Shuvankar Dey

A rhodamine B-functionalized oxacalix[4]arene architecture has been designed as a dual-responsive probe for the sequential recognition of Hg²⁺ and S²⁻ ions.

An oxacalix[4]arene-Ce(III) complex viz. L–Ce(III) has been introduced for the selective detection of As(V) and Cr(VI) oxyanions in aqueous medium. The binding mode of L–Ce(III) + AsO₄ ³⁻/CrO₄ ²⁻ was completely investigated with fluorometric titration, time resolve fluorescent decay and FTIR analyses. Photoinduced electron transfer (PET) and chelation-enhanced fluorescence (CHEF) play an important role in the sensing of these oxyanions. The characteristic fluorescence of the L–Ce(III) complex has been quenched by AsO₄ ³⁻ and CrO₄ ²⁻ through cascading the ligating sites. Cyclic voltammetry (CV) experiments with various scan rates suggest that the electrochemical processes on the electrodes were controlled by diffusion. Both the analytes exhibit a lower limit of detection (LOD) below their standard EPA permissible limits. Moreover, the probe successfully detects the oxyanions in environmental real samples with excellent recovery ranging from 97 to 101%.

N‐methyl‐4‐nitroaniline (MNA), an insensitive munition is selectively and sensitively recognized by a new resorcinarene bearing quinoline moiety, i.e, Tetra‐Methoxy Resorcinarene Tetra‐Quinoline Acetamide (TMRTQA). A simple and efficient spectrofluorimetric technique demonstrates the quenching of the fluorescence intensity of TMRTQA upon addition of MNA within concentration limits of 2 nM to 1 μM. Binding constant and quantum yield have been determined in this study. Molecular docking studies have been performed to predict the best binding affinity and the possible interactions for the formation of complex between TMRTQA and MNA supporting the 1:1 stoichiometry. Density functional theory calculation also support the excitation wavelength and geometry optimization. MNA being a hazardous environmental pollutant has been successfully detected from the water sample by standard addition method.

A newly synthesized thiacalix[4]arene dinaphthalene sulfonate, i.e. , TCDNS, has been used as a fluorescence quencher for 2,3-DNT as well as 4-NT. The complex was analyzed by ESI-MS and ¹ H-NMR titration, which has been further confirmed by the in silico study.