title: Fourteen-electron ring model and the anomalous magnetic circular dichroism of meso-triarylsubporphyrins.
abstract: The MCD spectra of meso-triarylsubporphyrins show a sign anomaly which is correlated with the acceptor properties of the aryl substituent. From the spectra, magnetic moments of the excited states are determined. In the context of a simplified orbital model, the sign change is attributed to the quenching of the magnetic moment of the LUMO by acceptor orbitals of the substituent. The actual calculation of this moment presents a major challenge to computational methods. It is shown that wave function techniques based on CASSCF underestimate the covalency effects that are responsible for the quenching. In contrast, a CI method based on DFT orbitals yields excellent results, which fully support the orbital model.
authors.affiliation: Department of Chemistry and Institute for Nanoscale Physics and Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Vancoillie
authors.forename: Marc
authors.initials: M
authors.lastname: Hendrickx
authors.forename: Minh Tho
authors.initials: MT
authors.lastname: Nguyen
authors.forename: Kristine
authors.initials: K
authors.lastname: Pierloot
authors.forename: Arnout
authors.initials: A
authors.lastname: Ceulemans
authors.forename: John
authors.initials: J
authors.lastname: Mack
authors.forename: Nagao
authors.initials: N
authors.lastname: Kobayashi