Investigation of 1, 10-Phenanthroline based Ionic Liquids using X-ray photoelectron spectroscopy

Abstract

Ionic liquids—low temperature molten salts composed entirely of mobile ions—are a fascinating class of materials that have experienced an incredible growth in research over recent years. This is because of their immense applications in not only academic but also industrial processes. Ultra high vacuum technique, i.e.  X-ray photoelectron spectroscopy is now accepted as a reliable method for the study of ionic liquid-based systems. To date, the main focus of research effort  employing X-ray photoelectron spectroscopy has been upon imidazoliumbased ionic liquids, quite simply because these are the materials most often employed by  synthetic chemists. However, X-ray photoelectron spectroscopy data (fitting  models) for other than 1, 3-dialkyimidazolium based ionic liquids are required and need to be developed. 1, 10-Phenanthrolinium based ionic liquids are among the new compounds reported recently. However, no attempt is observed to investigate the electronic environments of its component atoms. In this report, therefore, the electronic environments of six N-alkyl-1, 10-Phenathrolinium based ionic liquids, [CnPhen][Tf2N] (n=1, 2, 4, 6, 8, 10), were investigated using the X-ray  photoelectron spectroscopy and a good fitting is developed for C 1s, and N 1s that applies to each of the compounds studied. This model allows accurate charge  correction and the determination of reliable and reproducible binding energies of all the atoms for each compound studied. Hence, this model could be taken as  benchmark in investigating any compound containing 1, 10-phenanthroline  derivatives.

Keywords: 1, 10-phenanthroline, fitting model, Ionic liquids, X-ray photoelectron spectroscopy