Assignment of absorption and magnetic circular dichroism spectra of solid, α phase metallophthalocyanines

Abstract

Absorption and magnetic circular dichroism (m.c.d.) spectra of the α polymorphic form of a series of phthalocyanines CH₂Pc, CoPe, NiPc and CuPc have been observed between 12 000 and 40 000 cm^–1. Band shape analysis of both the absorption and m.c.d. data reveals Davydov splittings in both the Q and B (Soret) bands and suggests the existence of two π to π* transitions in the latter region. This lends support to previous assignments of the solution spectra of ZnPc. At higher energy no Davydov splittings are observed in the N band leading to a revised n→π* assignment.