Details

Autor(en) / Beteiligte

• Lopes Jesus, A.J.
• Redinha, J.S.

Titel

Self-association of 1,2-cyclohexanediols: A spectroscopic and computational study

Ist Teil von

• Journal of molecular structure, 2014-06, Vol.1067, p.104-111

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2014

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• [Display omitted] •IR study of the self-association of cis and trans-1,2-cyclohexanediol in CCl4 is performed.•Differences between the two isomers are observed.•DFT calculations are carried out on monomers, dimers and trimers.•A good agreement is found to exist between experimental and theoretical results.•The influence of cooperativity on both intra and intermolecular H-bonds is discussed. Solutions of the cis and trans isomers of 1,2-cyclohexanediol in carbon tetrachloride, with concentrations varying from 1 to 30mM and 2 to 20mM, respectively, are studied by infrared spectroscopy. A peak-fitting analysis of the OH stretching region followed by a statistical treatment of the spectral data reveals that dimers and especially trimers are the most likely oligomers to be formed in the working concentrations range. The equilibrium constants of molecular association and the molar fractions of the different species are estimated and discussed. Despite their chemical similarity, the self-association behavior of the two isomers is found to be different. In order to rationalize the experimental results, DFT calculations are performed on monomers, dimers and trimers using mainly the B3LYP functional in combination with the 6-311++G** basis set. Prior to aggregation, both isomers exist solely as intramolecular H-bonded conformers. These bonds are weakened or broken in the cyclic oligomers but are reinforced in the open ones. Hydrogen bonding cooperativity is found to assume an important role in the oligomers’ structure.