A novel photoresponsive and fully conjugated N‐heterocyclic carbene (NHC) has been synthesized that combines the excellent photophysical properties of arylazopyrazoles (AAPs) with an NHC that acts as a robust surface anchor (AAP‐BIMe). The formation of self‐assembled monolayers (SAMs) on gold was proven by ToF‐SIMS and XPS, and the organic film displayed a very high stability at elevated temperatures. This stability was also reflected in a high desorption energy, which was determined by temperature‐programmed SIMS measurements. E‐/Z‐AAP‐BIMe@Au photoisomerization resulted in reversible alterations of the surface energy (i.e. wettability), the surface potential (i.e. work function), and the conductance (i.e. resistance). The effects could be explained by the difference in the dipole moment of the isomers. Furthermore, sequential application of a dummy ligand by microcontact printing and subsequent backfilling with AAP‐BIMe allowed its patterning on gold. To the best of our knowledge, this is the first example of a photoswitchable NHC on a gold surface. These properties of AAP‐BIMe@Au illustrate its suitability as a molecular switch for electronic devices.

Surface coatings that respond to external influences and change their physical properties upon application of external stimuli are of great interest, with light being a particularly desirable choice. Photoswitches such as azobenzenes have been employed in a range of photoresponsive coatings. One striking change in physical property of many photoresponsive coatings is their responsive wettability upon illumination. In this work, we present photoswitchable self-assembled monolayers based on arylazopyrazoles (AAPs). In solution, AAPs offer significant improvements in terms of the photostationary state, thermal stability, and fatigue resistance. The AAP photoswitch is coupled to triethoxysilanes for an easy, one-step functionalization of glass and silicon oxide surfaces. We show the synthesis of AAP-based silanes and the successful surface functionalization, and we confirm the excellent photoswitchability of the AAPs in a self-assembled monolayer upon alternating irradiation with UV (365 nm) and green (520 nm) light. The self-assembled monolayers are investigated by UV/vis spectroscopy, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and contact angle goniometry. We furthermore investigate the effect of substitution of the AAPs on the photoresponsive wetting behavior and compare this with density functional theory (DFT) calculations of the dipole moments of the AAPs.

The first water-soluble spirobifluorene derivative has been synthesized, which exhibits high fluorescence quantum yield and a large Stokes shift (>100 nm). Proteins induce changes in the emission color, allowing to reach the nanomolar detection limit. Cellular uptake and cytotoxicity studies in living cells revealed its biocompatibility, indicating potential application for live cell imaging.

The emergence of multidrug-resistant (MDR) pathogenic bacteria constitutes a key threat to global health. Infections caused by multidrug-resistant Gram-negative bacteria are particularly challenging to treat due to the ability of pathogens to prevent antibiotic penetration inside the bacterial membrane. Antibiotic therapy is further rendered ineffective due to biofilm formation where the protective extracellular polymeric substance matrix limits the diffusion of antibiotics inside the biofilm. It is hypothesized that careful engineering of chemical groups on polymer scaffolds can enable polymers to penetrate the barriers of Gram-negative bacterial membrane and biofilm matrix. Here, the use of engineered polymeric nanoparticles in combination with antibiotics for synergistic antimicrobial therapy is presented. These polymeric nanoparticles enhance the accumulation of antibiotics inside Gram-negative bacteria and the biofilm matrix, resulting in increased potency of antibiotics in combination therapy. Sublethal concentrations of engineered polymeric nanoparticles reduce the antibiotic dosage by 32-fold to treat MDR bacteria and biofilms. Tailoring of chemical groups on polymers demonstrates a strong structure-activity relationship in generating additive and synergistic combinations with antibiotics. This study demonstrates the ability of polymeric nanoparticles to "rejuvenate" antibiotics rendered ineffective by resistant bacteria and provides a rationale to design novel compounds to achieve effective antimicrobial combination therapies.