Characterization of BF4- in terms of its effect on water by the 1-propanol probing methodology

One of the most common constituent anions for room temperature ionic liquids (RTILs), BF4-, was characterized in terms of its effect on H2O using the so-called 1-propanol (1P) probing methodology developed by us earlier {[}PCCP, 15(2013) 14548-14565]. The results indicated that BF4- is quantitatively characterized as an amphiphile with weak hydrophobic and moderate hydrophilic contributions. These results were plotted on a two-dimensional map with hydrophobicity and hydrophilicity axes, H2O defining the origin. The melting point of 1-ethyl-3-methylimidazoliumtetrafluoroborate ({[}C(2)mim]BF4) was found within the trend that the larger the hydrophobicity and the hydrophilicity of the chosen counter anion, the lower the melting point of the resulting RTIL made of {[}C(2)mim](+) cation and the chosen anion. For the 1-butyl-3-methylimidazolium ({[}C(4)mim](+)) based RTILs, however, redetermination of the melting point of the perfectly dry {[}C(4)mim]BF4 appears to be necessary. (C) 2014 Elsevier B.V. All rights reserved.