Dr. Biswajit Gayen
@surtech.edu.in
Assistant Professor
Dr. Sudhir Chandra Sur Institute of Technology & Sports Complex
RESEARCH INTERESTS
Synthesis of N-containing heterocycles, Material Science, Carbon Dots and its application
Scopus Publications
Scopus Publications
Biswajit Gayen, Soubantika Palchoudhury, and Joydeep Chowdhury
Hindawi Limited
Carbon dots (CDs) have received significant attention worldwide from the beginning of this century, and recently, it has bloomed in every branch of applied sciences. Because of their outstanding physical and chemical properties together with biocompatibilities, CDs find a wide spectrum of applications in drug delivery, explosive detection, chemical sensing, food safety, bioimaging, energy conversion, photocatalysis, etc. This brief review is focused on the synthesis of CDs and their applications. The photophysical properties of CDs are also discussed herewith.
Biswajit Gayen, Avijit Banerji, and Kaliprasanna Dhara
Informa UK Limited
ABSTRACT Simple and efficient strategies toward the synthesis of trisubstituted pyrrolizidines and disubstituted oxazolidine systems by 1,3-dipolar cycloaddition reactions using arylaldehydes and α-amino acids have been developed, followed by a one-pot, three-component strategy. Electron-deficient dipolarophiles, chalcones, were reacted with nonstabilized azomethine ylides derived from arylaldehyde and L-proline in dry dimethyl formamide, leading to substituted pyrrolizidines. The route to substituted oxazolidines involved cycloaddition to the C˭O bond of a second molecule of the aldehyde. The structures and stereochemistry of the cycloadducts were established by infrared (IR), NMR spectroscopy, and single-crystal x-ray crystallographic analyses. Condensed Fukui functions and local electrophilicity indices have been computed to characterize the reactive sites and predict the preferred interactions of azomethine ylides to planar chalcones. The softness-matching indices have been evaluated to determine the regioselectivity of the cycloaddition reactions. The theoretical predictions were found to be in complete agreement with the experimental results, implying that the density functional theory (DFT)-based reactivity indices correctly predict the regioselectivities of 1,3-dipolar cycloadditions of azomethine ylides to planar chalcones. The frontier molecular orbital (FMO) energies, electronic chemical potentials, chemical hardness, chemical softness, and global electrophilicity indices of azomethine ylides have been calculated at the DFT/B3LYP/6-31 + G (d, p) level of theory. GRAPHICAL ABSTRACT
Biswajit Gayen and Avijit Banerji
Wiley
Azomethine ylides derived in situ from l-proline and aryl aldehydes underwent regioselective and stereoselective cycloadditions with diaryl cycloahexanone to form a series of spiro-pyrrolizidine compounds. By using equimolar proportions of the reactants in DMF, only a single mono-adduct, namely 6′-arylidene-1-aryl-3-aryl-spiro[pyrrolizidine-2,2′-cyclohexanone], was formed, the second double bond in the dipolarophile remaining unaffected. Structure elucidation was achieved by detailed spectroscopic analyses and XRD studies. Interesting solid-state structural characteristics were revealed by XRD analysis.
Biswajit Gayen and Avijit Banerji
Informa UK Limited
Abstract A facile route to tetra-substituted pyrrolidines has been accomplished by 1,3-dipolar cycloaddition reaction. Several pyrrolidine compounds have significant biological activity. A highly electron-deficient dipolarophile, β-nitrostyrene, was reacted with nonstabilized azomethine ylides derived from aryl aldehyde and L-phenylglycine in dry dimethyl formanide. The structures and stereochemistry of the cycloadducts were established by infrared, NMR spectroscopy, and single-crystal x-ray crystallographic analyses. GRAPHICAL ABSTRACT
Biswajit Gayen and Avijit Banerji
Springer Science and Business Media LLC
Simple and efficient strategies towards the synthesis of substituted spiro-oxindole and oxazolidine systems by one-pot multi-component catalyst-free reactions utilising aryl aldehydes and α-amino acids have been developed. Owing to their complicated structure and ring strain spiro-oxindole moieties are not easily synthesised. In either route 1,3-dipolar cycloadditions involving non-stabilised azomethine ylides as intermediates, generated in situ from amino acids and aldehydes, with the dipolarophile present in the reaction mixture viz. (E)-β-nitrostyrene, were utilised. The route to substituted oxazolidines involved cycloaddition to the C=O bond of a second molecule of the aldehyde.Graphical Abstract