Ni9S8 and Ag2S. This work provides a simple design route to develop an efficient and durable electrocatalyst with outstanding OER and HER performance and the present catalyst (Ni9S8/Ag2S) deserves as a potential candidate in the field of energy conversion systems. � 2022 Wiley-VCH GmbH.
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    Facile synthesis of alkyl- and arylboronate esters enabled by a carbon nanotube supported copper catalyst
    (Royal Society of Chemistry, 2022-11-15T00:00:00) Saini, Suresh; Gavali, Deepak S.; Bhawar, Ramesh; Thapa, Ranjit; Dhayal, Rajendra S.; Bose, Shubhankar Kumar
    An efficient synthesis of alkylboronate esters via alkyl halide borylation catalysed by copper nanoparticles stabilised on nitrogen-doped carbon nanotubes (N-CNT) is reported. This nanocatalyst provides practical access to alkylboronate esters at room temperature in 1 h, with good functional group tolerance. The procedure is also applicable to the borylation of benzyl chlorides and bromides. Radical clock experiments suggest that the reaction involves a radical pathway. The catalyst can be recycled up to ten runs without appreciable loss in the activity. In addition, we demonstrated the use of this supported copper catalyst for the anti-Markovnikov-selective hydroboration of vinylarenes and borylation of aryl halides with B2pin2, providing alkyl- and arylboronate esters, respectively, in good to excellent yields. � 2023 The Royal Society of Chemistry.
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    Dithiophosphonate Anchored Heterometallic (Ag(I)/Fe(II)) Molecular Catalysts for Electrochemical Hydrogen Evolution Reaction
    (American Chemical Society, 2022-08-12T00:00:00) Jangid, Dilip Kumar; Dastider, Saptarshi G.; Biswas, Rathindranath; Khirid, Samreet; Meena, Sangeeta; Kumar, Pankaj; Sahoo, Subash C.; Verma, Ved Prakash; Makde, Ravindra D.; Kumar, Ashwani; Jangir, Ravindra; Mondal, Krishnakanta; Haldar, Krishna Kanta; Dhayal, Rajendra S.
    The dichalcogenide ligated molecules in catalysis to produce molecular hydrogen through electroreduction of water are rarely explored. Here, a series of heterometallic [Ag4(S2PFc(OR)4] [where Fc = Fe(?5-C5H4)(?5-C5H5), R = Me, 1; Et, 2; nPr, 3; isoAmyl, 4] clusters were synthesized and characterized by IR, absorption spectroscopy, NMR (1H, 31P), and electrospray ionization mass spectrometry. The molecular structures of 1, 2, and 3 clusters were established by single-crystal X-ray crystallographic analysis. The structural elucidation shows that each triangular face of a tetrahedral silver(I) core is capped by a ferrocenyl dithiophosphonate ligand in a trimetallic triconnective (?3 ?2, ?1) pattern. A comparative electrocatalytic hydrogen evolution reaction of 1-5 (R = iPr, 5) was studied in order to demonstrate the potential of these clusters in water splitting activity. The experimental results reveal that catalytic performance decreases with increases in the length of the carbon chain and branching within the alkoxy (-OR) group of these clusters. Catalytic durability was found effective even after 8 h of a chronoamperometric stability test along with 1500 cycles of linear sweep voltammetry performance, and only 15 mV overpotential was increased at 5 mA/cm2 current density for cluster 1. A catalytic mechanism was proposed by applying density functional theory (DFT) on clusters 1 and 2 as a representative. Here, a ?1 coordinated S-site between Ag4 core and ligand was found a reaction center. The experimental results are also in good accordance with the DFT analysis. � 2022 American Chemical Society.
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    Ferrocene decorated homoleptic silver(I) clusters: Synthesis, structure, and their electrochemical behaviour
    (Elsevier B.V., 2021-06-07T00:00:00) Khirid, Samreet; Jangid, Dilip Kumar; Biswas, Rathindranath; Meena, Sangeeta; Sahoo, Subash C.; Verma, Ved Prakash; Nandi, Chandan; Haldar, Krishna Kanta; Dhayal, Rajendra S.
    Silver(I) ferrocenyl dithiophosphonato [Ag{S2P(OiPr)Fc}]n I, [Fc = Fe(?5-C5H4)(?5-C5H4)] 1D polymer was yielded via a ligand exchange reaction between silver nanocluster [Ag21(S2P(OiPr2)12)]PF6 and monoanionic [S2P(OiPr)Fc]� ligand. As per molecular stoichiometry of 1, a direct reaction between [Ag(CH3CN)4]PF6 and [S2P(OiPr)Fc]? was performed in methanol solvent and surprisingly, generate a tetrahedral Ag4{S2P(OiPr)Fc}4 2 cluster instead of 1. Both (1 and 2) clusters are the novel example of homoleptic Ag(I) complexes supported by ferrocenyl dithiophosphonates. Molecular structure of these clusters was unequivocally established by single crystal X-ray crystallographic analyses and supported by the ESI-MS, and 1H and 31P NMR spectroscopy. Structural elucidations reveal that compound 1 has subsequently Ag2S2 square plane and Ag2S4P2 twisted boat units to build a long chain 1D polymer. The cluster 2 exhibits with a tetrahedral Ag(I) core framed by four [S2P(OiPr)Fc]? ligands. interstingly, the [S2P(OiPr)Fc]? ligand display a trimetallic triconnective (?3; �1, �2) bonding pattern in both molecules. The electrochemical behaviours of both compounds (1 and 2) were studied by using cyclic voltammetry, which shows a single wave for all the peripheral ferrocenes and implies negligible electrostatic factor between all ferrocene moieties. � 2021