New insights into oximic ligands: Synthesis and characterization of 1D chains by the use of pyridine 2-amidoxime and polycarboxylates

Abstract

The initial study of the ligand blend pyridine-2-amidoxime (pyaoxH2)/1,4-benzenedicarboxylic (H2bdc) or 1,3,5-benzenetricarboxylic acid (H3btc) provided access to four 1D coordination polymers, [Zn(bdc)(pyaoxH2)(DMF)]n (1), {[Ni(bdc)(pyaoxH2)2]·2DMF}n (2·2DMF), {[Mn(bdc)(pyaoxH2)2]·2DMF}n (3·2DMF) and [Ni(Hbtc)(pyaoxH2)2]n (5), and the discrete (0D) compound [Ni(H2btc)2(pyaoxH2)2]·2H2O (4·2H2O), whose further polymerization yielded 5. These compounds are the first metal coordination polymers bearing pyaoxH2 and rare examples of such species with any type of a 2-pyridyl oxime. The crystal structures of the compounds have been determined by single crystal X-ray crystallography, whereas their identity, purity and stability were confirmed by pxrd studies. Thermal stability studies were performed in 1, 2·2DMF, 4·2H2O and 5. The photoluminescence properties of 1 have been studied and revealed a maximum emission peak at 440 nm and a visible shoulder at 467 nm, assigned to the pyaoxH2 and bdc2− ligands, respectively.