Work

Photo-activatable second harmonic generation in centrosymmetric zinc porphyrinates: Experimental and theoretical study

Year: 2026

Type: article

Abstract: We investigated the Second Harmonic Generation (SHG) behavior in the solid state of zinc 5,10,15,20-tetraphenylporphyrinate which crystallizes in the centric I4/m space group and its two new centric derivatives. The new compounds were synthesized and characterized with single crystal X-ray diffraction, and the SHG response of each powdered sample was measured using a 1.907 μm and 0.930 μm pulsed laser radiation. During laser irradiation, the three compounds show a photoactivation phenomenon that is stable over time and dependent on the laser irradiation setup. We attempted to understand the origin of this SHG behavior, both through experimental analysis and theoretical calculations. Vibrational spectroscopies in solid state, before and after irradiation, do not evidence any chemical degradation. DFT calculations on small fragments of the structures appropriately simulate the structural feature of the complexes and their initial experimental SHG response. TD-DFT calculations better simulate the SHG responses after irradiation, leading to hypothesize a permanent change in the electronic state due to the high intensity of the lasers.

Source: Journal of Molecular Structure

DOI: 10.1016/j.molstruc.2026.145586