Nonlinear optical properties of peripheral symmetrically and non-symmetrically 4-(trifluoromethoxy)phenoxy substituted zinc phthalocyanines

In this work, new non-symmetrical, peripherally substituted metallophthalocyanines, namely 2(3)-[(4-nitrophenyl)ethynyl]-{9,10,16,17,23,24-hexakis-(4-(trifluoromethoxy)phenoxy)-phthalocyaninato}zinc (1b) and 2(3)-[(4-nitrophenyl)ethynyl]-{9(10),16(17),23(24)-tris-(4-(trifluoromethoxy)phenoxy)-phthalocyaninato}zinc (2b) were prepared. Structural elucidation of the novel zinc phthalocyanines was carried out with well-known spectroscopic methods. The solubility of the phthalocyanines was investigated in organic solvents like tetrahydrofuran, dichloromethane, and dimethyl sulfoxide. The effect of concentration on aggregation behavior of the resulting phthalocyanines (1b and 2b) was examined in a wide area ranging from 4 × 10⁻⁶ to 14 × 10⁻⁶ M in tetrahydrofuran. Aggregation properties of the macrocyclic molecules (1b and 2b) were also investigated in many organic solvents. Based on the data existing in the literature, peripherally octa- and tetra-substituted zinc phthalocyanines (1a and 2a) with 4-(trifluoromethoxy)phenoxy moieties were synthesized. Optical limiting and the third-order nonlinear properties of symmetrically and non-symmetrically substituted phthalocyanines were determined and compared with each other.