Koichi Kamijima

Novel silicon naphthalocyanines: synthesis and molecular arrangement in thin films

A series of highly organic-soluble [bis(trialkylsiloxy)]silicon tetrakis(alkylthio)-2,3-naphthalocyanines [(R13SiO)2SiNc(SR2)4] have been synthesized, and their 1H NMR, electronic absorption and fluorescence spectra measured. These spectra indicate that (R13SiO)2SiNc(SR2)4 are monomeric in solution (10–2–10–7 mol dm–3). In their solid films, all Q-band absorption maxima of (R13SiO)2SiNc(SR2)4 are red-shifted from their monomeric Q-band maximum. The extent of shift significantly increases with decreasing R1 length of the axial substituents, but the effect is far less with ring substituents, R2. These observations are clearly explained using the exiton model. Our results indicated that novel naphthalocyanine (R13SiO)2SiNc(SR2)4 molecules have a J-type molecular arrangement in thin solid films.