Synthesis, characterization and luminescence properties of zinc(II) complexes of pseudohalides and nitrite derived from 4-azidopyridine

Four new zinc(II) complexes with 4-azidopyridine (4-azpy) as co-ligand are reported: [Zn(4-azpy)2(N3)2]n (1), [Zn(4-azpy)4(NCS)2] (2), [Zn(4-azpy)2(NCO)2] (3) and [Zn(4-azpy)2(NO2)2] (4). Single crystal structure detn. revealed that complex 1 forms polymeric chains with di-EO and di-EE azide bridges and two 4-azpy ligands in trans positions. Coordination no. six is obsd. in monomeric complexes 2 and 4, whereas ZnN4 tetrahedral are found in 3. The 4-azidopyridine mols. in complexes 1-4 act exclusively as terminal ligands and are ligated via the pyridine-N donor atoms. The para-substituted covalent azide group is practically coplanar to the plane of its pyridine ring. Adjacent pyridine rings show noncovalent π-π interactions. The complexes reveal enhancement of luminescence emission, compared to the parent 4-azpy ligand, which decreases in the order: 1 > 3 > 4 > 2. [on SciFinder(R)]