title: Re-examination of the emission properties of alkoxy- and thioalkyl-substituted phthalocyanines.
abstract: The role of n-->pi( *) transitions in the optical spectra of alkoxy- and thioalkyl-substituted phthalocyanines with peripheral substituents is re-examined, based on a detailed analysis of UV-visible absorption, magnetic circular dichroism (MCD) and fluorescence emission spectral data and the results of density functional theory (DFT) and time dependent-density functional theory (TD-DFT) calculations. The npi( *) excited states associated with the lone pairs of the peripheral heteroatoms have been proposed as the origin of a second emission peak observed in the 400-600nm region, which has been assigned as S(2) emission, since S(1) fluorescence associated with the Q band is observed in the near IR region. Our results demonstrate that emission from a photodecomposition product can fully account for this violet emission and that reports of S(2) emission for peripherally substituted phthalocyanines and porphyrazines should be treated with caution.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: John
authors.initials: J
authors.lastname: Mack
authors.forename: Nagao
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Stillman
mesh_terms: D000042:Absorption; D002942:Circular Dichroism; D004583:Electrons; D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D008956:Models, Chemical; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D007211:Indoles; D054833:Isoindoles; D013438:Sulfhydryl Compounds; C013647:phthalocyanine