Coordination studies of a fluorescent sensor for Zn2+ detection: characterization in solution and solid state

Spectroscopic studies revealed that the ligand 2-(2′-hydroxyphenyl)-1,3-benzoxazin-4-one (1) exhibited a rather high selectivity for the Zn2+ cation. The quantum yield of 1 was increased by about 180-fold upon addition of an excess of Zn2+ at the emission maximum of 506 nm upon excitation at 406 nm. Coordination of 1 to Zn2+ ions led to the isolated complex 2 having a 1:1 stoichiometry and exhibiting characteristic modifications in the absorption and NMR spectra.