We introduce the formation of a dual responsive supramolecular star polymer system, displaying gated selfassembly behavior. The redox-and thermoresponsive star polymers are based on a 6-fold β-CD functionalized core molecule and RAFT-derived ferrocene end functionalized poly(N,N-dimethylacrylamide) (PDMA) and poly(N,N-diethylacrylamide) (PDEA) linear polymers. Complex formation is analyzed via various methods including dynamic light scattering (DLS). Chemical redox triggers, namely NaOCl and ascorbic acid, as well as electrochemical triggers can be utilized to shift the star polymers to the unbound state via CD/ferrocene complex dissociation. Moreover, heating above the lower critical solution temperature (approximately 34 °C) allows for a change from the coil to the globular state of the star polymers in the case of PDEA arms. For PDMA arms, heating to 70 °C allows shifting of the system to the unbound state. The response of the supramolecular star polymers is carefully studied via various methods including cyclic voltammetry (CV), DLS, and turbidimetry. Overall, the supramolecular star polymers can be transformed into predefined states via individually addressable temperature and/or redox stimuli, presenting a novel dual gated self-assembling supramolecular star polymer system in aqueous solution.

Dimethylmenaquinone (DMMK), a prevalent menaquinone (MK) derivative of uncertain function, is characteristic for members of the class Coriobacteriia. Such bacteria are frequently present in intestinal microbiomes and comprise several pathogenic species. The coriobacterial model organism Adlercreutzia equolifaciens was used to investigate the enzymology of DMMK biosynthesis. A HemN-like class C radical S-adenosylmethionine methyltransferase (MenK2) from A. equolifaciens was produced in Wolinella succinogenes or Escherichia coli cells and found to methylate MK specifically at position C-7. In combination with a previously described MK methyltransferase (MqnK/MenK) dedicated to MK methylation at C-8, 7,8-DMMK was produced in W. succinogenes. The position of the two methyl groups was confirmed by two-dimensional NMR and midpoint redox potentials of 7-MMK, 8-MMK and 7,8-DMMK were determined by cyclic voltammetry. A phylogenetic tree of MenK, MenK2 and HemN proteins revealed a Coriobacteriia-specific MenK2 clade. Using chimeric A. equolifaciens MenK/MenK2 proteins produced in E. coli it was shown that the combined linker and HemN domains determined the site-specificity of methylation. The results suggest that the use of MenK2 as a biomarker allows predicting the ability of DMMK synthesis in microbial species.

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Grubbs-catalyzed ring-opening metathesis polymerization (ROMP) of carborane- and phosphonate-containing monomers has been used for the generation of hybrid block copolymers. Molecular weights with Mn of 50,000 g/mol were readily obtained with polydispersity index values, Đ, between 1.03–1.08. Reaction of the phospha ester and carborane substituted oxanorbornene block copolymer with trimethylsilyl bromide led to a new polymer with phosphonic acid functionalities. In application studies, the phospha-carborane functionalized block polymer was tested as heat resistance material. Thermal stability was investigated by thermal gravimetric analysis (TGA) and microscale combustion calorimetry (MCC) analysis. Thermal treatment and ceramic yield under air were directly correlated to the carborane content of the block copolymer. However, phosphorus content in the polymer was more crucial for the char residues when heated under nitrogen atmosphere. The peak heat release rate (PHRR) increased as the number of phosphonate functionalities increased. However, corresponding phosphonic acid derivatives featured a lower heat release rate and total heat release. Moreover, the phosphonic acid functionalities of the block copolymer offer efficient chelating capabilities for iron nanoparticles, which is of interest for applications in biomedicine in the future. The complexation with iron oxide nanoparticles was studied by transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP–MS).

The photochromic and electrochemical switching capabilities of two dithienylethenes with different substitutions and their self-assembled monolayers on gold surfaces are characterized by in situ NMR-spectroscopy and cyclic voltammetry.