Quantum Study on the Hydrogen Bonding Interaction of Luteolin-(CH3OH)n

The optimized geometries and vibration frequencies of luteolin, methanol and luteolin-(CH3OH)(n) complexes have been investigated by density functional theory using B3LYP method. Four stable luteolin-CH3OH complexes, six stable luteolin-(CH3OH)(2) complexes and four stable luteolin-(CH3OH)(3) complexes have been obtained. The theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been used to analyze the hydrogen bonds of these compounds, and their interaction energies corrected by basis set superposition error are between -8.046 and -76.124 kJ/mol. The calculation results indicate strong hydrogen bonding interactions in the luteolin-(CH3OH)(n) complexes. Then the nuclear magnetic resonance (NMR) and electronic absorption spectrum of luteolin have been calculated, and the results are in agreement with the experimental data.