Alkylsulfides of Ag(I) and Au(I) as Metallosurfactants

Abstract

Several representative, interfacially active silver(I) nitrate alkylsulfide complexes were synthesized and characterized in detail. The complexes form extended structures in the solid state and in solution. Interestingly, a two-phase approach, in which aqueous silver nitrate is combined with organically dissolved sulfides, leads to the in situ formation of the complexes at the water-organic interface and a strong reduction of the surface tension. Despite their low solubility in water or organic solvent, these complexes are capable of stabilizing eicosane emulsions and dispersions in water. Thus, these silver nitrate alkyl sulfides represent a new class of metallosurfactants in which the metal ion is crucial for the interfacial activity. Gold(I) chloride alkyl sulfides show the same effect to a lesser extent.

A molecular “screw-clamp”: accelerating click reactions in miniemulsions

“…Previously, aliphatic carboxylic acids were deprotonated in the heterophase to generate ionic surfactants 20,21 while metallosurfactants and transition metal acetyl acetonates have also been produced in situ. 22,23 The generation of a surfactant in situ can have advantages such as faster stabilization of the (mini)emulsion and less secondary nucleation processes. 24 Here, we used the interfacial ''screw clamp'' for mediating a click reaction in a direct miniemulsion between dodecyl propiolate dispersed in styrene as the organic phase and N-e-azido-L-lysine hydrochloride dissolved in the aqueous phase.…”

“…Previously, aliphatic carboxylic acids were deprotonated in the heterophase to generate ionic surfactants 20,21 while metallosurfactants and transition metal acetyl acetonates have also been produced in situ. 22,23 The generation of a surfactant…”

Dynamic Imine Chemistry at Complex Double Emulsion Interfaces

“…The reversibility of imine bond formation has proved useful in creating materials with dynamic behaviors including in 2D assemblies, , biomimicry, systems chemistry, drug/receptor design, micelles, − and vesicles. , There have been limited examples of imine surfactant stabilized emulsions. − Additionally, imine bond equilibria are pH sensitive, allowing for manipulation of the bond and therefore the structures of double emulsions (Figure b). Although there are reported examples of in situ molecular surfactant generation for single emulsions, including deprotonation of carboxylic acids and metallosurfactants − and Pickering single and double emulsions, , we are unaware of any prior reports of double emulsions fabricated via in situ molecular surfactant synthesis.…”

Interfacial Activity of Metal β-Diketonato Complexes: In Situ Generation of Amphiphiles by Water Coordination

“…In such classical metallosurfactants, a metal cation is integrated in the headgroup of a surfactant ligand or well-shielded by the presence of chelating ligands . As an alternative, we recently presented a new class of metallosurfactants in which (in situ) coordination of Ag(I) and Au(I) cations to organic sulfides is crucial for the interfacial activity …”