Browsing by Author "Pawan Kumar Sada"

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A Novel Rhodamine Probe Acting as Chemosensor for Selective Recognition of Cu2+ and Hg2+ Ions: An Experimental and First Principle Studies
(Springer, 2024) Pawan Kumar Sada; Amit Bar; Amanpreet Kaur Jassal; Prabhat Kumar; S. Srikrishna; Alok Kumar Singh; Sumit Kumar; Laxman Singh; Abhishek Rai
Copper and Mercury ions have vital role to play in biological world as their excess or deficiency can cause different type of diseases in human being as well as biological species including plants and animals. Therefore, their detection at trace level becomes very important in term of biological. The current studies embody the fabrication, structural characterization and recognition behavior of a novel rhodamine B hydrazone formed when hydrazide of rhodamine B was condensed with 5-Allyl-3-methoxy salicylaldehyde (RBMA). RBMA was found to be responsive towards the very trace level of Cu2+ and Hg2+ among other tested cations so far. The sensing procedure is based on the classical opening of the spiroatom ring of rhodamine. The limit of detection (LOD) and binding constant is 5.35 ppm, 2.06 × 104 M−1 and 5.16 ppm, 1.26 × 104 M−1 for Cu2+ and Hg2+ ions respectively. The probable mechanism correlates the specific binding of RBMA with Cu2+ and Hg2+ ions. The 1:1 stoichiometry of RBMA with Cu2+ and Hg2+ ions have been supported by HRMS, FT-IR data, Job's plot, and binding constant data. Reversibility is well exhibited by RBMA by the involvement of CO32− ions via demetallation process. The real time application is well demonstrated by the use of paper strip test. The DFT study also carried out which agrees well with the experimental findings. The results displayed the novelty of this current work towards the trace level analysis of the Cu2+ and Hg2+ of the cations which are play the crucial role in industry. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2023.
Development of a new rhodamine 6G based probe and its application as an optical sensor of Cu2+ and Fe3+ ions: A comprehensive experimental and Theoretical studies
(Elsevier Inc., 2024) Pawan Kumar Sada; Amanpreet Kaur Jassal; Amit Bar; Prabhat Kumar; S. Srikrishna; Sumit Kumar; Alok Kumar Singh; Youngil Lee; Laxman Singh; Abhishek Rai
A new rhodamine appended probe 3-allyl salicylaldehyde rhodamine hydrazone (RGAL) has been synthesized and thoroughly characterized using various spectroscopic techniques, as well as single crystal XRD. The optical properties of RGAL were investigated in 10 mM HEPES buffer in H2O:CH3CN (2:8, v/v, pH=7.2) in the presence of various cations. RGAL showed selectivity and sensitivity towards Cu2+ during absorption process and “turn on” behavior towards Fe3+ during emission study owing to the opening of a spirolactum ring. The detection limits for Cu2+ and Fe3+ ions using RGAL were determined to be 6.15 ppm and 4.75 ppm, respectively. The binding constant of RGAL with Cu2+ and Fe3+ ions was found to be 1.20 × 104 M−1 and 1.71 × 104 M−1, respectively. Hirshfeld surface and fingerprint analysis of RGAL provides the in-depth analysis of pairwise interaction between two atoms. Furthermore, the topological analysis of RGAL is performed using NCI, AIM, ELF and LOL analysis. The analysis provides information about O78-H79…N71 and C40-H41…O77 hydrogen bonding interactions in the monomer of RGAL whereas various inter- and intra- molecular interactions give strength to the dimer pattern of RGAL. © 2024 Elsevier B.V.
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.
Metal Nanocomposites as Optical Sensor for Ions and Molecules of Environmental Concern
(Springer Nature, 2022) Pranshu Kumar Gupta; Pawan Kumar Sada; Vikas Kumar Sonu; Abhishek Rai
Multi phasic metal nanocomposites comprising a zero-dimensional metal nanoparticles phase (0.5–5% w/w) have significantly enhanced the material property and sensing ability of easily recoverable conventional matrices like glass, ceramics, metal, carbon allotropes or polymers. Over the past few years, promising chemical and physical properties of metal nanocomposites, developed via direct in situ chemical, photocatalytic, or thermal reduction of metal salts, over common matrix, or ex situ direct insertion of nanoparticles into the polymer. Colorimetric MNC sensors like metal–metal oxide NPs, quantum dots have depicted a relation between their type, structure, function and sensing performance, via aggregation/decomposition of NPs, fluorescence on/off and ligand-receptor interaction. Functional single/multilayered transition-metal dichalcogenides have been employed both, as a matrix for their decoration exhibiting synergism and quite recently as nanocomposites exhibiting ultra-fast and selective multi-sensor activity over narrow detection limits that are an urgent demand of national, homeland and environment safety. Fabrication of these biosensors endorse their progress in environmental and material aspects. They are employed as bio-analytic sensors against excess of heavy metal ions, nitro-compounds, poly-aromatic hydrocarbons, microbial proteins etc. imparting exclusive photo-chromatic and electronic properties, tuned at grass-root level by adjusting various supramolecular interactions and also the metal-ligands interactions at molecular level. Nanocomposites have several applications mainly in biological arenas, solar cells, communication field, optoelectronic devices etc. In this chapter we would discuss about recently developed nanocomposite-sensors, their synthesis, mechanism for their sensing action and environmental application involving mainly optical sensors. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.