15N, 13C and 1H NMR spectra and azo-hydrazone tautomerism of some dyes prepared by coupling of 1-naphthalenediazonium salt

A squarylium dye carrying a monoazacrown moiety has been synthesized and characterized. The new azacrown-squarylium (ACSQ) dye 7 demonstrates sensitivity to Li+ complexation with spectroscopic changes in fluorescence. Complex formation of ACSQ with Cu2+ was also investigated by UV¯Vis spectrometry.