Phthalocyanines with four 15-crown-5 ether voids at the 3,4-positions (MtCRPc) (Mt = H2, Zn, Co, Ni, Cu) have been synthesized and characterized. Dimerization of MtCRPc is induced in solvents such as methanol and by addition of some cations (K+, Ca2+, NH4+), especially K+> Cofacial dimer formation in the presence of these cations proceeds in a two-step three-stage process, as indicated by absorption and emission spectroscopy. These species have a highly specific DAh eclipsed configuration providing well-defined dimeric species for spectroscopic analysis. The ESR spectrum of the cation-induced dimeric CuCRPc shows axial symmetry and may be analyzed in terms of an interplanar separation of 4.1 A. The 1H NMR spectra of the cation-induced metal-free and zinc dimers are consistent with an eclipsed configuration. Upper excited state (Soret, S2) emission is observed for the first time in the phthalocyanine series.
ASJC Scopus subject areas
- Colloid and Surface Chemistry