Ab initio electronic structure theory has been applied to predict the structures and electronic spectra of free-base porphyrin (PH2) and its meso-tetrahalogenated derivatives (m-PX8H2, X = F, Cl, Br). Structures, singlet-triplet energy gaps, and electronic spectra are predicted using the B3LYP method in conjunction with the 6-31G(d) basis set and the effective core potentials/basis sets of Stevens et al. Minimum energy structures of the lowest triplet excited states (T1) were found to retain D2h symmetry with stretched Cb-Cb and Cb-Cm bond distances. We found that halogenation at the four meso-positions significantly changes the ground state excitation energies and the singlet-triplet gap for the free-base parent compound.
Journal: TechConnect Briefs
Volume: Technical Proceedings of the 1999 International Conference on Modeling and Simulation of Microsystems
Published: April 19, 1999
Pages: 57 - 60
Industry sector: Advanced Materials & Manufacturing
Topics: Informatics, Modeling & Simulation