2D frameworks self-assembled from a hydrazone ligand and azide salts: synthesis, structures, and luminescent property

Abstract

Three metal-organic coordination polymers {[Cu(L)(N₃)]·(H₂O)_0.25}_n (1), {[Zn(L)(N₃)]·(H₂O)_0.5}_n(2)and [Cd₂(L)₂(N₃)₂(H₂O)]_n(3)have been synthesized from hydrazone ligand N′-(1-(pyrazin-2-yl)ethylidene)isonicotinohydrazide (HL), NaN₃ and corresponding metal nitrates. Complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. All three complexes feature 2D coordination network in which L^1– acts as NNON tetradentate ligand and azide acts as end-on bridging ligand. In complexes 1 and 2, only intra-sheet hydrogen bonding interactions are found, while the hydrogen bonding interactions between water molecules and host framework result in 3D network for 3. In addition, complexes 2 and 3 exhibited intense fluorescent emissions in the solid state at room temperature.