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Short Note

(E)-1-(3,4-Dimethoxyphenyl)-2-methyl-3-phenylprop-2-en-1-one: A P-Type Acid-Stable Photochromic α-Methylchalcone

Department of Chemistry, Faculty of Natural Sciences and Mathematics, University of Cologne, Greinstr. 4-6, 50939 Köln, Germany
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Author to whom correspondence should be addressed.
Academic Editor: Nicholas E. Leadbeater
Molbank 2021, 2021(2), M1226; https://doi.org/10.3390/M1226
Received: 5 May 2021 / Revised: 28 May 2021 / Accepted: 1 June 2021 / Published: 4 June 2021
(This article belongs to the Section Organic Synthesis)
The α-methylated chalcone 3 with an electron-donor substituted A-aryl ring and an unsubstituted B-phenyl ring was synthesized by base-catalyzed aldehyde/acetophenone condensation. Compound 3 can be photo-switched from E→Z by irradiation with long-wavelength light λ > 350 nm, whereas irradiation with shorter wavelengths leads to photo-stationary states (PSS) with lower amounts of the Z-isomer. The limiting wavelength for fully equilibrated E⮀Z (PSS = 1) can be achieved around 240 nm. The stability of both E- and Z-isomers at the wavelength-dependent PSS under UV-irradiation between 250 and 350 nm is remarkably high as observed from UV and NMR spectroscopy. Compound 3 is fatigue resistant even after more than 10 days continuous irradiation and is also oxygenation-stable under singlet oxygen sensitization conditions. In remarkable contrast to many other α-methylated chalcones, no change in the E/Z-ratio was detected when PSS samples were treated with Broensted acids. The negative photochromic E→Z switch of 3 is accompanied by a conformational switch from the E-form in its preferred s-trans conformation to the Z-form in a distorted s-cis conformation (Es-c→Zs-t). View Full-Text
Keywords: photochromism; chalcones; quantum yields; photo-switch photochromism; chalcones; quantum yields; photo-switch
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MDPI and ACS Style

Öngel, B.; Neudörfl, J.M.; Griesbeck, A.G. (E)-1-(3,4-Dimethoxyphenyl)-2-methyl-3-phenylprop-2-en-1-one: A P-Type Acid-Stable Photochromic α-Methylchalcone. Molbank 2021, 2021, M1226. https://doi.org/10.3390/M1226

AMA Style

Öngel B, Neudörfl JM, Griesbeck AG. (E)-1-(3,4-Dimethoxyphenyl)-2-methyl-3-phenylprop-2-en-1-one: A P-Type Acid-Stable Photochromic α-Methylchalcone. Molbank. 2021; 2021(2):M1226. https://doi.org/10.3390/M1226

Chicago/Turabian Style

Öngel, Banu; Neudörfl, Jörg M.; Griesbeck, Axel G. 2021. "(E)-1-(3,4-Dimethoxyphenyl)-2-methyl-3-phenylprop-2-en-1-one: A P-Type Acid-Stable Photochromic α-Methylchalcone" Molbank 2021, no. 2: M1226. https://doi.org/10.3390/M1226

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