A new benzothiazin-functionalized calix[4]arene-based fluorescent chemosensor for the selective and sensitive detection of Co2+ ion

Abstract

Calixarenes, which have a great place in supramolecular chemistry, has become the most prominent macrocyclic compounds in synthetic organic chemistry due to their easy synthesis and functionalization. In this study, p-tert-butyl calix[4]arene dihydrazide derivative was synthesized and then reacted with 3-oxo-3,4-dihydro-2H-benzo[b][1, 4] thiazin-2-ylideneacetyl chloride to prepare new calixarene based chromophore compound 4. The structure of the synthesized compound was elucidated by spectroscopic methods such as 1H-NMR 13C-NMR and FT-IR spectroscopy. Chromogenic and fluorescence properties of compound 4 were evaluated. It was observed from both studies that compound 4 was Co2+ selective and shows fluorescence Switched-off behavior. Stoichiometry, binding constant and the detection limit was calculated. The stoichiometry between compound 4 and Co2+ was found to be 1:1. The binding constant value (K) was calculated as 666.67 M− 1 using Benesi–Hildebrand equation, while the detection limit for Co2+ ion was calculated as 0.0465 µM.