Aroylhydrazone derivative as fluorescent sensor for highly selective recognition of Zn2+ ions: syntheses, characterization, crystal structures and spectroscopic properties

A new Zn(2+) fluorescent chemosensor N'-(3,5-di-tert-butylsalicylidene)-2-hydroxybenzoylhydrazine (H(3)L(1)) and its complexes Zn(HL(1))C(2)H(5)OH](∞) (1) and Cu(HL(1))(H(2)O)]CH(3)OH (2) have been synthesized and characterized in terms of their crystal structures, absorption and emission spectra. H(3)L(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(2)O = 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(2)L(2)), which lacks the hydroxyl group substituent in salicyloyl hydrazide compared with H(3)L(1), and its complex Zn(2)(HL(2))(2)(CH(3)COO)(2)(C(2)H(5)OH)] (3), Co(L(2))(2)]Co(DMF)(4)(C(2)H(5)OH)(H(2)O)] (4), Fe(HL(2))(2)]Cl·2CH(3)OH (5), have also been investigated as a reference. H(3)L(1) exhibits improved selectivity for Zn(2+) compared to H(2)L(2). The findings indicate that the hydroxyl group substituent exerts an effect on the spectroscopic properties, complex structures and selectivity of the fluorescent sensor.