Chemistry - Research Publications
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Item Visible-Light-Induced Metal- and Photocatalyst-Free Radical Cascade Cyclization of Cinnamamides for Synthesis of Functionalized Dihydroquinolinones(American Chemical Society, 2023-07-18T00:00:00) Nishad, Chandra Shekhar; Suman, Pallav; Saha, Himadri; Banerjee, BiplabVisible-light-promoted metal- and photocatalyst-free radical cascade cyclization of cinnamamides with ?-oxocarboxylic acids is described for sustainable synthesis of diverse pharmaceutically important dihydroquinolinone scaffolds in one pot under mild conditions. The decarboxylative cascade cyclization proceeded efficiently at room temperature without the need for expensive photocatalysts such as Ir or Ru complexes, which indicates the practicability and environmentally benign nature of this protocol. Preliminary mechanistic studies reveal that the blue LED irradiation efficiently cleaves the I-O bond of the hypervalent iodine reagent PhI(O2CCOAr)2 formed through ligand exchange between iodobenzene diacetate and arylglyoxylic acid to initiate the cascade reaction. The synthetic value of this operationally simple and energy-efficient method is further demonstrated by late-stage functionalization of drug molecules in excellent yields. � 2023 American Chemical Society.Item 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.Item Metal-Free Direct Access to N-Sulfonyl Amidines from Sulfonamides and Secondary Amines Involving Tandem C-N Bond Formations(American Chemical Society, 2022-08-17T00:00:00) Nishad, Chandra Shekhar; Haldar, Krishna Kanta; Banerjee, BiplabWe report a mild and efficient metal-free one-pot procedure for the synthesis of N-sulfonyl amidines via the direct reaction of sulfonamides with secondary amines without using any additives. A wide range of substrates with variety of functional groups is well tolerated under the reaction conditions. Preliminary mechanistic studies indicate that the secondary amine plays a dual role as a C1 source of the amidine group and an aminating agent. Synthetic utility of this method is shown in the late-stage functionalization of drug molecules on the gram scale. � 2022 American Chemical Society.Item Genomic DNA-mediated formation of a porous Cu2(OH)PO4/Co3(PO4)2�8H2O rolling pin shape bifunctional electrocatalyst for water splitting reactions(Royal Society of Chemistry, 2022-01-28T00:00:00) Singh, Harjinder; Ahmed, Imtiaz; Biswas, Rathindranath; Mete, Shouvik; Halder, Krishna Kamal; Banerjee, Biplab; Haldar, Krishna KantaAmong the accessible techniques, the production of hydrogen by electrocatalytic water oxidation is the most established process, which comprises oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Here, we synthesized a genomic DNA-guided porous Cu2(OH)PO4/Co3(PO4)2�8H2O rolling pin shape composite structure in one pot. The nucleation and development of the porous rolling pin shape Cu2(OH)PO4/Co3(PO4)2�8H2O composite was controlled and stabilized by the DNA biomolecules. This porous rolling pin shape composite was explored towards electrocatalytic water oxidation for both OER and HER as a bi-functional catalyst. The as-prepared catalyst exhibited a very high OER and HER activity compared to its various counterparts in the absence of an external binder (such as Nafion). The synergistic effects between Cu and Co metals together with the porous structure of the composite greatly helped in enhancing the catalytic activity. These outcomes undoubtedly demonstrated the beneficial utilization of the genomic DNA-stabilised porous electrocatalyst for OER and HER, which has never been observed. This journal is � The Royal Society of Chemistry.Item Dumbbell-Shaped Ternary Transition-Metal (Cu, Ni, Co) Phosphate Bundles: A Promising Catalyst for the Oxygen Evolution Reaction(American Chemical Society, 2022-01-27T00:00:00) Singh, Harjinder; Biswas, Rathindranath; Ahmed, Imtiaz; Thakur, Pooja; Kundu, Avinava; Panigrahi, Abhishek Ramachandra; Banerjee, Biplab; Halder, Krishna Kamal; Lahtinen, Jouko; Mondal, Krishnakanta; Haldar, Krishna KantaDevelopment of economical and high-performance electrocatalysts for the oxygen evolution reaction (OER) is of tremendous interest for future applications as sustainable energy materials. Here, a unique member of efficient OER electrocatalysts has been developed based upon structurally versatile dumbbell-shaped ternary transition-metal (Cu, Ni, Co) phosphates with a three-dimensional (3D) (Cu2(OH)(PO4)/Ni3(PO4)2�8H2O/Co3(PO4)2�8H2O) (CNCP) structure. This structure is prepared using a simple aqueous stepwise addition of metal ion source approach. Various structural investigations demonstrate highly crystalline nature of the composite structure. Apart from the unique structural aspect, it is important that the CNCP composite structure has proved to be an excellent electrocatalyst for OER performance in comparison with its binary or constituent phosphate under alkaline and neutral conditions. Notably, the CNCP electrocatalyst displays a much lower overpotential of 224 mV at a current density of 10 mA cm-2 and a lower Tafel slope of 53 mV dec-1 with high stability in alkaline medium. In addition, X-ray photoelectron spectroscopy analysis suggested that the activity and long-term durability for the OER of the ternary 3D metal phosphate are due to the presence of electrochemically dynamic constituents such as Ni and Co and their resulting synergistic effects, which was further supported by theoretical studies. Theoretical calculations also reveal that the incredible OER execution was ascribed to the electron redistribution set off in the presence of Ni and Cu and the most favorable interaction between the *OOH intermediate and the active sites of CNCP. This work may attract the