Theoretical Study on Geometry and Intramolecular Hydrogen Bonding in 8‐Hydroxy‐1‐Naphthaldehyde

Abstract

Calculated geometrical parameters in the gas phase and solvents for 8-hydroxy-1-naphthaldehyde (8H1N) were carried out using density functional theory (DFT) at the 6-311++G(d,p) level, and the Time Dependent-DFT/6-311++G(d,p) method was used for the excited state calculations. 8H1N is found to exist in two main conforms, the cis-cis conformer (where the dihedral angels C 3 C 2 -OH is 0 , C 3 C 8 -CO is 0 ) was found to be more stable than the trans-trans form (where the dihedral angels C 3 C 2 -OH is 180 , C 3 C 8 -CO is 180.0 ) by about 6.47 kcal/mol. The possibility of intramolecular hydrogen bonding between the hydroxyl (OH) and aldehyde (CHO) moieties is predicted. The hydrogen bond becomes stronger in polar solvents and in the excited state. Energies of 8H1N-one water molecule complexes are calculated using the DFT-D3 level of theory and results indicate that at least one solvent molecule is required to assist the proton transfer process.

Rearrangement of aniline(H2O)n (n = 0–12) clusters upon photoionization and their excited state properties: Density functional theory and time‐dependent density functional theory study

“…[1][2][3][4][5][6][7][8][9][10] In particular, hydration of biomolecules has utmost research interest because the surrounding water molecules are key factors to determine the structures and functions of biological molecules in the physiological conditions by affecting thermodynamic properties such as enthalpy, entropy, and free energy. [11][12][13] Moreover, H-bonding environment triggers many photochemical and photophysical phenomena such as proton transfer reactions, 14 vibrational energy relaxation, 15 and intramolecular charge transfer (ICT). 16 Besides, molecular level understanding of H-bonded structural rearrangement is critical to unravel biological folding process.…”