[Influence of substituents on Langmuir-Blodgett films and spectral properties of thulium bisphthalocyanine derivatives].

The aggregation and spectral properties of three sandwich thulium bisphthalocyanine compounds in chloroform solution and LB films were investigated by using UV-Vis absorption spectra. The experimental results indicated that the three sandwich thulium bisphthalocyanine molecules formed H-aggregates in the chloroform solution, but the absorption spectra of the three sandwich thulium bisphthalocyanine compounds display strong absorption peaks of monomer when the concentration of the sandwich thulium bisphthalocyanine solutions was 10(-7) mol x L(-1). The addition of substitutent --OC8H17 not only decreased the aggregation behaviors of the sandwich thulium bisphthalocyanine, but also leaded to red-shift of the absorption peaks, and it had a biggish influence on the intensity of absorption spectra. The absorption Soret bands were splitting when the substitutent --OC8H17 was added. The substitutent --OC8H17 had a strong effect on the existence state of bisphthalocyaines in LB films, while TmPc2 and TmPcPc* molecules formed H-aggregates in LB films, however TmPc2* molecule formed T-aggregates. In the LB films, the distance between sandwich thulium bisphthalocyanine molecule was shortened, and the interaction of molecules was enhanced, therefore the absorption peaks were red-shifted compared with those in the solution, and the arranging state of sandwich thulium bisphthalocyanine molecule has biggish influence on the peaks of absorption spectra.