Self-assembly of 1D metalloporphyrin array within pseudo-hexagonal channels of polyoxometalates

Self-assembly of the robust Keggin cluster [SiW12O40]4− and metalloporphyrin building blocks [M(TpyPHn)]n+ under hydrothermal conditions gives two new organic–inorganic hybrid solid compounds. The hydrothermal reactions of H4SiO4·12WO3·xH2O, Cu(NO3)2·2.5H2O, meso-tetra(4-pyridyl)porphine (H2TpyP) and H2O at 200 °C for 72 h yield a solid compound [Cu(TpyPH3)]2[Cu(TpyPH2)][SiW12O40]2·8H2O (1). Using ZnCl2 instead of Cu(NO3)2·2.5H2O in the syntheses leads to the crystallization of a compound [Zn(TpyPH4)(H2O)][SiW12O40]·3H2O (2). Both compounds consist of discrete anionic α-[SiW12O40]4− clusters, cationic metalloporphyrins and crystalline water molecules. Hydrogen bonds, π–π aromatic interactions and CH···π interactions in these two new hybrid solids lead to the formation of 3D framework structures. Pseudo-hexagonal channels are formed by polyoxometalates and are occupied by one-dimensional metalloporphyrin arrays. Both compounds were characterized by single crystal X-ray, UV–Vis, IR spectroscopy and thermogravimetric analysis.