Mitsuo Katayose

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.

Organic Optical Storage Medium with a Read-Out Stability under 1 mW Laser Irradiation

The basic characteristics of new naphthalocyanine derivatives used as a recording layer for a write-once optical storage medium were studied. Read-out stability could be improved by mixing two types of naphthalocyanines: one had a bulky structure with large side chains on the central atom, while the other had a flat structure. The stability of the medium under 1 mW laser irradiation for read-out was substantially improved by a hundredfold times compared with that of a single-component system.

UNIQUE REFLECTION PROPERTIES OF THIN FILMS OF ORGANIC SOLUBLE NAPHTHALOCYANINES

The reflection properties of a series of organic-soluble naphthalocyanines (Y2MNcX41 and MNcX4 2), in thin films have been studied: their reflection properties were quite different. The maximal reflectivity of a thin film of an example of naphthalocyanine 1 such as (Et3SiO)2SiNc(SC10H21)4(1b) was over 0.5 around the near IR region, whereas an example of compound 2 such as NiNc(But)4(2a) showed broad reflection spectra below a reflectivity of 0.25 as a thin film. To explain these different reflection properties of thin films of 1 and 2, their complex dielectric constants (relative permittivities) determined from their experimentally obtained spectral data were analysed. The highly ordered J-type molecular arrangement of a thin film of 1 generated a sharp dielectric maximum with a large oscillator strength and a narrow peak width, whereas the complex and disordered molecular aggregation of a thin film of 2 induced a broad dielectric maximum. The unique differences between thin films of 1 and 2 arose from their dielectric properties.