Two-photon absorption properties of meso-substituted A3-corroles

We report for the first time two-photon absorption (2PA) cross sections and spectra of corroles within a broad spectral range of excitation wavelengths, 800–1400 nm. Compared to symmetrically-substituted porphyrins, the 2PA spectrum of corroles contains a distinct peak at the laser wavelength close to twice the wavelength of Soret maximum (∼850 nm), with a quite significant cross section, σ2 = 60–130 GM. Lowering of the symmetry relaxes the parity selection rules for 2PA, thus making the Soret band allowed for two-photon transition. We also observe that the strength of the 2PA peak in Soret region strongly decreases with the electron-withdrawing ability of the side substituents.