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Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification

Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification

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BITTER, Stefan, Marius KUNKEL, Lisa BURKART, André MANG, Rainer WINTER, Sebastian POLARZ, 2018. Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification. In: ACS Omega. 3(8), pp. 8854-8864. eISSN 2470-1343. Available under: doi: 10.1021/acsomega.8b01405

@article{Bitter2018-08-31Organ-43093, title={Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification}, year={2018}, doi={10.1021/acsomega.8b01405}, number={8}, volume={3}, journal={ACS Omega}, pages={8854--8864}, author={Bitter, Stefan and Kunkel, Marius and Burkart, Lisa and Mang, André and Winter, Rainer and Polarz, Sebastian} }

Kunkel, Marius Mang, André Burkart, Lisa Winter, Rainer Kunkel, Marius eng Bitter, Stefan Polarz, Sebastian 2018-08-31 Mang, André terms-of-use Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification Surfactants are functional molecules comprising a water-compatible head group and a hydrophobic tail. One of their features is the formation of self-assembled structures in contact with water, for instance, micelles, vesicles, or lyotropic liquid crystals. One way to increase the functionality of surfactants is to implement moieties containing transition-metal species. Ferrocene-based surfactants represent an excellent example because of the distinguished redox features. In most existing ferrocene-based amphiphiles, an alkyl chain is classically used as the hydrophobic tail. We report the synthesis and properties of 1-triisopropylsilylethynyl-1′-trimethylammoniummethylferrocene (FcNMe<sub>3</sub>TIPS). In FcNMe<sub>3</sub>TIPS, ferrocene is part of the head group (Gemini design) but is also attached to a (protected) π-conjugated ethynyl group. Although this architecture differs from that of classical amphiphiles and those of other ferrocene-based amphiphiles, the compound shows marked surfactant properties comparable to those of lipids, exhibiting a very low value of critical aggregation concentration in water (cac = 0.03 mM). It forms classical micelles only in a very narrow concentration range, which then convert into monolayer vesicles. Unlike classical surfactants, aggregates already form at a very low concentration, far beneath that required for the formation of a monolayer at the air–water interface. At even higher concentration, FcNMe<sub>3</sub>TIPS forms lyotropic liquid crystals, not only in contact with water, but also in a variety of organic solvents. As an additional intriguing feature, FcNMe<sub>3</sub>TIPS is amenable to a range of further modification reactions. The TIPS group is easily cleaved, and the resulting ethynyl function can be used to construct heterobimetallic platinum-ferrocene conjugates with trans-Pt(PEt<sub>3</sub>)<sub>2</sub>X (X = Cl, I) complex entities, leading to a heterobimetallic surfactant. We also found that the benzylic α-position of FcNMe<sub>3</sub>TIPS is rather reactive and that the attached ammonium group can be exchanged by other substituents (e.g., −CN), which offers additional opportunities for further functionalization. Although FcNMe<sub>3</sub>TIPS is reversibly oxidized in voltammetric and UV–vis spectroelectrochemical experiments, the high reactivity at the α-position is also responsible for the instability of the corresponding ferrocenium ion, leading to a polymerization reaction. Winter, Rainer Burkart, Lisa 2018-08-16T09:04:52Z Bitter, Stefan Polarz, Sebastian 2018-08-16T09:04:52Z

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