Polymere Cumarsäuren

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

“…66,67 In 1904, Ström reported a dimer with a melting point above 320°C. 67,68 In the early 1960s, Anet synthesized the head-to-head cis and the headto-tail trans coumarin dimers via sunlight exposure. 69,70 Since the first studies reported two different melting points, it was not resolved until Schenck and co-workers observed that both structures were in fact dimers of coumarin.…”

“…The photodimerization of coumarin was discovered by Ciamician and Silber in 1902, when they used sunlight to irradiate coumarin dissolved in alcohol for over 2 years . The dimerized product exhibited a melting point of 262 °C, much higher than the original coumarin's melting temperature of 68−70 °C. , In 1904, Ström reported a dimer with a melting point above 320 °C. , In the early 1960s, Anet synthesized the head-to-head cis and the head-to-tail trans coumarin dimers via sunlight exposure. , Since the first studies reported two different melting points, it was not resolved until Schenck and co-workers observed that both structures were in fact dimers of coumarin . Schenck used 1 H NMR spectroscopy to determine the structure of the four possible dimers that were produced from the irradiation of coumarin at different reaction conditions.…”

Photoreversible Chain Extension of Poly(ethylene glycol)

“…320 8C, although most coumarin dimers melt between 170 and 200 8C depending on configuration. [12][13][14][15][16] Although Ciamician and Silber first discovered photodimerization reactions involving coumarin in 1902, the photocleavage reaction was not discovered until the 1960's when Schenck and coworkers further studied the photodimerization reaction. [14,15] It is important to note that neither the photodimerization nor the photocleavage reactions are thermally allowed.…”