Rhodamine‐labeled Sensor Bead as a Colorimetric and Fluorometric Dual Assay for Hg 2+ Ions in Water

Rhodamine‐based receptor 1 recognizes Hg 2+ and Cu 2+ ions in aqueous CH 3 CN, but when immobilized onto Merrifield resin to give bead 2 , this sensor system selectively detects Hg 2+ ions over a series of other metal cations in water. The detection can be performed colorimetrically and fluorimetrically. The ensemble of 2 –Hg 2+ can also distinguish dl ‐homocysteine from L ‐cysteine in water by both analytical methods.