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The lowest excited triplet (T1) ππ*states of gallium (Ga) and various rhodium (Rh) 5,10,15-trispentafluorophenylcorroles (Cors) were studied in the liquid crystal (LC) E-7 and inrigid glasses by time-resolved electron paramagnetic resonance (TR-EPR)spectroscopy. The triplet sublevel energies were experimentally determinedby the alignment of the molecules in the LC and by magnetophotoselectionin the glass. The sublevel scheme of GaCor was determined by calculatingthe zero field splitting (ZFS) parameters. Axial ligand effects andquantum chemical calculations were used for the sublevel assignmentof RhCors. The anisotropic EPR parameters were used to determine theimportant higher excited states and the magnitudes of their spin–orbitcoupling (SOC) contributions were evaluated. On the basis of theseresults and analyses, the EPR parameters and triplet lifetime werediscussed for each RhCor complex. [ABSTRACT FROM AUTHOR]

Möbius aromatic molecules have attracted great attention as new functional materials because of their π-orbital cyclic conjugations lying along the twisted Möbius topology. To elucidate the electronic character of the lowest excited triplet (T 1 ) state of a Möbius aromatic [28]hexaphyrin, we employed a time-resolved electron paramagnetic resonance (TREPR) method with applied magnetophotoselection measurements at 77 K. Analyses of the EPR parameters have revealed that the T 1 state possesses intramolecular charge-transfer (CT) character together with local excitation character residing at one side in the Möbius strip ring. We have also demonstrated that the CT character between orthogonal unpaired orbitals triggers quick triplet deactivation by spin-orbit coupling. This deactivation can be an important barometer to represent the "antiaromaticity" because of a connection between the orthogonal CT character and instability by a weakened spin-spin exchange coupling in the T 1 state.