The effect of counterions was investigated and analyzed to probe the principal ionic effects influencing the micellization behavior of dimeric cationic surfactant ethanediylbis(dimethyltetradecylammonium), referred to as gemini 14-2-14. The 30 counterions were classified to four different families depending on their nature: (1) small and inorganic counterions which are typically taken from the Hofmeister series were studied to focus on the effect of ion type; (2) n-alkyl carboxylate counterions were studied to focus on the effect of the hydrophobicity of counterions; (3) aromatic carboxylate counterions were included to focus on the effect of the position of substitutions; and (4) other counterions were included in order to shed light on other parameters. By investigating the critical micelle concentration (CMC), ionization degree of micelle (alpha), free energy of micellization (DeltaG(M)), and aggregation numbers N of the gemini surfactant with these different types of anions, we demonstrated the effect of different ion properties independently. This approach allowed us to describe the effect of counterions on the micellization behavior of the gemini surfactant in terms of complex interplay between hydrophobicity of anions and other ion properties such as counterion hydration, interfacial packing of ions, and ionic morphology. Indeed, our results clearly demonstrate that a counterion effect on micellization properties cannot be described as a result of one single parameter of ions, as is too often assumed, but rather the balancing effects cooperatively affect the propensity of counterions to form ion pairs with surfactant headgroups and the entropy gain upon micellization. These results provide new insight in understanding the effect of ions on the delicate balance of forces controlling aggregate morphology and solution properties of charged amphiphilic molecules.

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A series of L-phenylalanine ionic liquids (ILs), L-tyrosine ILs, tertiary amino analogues and proposed transformation products (PTPs) have been synthesised. Antimicrobial toxicity data, as part of the green chemistry metrics evaluation and to supplement preliminary biodegradation studies, was determined for ILs, tertiary amino analogues and PTPs. Good to very good overall yields (76 to 87%) for the synthesis of 6 ILs from L-phenylalanine were achieved. A C 2 -symmetric IL was prepared from TMS-imidazole in a one-pot two-step method in excellent yield (91%). Synthesis of the L-tyrosine IL derivatives utilised a simple protection group strategy by using an extra equivalent of the bromoacetyl bromide reagent. Improvements in the synthesis of the α-bromoamide alkylating reagent from L-phenylalanine were achieved, directed by green chemistry metric analysis. A solvent switch from dichloromethane to THF is described, however the yield was 15% lower. Antimicrobial activity testing of L-phenylalanine ILs, L-tyrosine ILs, tertiary amino analogues and PTPs, against 8 bacteria and 12 fungi strains, showed that no compound had a high antimicrobial activity, apart from an L-proline analogue. In this exceptional case, the highest toxicity (IC 95 = 125 and 250 µM) was observed towards the two Gram positive strains Staphylococcus aureus and Staphylococcus epidermidis respectively. High antimicrobial activity was not found for the other bacteria or fungi strains screened. The limitations of the antimicrobial activity study is discussed in relation to SAR studies. Preliminary analysis of biodegradation data (Closed Bottle Test, OECD 301D) is presented. The pyridinium IL derivative is the preferred green IL of the series based on synthesis, toxicity and biodegradation considerations. This work is a joint study with Kümmerer and co-workers and the PTPs were selected as target compounds based on concurrent biodegradation studies by the Kümmerer group. For the comprehensive biodegradation and transformation product analysis see the accompanying paper.

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We report on a new approach for creating water-soluble functionalized vesicles employing N-alkyl-3-boronopyridinium triflates (alkyl = Me, C12H25, C16H33) as sensors for monosaccharides. The nanoaggregate properties were studied by means of DLS, TEM, high-resolution (1)H NMR, and the solvatochromic dyes Reichardt's betaine and Methyl Orange. The vesicles were shown to have 30-200 nm diameters depending on the amphiphile chain length. Diol binding to the vesicles was studied by steady-state fluorescence and UV-vis using Alizarin Red S as a probe in the solution at pH 7.4 in the presence and in the absence of D-glucose and D-fructose. Strong sensing ability of boronic acid functional moieties in the order D-fructose > D-glucose was demonstrated, and apparent binding constants were estimated.

Micelles of deprotonated 1-cetyl-3-(2-oximopropyl)imidazolium chloride strongly accelerate displacements of 4-nitrophenoxide ion from 4-nitrophenyl diethyl phosphate and 4-nitrophenyl tosylate. The first-order rate constants of reactions of fully bound substrates are similar to those predicted from second-order rate constants of reactions of deprotonated 1-methyl-3-(2-oximopropyl)imidazolium chloride in water and a reasonable value of the molar volume of the micellar interfacial region.