화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.103, No.5, 614-616, 1999
Molecular distortion and exciton coupling effects in beta metal-free phthalocyanine
pointed out in titanylphthalocyanine, molecular distortion (reduction in molecular symmetry) upon crystallization exerts a significant influence on the optical absorption in the near-IR region. The electronic spectra of beta metal-free phthalocyanine (MfPc) has been investigated from the standpoint of molecular distortion and exciton coupling effects. Close examination of the crystal structure of MfPc revealed that the molecular symmetry is reduced from D-2h, to C-i on going from solution to the solid state. Molecular distortion is found to enhance the band splitting in such a way that the longer-wavelength band is mon displaced toward longer wavelengths while the shorter-wavelength band is more shifted toward shorter wavelengths. The electronic spectra of MfPc can mostly be interpreted in terms of the distortion of molecular framework. However, some exciton coupling effect is also observed, as shown by polarized reflection spectra on single crystals as well as the temperature dependence of absorption spectra.