Photo-controlled metal-ion (Zn2+ and Cd2+) release in aqueous Tween-20 micelle solution.

Photo-controlled metal-ion (Zn(2+) and Cd(2+)) release in aqueous micelle solution (tris-HCl, pH = 7.4) has been described using 2-((2-mercaptophenylimino)methyl) phenol as ligand. It is found that both the ligand-Zn complex (1) and the ligand-Cd complex (2) are stable in micelle solution, and Zn(2+) (Cd(2+)) can be released from the complex with 365 nm light trigger. Accompanying the metal-ion release, the ligand is photo-converted to 2-(benzothiazol-2-yl) phenol (3) as product, and the turn-on fluorescence is detected. The fluorescence intensity increases with the photo-triggered release until Zn(2+) (Cd(2+)) is completely released, which is beneficial for monitoring the process of photo-controlled metal ion release. Control experiments demonstrate that no binding occurs between 3 and Zn(2+) (Cd(2+)) in micelle solution and there is no binding between cations and micelle, either.