New photoluminescence acylhydrazidate-coordinated complexes

Abstract

Under the hydrothermal conditions, five new acylhydrazidate-containing compounds [Cd(EPDH)₂(H₂O)] 1, [Cd(MPDH)₂] 2, [Zn(MPDH)₂(H₂O)₂]·2H₂O 3, [Pb₂(ODPTH)₂(phen)₂(H₂O)₂] 4 and [Cd₂(APTH)₄(phen)₂]·2H₂O 5 (EPDH = 5-ethylpyridine-2,3-dicarboxylhydrazidate, MPDH = 6-methylpyridine-2,3-dicarboxylhydrazidate, ODPTH = 4,4′-oxydiphthalhydrazidate, APTH = 3-amiophthalhydrazidate, phen = 1,10-phenanthroline) were luckily obtained. Note that MPDH, EPDH and ODPTH were derived from the hydrothermal in situacylation reactions between organic polycarboxylic acids and N₂H₄·H₂O, whereas APTH originated from the hydrothermal in situreduction reaction of NPTH (NPTH = 3-nitrophthalhydrazidate) in the presence of N₂H₄·H₂O. The photoluminescence analysis indicates that all of the title compounds are fluorescent materials with maximum emissions at 530 nm for 1, 540 nm for 2, 517 nm for 3, 413 nm for 4 and 563 nm for 5, respectively. The density functional theory (DFT) calculations on the excited electronic states of compound 3 indicate that the emission is associated with the ligands, corresponding to the charge transfer from the π orbital of the acylhydrazidate ring to the π* orbital of the pyridine ring.