Details
Originalsprache | Englisch |
---|---|
Seiten (von - bis) | 8854-8864 |
Seitenumfang | 11 |
Fachzeitschrift | ACS Omega |
Jahrgang | 3 |
Ausgabenummer | 8 |
Frühes Online-Datum | 9 Aug. 2018 |
Publikationsstatus | Veröffentlicht - 31 Aug. 2018 |
Extern publiziert | Ja |
Abstract
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 3TIPS). In FcNMe 3TIPS, 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 3TIPS forms lyotropic liquid crystals, not only in contact with water, but also in a variety of organic solvents. As an additional intriguing feature, FcNMe 3TIPS 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 3) 2X (X = Cl, I) complex entities, leading to a heterobimetallic surfactant. We also found that the benzylic α-position of FcNMe 3TIPS 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 3TIPS 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.
ASJC Scopus Sachgebiete
- Chemie (insg.)
- Allgemeine Chemie
- Chemische Verfahrenstechnik (insg.)
- Allgemeine chemische Verfahrenstechnik
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in: ACS Omega, Jahrgang 3, Nr. 8, 31.08.2018, S. 8854-8864.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification
AU - Bitter, Stefan
AU - Kunkel, Marius
AU - Burkart, Lisa
AU - Mang, André
AU - Winter, Rainer F.
AU - Polarz, Sebastian
N1 - Funding Information: Funding The current research was funded by an ERC consolidator grant (I-SURF; project 614606). Notes The authors declare no competing financial interest.
PY - 2018/8/31
Y1 - 2018/8/31
N2 - 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 3TIPS). In FcNMe 3TIPS, 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 3TIPS forms lyotropic liquid crystals, not only in contact with water, but also in a variety of organic solvents. As an additional intriguing feature, FcNMe 3TIPS 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 3) 2X (X = Cl, I) complex entities, leading to a heterobimetallic surfactant. We also found that the benzylic α-position of FcNMe 3TIPS 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 3TIPS 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.
AB - 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 3TIPS). In FcNMe 3TIPS, 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 3TIPS forms lyotropic liquid crystals, not only in contact with water, but also in a variety of organic solvents. As an additional intriguing feature, FcNMe 3TIPS 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 3) 2X (X = Cl, I) complex entities, leading to a heterobimetallic surfactant. We also found that the benzylic α-position of FcNMe 3TIPS 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 3TIPS 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.
UR - http://www.scopus.com/inward/record.url?scp=85051255207&partnerID=8YFLogxK
U2 - 10.1021/acsomega.8b01405
DO - 10.1021/acsomega.8b01405
M3 - Article
C2 - 30197995
VL - 3
SP - 8854
EP - 8864
JO - ACS Omega
JF - ACS Omega
IS - 8
ER -