Solvation investigative tools

Pulse radiolysis is a powerful tool for the creation and kinetic investigation of highly reactive species. It was introduced to the field of radiation chemistry at the end of the 1950s and became popular in the early 1960s. Although the objects of this modern technique were, at first, limited to solvated electrons and related intermediates, it was soon applied to a variety of organic and inorganic substances. As early as 1964, ionic intermediates produced by electron pulses in vinyl monomers were reported for the first time. Since then, the pulse radiolysis method has achieved considerable success in the field of polymer science. 

The modern developments of solvation theory will not be discussed at this point because nearly all the tools for investigating the ion-solvent interaction have become available since 1933. One has to see some of the information they have provided before ion-solvent interactions can be worked out in a more quantitative way. 

HS-GC has been developed to serve as a sensitive tool to determine even small differences in the solvation properties of ionic liquids using a choice of model solutes featuring specific interactions molecular ion-dipol interactions, hydrogen bond donor and acceptor interactions, and n- and n-electron dispersion forces can be probed by model solutes such as acetonitrile, 1,4-dioxane, n-propanol, n-heptane and toluene, respectively. Bearing in mind that no solute exhibits exclusively one specific interaction, the systematic investigation of the effect of the variation of the structural elements of ionic liquids, i.e. choice of cation, cation substitution and anion, lead to the following conclusions. 

The ionic liquids investigated display similar solvation properties for the molecular dipoles, and the choice of anion can be singled out as the main tool to tune the solvation by this means. From the combination of the results of this set of ionic liquids, [C.mpyr CII. S04 is predicted as the ionic liquid most capable to interact with dipoles. On the other hand, [Cnquin]Cl would exhibit the least tendencies in this respect. 

Spectroscopic methods, molten salts, 702 Spectroscopy detection of stmctnral nnits in liquid silicates, 747 and structure near an ion, 72 Standard partial gram ionic entropies, absolute, II Thermodynamics, applied to heats of solvation, 51 of ions in solution, 55 Time average positions of water near ions. 163 Tools, for investigating solvation, 50 Transformation, chemical, involving electrons, 8 Transition metals... 

Time-resolved spectroscopic techniques are important and effective tools for mechanistic photochemical studies. The most widely used of these tools, time-resolved ultraviolet-visible (UV-Vis) absorption spectroscopy, has been applied to a variety of problems since its introduction by Norrish and Porter [1] over 50 years ago. Although a great deal of information about the reactivity of organic photochemical intermediates (e.g., excited states, radicals, carbenes, and nitrenes) in solution at ambient temperatures has been amassed with this technique, only limited structural information can be extracted from such investigations because absorption bands are usually quite broad and featureless. Questions of bonding, charge distribution, and solvation (in addition to those of dynamics) are more readily addressed with time-resolved vibrational spectroscopy. 

---