Structures, electronic, and magnetic properties of the transition metal-loaded 5,10,15,20-(tetra-4-aminophenyl) porphyrins

Porphyrins emerge as promising catalysts due to their excellent activity. The incorporation of the transition metal (TM) atoms into the porphyrin cores can modulate their properties and catalytic characters. The structures, electronic, and magnetic properties of the transition metal (TM) loaded 5,10,15,20-(tetra-4-aminophenyl) porphyrins (TAPP-M) have been investigated using the density functional theory. The results indicate that most TM atoms are located at the center planes of the TAPP-M, with exceptions for the Y, Zr, and Nb atoms. The TAPP-Ti and TAPP-Zr demonstrate high binding energies per atom of − 5.528 eV and − 5.535 eV, indicating high structural stability. The TAPP-Cr and TAPP-Mo porphyrins exhibit narrower energy gaps, indicating potentially high reactivity as excellent electrocatalytic materials. The TAPP-Ti, TAPP-Co, TAPP-Zr, and TAPP-Ru display more adsorption energies than their neighbors. Higher charges were obtained for the TM atoms (TM = Sc, Zn, Y, and Cd) in TAPP-M, with the values of 1.378 |e|, 0.715 |e|, 1.674 |e|, and 0.833 |e|. Spin densities of the TM atoms in the TAPP-M porphyrins generally approach zero, while that of the TAPP-V is an exception at 2.484 |e|. It suggests that the spatial distributions of biological enzymes with TAPP-V as active centers can be regulated by external magnetic fields, allowing enzymes to exhibit higher catalytic efficiency.