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 (CrO, SCN, F, Cl, NO) and metal ions (Hg, Cd, Ag) by UV-vis and fluorescence spectroscopies. It was detected that the 3-receptor has only sensing ability for CrO and Hg ions, resulting in the association constants higher for CrO than to the Hg ions. High selectivity towards CrO were also observed by fluorescence measurement among other ions (F, Cl SCN, Hg, Cd, Ag) with a low limit of detection (7.36×10moldm). Proton NMR anion-binding investigations revealed a strong interaction of CrO 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.