Quantum mechanics (QM) calculations at DFT-B3LYP/6-311 + G * * level in conjunction with po-larized continuum model (PCM) were adopted to simulate gas-phase structure of naphthalene acetic acid(NAA) and solvation structures in water,ethanol and acetone solutions,respectively.With regard to the results of bond lengths,Mulliken populations and atomic charges,it is noted that the O-H bond becomes weaker and the acidity of NAA increases in solutions since water,ethanol and acetone are all polar solvents.Molecular me-chanics (MM) simulations were carried out on the radial distribution functions for solvent hydrogen around oxy-gen of NAA's carboxyl group and mean square displacements of NAA in NAA/H2O,NAA/EtOH and NAA/Ac-etone systems,respectively.The results indicate that solute-solvent intermolecular interactions could be as-cribed to short-range effect (hydrogen-bonding effect) and long-range effect (van der Waals effect).The interrnolecular interactions in NAA/EtOH system are more intense where hydrogen-bonding effect prevails,while the ones in NAA/H2O system are less.NAA has lower diffusion in water solution and larger in ethanol so-lution.
Naphthalene acetic acid (NAA)Solvent effectQuantum mechanics (QM)Molecular mechanics(MM)Radial distribution function (RDF)
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