Mukesh Chandiramani

Design of a dual sensing highly selective cyanide chemodosimeter based on pyridinium ring chemistry

A new chemodosimeter, Quino-P, recognizes the strongly nucleophilic cyanide by dual colorimetric and fluorescence ‘off–on’ signalling responses. Noteworthily, several other anions, even in significantly higher concentrations, induce no detectable photophysical perturbations. The chemodosimeter mechanism involves formation of a C4–cyano adduct, which exhibits an uncommon phenomenon of enhanced internal charge transfer interaction.

New 1,8-naphthyridine-based probes for the selective fluorescence signalling of toxic cadmium: synthesis, photophysical studies and molecular modelling

Newly synthesised 1,8-naphthyridine-based molecular probes, NAP-1 and NAP-2, exhibit highly selective fluorescence responses towards the toxic cadmium over coordinatively competing Zn2+ and several other metal ions examined. On the one hand, NAP-1 (MeOH:H2O, v/v 80:20, pH 7.4) exhibits ca. 1.5 order of magnitude higher stability constant for Cd2+ over Zn2+; on the other hand, NAP-2 in MeOH offers unique selectivity only towards Cd2+, exhibiting both absorbance and emission red shifts as well as fluorescence enhancement. By 1H NMR analysis, the tetra-coordinated binding is indicated at least for the NAP-1+Cd2+ complex and theoretical calculations reveal relatively stronger binding of Cd2+ over Zn2+.

A simple 2,6-bis(2-benzimidazole)pyridyl incorporated optical probe affording selective ratiometric targeting of biologically and environmentally significant Zn2+ under buffer condition

AbstractA new chemosensor, designated as Dibcid has been synthesized in two steps from readily accessible 2,6-bis(2-benzimidazole)pyridine. Our photophysical studies revealed that of the several metal ions examined, biologically and environmentally significant Zn2+ exhibited highly selective emission wavelength shifts under the buffer condition. In contrast to Zn2+, the coordinatively competing and toxic Cd2+ elicited less remarkable optical responses as evidenced by its two order of magnitude lower stability constant compared to that of Zn2+. Moreover, metal ions, viz. Li+, Na+, K+, Mg2+, Ca2+, Ba2+, Co2+, Ni2+, Cu2+, Hg2+ and Pb2+ exhibited insignificant optical perturbations even in concentrations far exceeding Zn2+. Clearly, the probe has the attributes to selectively target Zn2+ by ratiometric analysis under buffer conditions.