A Cr(VI) selective probe based on a quinoline-amide calix[4]arene.

A new quinoline-amide calix[4]arene 3-receptor for detection of hazardous anions and cations have been synthesized. The 3-receptor was examined for its sensing properties towards several different anions (Cr2O72-, SCN-, F-, Cl-, NO3-) and metal ions (Hg2+, Cd2+, Ag+) by UV-vis and fluorescence spectroscopies. It was detected that the 3-receptor has only sensing ability for Cr2O72- and Hg2+ ions, resulting in the association constants higher for Cr2O72- than to the Hg2+ ions. High selectivity towards Cr2O72- were also observed by fluorescence measurement among other ions (F-, Cl-, SCN-, Hg2+, Cd2+, Ag+) with a low limit of detection (7.36×10-6moldm-3). Proton NMR anion-binding investigations revealed a strong interaction of Cr2O72- anion with NH and CH groups of the receptor, showing that the combination with hydrogen-bonds donor groups strengthened the anion receptor association. Furthermore, remarkable association constants for dichromate anion obtained by all techniques strongly suggest the 3-receptor as a selective Cr(VI) sensor.