Photodimerization of coumarin in aqueous and micellar media

Guest‐Release Control in Enzyme‐Sensitive, Amphiphilic‐Dendrimer‐Based Nanoparticles through Photochemical Crosslinking

“…We decided to utilize the coumarin functionality to controllably crosslink the aggregates formed by the dendron. Photodimerization of coumarin functionalities by [2+2] cycloaddition reaction is well known [3l,13,14] (Figure 7 a). For effective crosslinking of these aggregates, we need at least three coumarin functionalities per molecule involved in the assembly.…”

Supramolecular Control of the Template‐Induced Selective Photodimerization of 4‐Methyl‐7‐O‐hexylcoumarin

“…[8] The transition moments can further be influenced by solvent polarity [11] and the use of cyclodextrin or micelles. [12,15,16] With respect to previous reports, [30±34] we set forth the design and subsequent synthesis of a template, which Scheme 1. Schematic representation of the reaction pathway responsible for selective syn photodimer formation within a supramolecular 2:1 species.…”

“…Under typical experimental conditions, however, the two syn (2 A and 2 B) photoproducts are formed predominately, while only trace amounts of the anti dimers 2 C and 2 D are observed. [7] The ratio of coumarin photoproducts can significantly be altered through control of the reaction conditions such as solvent choice, [9,11,12] Lewis acid addition, [13,14] micellar environment, [15,16] solid-state irradiation, [13,14] modification of the coumarin precursor, [17,18] use of inclusion complexes [15] and tethered precursors, [17, 19±21] or recently with pseudo-rotaxanes. [22] Much effort has been focused on crystal engineering and packing within the solid state to influence the product distribution.…”

Shikimic Acid Pathway

“…[43] (B) Ref. [44] (A) Ref. generating singlet coumarin, the latter transfers its energy to benzophenone to form benzophenone singlet.…”

“…The enhanced reactivity and selectivity during dimerization might be due to the polarity of the solvents. The micelle provides a hydrophobic pocket with the bulk of water causing hydrophobic interaction and allowing the aggregation of coumarin molecules in water [44].…”