[Show abstract][Hide abstract] ABSTRACT: A practical protocol for the preparation of parallel solution-phase libraries of the quaternary carbon-containing oxazatricycles and spiropyrans is reported. Target compounds were obtained in moderate to excellent yields by an Et(3)N-mediated multicomponent reaction from various N-methylisoquinolium or flavylium salts and 4-hydroxycoumarins or dimedone in acetone. Purification of the final products by recrystallization in ethyl acetate/methylene chloride or by column chromatography allowed easy isolation of nine compounds of each array. Preliminary studies indicated that some of the prepared compounds exhibit redox switching, photochromic, and thermochromic properties.
[Show abstract][Hide abstract] ABSTRACT: An o-hydroxyphenyl-containing spiropyran thermochromic colorant was designed and synthesized. The prepared compound is sensitive to temperature and has a reversible color change with temperature variation. X-ray diffraction analysis and variable-temperature NMR studies suggest that the thermochromism of the compound presumably involved a ring-opening C-O bond cleavage of the spiropyran moiety followed by an intramolecular hydrogen transfer.
[Show abstract][Hide abstract] ABSTRACT: Two coumarin-based spiropyran derivatives were synthesized and characterized in two steps to explore their photochromic properties. Both prepared compounds are sensitive to UV light and change colors upon irradiation. The resulting photogenerated zwitterions revert to the original compounds while being heated. A new family of organic photochromic colorants is introduced.