Unusual Formation of a Stable 2D Copper Porphyrin Network

Copper­(II) 5,15-bis­(diethoxyphosphoryl)-10,20-diphenylporphyrin was obtained and characterized by means of cyclic voltammetry, electron paramagnetic resonance, Fourier transform infrared, and UV–visible spectroscopy. Three crystalline forms were grown and studied by means of X-ray diffraction methods (single crystal and powder). The highly electron-withdrawing effect of phosphoryl groups attached directly to the porphyrin macrocycle results in a self-assembling process, with formation of a stable 2D coordination network, which is unusual for copper­(II) porphyrins. The resulting 2D structure is a rare example of an assembly based on copper­(II) porphyrins where the copper­(II) central metal ion is six-coordinated because of a weak interaction with two phosphoryl groups of adjacent porphyrins. The other polymorph of copper­(II) 5,15-bis­(diethoxyphosphoryl)-10,20-diphenylporphyrin contains individual (isolated) porphyrin molecules with four-coordinated copper­(II) in a distorted porphyrin core. This polymorph can be obtained only by slow diffusion of a copper acetate/methanol solution into solutions of free base 5,15-bis­(diethoxyphosphoryl)-10,20-diphenylporphyrin in chloroform. It converts to the 2D structure after dissolution in chloroform followed by consecutive crystallizations, using slow diffusion of hexane. A six-coordinated copper­(II) porphyrin containing two axially coordinated dioxane molecules was also obtained and characterized by X-ray diffraction crystallography. The association of copper­(II) 5,15-bis­(diethoxyphosphoryl)-10,20-diphenylporphyrin in solution was also studied.