Coumarins in Polymers:  From Light Harvesting to Photo-Cross-Linkable Tissue Scaffolds

Synthesis, kinetics of photo-dimerization/photo-cleavage and physical properties of coumarin-containing branched polyurethanes based on polycaprolactones

“…When the polymer film was irradiated with 354 or 365 nm lamps, conversion increased continuously with irradiation time until a plateau was reached, at approximately 85-90% conversion ( Figure 9). This ultimate conversion is similar to the conversion found in other methylcoumarin containing polymers, for which maximum conversions reported are 77.5% [20], 81.5% [22] and approximately 80% [11]. Repeatability in conversion was as good as for the curves in Figure 6.…”

“…In Figure 11 for example, for irradiation with 354 nm lamp, it can be found that photo-cleavage had approximately the same efficiency at any dimerization conversion but photo-cleavage was not complete and always a dimerized material (approximately 20-25%) remained. It has been shown extensively by other authors that photo-cleavage is never complete and is attributed to a dynamic equilibrium between photo-dimerization and photo-cleavage [11,[19][20][21][22]25]. It was also pointed out that prolonged exposure to 254 nm light would result in an irreversible structure [20].…”

SFRP Synthesis of Acenaphthylene Oligomers and Block Copolymers. Potential Light Harvesting Structures

“…[1][2][3][4][5][6][7] Part of our ongoing research in the area of materials science [8][9][10][11] involves investigation of the underlying processes of light harvesting, including absorption of light by suitable donor (D) moieties and efficient energy (and/or) electron transfer to acceptor (A) moieties in LH model molecules.…”

Facile Synthesis of 3-Thioxo-3H-benzo[f]chromen-2-yl methanone and 3H-Benzo[f]chromene-3-one Under Solvent Free Condition

“…Knoevenagel condensation is reported recently to proceed with high selectivity and reactivity in the formation of coumarins over solid base catalysts. 7 Microwave irradiation accelerates these reactions several-fold with better yields of the products where the reactants, however, are taken in millimolar quantities. 8 There have been reports on the synthesis of dihydrocoumarins from o-hydroxycinnamaldehydes in a mild, atom-economic N-heterocyclic carbene-catalyzed redox lactonization.…”