Different measures of polarity and nucleophilicity of a range of ionic liquids have been investigated using two solvatochromic dyes; the polarity appears to be largely cation controlled, while the donor strength is entirely anion dependent.

Ultrafast solvent dynamics of room-temperature ionic liquids have been investigated by optical heterodyne-detected Raman-induced Kerr-effect spectroscopy ~OHD-RIKES! by studying the effects of cation and anion substitution on the low frequency librational modes. The spectra of two series of imidazolium salts are presented. The first series is based on the 1-butyl-3-methylimidazolium salts @bmim#1 containing the anions trifluoromethanesulfate @TfO#2, bis~trifluoromethanesulfonyl!imide @Tf2N#2, and hexafluorophosphate @PF6#2. The second series is based on @Tf2N#2 salts containing the three cations 1-butyl-2,3-dimethylimidazolium @bmmim#1, 1-methyl-3-octylimidazolium @omim#1, and @bmim#1. It is found in all five samples that the signal is due to libration of the imidazolium ring at three frequencies around 30, 65, and 100 cm21 corresponding to three local configurations of the anion with respect to the cation

The novel application of ionic liquids as media for radiolytic generation and UV-vis-NIR spectroscopic characterization of radical ions is described. The redox properties of neat 1-butyl-3-methylimidazolium salts and their aqueous solutions have been investigated by means of pulse radiolysis. Furthermore, ionic liquids prove to be ideal media for the simultaneous generation of radical cations and anions. The radical cations generated from 1-methyl-1,4-dihydronicotinamide, a structural analogue of NADH, have been spectroscopically characterized under matrix conditions for the first time.

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Photodestructible surfactants, sodium 4-(2-cyano-2-undecylazo)benzoate and a series of sodium 4alkylphenylazosulfonates, have been synthesized and were shown to be surface active in solution, each exhibiting a distinct critical micelle concentration (CMC). UV irradiation of aqueous solutions of the alkylazobenzoate led to a distinct increase in surface tension, but even after complete photolysis significant surface activity remained, indicating a substantial amount of cage recombination after nitrogen evolution. UV irradiation of sodium 4-dodecylazosulfonate caused a photoscission reaction, completely destroying its surface active properties. In the case of azosulfonates with shorter alkyl chains, however, some residual surface activity remained after complete removal of the azo linkage, indicating that secondary surfactants were formed by the photolysis. The 4-alkylphenylazosulfonates were able to solubilize an oil-soluble dye in water to produce isotropic coloured solutions. Photoirradiation of these solutions led to complete loss of colour, presumably as a result of microprecipitation of the dye. The azosulfonate surfactants also readily emulsified vinyl monomers, such as styrene, in water. Attempts to achieve emulsion polymerization led to only low conversion of monomer, most likely owing to side reactions between initiating radicals and the azo linkage of the surfactant, leading in turn to disruption of the micelle.

U.V. irradiation of 1-and 2-azidonaphthalene in PHOTOLYSIS of phenyl azide (PhN,) in the presence of nucleophiles results in a ring-expansion to give azepines.1J Previous workers have proposed either the azirine (1) or the didehydroazepine (2) as intermediates. Of the two, the N, or Ar matrices a t 12 K leads to the formation of didehydrobenzazepines via photolabile precursors which are assigned tricyclic azirine structures.