Multiprobe Spectroscopic Evidence for "Hyperpolarity" within 1-Butyl-3-methylimidazolium Hexafluorophosphate Mixtures with Tetraethylene Glycol

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Journal of Physical Chemistry B

DOI:https://doi.org/10.1021/jp804591q· OSTI ID:1078205

Sarkar, Abhra ^[1]; Trivedi, Shruti ^[1]; Baker, Gary A ^[2]; Pandey, Siddharth ^[1]

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1. Indian Institute of Technology, Delhi
2. ORNL

A hybrid, potentially green solvent system composed of tetraethylene glycol (TEG) and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) was investigated across all mole fractions with regard to the solvent properties of the mixture. For this purpose, a suite of absorbance- and fluorescence-based solvatochromic probes were utilized to explore solute-solvent and solvent-solvent interactions existing within the [bmim][PF6] + TEG system. These studies revealed an interesting and unusual synergistic solvent effect. In particular, a remarkable hyperpolarity was observed in which the ET value, comprising dipolarity/polarizability and hydrogen bond donor (HBD) acidity contributions, at intermediate mole fractions of the binary mixture well exceeded that of the most polar pure component (i.e., [bmim][PF6]). Independently determined dipolarity/polarizability ( *) and HBD acidity (R) Kamlet-Taft values for the [bmim][PF6] + TEG mixtures were also observed to be anomalously high at intermediate mole fractions, whereas hydrogen bond acceptor (HBA) basicities ( values) were much more in line with the ideal arithmetic values predicted on a mole fraction basis.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1078205
• Journal Information: Journal of Physical Chemistry B, Journal Name: Journal of Physical Chemistry B Journal Issue: 47 Vol. 112; ISSN 1520-6106
• Country of Publication: United States
• Language: English