Two-photon-induced intramolecular excited-state proton transfer process and nonlinear optical properties of HBI in ethanol solution

The two-photon-induced excited state intramolecular proton transfer (ESIPT) process of 2-(2′-hydroxyphenyl) benzimidazole (HBI) in ethanol solution has been investigated. We focused on the calculation of TPA coefficient and nonlinear refraction index of HBI, and found that the theoretical calculated results were in good agreement with the experimental ones. By establishing the two-photon-induced ESIPT kinetic model for HBI, the TPA cross section was determined to be 2.09 × 104 GM. For their large TPA cross section, HBI is a promising TPA candidate material for their potential application in many fields.