attention of researchers to construct efficient 3D ternary metal phosphate catalysts for various applications in the field of electrochemistry. � 2022 American Chemical Society.Item Graphitic Carbon Nitride Composites with MoO3-Decorated Co3O4Nanorods as Catalysts for Oxygen and Hydrogen Evolution(American Chemical Society, 2021-10-22T00:00:00) Ahmed, Imtiaz; Biswas, Rathindranath; Patil, Ranjit A.; Halder, Krishna Kamal; Singh, Harjinder; Banerjee, Biplab; Kumar, Bhupender; Ma, Yuan-Ron; Haldar, Krishna KantaWe have prepared a graphitic carbon nitride (g-C3N4) composite with MoO3-decorated Co3O4 nanorods (Co3O4/MoO3/g-C3N4) via the hydrothermal approach, and this hybrid material acts as a highly active and durable electrocatalyst for water splitting reactions. This material could fundamentally influence the catalytic processes and performance of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The OER and HER activities of Co3O4-/MoO3-based nanorods are enhanced by blending with conducting support, for example, graphitic carbon nitrides (g-C3N4). The X-ray diffraction pattern and the attenuated total reflectance-Fourier transform infrared data revealed that the as-synthesized nanorods are highly crystalline in nature and are attached to the g-C3N4 support. Transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy studies also affirm the successful heterointerface formation between Co3O4/MoO3 nanorods and g-C3N4. This Co3O4/MoO3/g-C3N4 rod-shaped catalyst is highly stable in comparison to its individual constituent and generates a current density of 10 mA cm-2 at a low overpotential of 206 mV for OER and 125 mV for HER in alkaline and acidic media, respectively. This work could pave the way for developing Co3O4/MoO3/g-C3N4 composite materials as electrocatalysts for overall water splitting reactions. � 2021 American Chemical Society. All rights reserved.Item Interfacial Engineering of CuCo2S4/g-C3N4Hybrid Nanorods for Efficient Oxygen Evolution Reaction(American Chemical Society, 2021-07-29T00:00:00) Biswas, Rathindranath; Thakur, Pooja; Kaur, Gagandeep; Som, Shubham; Saha, Monochura; Jhajhria, Vandna; Singh, Harjinder; Ahmed, Imtiaz; Banerjee, Biplab; Chopra, Deepak; Sen, Tapasi; Haldar, Krishna KantaAltering the morphology of electrochemically active nanostructured materials could fundamentally influence their subsequent catalytic as well as oxygen evolution reaction (OER) performance. Enhanced OER activity for mixed-metal spinel-type sulfide (CuCo2S4) nanorods is generally done by blending the material that has high conductive supports together with those having a high surface volume ratio, for example, graphitic carbon nitrides (g-C3N4). Here, we report a noble-metal-free CuCo2S4 nanorod-based electrocatalyst appropriate for basic OER and neutral media, through a simple one-step thermal decomposition approach from its molecular precursors pyrrolidine dithiocarbamate-copper(II), Cu[PDTC]2, and pyrrolidine dithiocarbamate-cobalt(II), Co[PDTC]2 complexes. Transmission electron microscopy (TEM) images as well as X-ray diffraction (XRD) patterns suggest that as-synthesized CuCo2S4 nanorods are highly crystalline in nature and are connected on the g-C3N4 support. Attenuated total reflectance-Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy studies affirm the successful formation of bonds that bridge (Co-N/S-C) at the interface of CuCo2S4 nanorods and g-C3N4. The kinetics of the reaction are expedited, as these bridging bonds function as an electron transport chain, empowering OER electrocatalytically under a low overpotential (242 mV) of a current density at 10 mA cm-2 under basic conditions, resulting in very high durability. Moreover, CuCo2S4/g-C3N4 composite nanorods exhibit a high catalytic activity of OER under a neutral medium at an overpotential of 406 mV and a current density of 10 mA cm-2. � 2021 American Chemical Society.Item Green Approach for the Fabrication of Au/ZnO Nanoflowers: A Catalytic Aspect(American Chemical Society, 2021-03-19T00:00:00) Biswas, Rathindranath; Banerjee, Biplab; Saha, Monochura; Ahmed, Imtiaz; Mete, Shouvik; Patil, Ranjit A.; Ma, Yuan-Ron; Haldar, Krishna KantaAn easy, environmentally benign, and biomimetic approach employing Azadirachta indica (neem) leaf extract as a reducing as well as capping agent was used for the fabrication of gold (Au)/zinc oxide (ZnO) hybrid nanoflowers in one pot without utilizing any hazardous chemicals. The different phytoconstituents, for example, nimbolide, azadirachtin, ascorbate, etc., present in A. indica (neem) leaf extract synergistically reduce gold(III) ions to gold(0), which later on acts as an active surface for the growth of zinc oxide (ZnO) via thermal decomposition of sodium zincate [Na2Zn(OH)4]. The development of Au/ZnO hybrid nanoflowers was observed by estimating the absorption maxima at various time intervals in the wake of adding a Au precursor to the aqueous extract. X-ray diffraction (XRD) studies and X-ray photoelectron spectroscopy (XPS) investigation unambiguously confirm the formation of highly crystalline Au/ZnO composed of Au(0) and ZnO. The as-synthesized Au/ZnO hybrid nanoflowers were analyzed utilizing different spectroscopic and microscopic techniques. The transmission electron microscopy (TEM) images clearly show that the synthesized hybrid Au/ZnO nanoflowers are monodisperse and uniform. The fabricated Au/ZnO nanoflowers were used as a catalyst for the efficient reduction of various aromatic nitro compounds to corresponding amino compounds with excellent yield (76-94%) in the presence of reducing agent sodium borohydride. The superior catalytic properties were credited to the extraordinary nanoflower morphology and the synergistic impact of the typified Au nanoparticles. � 2021 American Chemical Society.