Effect of the central ion of metals on the luminescent and photophysical parameters of metallophthalocyanines

Based on the data on the spectral and photophysical parameters of the metal complexes of tetraazaporphyrins and phthalocyanines, the effect of the central metal ion on the manifestation of spin-orbit interaction is considered. For complexes of phthalocyanines with Mg(II), Zn(II), Pd(II), and Pt(II) ions, the absorption spectra, luminescence spectra, and luminescence excitation spectra were measured, and the lifetimes and quantum yields of luminescence were determined. It was shown that metal phthalocyanines with Mg(II) and Zn(II) ions, as well as Mg-tetaraazaporphyrin, exhibit intense fluorescence with high quantum yields. For single molecules of Mg-tetaraazaporphyrin in a polymer film at $T$ = 6 K, the fluorescence excitation spectra consisting both exclusively of zero-phonon lines and containing phonon wings were measured. A wide distribution of the measured zero-phonon line widths was observed. It is demonstrated, that the introduction of Pd(II) and Pt(II) ions into the center of phthalocyanine macrocycles leads to a decrease in fluorescence and the appearance of intense phosphorescence even at room temperature. Based on measurements of quantum yields of photosensitized generation of singlet molecular oxygen, the quantum yield of interconversion into triplet states for the compounds under study was defined. Deactivation of the lower triplet state of phthalocyanines with Pd(II) and Pt(II) ions indicates the influence of the internal heavy atom effect on the rate of triplet state deactivation at room temperature and at 77 K.