The bisbenzothiazole-p-tert-butylcalix[4]arene-thiourea Langmuir-Blodgett thin films: preparation, optical properties, swelling dynamics and gas sensing properties via host-guest principles

Abstract

Calix[4]arene-based materials have been investigated to develop selective, sensitive, and low cost chemical sensors due to their simple, low cost synthesis, and wide range of chemical and physical properties. In this study, bisbenzothiazole-p-tertbutylcalix[4]arene-thiourea (BBTC[4]T) molecules were employed to produce thin flms via Langmuir–Blodgett (LB) thin flm fabrication technique. The optical properties and gas sensing abilities of these BBTC[4]T LB flms were examined by Surface Plasmon Resonance (SPR) method. In order to illuminate the optical properties of calix[4]arene-based LB flms the Winspall software was utilized by ftting the experimental data obtained from SPR device. The values of 1.23±0.07 nm and 1.53±0.05 were determined for the thickness per monolayer and the refractive index of BBTC[4]T-based LB flms, respectively. The fabricated optical sensor was employed for its sensing abilities against to organic vapours (acetone, ethyl alcohol, methyl alcohol and isopropyl alcohol) via the mechanism of host–guest interaction. The current study also describes the difusion coefcients of these organic vapours to illuminate the swelling dynamics’ BBTC[4]T-based LB thin flms by performing the early-time Fick’s difusion equation. The responses of calix[4]arene-based optical sensor in terms of the shift in refective intensity and the values of difusion coefcients showed that BBTC[4]T molecules can be developed as potential chemical sensor element for acetone vapour compared to alcohol vapours.