Universität zu Köln

Lippold, Tim, Neudoerfl, Jorg M. and Griesbeck, Axel ORCID: 0000-0002-6546-3482 (2021). New Acridone- and (Thio)Xanthone-Derived 1,1-Donor-Acceptor-Substituted Alkenes: pH-Dependent Fluorescence and Unusual Photooxygenation Properties. Molecules, 26 (11). BASEL: MDPI. ISSN 1420-3049

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Abstract

A synthetic route to new heterocyclic 1,1-donor-acceptor-substituted alkenes starting with N-methyl-acridone, xanthone, and thioxanthone was investigated, leading to the acridone- and xanthone-derived products methyl 2-methoxy-2-(10-methylacridin-9 (10H)-ylidene)acetate (7) and methyl 2-methoxy-2-(9H-xanthen-9-ylidene)acetate (10) in low yields with the de-methoxylated product methyl 2-(10-methylacridin-9 (10H)-ylidene)acetate (8) and the reduced compound methyl 2-methoxy-2-(9H-xanthen-9-yl)acetate (11) as the major products from N-methyl acridone and xanthone. From thioxanthone, only the rearrangement and reduction products (14) and (15) resulted. The photophysical properties of compounds (7), (8), and (10) were investigated in the presence and absence of the Bronsted acid TFA by NMR, UV-VIS absorption, and fluorescence spectroscopy. Protonation of the acridone-derived alkenes (7) and (8) led to strong bathochromic and hyperchromic fluorescence shifts and a substantial increase in Stokes shift. The photooxygenation experiments with these substrates showed an unusual reactivity pattern in the singlet oxygen processes: whereas the electron-rich enolether (7) was chemically unreactive, (8) and (10) were oxidatively cleaved, presumably via intermediate 1,2-dioxetanes.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Lippold, Tim UNSPECIFIED UNSPECIFIED UNSPECIFIED Neudoerfl, Jorg M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Griesbeck, Axel UNSPECIFIED orcid.org/0000-0002-6546-3482 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-567573
DOI:	10.3390/molecules26113305
Journal or Publication Title:	Molecules
Volume:	26
Number:	11
Date:	2021
Publisher:	MDPI
Place of Publication:	BASEL
ISSN:	1420-3049
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ELECTRON-EXCHANGE LUMINESCENCE; KNOEVENAGEL CONDENSATIONS; CHEMO-LUMINESCENCE; CHEMILUMINESCENCE; MECHANISM; DECOMPOSITION; BASE; 1,2-DIOXETANE; REACTIVITY; PEROXIDE Multiple languages Biochemistry & Molecular Biology; Chemistry, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/56757