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Issue 14, 2016
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A thiosemicarbazone based chemo and fluorogenic sensor for Zn2+ with CHEF and ESIPT behaviour: computational studies and cell imaging application

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Abstract

We report herein the development of a novel, diformyl-p-cresol (DFC)–thiosemicarbazide (TS) based sensor (DFC–TS) that selectively and sensitively recognizes Zn2+ by both UV-Vis and fluorescence methods. The gradual addition of Zn2+ to a solution of the ligand developed a new absorption band at 430 nm, while the bands at 370 and 316 nm gradually decrease generating one well defined isosbestic point at 390 nm exhibiting ∼17 fold turn-on fluorescent enhancement (FE). When we plot absorbance (at 430 nm) vs. [Zn2+] there is a gradual increase in absorption with [Zn2+], becoming saturated at ∼1 equivalent of Zn2+ and then again it increases with the increase in [Zn2+] and ultimately becomes saturated at ∼2 equivalents of added Zn2+. This clearly demonstrates that the Zn2+ binding event to the ligand occurs in two steps, one at a time. Non-linear least-squares computer-fitting of these data gives the parameters: Kf1 = (9.70 ± 5.51) × 105 M−1, n = (1.28 ± 0.05) for the first step and Kf2 = (1.11 ± 0.65) × 105 M−1 and n = (1.01 ± 0.06) for the second step. So far, this study provides the opportunity where we have successfully, for the first time, determined the stepwise formation constants; though they have values of the same order of magnitude. The ground state geometries of DFC–TS, both enol and keto forms and [Zn(DFC–TS)(OAc)], [Zn(DFC–TS)(OAc)], and [Zn2(DFC–TS)(OAc)2] were optimized using the Gaussian-03 suit program and bond distances of all species are in reasonable agreement with the reported values.

Graphical abstract: A thiosemicarbazone based chemo and fluorogenic sensor for Zn2+ with CHEF and ESIPT behaviour: computational studies and cell imaging application

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Publication details

The article was received on 02 Dec 2015, accepted on 17 Jan 2016 and first published on 20 Jan 2016


Article type: Paper
DOI: 10.1039/C5RA25653D
RSC Adv., 2016,6, 11388-11399

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    A thiosemicarbazone based chemo and fluorogenic sensor for Zn2+ with CHEF and ESIPT behaviour: computational studies and cell imaging application

    R. Bhowmick, R. Alam, T. Mistri, K. K. Das, A. Katarkar, K. Chaudhuri and M. Ali, RSC Adv., 2016, 6, 11388
    DOI: 10.1039/C5RA25653D

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