title: Spectroscopic Evidence for Clusters of Like-Charged Ions in Ionic Liquids Stabilized by Cooperative Hydrogen Bonding.
abstract: Direct spectroscopic evidence for hydrogen-bonded clusters of like-charged ions is reported for ionic liquids. The measured infrared O-H vibrational bands of the hydroxyethyl groups in the cations can be assigned to the dispersion-corrected DFT calculated frequencies of linear and cyclic clusters. Compensating the like-charge Coulomb repulsion, these cationic clusters can range up to cyclic tetramers resembling molecular clusters of water and alcohols. These ionic clusters are mainly present at low temperature and show strong cooperative effects in hydrogen bonding. DFT-D3 calculations of the pure multiply charged clusters suggest that the attractive hydrogen bonds can compete with repulsive Coulomb forces.
authors.affiliation: Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 1, 18059, Rostock, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Knorr
authors.affiliation: Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 1, 18059, Rostock, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Stange
authors.affiliation: Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 1, 18059, Rostock, Germany.
authors.forename: Koichi
authors.initials: K
authors.lastname: Fumino
authors.affiliation: Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, WI, 53706, USA. weinhold@chem.wisc.edu.
authors.forename: Frank
authors.initials: F
authors.lastname: Weinhold
authors.affiliation: Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 1, 18059, Rostock, Germany. ralf.ludwig@uni-rostock.de.|Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein-Str. 29a, 18059, Rostock, Germany. ralf.ludwig@uni-rostock.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Ludwig
keywords: DFT calculations; IR spectroscopy; hydrogen bonding; ionic liquids; like-charge interaction