3 research outputs found
Freezing-Induced Loading of TiO2 into Porous Vaterite Microparticles: Preparation of CaCO3/TiO2 Composites as Templates To Assemble UV-Responsive Microcapsules for Wastewater Treatment
Synthesis and Comparative Photoswitching Studies of Unsymmetrical 2,3-Diarylcyclopent-2-en-1-ones
Photochromic diarylethenes (DAEs)
based on the unsymmetrical ethene
“bridge” bearing heterocycles of the different nature
(oxazole and thiophene) as aromatic moieties have been designed and
the photoswitching properties have been studied. The comparative studies
of the photochromic characteristics of unsymmetrical isomeric 2,3-diarylcyclopent-2-en-1-ones
have shown that the isomers have different thermal stability, absorption
maxima, and quantum yields. It was found that the unsymmetrical diarylcyclopentenone
bearing at second position of the cyclopentenone ring the thiophene
unit displays high thermally stability, hypsochromic shift of absorption
maxima wavelengths of initial and cyclic forms, and high quantum yields
of cyclization and cycloreversion reactions. The replacement of the
carbonyl group with oxime leads to a reduction of the difference in
the photochromic properties of these isomers and just as the reduction
of the carbonyl group to the hydroxy-group negates this difference
to zero. The intramolecular hydrogen bond formation in the oxime and
hydroxy derivatives was confirmed by IR and <sup>1</sup>H NMR spectral
analysis, but the increase of the quantum yields of the cyclization
reaction in a nonpolar hexane is observed only in the case of hydroxy
derivatives that can be explained by the formation of more rigid six-membered
heterocycle in hydrogen bonding