Structure and photophysical and electrochemical properties of a copper porphyrin complex with a three-dimensional framework

Porphyrins and metalloporphyrins can generally show attractive structural motifs and interesting properties. A new copper porphyrin, namely poly[[μ-chlorido-[μ5-5,10,15,20-tetrakis(pyridin-4-yl)-21H,23H-porphine]tricopper(I)] [aquadichloridocopper(II)]], {[Cu3(C40H24N8)Cl][CuCl2(H2O)]} n (1), was synthesized by the self-assembly of copper chloride with 5,10,15,20-tetrakis(pyridin-4-yl)-21H,23H-porphine under solvothermal conditions. The structure of this copper porphyrin was characterized by single-crystal X-ray crystallography and elemental analysis. The porphyrin macrocycle shows a distorted saddle geometry, with the four pyrrole rings slightly distorted in an alternating mode either upwards or downwards. The copper ions show three-coordinated triangular and four-coordinated square-planar geometries. Every copper–porphyrin unit connects to 12 others via four μ4-bridging Cu2Cl moieties to complete the three-dimensional framework of compound 1, with isolated CuCl2(H2O) units located in the voids. This copper porphyrin displays a red photoluminescence. Electrochemical measurements showed that compound 1 has two redox waves (E 1/2 = −160 and 91 mV).