Hg 2+ -promoted photoactivation of triazolyl rhodamine

Hg 2+ was able to induce the ring-opening of glycosyl triazolyl rhodamines after 26 h incubation at room temperature in MeCN—DMSO (99:1). This reaction can be dramatically accelerated by irradiation at 313 nm, by reducing the response time to 2 min. Selectivity towards Hg 2+ has also been demonstrated, except for Cu 2+ , other metal ions showed almost no influence on this photochromic process. Detailed mechanistic investigations indicated that a small amount of DMSO played an important role during the photochromic transformation, probably by stabilising the excited open form of the triazolyl rhodamine—Hg 2+ complex.