Self-association of (R)-1,3-butanediol in an inert dilute solution studied by infrared spectroscopy in combination with density functional theory and chemometrics

Self-association of (R)-1,3-butanediol in a dilute carbon tetrachloride (CCl4) solution was studied by infrared (IR) spectroscopy in combination with density functional theory (DFT), Sugeta’s nonlinear least square (NLS) method and chemometrics methods including fixed-size moving window evolving factor analysis (FSMWEFA), principal component analysis (PCA), simple-to-use interactive self-modeling mixture analysis (SIMPLISMA), and iterative target transformation factor analysis (ITTFA). The association size of (R)-1,3-butanediol in the CCl4 solution estimated from PCA, SIMPLISMA and ITTFA are 3.2730, 3.2797 and 3.2950, respectively, suggesting that the major multimer species of (R)-1,3-butanediol in the solution are trimers. A theoretical investigation of trimer structures of (R)-1,3-butanediol was carried out with DFT. It was found from the DFT calculation that cyclic trimers are more stable than linear ones. Structure of hydrogen-bonded OH ring and position of side chains are the two main factors that determine the stability of trimers. The intra-molecular hydrogen bonded OH…OH structure in the (R)-1,3-butanediol monomer brings additional influence on the trimers’ structures.