Structural and spectral studies on indium(III) complexes with 2,6-diacetylpyridine bis(benzoylhydrazones)

Abstract

Complexes [In(L1)Cl(H2O)] (1), [In(L2)Cl(H2O)] (2) and [In(L3)Cl(H2O)] (3) were obtained with 2,6-diacetylpyridine bis(benzoylhydrazone) (H2L1) and its 2,6-diacetylpyridine bis(para-chlorobenzoylhydrazone) (H2L2) and 2,6-diacetylpyridine bis(para-methylbenzoylhydrazone) (H2L3) derivatives. The crystal structures of complexes (1) and (2) were determined, revealing a pentagonal bipyramidal arrangement around the indium(III) center. The spectral properties of complexes (1–3) were investigated. The complexes show fluorescence in DMSO solution resulting from increased conjugation and rigidity of the ligand, and a significant fluorescence brightness due to the strong light absorption in the near UV region. From the fluorescence spectra of 1–3 quantum yields in the 0.5 – 0.7 % range were determined using quinine hemisulfate monohydrate in H2SO4 0.5 M (ΦF = 0.546) as standard.