Single- and two-photon absorption properties of gallium corroles

Abstract

Corrole can offer the advantages of strong optical nonlinearity and fast optical response, because of its highly conjugated π-electron distribution and the reduced symmetry as compared to porphyrin, and it has been studied as a new kind of nonlinear optical materials recently. Gallium corroles are highly fluorescent, of which the two-photon excited emission may facilitate the treatment of deep-seated tumors. This is the first report of two-photon absorption (TPA) spectrum of corrole gallium complex, and single- and two-photon absorption properties of three gallium corroles (F10Ga, F15Ga, and F15GaS) have been studied to explore the effects of solvent and peripheral substituent on the TPA properties of gallium corrole. Larger TPA intensities of F10Ga and F15Ga are obtained in polar solvent DMF compared to nonpolar solvent toluene. The introduction of two sulfonated groups results in a decrease in TPA intensity, which may be associated with an increase in symmetry. Nonplanar distortion produced for the absence of one penta-fluorophenyl group however leads to a TPA enhancement. These results may be instructive for the development of corroles to be used in the areas of cancer diagnosis and therapy.