Improvement of nonlinear optical properties of phthalocyanine bearing diethyleneglycole chains: Influence of symmetry lowering vs. heavy atom effect

This paper reports the successful synthesis of the low symmetry phthalocyanines: metalfree 2,3-bis[2'-(2''-hydroxyethoxy) ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine H-1(2) and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. H-1 NMR investigations evidenced of higher dissymmetry of electronic density in 1H2 in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[chi((3))]/alpha, beta(eff), and gamma for 1H(2) in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[chi((3))]/alpha values of the order of 10(-11) in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H-2[(BuO)(8)Pc]. NLO properties of 1H(2) were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[chi(3)]/alpha was almost three times higher in comparison with 1H(2) solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation.