A Vanadium Porphyrin with Temperature‐Dependent Phase Transformation: Synthesis, Crystal Structures, Supramolecular Motifs and Properties

Abstract A vanadium porphyrin, V(O)TMeOPP ( 1 ; TMeOPP=5, 10, 15, 20‐tetrakis(4‐methoxyphenyl)‐21 H, 23H‐porphyrin), has been synthesized by solvothermal reactions and characterized by single‐crystal X‐ray diffractions at room temperature and low temperature to reveal two different structures 1R and 1L , respectively. Both 1R and 1L crystallized in the orthorhombic system, but their space groups were different: Pbca and Pca 2 1 for 1R and 1L , respectively. The cell parameters of a , b , and c were different and the cell volume of 1R was larger than that of 1L by circa 200 Å 3 . 1R and 1L were characteristic of an isolated motif with a five‐coordinate vanadium(IV) ion and a saddle‐distorted nonplanar porphyrin macrocycle. Molecules of 1R were interconnected through hydrogen‐bonding interactions to yield a 3D framework; whilst for the low‐temperature phase 1L , there were more hydrogen‐bonding interactions that link the molecules to construct a more‐complex 3D supramolecular network. In a solution of acetone, the title compound exhibited purple and green colors at room temperature and low temperature, respectively, which is unprecedented for vanadium porphyrins. The spectral data of UV/Vis, FT‐IR, and MALDI‐TOF‐MS of 1R and 1L are reported together with the electrochemical data.