Synthesis, photochromic and fluorescence properties of new bithiazole-containing diarylethenes as cation sensors

Two new bithiazole-containing diarylethenes, 1[5-methyl-2-(5-methyl-2-thiazolyl)-4-thiazolyl]-2,5-dimethy1-3-thienyl-3,3,4,4,5,5-hexafluorocyclopentene and 1[5-methyl-2-(5-methyl-2-thiazolyl)-4-thiazolyl]1-2-methyl-3-benzothienyl-3,3,4,4,5,5-hexafluorocyclopentene were synthesized and their photochromic and fluorescent properties have been investigated. They exhibited thermally irreversible photochromism and fluorescent switching in toluene. The effects of complexation of these two compounds with various metal cations such as Na+, Ag+, Hg+, Co2+, Ni2+, Cu2+, Ba2+, Zn2+, Cr3+, Pb2+, Cd2+, Sn2+, Al3+, Fe3+ on photochromic and fluorescent properties were also studied. Metal cations caused small effects on the absorption bands of their ring closed forms. However, fluorescence intensities of both compounds were strongly suppressed by Ni2+, Cu2+ and Fe3+.