A DFT and TDDFT investigation of interactions between 1-hydroxypyrene and aromatic amino acids


COMPUTATIONAL AND THEORETICAL CHEMISTRY, vol.1073, pp.9-19, 2015 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 1073
  • Publication Date: 2015
  • Doi Number: 10.1016/j.comptc.2015.09.009
  • Page Numbers: pp.9-19


This study presents a computational investigation of formation photoinduced charge transfer complexes between 1-hydroxypyrene (PyOH) and aromatic amino acids (Phenylalanine: Phe, Tyrosine: Tyr, Tryptophan: Trp) in gas phase and in water. Geometry optimizations were performed by density functional theory (DFT) at omega B97XD/6-31 1++G(d,p) level. Time-dependent density functional theory (TDDFT) was used to calculate the electronic transitions of molecules at B3INP/6-311++G(d,p) and CAM-B3LYP/6-311++G(d,p) levels using the ground-state geometries from omega B97XD/6-311++G(d,p). Polarizable Continuum Model (PCM) is used for calculations in water. Total electronic energies, complexation energies, free energy differences, solvation energies, excitation wavelengths, and HOMO-LUMO energy gaps of complexes have been analyzed and compared in gas phase and in solution. The intermolecular distances between PyOH and amino acids increased in water compared to the gas phase. The optimized complexes display an increasing complex stability in the order Trp > Tyr > Phe. Analyses of first excited singlet states have revealed that there are charge transfers between PyOH and amino acids through pi-pi stacking except PyOH-Phe complexes in both media. The charge distributions increased in water. Among all studied systems, PyOH-Trp systems have the most significant charge transfer between HOMO-1 and LUMO (full CT, 59%). However, dipole moment and oscillator strength of this transition (S-0-S-1) are weaker compared to the other studied systems. PyOH-Trp systems are determined to be the best model to investigate and design bioorganic photosensitive materials with its charge transfer character. (C) 2015 Elsevier B.V. All rights reserved.