Avik Ranjan Sarkar

Design and synthesis of anthracene-based bispyridinium amides: anion binding, cell staining and DNA interaction studies

The design and synthesis of anthracene labeled bispyridinium amides 1–4 along with their anion binding, cell staining and DNA interaction studies are reported. All the chemosensors exhibit significant response towards H2PO4− in CH3CN. Furthermore, sensors 2 and 3 are quite interesting for the selective sensing of aliphatic dicarboxylates. Among these compounds, 1 is found to be useful in cell staining. Also all of them exhibit significant interaction with DNA. All these properties are found to be dependent on the nature of the spacer that holds the pyridinium binding sites.

Progress of 3-aminopyridinium-based synthetic receptors in anion recognition

This review describes the overall development on synthetic receptors built on the pyridinium motif with different functionalities at the 3-position in anion recognition. The review covers only the organic systems. In the designs, the pyridinium group along with the other functional motifs plays a crucial role in the binding of various anions of different shapes and sizes. Complexation characteristics are communicated through changes in 1H NMR, emission, color or gelation behaviours.

Naphthyridine-based symmetrical and unsymmetrical pyridinium amides in sensing of biotin salt

Two naphthyridine-based receptors have been designed and synthesised for biotin salt. The compounds serve as good hosts for the detection of biotin carboxylate rather than biotin ester. The correct dispositions of the binding groups under an isophthaloyl spacer enable the receptors to bind both the cyclic urea and the carboxylate ends simultaneously with moderate binding constant values. The receptors are effective for the binding of tetrabutylammonium salt of biotin with a concomitant increase in the fluorescence of naphthyridine and show appreciable binding of biotin salt in CH3CN containing 1.2% DMSO. The binding was monitored in CH3CN containing 1.2% DMSO and DMSO using 1H NMR, UV–vis and fluorescence spectroscopic methods.

Pyrene-based simple new hetero bis amide pyridinium salt for selective sensing of benzoate and hydrogen sulphate

A new pyrene-based hetero bis amide pyridinium salt 1 has been designed and synthesised. The hetero bis amide salt 1 selectively recognises benzoate over a range of aliphatic monocarboxylates in CHCl3 containing 2% CH3CN by showing concomitant increase in emission of pyrene. The flexible cleft of 1 also showed selective sensing of tetrahedral-shaped ion over ion. The recognition property of 1 was evaluated by 1H NMR, UV–vis and fluorescence studies.

Anthracene-based hetero bisamide chemosensor in fluorescence sensing of monocarboxylates over monocarboxylic acids

A fluorescent chemosensor 1 with different amide moieties as recognition elements has been designed and synthesised. The recognition behaviour of the chemosensor towards various monocarboxylates and their conjugate acids has been evaluated. Although the sensor 1 shows significant quenching of emission of anthracene in CH3CN, it shows an increase in emission in CHCl3 containing 2% CH3CN upon complexation of aliphatic monocarboxylates. Receptor 1 shows selectivity for acetate, propanoate and dihydrogen phosphate over the other anions studied under different conditions. The binding features have been established by 1H NMR, UV–vis and fluorescence spectroscopic methods.