Synthesis and optical properties of axially bromo-substituted subphthalocyanines

Subphthalocyanines (SubPc) are composed of three iso-indole units containing boron inside, which defines a molecular axis and forms a cone-shaped structure. Despite being non-planar, they show a delocalized 14pi-electron system similar to that present in phthalocyanines. The attractive characteristics of SubPc are their chemical stability and thermal stability. In this paper, we report here the synthesis of five SubPc compounds, in which the axial substituent is a bromide. The peripheral substituent in the compounds leads to an improved solubility in common organic solvents such as ethanol and chloroform etc. The spectral and optical properties of these compounds were studied. The spectra and optical constants (refractive index, extinction coefficient) of the sublimed films of these SubPcs were measured by a spectrophotometer and an ellipsometer respectively. We also measured the static optical recording performance of these films with a thin Al (or Ag) reflective layer on them. These results demonstrated that SubPc showed a strong and broad absorption region near 600 nm and it will be a promising candidate for short-wavelength optical recording (such as DVD-R), if high-quality films can be got. (C) 2002 Elsevier Science Ltd. All rights reserved.