Synthesis of a bisphthalocyanine and its nonlinear optical properties

The synthesis and the nonlinear optical properties of an axially substituted binuclear InCl/InCl phthalocyanine 1 with an unsymmetrical substitution pattern are described. The preparation of this new type of binuclear phthalocyanine has been carried out through a multi-step synthetic strategy, which was specially developed for binuclear phthalocyanines. The study has been carried out with the aim of analyzing which variations of the electronic properties accompany the unsymmetrical extension of the pi-electron system of a binuclear Pc when compared to a mononuclear Pc (the complex tBu(4)PcInCl is here taken for comparison). The nonlinear optical properties of InCl/InCl plithalocyanine 1 in toluene were studied with the Z-scan technique in both open- and closed-aperture configurations at 532 nm with nanosecond laser pulses, The binuclear complex displayed a positive nonlinear absorption coefficient. It is found that the linear optical properties were little changed but the optical limiting effectiveness of the binuclear fused phthalocyanine 1 is lower relative to tBu(4)PcInCl. Explanations for such differences are given. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)