Browsing by Author "Sumit K. Panja"

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Coumarin-based photoacid as a dual-state probe for studying proton transfer dynamics from solute to solvents
(Elsevier B.V., 2025) Anas D. Fazal; Trupti D. Solanky; Abhishek R. Patel; Om Prakash; Subhendu Dhibar; Sumit Mohan Kumar; Sumit K. Panja
In present work, we have developed a coumarin based water-soluble photoacid (3-acetyl-7-hydroxy-2H-chromen-2-one: HyCAc) which acts as a dual-state probe for investigating proton transfer processes from solute to solvents at ground and excited state. Intermolecular hydrogen bonding interactions significantly enhance the proton transfer process. A solvent-dependent proton transfer is evident from the relative intensity of the ICT band in UV–Vis spectra at the ground state. Polar aprotic and protic and aprotic solvents participate in the proton transfer from solute to solvent through intermolecular hydrogen bonding interactions at ground state. Additionally, HyCAc exhibits solvent-specific dual fluorescence and photodissociation behavior in solution at excited states. Photodissociation of HyCAc is observed due to the proton transfer process from solute to solvents at excited state. To deepen the mechanistic understanding, we performed Natural Bond Orbital (NBO) analysis to explore intermolecular interactions through second-order perturbation energy calculations. Atoms in Molecules (AIM), Non-Covalent Interaction (NCI) analysis, Electron Localization Function (ELF), and Localized Orbital Locator (LOL) analyses to elucidate the nature of non-covalent interactions and are also carried out to explore solvent-dependent solute–solvent interactions. © 2024
Influence of alkyl chain length on thermophysical, structural properties and molecular dynamics of new pyridinium-ester based room temperature ionic liquids
(Elsevier B.V., 2025) Anas D. Fazal; Trupti D. Solanky; Abhishek R. Patel; Anil H. Gore; Amrutlal L. Prajapat; Om Prakash; Sumit Mohan Kumar; Sumit K. Panja
In present work, a series of new pyridinium-ester-based room-temperature ionic liquids (RTILs) have been synthesized. Thermal stability and the changes of viscosity properties of these RTILs have been studied on the basis of the ester functionality on pyridinium cation moiety and with alkyl chain length size. Drastic change in viscosity is explained on basis of hydrogen bonding interaction and microheterogeneity. The origin of microscopic properties and the heterogeneity of these ILs are examined in terms of the interactions between cations and anions. Viscosity results of these RTILs are fitted and analysed by using Arrhenius model and Vogel-Tammann-Fulcher (VTF) model. Furthermore, Natural Bond Orbital (NBO) analysis is conducted to enhance the understanding of intermolecular interactions through second-order perturbation energy calculations. Complementary computational methods, including Atoms in Molecules (AIM) analysis, Non-Covalent Interaction (NCI) analysis, Electron Localization Function (ELF), as well as Localized Orbital Locator (LOL), offer valuable insights into the characteristics and nature of non-covalent interactions in these RTILs. Based on our experimental results, these RTILs exhibit excellent viscosity properties and may have the potential to be used as lubricants for suitable designs and future applications. © 2025 The Authors.
NIR luminescent heterodinuclear [ZnII LnIII] complexes: Synthesis, crystal structures and photophysical properties
(Elsevier B.V., 2017) Nidhi Dwivedi; Sumit K. Panja; Abhineet Verma; Tomohisa Takaya; Koichi Iwata; Sailaja S. Sunkari; Satyen Saha
Two series of new 3d-4f heterodinuclear [ZnIILnIII] Schiff base complexes of general formula [Zn(µ-L1)(µ-CH3COO)Ln(NO3)2(S)] [Ln = Pr (1), Nd (2), Sm (3), Gd (4); S = MeOH; H2L1= N,N-bis(3-methoxysalicylidene)-1,4-diaminobutane] and [Zn(µ-L2)(µ-CH3COO)Ln(NO3)2(S)] [Ln= Pr (5), Nd (6), Sm (7), Gd (8), S= MeOH; H2L2= N,N-bis(3-ethoxysalicylidene)-1,4-diaminobutane] are synthesized and fully characterized. Complexes 1, 2, 3, 4, 5 & 7 are structurally characterized by single crystal X-ray crystallography. The crystallographic investigation indicates that the complexes contain 9 and 10-coordinated LnIII ions, while the ZnII ions always display a distorted square-pyramidal geometry. The crystal structure of the complexes are stabilized by inter molecular extended hydrogen bonding and C-H····π interactions resulting in supramolecular frameworks. Luminescence studies for the heterodinuclear compounds containing NdIII & SmIII reveal that the Zn-complex moiety acts as antenna for the emission from LnIII ions. In addition to the ligand-centered emission in the UV–Vis region, complex 2 (having NdIII) exhibits emission in NIR region also, thus resulting a new NIR emitting material. © 2017
Thiophene oligomer based NIR dyes: Photophysical properties and application in dye sensitized solar cells
(Elsevier B.V., 2025) Sumit K. Panja; Shyam Sunder Sharma; Khushboo Sharma; Kinjal K. Patel; Amrutlal L. Prajapat; Satyen Saha; Sayantan Bera; Nitin Srivastava; Jaymin R. Ray
Oligomers based on thiophene, or oligothiophenes, are the carbon substrates families that show great promise for use as molecular semiconductors in organic electronics. Dicyanovinyl-substituted oligothiophenes (Figure: 1; TH2CN4 and TH3CN4) have shown interesting photophysical properties at NIR region in solution. Both TH2CN4 and TH3CN4 analysed thoroughly and further utilized as a photosensitizer in the Dye Sensitized Solar Cells (DSSCs). The Current–Voltage (I-V) performance of photovoltaic cells is quite inspiring for the future further investigation. Apart from I-V, the cells are also characterized by Scanning electron microscopy and Electrochemical Impedance Spectroscopy. © 2025 Elsevier B.V.