Gallium chloride phthalocyanines possessing 4-(trifluoromethoxy)phenoxy units: Synthesis, characterization, and photophysicochemical investigations

This study reports synthesis of three new metallophthalocyanines namely 1(4),8(11),15(18),22(25)-tetrakis-(4-(trifluoromethoxy)phenoxy) phthalocyaninato} Gallium chloride (1-Ga), {2(3),9(10),16(17),23(24)-tetrakis-(4-(trifluoromethoxy)phenoxy)phthalocyaninato} Gallium chloride (2-Ga), and {2,3,9,10,17,18,23,24-octakis-(4-(trifluoromethoxy)phenoxy)phthalocyaninato} Gallium chloride (3-Ga). The newly synthesized macromolecules were characterized using different spectroscopic approaches, such as Fourier-transform infrared (FT-IR), ultraviolet-visible (UV-vis), and mass (MS) spectroscopy. Aggregation properties of the resulting compounds were studied at different concentrations ranging from 4 x 10(-6) to 14 x 10(-6) M. Density functional theory level computations were conducted to shed light on their electronic properties. The effect of the number and position of the substituent on photophysicochemical properties of the gallium chloride complexes (1-Ga, 2-Ga, and 3-Ga) was studied for the examination of their performance as photosensitizer candidates in photodynamic therapy (PDT), comparatively. The complex 3-Ga shows up the highest singlet oxygen quantum yield (phi(Delta) = 0.87). The photophysical and photochemical features of the stated compounds are useful for PDT applications.