Two New Quinoline‐Benzothiazole Blended 'Off‐On' Type Fluorescent Probes Exclusively Detect Cd2+.

In this paper, two new quinoline‐benzothiazole based probes (QBTP1 and QBTP2) have been synthsized for the selective detection of Cd2+. Both the probes showed selective 'Turn‐On' emission change towards Cd2+. Structure of QBTP1 was confirmed through its single crystal X‐ray study. QBTP1 itself showed a weak emission band at 488 nm which upon addition of Cd2+ enhanced dramatically with a slight redshift to 507 nm. Consequently, weak cyan emission of QBTP1 changes to green which is easily observable through naked eyes. QBTP2 also showed almost similar fluorescence change upon addition of Cd2+ to that of QBTP1. The intramolecular charge tranfer (ICT) and chelation enhanced fluorescence (CHEF) mechanisms may play here the key role for this type of redshift of emission maximum and enhancement of fluorescence intensity respectively, upon addition of Cd2+ to the probes. Both the probes exclusively detecs Cd2+ over any other cations tested. Most importantly, not a minute interference was observed by Zn2+ or Hg2+. Capabilities of the probes to be used as portable kits for on‐site detection of Cd2+ without using any expensive instrumental help was also shown here. Furthermore, the limit of detection of both the probes were found in the order of 10−9 to 10−10 M range which indicates the high sensitivity of the probes towards Cd2+. [ABSTRACT FROM AUTHOR]