title: Structure and dynamics of aqueous 2-propanol: a THz-TDS, NMR and neutron diffraction study.
abstract: Aqueous liquid mixtures, in particular, those involving amphiphilic species, play an important role in many physical, chemical and biological processes. Of particular interest are alcohol/water mixtures; however, the structural dynamics of such systems are still not fully understood. Herein, a combination of terahertz time-domain spectroscopy (THz-TDS) and NMR relaxation time analysis has been applied to investigate 2-propanol/water mixtures across the entire composition range; while neutron diffraction studies have been carried out at two specific concentrations. Excellent agreement is seen between the techniques with a maximum in both the relative absorption coefficient and the activation energy to molecular motion occurring at ∼90 mol% H2O. Furthermore, this is the same value at which well-established excess thermodynamic functions exhibit a maximum/minimum. Additionally, both neutron diffraction and THz-TDS have been used to provide estimates of the size of the hydration shell around 2-propanol in solution. Both methods determine that between 4 and 5 H2O molecules per 2-propanol are found in the 2-propanol/water clusters at 90 mol% H2O. Based on the acquired data, a description of the structure of 2-propanol/water across the composition range is presented.
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, UK. james.mcgregor@sheffield.ac.uk.
authors.forename: James
authors.initials: J
authors.lastname: McGregor
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, UK. james.mcgregor@sheffield.ac.uk.
authors.forename: Ruoyu
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, UK. james.mcgregor@sheffield.ac.uk.
authors.forename: J Axel
authors.initials: JA
authors.lastname: Zeitler
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, UK. james.mcgregor@sheffield.ac.uk.
authors.forename: Carmine
authors.initials: C
authors.lastname: D'Agostino
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, UK. james.mcgregor@sheffield.ac.uk.
authors.forename: James H P
authors.initials: JH
authors.lastname: Collins
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, UK. james.mcgregor@sheffield.ac.uk.
authors.forename: Mick D
authors.initials: MD
authors.lastname: Mantle
authors.affiliation: School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast BT9 5AG, UK.
authors.forename: Haresh
authors.initials: H
authors.lastname: Manyar
authors.affiliation: School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast BT9 5AG, UK.
authors.forename: John D
authors.initials: JD
authors.lastname: Holbrey
authors.affiliation: School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast BT9 5AG, UK.
authors.forename: Marta
authors.initials: M
authors.lastname: Falkowska
authors.affiliation: School of Mathematics and Physics, Queen's University Belfast, Belfast BT9 5AG, UK.
authors.forename: Tristan G A
authors.initials: TG
authors.lastname: Youngs
authors.affiliation: School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast BT9 5AG, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Hardacre
authors.affiliation: Johnson Matthey Catalysts, P.O. Box 1, Belasis Avenue, Billingham, Cleveland TS23 1LB, UK.
authors.forename: E Hugh
authors.initials: EH
authors.lastname: Stitt
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, UK. james.mcgregor@sheffield.ac.uk.
authors.forename: Lynn F
authors.initials: LF
authors.lastname: Gladden