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

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.