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Imidazolium-based dicationic ILs (DILs) presenting antimicrobial activity and relatively low toxicity are highly desirable and are envisioned for use in live tissue to prevent bacterial or fungal infections. In this context, we present here DILs with dicarboxylate anions [Cn(MIM)2[Cn(MIM)2][CO2-(CH2)mCO2], in which n = 4, 6, 8, and 10, and m = 0, 1, 2, 3, 4, and 5. The results showed that DILs with an alkyl chain spacer of ten carbons were active against yeasts and the bacterial strains tested. However, most of the DILs were cytotoxic and toxic at 1 mM. By contrast, DILs with alkyl chains possessing less than ten carbons were active against some specific Candidas and bacteria (mainly S. aureus), and they showed moderate cytotoxicity. The best activity against Gram-positive bacteria was observed for [C4(MIM)2][Pim] toward MRSA. For the DILs described herein, their level of toxicity against C. elegans was lower than that of most of the mono- and dicationic IL analogs with other anions. Our results showed that the presence of carboxylate anions reduces the toxicity of DILs compared to DILs containing halide anions, which is particularly significant to the means of designing biologically active compounds in antimicrobial formulations.

Deep eutectic solvents (DES) have been used to modulate the catalytic activity of TiO2 nanoparticles.

Phase transitions, thermal stability, thermokinetics and activation parameters of degradation reaction of the dicationic ionic liquids (ILs), 1,n-bis(3-methylimidazolium-1-yl)alkane ([BisAlk(MIM) 2 ][2Br]) and monocationic ILs, 1-(3-methylimidazolium-1-yl)alkane ([Alk(MIM)] [Br]), where Alk = Dec, DoDec, TetDec, (decane, dodecane, tetradecane) were evaluated. The influence of an additional cationic head and the alkyl chain length in thermal parameters were also evaluated. The dicationic ILs are more stable than monocationic and thermal degradation of ILs mono-and dicationic did not show linear dependence on the alkyl chain length. Thermokinetic parameters indicated degradation in multiple steps. The monocationic ILs showed a more persistent crystalline phase than dicationic IL, which became totally amorphous after heating. The estimate temperature decomposition, activation energy and thermal transitions enable the determination of which types of ILs are applicable for specific purposes, such as lubricants or solvents at high temperatures, while maintaining ILs physical and chemical properties.

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