Browsing by Author "Lokman H. Choudhury"

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A reversible and efficient probe for dual mode recognition of Al3+ and Cu2+ with logic gate behaviour: Crystal structure, theoretical and in-vivo bio-imaging investigations
(Elsevier B.V., 2022) Pranjalee Yadav; Rohit Kumar; S. Srikrishna; Anoop Kumar Pandey; Lokman H. Choudhury; Chandan Upadhyay; Vinod P. Singh
This work presents the synthesis, characterization, crystal structure and spectroscopic investigations of isophthalohydrazide based probe. Among various tested metal ions, the probe selectively detects Al3+ and Cu2+ in aqueous ethanol via fluorometric and colorimetric methods, respectively. It displays a fluorescence “turn-on” response with Al3+ and visual colour change from colourless to yellow with Cu2+. Sensing mechanism is explored with UV–Vis, fluorescence spectroscopy and 1H NMR titration, and confirmed with computational results. Suppression of C[dbnd]N isomerization and photo-induced electron transfer (PET) along with chelation enhanced fluorescence emission (CHEF) result in “turn-on” fluorescence with Al3+ while ligand to metal charge transfer (LMCT) accounts for visual colour change with Cu2+. Job's plot and HRMS confirm 1:2 (L:M) stoichiometry. The probe also exhibits efficient reversibility and reproducibility with EDTA which are successfully mimicked with combinatorial logic gate and truth table. Additionally, solid state applications and bio-imaging investigation on gut tissue of Drosophila 3rd instar larvae are performed. © 2021 Elsevier B.V.
Aroyl hydrazone with large Stokes shift as a fluorescent probe for detection of Cu2+ in pure aqueous medium and in vivo studies
(Elsevier B.V., 2020) Romi Dwivedi; Saumya Singh; Brijesh Singh Chauhan; S. Srikrishna; Anoop Kumar Panday; Lokman H. Choudhury; Vinod Prasad Singh
An aroyl hydrazone based fluorescent probe, hpsh, has been developed for the selective detection of Cu2+ ions in pure aqueous medium by static fluorescence quenching. The fluorescence quenching of hpsh in the presence of Cu2+ takes place as a result of ground state complex formation through intramolecular charge transfer (ICT). Addition of Cu2+ ions changes the color of the solution from colorless to yellow-green which is clearly visible by naked eye. Large Stokes shift of hpsh prevents the self-quenching of the probe in absence of metal ions. The observed stoichiometry between Cu2+ and probe has been found as 1:2 (M: L). MTT assay of hpsh on fruit flies confirms that the probe is non-toxic and biocompatible. The plausible in vivo bioimaging application of the probe to detect Cu2+ in Drosophila gut tissues as well as in adult fruit fly has been investigated with excellent results. © 2020 Elsevier B.V.
Intracellular application and logic gate behavior of a ‘turn off-on-off’ type probe for selective detection of Al3+ and F− ions in pure aqueous medium
(Elsevier B.V., 2018) Romi Dwivedi; Divya Pratap Singh; Brijesh Singh Chauhan; S. Srikrishna; Anoop Kumar Panday; Lokman H. Choudhury; Vinod Prasad Singh
A new Schiff base tcph, derived from 2-thiophene carboxylic acid hydrazide, has been synthesized and characterized by various spectroscopic techniques. The molecular structure of the compound has also been determined by X-ray crystallography. The tcph acts as a selective Al3+ and F− induced OFF-ON-OFF type of probe in aqueous media. The 1:1 binding stoichiometry between probe and Al3+ has been established from Job's plot and further supported by ESI–MS studies. The limit of detection of Al3+ ions is determined by 3σ methods, which is found to be 1.35 × 10−9 M. The coordination environment for the tcph-Al3+ complex is delineated by NMR titration and DFT calculations. Detailed insights of probe–metal interaction mechanism have been studied by density functional theory (DFT) as well as time dependent–DFT calculations. MTT assay of the probe on live SiHa cells suggests no serious cytotoxicity in cells even at higher concentration. The probe tcph and its tcph-Al3+ complex have also been successfully applied to detect Al3+ and F− ions in living cells (SiHa cells), respectively. © 2017 Elsevier B.V.