A naphthalene–thiophene hybrid molecule as a fluorescent AND logic gate with Zn2+ and OAc− ions as inputs: cell imaging and computational studies

Abstract

A naphthalene–thiophene hybrid molecule (Z)-1-((thiophen-2-ylmethylamino)methylene)naphthalen-2(1H)-one (HL) was prepared by condensation of 2-thiophenemethylamine and 2-hydroxy-1-naphthaldehyde. According to FTIR, ¹H NMR spectrometry and single crystal X-ray analysis, HL exists in the cis-keto-amine tautomeric form. HL behaves like a molecular AND type binary logic gate with two inputs viz. Zn²⁺ and OAc⁻ ions whereby the fluorescence of the system turns on. The structures of HL and its zinc acetate complex were also optimized by DFT calculations. HL binds Zn²⁺ in a 1 : 1 ratio with an association constant K_a = 2.05 × 10⁴ M⁻¹, and detects Zn²⁺ as low as 3 × 10⁻⁸ M. HL is useful for the detection of intracellular Zn²⁺ under a fluorescence microscope.