The excited multiplet states of 5,10,15-tri-n-pentyl-20-(1′,1′,3′,3′-tetramethylisoindolin-2′-yloxyl-5′-yl)porphyrinato zinc(II)

Photo-physical properties of 5,10,15-tri-n-pentyl-20-(1′,1′,3′,3′-tetramethylisoindolin-2′-yloxyl-5′-yl)porphyrinato zinc(II), 1, have been investigated using time-resolved EPR (TREPR) and transient absorption measurements. A formation of the excited doublet (D1) and quartet (Q1) states constituted by excited triplet zinc porphyrin (ZnP) and doublet nitroxide is confirmed by TREPR. This is the first D1 and Q1 observation in a system where the nitroxide is directly substituted to a porphyrin ligand. Compound 1 exhibits the longest lifetime of any nitroxide–porphyrin systems in the lowest excited state, indicating a relatively weak electron exchange interaction between triplet ZnP and doublet nitroxide.