B06 • Chiral Azaboroles and Azaborines for Sensoric Applications

The goal of this project is the synthesis and characterization of helically chiral azaborole and azaborine helicenes, as well as organoboron photoswitches derived from both overcrowded alkenes (OAs) and diarylethenes (DAEs). Such compounds are of interest for developing new sensors and photoswitchable labels that can be used in bioimaging applications. Replacing carbon by an electrondeficient boron atom modifies the HOMO/LUMO gap allowing tunability of the photoswitch optical properties. The utilization of boron atoms also provides a unique opportunity to obtain multi-stimuli responsive materials exploiting reversible formation of B-N dative bonds as additional switching units.
The absolute configuration of these helicenes and chiral photoswitches will be characterized using Raman optical activity (ROA) spectroscopy, while (accelerated) molecular dynamics simulations and multistate Nudged Elastic Band (NEB) simulations will provide insight in the energy landscape of the switching process and the interpretation of ROA spectra. The combination of spectroscopy with simulations will support the design of OA photoswitches to achieve temporal control over the switching
process in the visible spectral range. Furthermore, the project will contribute to the development of DAE chiroptical photoswitches displaying high stereoselectivity in photocyclization reactions, high reversibility, large changes in ROA spectra, and thermal stability in both states (p-type photochromes).
These studies will provide a basis for the development of novel multi-stimuli responsive switches exhibiting both photoisomerization and reversible boron-heteroatom dative bond formation.