In situ ligand formation-driven synthesis of two acylhydrazide compounds: Synthesis, structure and photoluminescence properties

Abstract

In situ ligand synthesis has evolved as an effective method for the preparation of novel organic molecules and coordination polymers. In this report, one novel acylhydrazidate-based coordination polymer [Pb(PMDH)] 1 and a new organic acylhydrazide molecule [PMDH] 2 (PMDH = pyromellitdihydrazide) have been isolated, in which the PMDH molecule was generated via in situ acylation reaction between pyromellitic acid and N2H4. X-ray single-crystal diffraction analysis reveals that in compound 1, PMDH I molecules link the Pb2+ centers into a two-dimensional (2-D) layer, and then PMDH II molecules extend these layers into a three-dimensional (3-D) network with the point (Schläfli) symbol of (412·63). Compound 2 selfassembles into a 3-D supramolecular network through weak interactions as hydrogen-bonding and π⋯π stacking. The structures, CHN analysis, IR analysis of both compounds were researched. Thermal stability and solid-state photoluminescence property of 1 were intensively investigated. Compound 1 emits orange-red phosphorescence in the solid state at ambient conditions, with a quantum yield of 3% and a double exponential functioned phosphorescence lifetime of τ1 = 23.2 μs (36%), τ2 = 81.4 μs (64%). Compound 2 has a blue light fluorescence emission with a quantum yield of 2%.