M. Amati, S. Belviso, M. D’Auria
Jun 1, 2010
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Influential Citations
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Journal
European Journal of Organic Chemistry
Abstract
The photochemical reaction between ethyl 2-chlorothiazole-5-carboxylate and benzene gave no product. In contrast, the reaction with ethyl 2-iodothiazole-5-carboxylate gave ethyl 3-phenylisothiazole-4-carboxylate. The same behaviour was observed if the reaction was performed in the presence of furan, thiophene and 2-bromothiophene. The products thus obtained were studied for their photophysical properties and it was found that the observed absorptions [λ max =257 nm (e = 7000 M -1 cm -1 ) for ethyl 3-phenylisothiazole-4-carboxylate, 278 nm (e = 7000 M -1 cm -1 ) for ethyl 3-(2-furyl)isothiazole-4-carboxylate, 269 and 285 nm (e = 7500 M -1 cm -1 ) for ethyl 3-(2-thienyl)isothiazole-4-carboxylate] are mainly due to π→π* transitions from the HOMO to the LUMO+1 orbital. The tested compounds showed fluorescence [λ em = 350-400 (λ exc = 300 nm), 360 and 410 nm (λ exc = 320 nm), 412 nm (λ exc = 340 nm) for ethyl 3-phenylisothiazole-4-carboxylate, 397 and 460 nm (λ exc = 300 nm), 381, 394 and 460 nm (λ exc = 320 nm), 381, 398 and 466 nm (λ exc = 340 nm) for ethyl 3-(2-furyl)iso-thiazole-4-carboxylate, 372, 377 and 414 nm (λ exc = 300, 320 and 340 nm respectively) for ethyl 3-(2-thienyl)isothiazole-4-carboxylate], possibly due to dual emission from different excited states. The use of the compound obtained as a sensitizer in the photo-oxidation of trans-α,α'-dimethylstilbene showed that all the new compounds are singlet-oxygen sensitizers.