Universität zu Köln

Oengel, Banu, Neudoerfl, Joerg M. and Griesbeck, Axel G. (2021). (E)-1-(3,4-Dimethoxyphenyl)-2-methyl-3-phenylprop-2-en-1-one: A P-Type Acid-Stable Photochromic alpha-Methylchalcone. Molbank, 2021 (2). BASEL: MDPI. ISSN 1422-8599

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Abstract

The alpha-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 lambda > 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 reversible arrow 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 alpha-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 -> Z(s-t)).

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Oengel, Banu UNSPECIFIED UNSPECIFIED UNSPECIFIED Neudoerfl, Joerg M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Griesbeck, Axel G. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-564709
DOI:	10.3390/M1226
Journal or Publication Title:	Molbank
Volume:	2021
Number:	2
Date:	2021
Publisher:	MDPI
Place of Publication:	BASEL
ISSN:	1422-8599
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language Chemistry, Organic Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/56470