Two highly connected POM-based hybrids varying from 2D to 3D: The use of the isomeric ligands

Through employing two isomeric ligands, isonicotinic acid (HINA) and nicotinic acid (HNA), with different electron delocalization nature, two high-dimensional hybrids based on highly connected α-metatungstate clusters, [Na2(H2O)8Ag2(HINA)3(INA)][Na(H2O)2Ag2(HINA)4(H2W12O40)]·2H2O (1) and [Na2(H2O)4Ag6(HNA)2(NA)2(H2W12O40)]·8H2O (2), have been conventionally synthesized and structurally characterized. 1 exhibits an unusual 1D-in-2D pseudo-polyrotaxane entangled structure, namely, the 2D sheets [Na(H2O)2Ag2(HINA)4(H2W12O40)]n3n− are penetrated by enantiomorphous meso-helical chains [Na2(H2O)8Ag2(HINA)3(INA)]n3n+. In the 2D sheets, each [H2W12O40]6− cluster is surrounded by six Ag and two Na atoms. 2 exhibits a 3D (4, 6)-net structure with (326272)(324454647)(3244687) topology, in which each [H2W12O40]6− cluster is connected with ten Ag atoms. These facts indicate that the isomeric ligands play a key role in the formation of final structures. From 1 to 2, the connection number of the [H2W12O40]6− cluster changes from 8 to 10 and the dimensionality increases from 2 to 3. Moreover, 1 and 2 display photoluminescent properties in the blue range at room temperature.