Molecular Engineering To Enhance Reactivity and Selectivity in an Ultrafast Photoclick Reaction

• Published in: Angewandte Chemie 2023-04, Vol.135 (16), p.n/a
• Main Authors: Fu, Youxin, Simeth, Nadja A., Toyoda, Ryojun, Brilmayer, Robert, Szymanski, Wiktor, Feringa, Ben L.
• Format: Article
• Language: English
• Subjects: Adducts; Biocompatibility; Chemistry; Click Chemistry; Fluorescence; Nanoparticles; Orthogonality; Phenanthrenequinone; Photochemicals; Photochemistry; Photoclick
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202218203

Light‐induced 9,10‐phenanthrenequinone‐electron‐rich alkene (PQ‐ERA) photocycloadditions are an attractive new type of photoclick reaction, featuring fast conversions and high biocompatibility. However, the tunability of the reaction was hardly investigated up to now. To this end, we explored the influence of substituents on both reaction partners and the reaction rate between the PQs and ERAs. We identified new handles for functionalization and discovered that using enamines as ERAs leads to drastically enhanced rates (>5400 times faster), high photoreaction quantum yields (ΦP, up to 65 %), and multicolor emission output as well as a high fluorescence quantum yield of the adducts (ΦF, up to 97 %). Further investigation of the photophysical and photochemical properties provided insights to design orthogonal reaction systems both in solution and on nanoparticle surfaces for ultrafast chemoselective functionalization by photoclick reactions. Modification of the key parameters of the 9,10‐phenanthrenequinone‐electron‐rich alkene (PQ‐ERA) photocycloaddition has led to a system that combines PQs and enamines. This next‐generation system shows drastically enhanced rates, high photoreaction quantum yields, tunable fluorescence output, and high fluorescence quantum yields of the adducts. Furthermore, an orthogonal reaction system was achieved in both solution and on nanoparticle surfaces.