Aroylhydrazone derivative as fluorescent sensor for highly selective recognition of Zn~(2+) ions: Syntheses, characterization, crystal structures and spectroscopic properties

摘要

A new Zn~(2+) fluorescent chemosensor N′-(3,5-di-tert- butylsalicylidene)-2-hydroxybenzoylhydrazine (H_3L~1) and its complexes [Zn(HL~1)C_2H_5OH]_∞ (1) and [Cu(HL~1)(H_2O)]CH_3OH (2) have been synthesized and characterized in terms of their crystal structures, absorption and emission spectra. H_3L~1 displays high selectivity for Zn~(2+) over Na~+, K~+, Mg~(2+), Ca ~(2+) and other transition metal ions in Tris-HCl buffer solution (pH = 7.13, EtOH-H_2O = 8:2 v/v). To obtain insight into the relation between the structure and selectivity, a similar ligand 3,5-di-tert- butylsalicylidene benzoylhydrazine (H_2L~2), which lacks the hydroxyl group substituent in salicyloyl hydrazide compared with H _3L~1, and its complex [Zn_2(HL~2) _2(CH_3COO)_2(C_2H_5OH)] (3), [Co(L~2)_2][Co(DMF)_4(C_2H _5OH)(H_2O)] (4), [Fe(HL~2)_2] Cl·2CH_3OH (5), have also been investigated as a reference. H_3L~1 exhibits improved selectivity for Zn~(2+) compared to H_2L~2. The findings indicate that the hydroxyl group substituent exerts an effect on the spectroscopic properties, complex structures and selectivity of the fluorescent sensor.