RESUMO
Biological tissue exhibits an absorbance minimum in the near-infrared between 700 and 900 nm that permits deep penetration of light. Molecules that undergo photoisomerization in this bio-optical window are highly desirable as core structures for the development of photopharmaceuticals and as components of chemical-biological tools. We report the systematic design, synthesis, and testing of an azobenzene derivative tailored to undergo single-photon photoswitching with near-infrared light under physiological conditions. A fused dioxane ring and a methoxy substituent were used to place oxygen atoms in all four ortho positions, as well as two meta positions, relative to the azobenzene NâN double bond. This substitution pattern, together with a para pyrrolidine group, raises the pKa of the molecule so that it is protonated at physiological pH and absorbs at wavelengths >700 nm. This azobenzene derivative, termed DOM-azo, is stable for months in neutral aqueous solutions, undergoes trans-to-cis photoswitching with 720 nm light, and thermally reverts to the stable trans isomer with a half-life near 1 s.
Assuntos
Compostos Azo/química , Compostos Azo/efeitos da radiação , Raios Infravermelhos , Processos Fotoquímicos/efeitos da radiação , Concentração de Íons de Hidrogênio , Isomerismo , Prótons , Pirrolidinas/químicaRESUMO
In the presence of a borinic acid derived catalyst, 2,3-epoxy alcohols undergo couplings with acyl and sulfonyl chlorides. This transformation directly generates O-acylated or O-sulfonylated chlorohydrin diols, with significant levels of regioselectivity for both the ring-opening and O-functionalization steps.