Intermolecular interactions in porphin dimers: A quantum mechanical study

Both short‐range and long‐range intermolecular interaction energies between two prophin molecules, both in their ground state, separated by a range of interplanar distances from 3 to 4.5 Å, are estimated using the standard perturbation theory. The results indicate that a 60° rotated sandwich structure is the most stable conformation for the dimer. Certain translated as well as the perfect sandwich forms are other favoured structures. The stability of the dimer is mainly due to the van der Waals interactions with no significant contribution from the charge‐transfer interactions. Biochemical implications of these findings are discussed.