A previously reported non-toxic guanidine-iron catalyst active in the ring opening polymerization (ROP) of polylactide (PLA) under industrially relevant conditions was evaluated for its activity in the alcoholysis and aminolysis of PLA under mild conditions. Kinetic and thermodynamic parameters were determined for the methanolysis of PLA with [FeCl 2 (TMG5NMe 2 asme)] (C1) using 1 H NMR spectroscopy. A comparison with the Zn analog of C1 showed that the metal center has a large impact on the activity for the alcoholysis. Further, the influence of different nucleophiles was tested broadening the scope of products from PLA waste. C1 is the first discrete metal catalyst reported to be active in the selective aminolysis of PLA. Catalyst recycling, scale-up experiments and solvent-free alcoholysis were conducted successfully strengthening the industrial relevance and highlighting aspects of green chemistry. Moreover, the selective depolymerization of PLA in polymer blends was successful. C1 is a promising catalyst for a circular (bio)plastics economy.

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 (FcNMe3TIPS). In FcNMe3TIPS, 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, FcNMe3TIPS forms lyotropic liquid crystals, not only in contact with water, but also in a variety of organic solvents. As an additional intriguing feature, FcNMe3TIPS 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(PEt3)2X (X = Cl, I) complex entities, leading to a heterobimetallic surfactant. We also found that the benzylic α-position of FcNMe3TIPS 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 FcNMe3TIPS 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.

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