Synthesis of photo- and ionochromic N-acylated 2-aminomethylenebenzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

Submitting author affiliation:
Russian Academy of Sciences, Rostov on Don, Russian Federation

Beilstein Arch. 2023, 202348.

Published 14 Nov 2023

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A series of N-acylated 2-aminomethylenebenzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline receptor substituent was synthesized. Upon irradiation in CH3CN or DMSO with light of 436 nm, they undergo Z/E isomerization around the C=C bond followed by rapid N→O migration of the acyl group and the formation of non-emissive O-acylated isomers. These isomers were separated preparatively and fully characterized by IR, 1H, 13C NMR, HRMS and XRD methods. The reverse thermal reaction is catalyzed by protonic acids. N-Acylated compounds exclusively with Fe2+ ions form non-fluorescent complexes with a contrast naked eye effect - color change of the solutions from yellow to pink-crimson. Subsequent selective interaction with acetate anions leads to the restoration of the initial absorption and emission spectra. Thus, the obtained compounds represent dual-mode “on-off-on” switches of optical and fluorescent properties under sequential exposure to light/H+ or sequential addition of Fe2+/AcO- ions.

Keywords: acylated ketoenamines; photochromism; fluorescence; naked eye effect; molecular switches

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Rybalkin, V. P.; Zmeeva, S. Y.; Popova, L. L.; Dubonosova, I. V.; Karlutova, O. Y.; Demidov, O. P.; Dubonosov, A. D.; Bren, V. A. Beilstein Arch. 2023, 202348. doi:10.3762/bxiv.2023.48.v1

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