Abstract
Three metal-organic coordination polymers [Cu(L)(N3)]·(H2O)0.25n (1), [Zn(L)(N3)]·(H2O)0.5n (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 L1- 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.
Highlights
Metal compounds have attracted considerable interest because of their fascinating structures,[1] and functional applications in many research fields such as adsorption,[2] gas storage and separation,[3,4] photoluminescence,[5] and ion exchange.[6,7] The organic ligands are considered to be the most important factor that affects the structures and properties of the coordination polymers.[8]Hydrazone ligands obtained from condensation reaction of aldehydes and hydrazide are an important class of Schiff bases.[9]
We have been interested in coordination compounds involving hydrazone ligands owning to their facile keto-enol tautomerization, the versatile coordination modes, and the strong hydrogen-bonding capability
Whereas the same band in the free l igand hydrazone ligand N’-(1-(pyrazin-2-yl)ethylidene)isonicotinohydrazide (HL) was observed at 1632 cm–1
Summary
Metal compounds have attracted considerable interest because of their fascinating structures,[1] and functional applications in many research fields such as adsorption,[2] gas storage and separation,[3,4] photoluminescence,[5] and ion exchange.[6,7] The organic ligands are considered to be the most important factor that affects the structures and properties of the coordination polymers.[8]. We synthesized a series of complexes derived from Schiff bases with metal chloride, acetate or nitrate. These complexes showed mononuclear, 1D chain or 3D network.[10,11,12]. Shaabani and coworkers reported Cr(III), Mn(II) and Fe(III) complexes with 4-hydroxy-N’-((pyridin-2-yl)-methylene)benzohydrazide and azide as bridging ligands These three complexes showed mononuclear or dinuclear structure with moderate antimicrobial activity.[18] Xu and coworkers reported a series of copper complexes showing antitumor activities based on N’-(1-(pyrazin-2-yl)ethylidene)isonicotinohydrazide (HL) (Scheme 1).[19] In this paper, we were prompted to study the coordination chemistry of HL in the presence of azide. Three complexes namely {[Cu(L)(N3)] (H2O)0.25}n (1), {[Zn(L)(N3)] · (H2O)0.25}n (2) and [Cd2(L)2(N3)2(H2O)]n (3) were synthesized, their crystal structure and luminescence properties were studied
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