A new 2-hydroxynaphthalene based Schiff base receptor for detection of Cu2+, Fe3+, HSO4−, CN− ions and D–amino acids in aqueous DMSO solution

Abstract

A new Schiff base receptor L2 was prepared and characterized by elemental analyses, IR, 1H/13C NMR, UV–vis, HRMS and PL data. It exhibited one emission band (λem = 711 nm) with red-point luminescence in the solid state, and one emission band (λem = 603–613 nm) with yellow luminescence in DMSO solution, which point out the existence of excited state intramolecular proton transfer (ESIPT) reaction between tautomeric forms in the excited state. The recognizing ability of receptor against metal ions (Cr3+, Al3+, Fe3+, Pb2+, Co2+, Cu2+, Mn2+, Cd2+, Zn2+ and Ni2+), α–D–amino acids (glycine, alanine, phenylalanine, valine, serine and threonine) and inorganic anions (F−, Cl−, Br−, CH3COO−, H2PO4−, SO32–, S2O32−, NO3−, HSO4−, CN− and OH−) was determined in DMSO–H2O solution by colorimetric and UV–vis experiments. L2 selectively detected Cu2+ and Fe3+ ions through visual color change as well as UV–vis spectra. Addition of acidic and basic amino acid solution to L2 caused the change of light orange color of receptor to bright light orange and pale lemon color, respectively. L2 had a better selectivity for detecting of cationic form of glycine, while it showed good recognition towards anionic form of all the tested D–amino acids. Besides, L2 exhibited a highly selective naked-eye sensing of hydrogen sulfate, cyanide and hydroxide ion comparing to the other ions.