Browsing by Author "Sumit Mohan Kumar"

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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
Exploring the recognition behavior of a fluorescein-based probe towards the significant detection of Cu2+ and Zn2+ ions: Experimental and computational studies
(Elsevier B.V., 2025) Navneet Kumar; Pawan Kumar Sada; Amit Kumar Kundan; Amit Bar; Amanpreet Kaur Jassal; Surya Prakash Rai; Vipendra Kumar Singh; Neha Garg; Alok Kumar Singh; Ankit Kumar Singh; Sumit Mohan Kumar; Laxman Singh; Abhishek Rai
A new fluorescein hydrazone (FA1) has been synthesized employing fluorescein hydrazide and 3,5-diiodosalicylaldehyde and its complete physiochemical characterization have been carried out. A single crystal XRD studies of FA1 has been performed. Among the tested metal ions FA1 significantly detects Cu2+ and Zn2+ in EtOH/H2O (8:2, v/v)). There is an emergence of a new absorbance peak at λmax 431 nm with Cu2+ ions. A “turn-on” behavior in fluorescence at λem510 nm was observed with Zn2+ ions owing to chelation enhanced fluorescence. This act of spectrophotometric changes and naked eye color variation from colorless to yellow is because of coordination with the metal ions rather than most common opening of spirolactum ring. FA1-Cu2+ and FA1-Zn2+ensembles display reversible behavior with EDTA2− ions. In a study on latent fingerprint detection using powder compounds, it was found that FA1 and FA1–Zn2+ showed excellent adherence to finger ridges and produced clear features without any background stains. The Hirshfeld surface and fingerprint analysis of FA1 offer a detailed examination of pairwise interactions between atoms. Additionally, topological analysis of FA1 has been conducted using NCI, AIM, ELF, and LOL methodologies. Alamar assay of FA1 on HEK-293 cell lines exhibited biocompatibility with minimal cytotoxicity. Hence, they were effectively applied for live cell imaging for intracellular sensing of Cu2+ and Zn2+ in HEK-293 cells. © 2025 Elsevier B.V.
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.