Ionic liquids with chlorometallate anions may not have been the first ionic liquids, however, it was their development that lead to the recognition that ionic liquids are a distinct, and useful, class of (functional) materials. While much of the phenomenal interest and attention over the past two decades has focussed on ‘air and water stable’ ionic liquids, research and application of chlorometallate systems has continued unabated albeit largely out of the main spotlight. The defining characteristic of chlorometallates is the presence of complex anionic equilibria, which depend both on the type and on the concentration of metal present, and leads directly to their characteristic and individual properties. Here, we review the experimental techniques that can be applied to study and characterise the anion speciation in these ionic liquids and, using recent examples, illustrate how their applications base is evolving beyond traditional applications in Lewis acidic catalysis and electrochemistry through to uses as soft and component materials, in the ionothermal synthesis of semiconductors, gas storage systems and key components in the development of biomass processing.

Vitamin C is one of the most sensitive cosmetic active ingredients. To avoid its degradation, its encapsulation into biobased carriers such as dendrimers is one alternative of interest. In this work, we wanted to evaluate the potential of two biobased glycerodendrimer families (GlyceroDendrimers-Poly(AmidoAmine) (GD-PAMAMs) or GlyceroDendrimers-Poly(Propylene Imine) (GD-PPIs)) as a vitamin C carrier for topical application. The higher encapsulation capacity of GD-PAMAM-3 compared to commercial PAMAM-3 and different GD-PPIs, and its absence of cytotoxicity towards dermal cells, make it a good candidate. Investigation of its mechanism of action was done by using two kinds of biomimetic models of stratum corneum (SC), lipid monolayers and liposomes. GD-PAMAM-3 and VitC@GD-PAMAM-3 (GD-PAMAM-3 with encapsulated vitamin C) can both interact with the lipid representatives of the SC lipid matrix, whichever pH is considered. However, only pH 5.0 is suggested to be favorable to release vitamin C into the SC matrix. Their binding to SC-biomimetic liposomes revealed only a slight effect on membrane permeability in accordance with the absence of cytotoxicity but an increase in membrane rigidity, suggesting a reinforcement of the SC barrier property. Globally, our results suggest that the dendrimer GD-PAMAM-3 could be an efficient carrier for cosmetic applications.

For this study, new dendrimers were prepared from poly(propylene imine) (PPI) and polyamidoamine (PAMAM) dendrimers using an efficient acid-base reaction with various phenolic acids. The syntheses were also optimized in both microwave and microfluidic reactors. These ionic and hydrophilic dendrimers were fully characterized and showed excellent antioxidant properties. Their cytotoxic properties have been also determined in the case of fibroblast dermal cells.