Crystal structure and photophysical properties of a novel polyoxomolybdate porphyrin

A novel polyoxomolybdate with a diprotonated porphyrin as counter-cation, namely, 5,10,15,20-tetrakis(4-carboxyphenyl)-21 H ,22 H ,23 H ,24 H -porphine(2+) hexamolybdate(VI) pentahydrate, (C 48 H 32 N 4 O 8 )[Mo 6 O 19 ]·5H 2 O or (H 2 TCPP)[Mo 6 O 19 ]·5H 2 O, I , was prepared via the hydrothermal reaction of MoCl 5 , 5,10,15,20-tetrakis(4-carboxyphenyl)-21 H ,23 H -porphine (TCPP) and distilled water. The crystal structure of hydrated polyoxometalate (POM) salt I was characterized by single-crystal X-ray diffraction. The compound is characterized by an isolated (zero-dimensional, 0D) structure, because it cannot extend via covalent bonds. The structure contains one [Mo 6 O 19 ] 2− anion, one (H 2 TCPP) 2+ cation and five lattice water molecules. Each of the Mo 6+ ions is six-coordinated and displays a distorted octahedral motif. The (H 2 TCPP) 2+ cation displays a distorted saddle motif. A three-dimensional (3D) supramolecular framework is formed via hydrogen-bonding interactions. The compound shows a red photoluminescence emission.