Crystal structure and photophysical and electrochemical properties of the first octamolybdate porphyrin

Abstract

A novel molybdenum polyoxometalate (POM) porphyrinic compound, i.e. (Mo8O26)(5,10,15,20-tetra-3-H-pyridinyl-21H,23H-porphine)·2H2O (1) was synthesized via a hydrothermal reaction of MoCl5, 5,10,15,20-tetra-3-pyridinyl-21H,23H-porphine and distilled water. This is the first octamolybdate porphyrinic compound. Its crystal structure and properties have been unlocked thoroughly by virtue of single-crystal X-ray diffraction, PXRD (powder X-ray diffraction), UV/vis, FTIR, photoluminescence, CIE (Commission Internationale de I'Éclairage), CT (color temperature) and cyclic voltammetric (CV) spectral analyses. The crystal structure of this compound is characteristic of an isolated (0D) motif and it is comprised of a (Mo8O26)4− anion, a (5,10,15,20-tetra-3-H-pyridinyl-21H,23H-porphine)4+ cation and two lattice water molecues. A three-dimensional (3D) framework is formed by the π-π stacking and hydrogen bonding interactions. The solid state photoluminescence measurements show that compound 1 emits red photoluminescence which results from the (5,10,15,20-tetra-3-H-pyridinyl-21H,23H-porphine)4+ cations. Compound 1 has CIE chromaticity coordinates of (0.7236, 0.2764). The CT is 7978 K. The slow sweep CV of 1 exhibits a reversible wave with E1/2 being of 0.78 V.