Photo- and ionochromic thienyl(coumarinyl)thiazoles

Thienyl (6-methoxycoumarinyl)thiazoles containing various amino groups in bridging fragment were synthesized. In the ring-opened form, the dihetarylethenes display fluorescence with quantum yields of 0.012-0.015. Irradiation of their solutions with light of 365 or 436 nm results in the formation of non-fluorescent ring-closed isomers. Re-opening of the cyclohexadiene ring occurs under exposure to visible light (λ > 500 nm). The prepared compounds represent bifunctional chemosensors - “naked-eye” chromogenic for F− anions (change of the solution color from yellow to brown-red) and fluorogenic for Hg2+ cations (with CHEQ effect).