A naphthalene-thiophene hybrid molecule as a fluorescent and logic gate with Zn2+ and OAc- ions as inputs: Cell imaging and computational studies

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 Zn 2+ in a 1 : 1 ratio with an association constant Ka = 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. © The Royal Society of Chemistry 2013