title: Association of symmetrical alkane diols with pyridine: DFT/GIAO calculation of1H NMR chemical shifts.
abstract: Proton nuclear magnetic resonance (NMR) shifts of the free diol and of its 1 : 1 and 1 : 2 hydrogen-bonded complexes with pyridine have been computed for five symmetrical alkane diols on the basis of density functional theory, by applying the gauge-including atomic orbital method to geometry-optimized conformers. For certain conformers, intramolecular OH···OH interactions, evidenced by high NMR OH proton shifts, are further enhanced on going from the free diol to the corresponding 1 : 1 diol/pyridine complex. This is confirmed by atoms-in-molecules and non-covalent interaction plots. The computed OH and CH proton shifts for the diol and the two complexes correlate well with values obtained by analysing data from the NMR titration of the diols in benzene against pyridine. Shift values for the diols in neat pyridine are calculated by weighting the shifts of the various protons in the three forms (free diol, 1 : 1 and 1 : 2 diol/pyridine complexes) according to the experimentally determined association constants. The results are in good agreement with those observed, and after empirical scaling, the root mean square difference is 0.18 ppm. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: ITODYS (UMR 7086), Univ Paris Diderot, Sorbonne Paris Cité, Paris, France.
authors.forename: John S
authors.initials: JS
authors.lastname: Lomas
authors.affiliation: Normandy Univ., COBRA UMR 6014 & FR 3038, Université de Rouen, INSA Rouen, CNRS, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Joubert
authors.affiliation: ITODYS (UMR 7086), Univ Paris Diderot, Sorbonne Paris Cité, Paris, France.
authors.forename: François
authors.initials: F
authors.lastname: Maurel
keywords: GIAO; Gaussian 09; NCI; QTAIM-IQA; cooperativity; diols; pyridine