Using Vibrational Spectroscopy and Ab Initio Calculations to Study Hydrogen-Bonded Complexes in Aqueous Solutions of Acetylacetone

The authors study Raman scattering and FTIR absorption spectra of pure acetylacetone and aqueous solutions of it at room temperature and atmospheric pressure. Results from experiments and calculations show that a red shift of the C=O stretching vibrational band and a blue shift of the C–H stretching vibrational band are observed when the amount of acetylacetone in a solution is reduced. The distribution of potential energy is analyzed for the monomeric molecule of the keto form of acetylacetone. The calculated and observed frequencies of vibration are in good agreement. It is shown that acetylacetone creates molecular clusters with water molecules in the form of C=O…H and C–H…O hydrogen bonds, altering the shape of the spectral bands.