Chasing the rainbow: Exploiting photosensitizers to drive photoisomerization reactions

AbstractPhotoswitchable molecules have garnered considerable attention for their versatility and diverse applications, spanning from solar energy harvesting and storage to drug delivery and molecular motors. The chemical conversions that make photoswitches a desirable system are driven by specific wavelengths of light, which often demand intricate molecular modifications. An alternative approach to achieve the photoisomerization reaction is through energy transfer with photosensitizers. Photosensitizers play a pivotal role in various light‐induced processes and have demonstrated successful applications in photodynamic therapy, dye‐sensitized solar cells, and activating photochemical reactions. Therefore, combining photoswitching systems with sensitizers presents an attractive alternative for advancing light‐responsive material design and enabling innovative light‐controlled technologies. This review summarizes the energy transfer mechanisms and strategies involved in sensitized molecular photoswitchable systems, emphasizing the performance of various combined systems, and potential applications. Furthermore, recent advances and emerging trends in this field are also discussed, offering insights into prospective future directions for the development of light‐responsive materials.</jats:p

Pyrene Functionalized Norbornadiene-Quadricyclane Fluorescent Photoswitches: Characterization of their Spectral Properties and Application in Imaging of Amyloid Beta Plaques.

Publication status: PublishedThis study presents the synthesis and characterization of two fluorescent norbornadiene (NBD) photoswitches, each incorporating two conjugated pyrene units. Expanding on the limited repertoire of reported photoswitchable fluorescent NBDs, we explore their properties with a focus on applications in bioimaging of amyloid beta (Aβ) plaques. While the fluorescence emission of the NBD decreases upon photoisomerization, aligning with what has been previously reported, for the first time we observed luminescence after irradiation of the quadricyclane (QC) isomer. We deduce how the observed emission is induced by photoisomerization to the excited state of the parent isomer (NBD) which is then the emitting species. Thorough characterizations including NMR, UV-Vis, fluorescence, X-ray structural analysis and density functional theory (DFT) calculations provide a comprehensive understanding of these systems. Notably, one NBD-QC system exhibits exceptional durability. Additionally, these molecules serve as effective fluorescent stains targeting Aβ plaques in situ, with observed NBD/QC switching within the plaques. Molecular docking simulations explore NBD interactions with amyloid, unveiling novel binding modes. These insights mark a crucial advancement in the comprehension and design of future photochromic NBDs for bioimaging applications and beyond, emphasizing their potential in studying and addressing protein aggregates