Polyoxometalate-based organic–inorganic hybrid compounds containing transition metal mixed-organic-ligand complexes of N-containing and pyridinecarboxylate ligands

Abstract

Five new organic–inorganic hybrid compounds based on the Keggin-type polyoxoanion [SiW12O40]4−, namely [Cu3(2,2′-bpy)3(inic)(μ2-OH)(H2O)][SiW12O40]·2H2O (1), [Cu6(phen)6(μ3-Cl)2(μ2-Cl)2Cl2(inic)2][SiW12O40]·6H2O (2), [Cu2(hnic)(2,2′-bpy)2Cl]2[H2SiW12O40] (3), [Cu2(nic)(phen)2Cl2]2[SiW12O40] (4) and [Cu2(pic)(2,2′-bpy)2Cl]2[SiW12O40] (5) (inic = isonicotinic acid, hnic = 2-hydroxy-nicotinic acid, nic = nicotinic acid, pic = picolinic acid, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been synthesized and characterized by IR, UV-Vis, XPS, XRD, cyclic voltammetric measurements, photoluminescence analysis and single crystal X-ray diffraction analysis. Crystal analysis reveals that compound 1 exhibits a 2-D double layered framework structure constructed from [SiW12O40]4− and copper-aqua-2,2′-bipy-hydroxyl-isonicotinate complexes. Compound 2 is a 0-D discrete structure formed by [SiW12O40]4− and copper-chloro-isonicotinate-phenanthroline complexes. Compound 3 shows a 1-D single chain structure based on the linkage of copper-2,2-bpy-chloro-2-hydroxy-nicotinate complexes and [SiW12O40]4−. Compounds 4 and 5 both contain polyoxometalate supported transition metal complexes, one is a polyoxometalate supported copper-chloro-nicotinate-phenanthroline complex in 4, and the other is a polyoxometalate supported copper-2,2-bpy-chloro-nicotinate complex in 5. It should be noted that nicotinic, isonicotinic and picolinic acids are structural isomers and 2-hydroxy-nicotinic acid is an in situ hydroxylated product of nicotinic acid. In addition, photocatalytic degradation of Rhodamine B (RhB) by compounds 1–5 has been investigated in aqueous solutions.

Tuning the structures based on polyoxometalates from 1-D to 2-D by using different secondary organic ligands

“…It should be noted that picin the compound that is similar to compounds 4-6 reported by us very recently, also adopts the second coordination mode. 10 Crystal structure of 1. The crystal structures of compounds 1-3 are isomorphous and isostructural, belonging to the triclinic space group P-1.…”

“…10 The formula of the reported compound is [Cu 2 (pic)(2,2'-bpy) 2 Cl] 2 [SiW 12 O 40 ], the main difference in the formulas between compound 4 and the reported compound is the TMMC water in compound 4 replacing the TMMC chloride in the reported compound. The structure of compound 4 are thoroughly different from that of the reported compound, the reported compound is only a discrete polyoxometalate supported copper-2,2'-bpy-chloronicotinate complex.…”

“…We have already synthesized some type A and type C hybrids. 5d, 10 We have pointed out that the synthesis of compounds constructed from POMs and TMMCs of a N-containing ligand and a pyridinecarboxylate should be the breakthrough point for the synthesis of the above-mentioned second and third types of compounds. 10 After the syntheses of the compounds containing pyridinecarboxylates, 10 we want to further our study by introducing some new organic ligands.…”

“…5d, 10 We have pointed out that the synthesis of compounds constructed from POMs and TMMCs of a N-containing ligand and a pyridinecarboxylate should be the breakthrough point for the synthesis of the above-mentioned second and third types of compounds. 10 After the syntheses of the compounds containing pyridinecarboxylates, 10 we want to further our study by introducing some new organic ligands. Therefore, we choose picolinic acid as the pyridinecarboxylate ligand and apy, 2,2'bpy, and phen as N-containing organic ligands (secondary organic ligands) to explore the roles of these selected organic ligands in the synthesis of the hybrids.…”

Ba(dl-C4H4O5) — An alkaline earth metal-dicarboxylate hybrid crystal with the synergy of multi-bonds

“…[1][2][3][4][5][6][7][8][9] Many efforts have been devoted to designing and controlling synthesis of organic-inorganic hybrid materials which is formed through coordination bonds, hydrogenbonding and other intermolecular interactions. [10][11][12][13][14][15][16][17] The investigation of metal-dicarboxylate and substituted acids like tartrates and lactates [18][19][20][21] complex crystals (such as oxalates, malonates and maleates) is popular due to their optical and ferroelectric properties. The carboxylate ligand can coordinate with various metals leading to the formation of two and three dimensional complexes with an extensive network connecting by hydrogen bonds.…”