Theoretical Study of Structure, Energetic, Hydrogen Bonds Strength and Intramolecular Proton Transfer of 2-(2-R (ROH, NH2, SH) Phenyl (or Pyridyl)) Benzoxazoles (or Benzothiazoles)

Abstract

The ground- and excited-state intramolecular proton transfer processes of 2-(2-R (ROH, NH2, SH) phenyl (or pyridyl)) benzoxazoles (or benzothiazoles) are investigated by the DFT methods. The calculated results indicate that in the ground state there is a high correlation (R=0.9950) between the proton transfer barrier and the intramolecular hydrogen bonds (IMHB) strength. The increase of the strength of IMHB in the proton transfer processes leads to a larger barrier contributions. Intramolecular proton transfer process pathway is along with the minimal difference of change value in the IMHB angle. In the excited-state, there is a similar relationship between the IMHB and the barrier.