An efficient pyrimidine-based colorimetric chemosensor for naked-eye recognition of copper in aqueous medium

A pyrimidine-based receptor 1-(9H-fluoren-9-ylidene)-2-(4,6-dimethylpyrimidin-2-yl)hydrazine (HPF) was designed for naked-eye detection of Cu2+ with high selectivity in the presence of other competitive metal ions. In aqueous solution, upon addition of Cu2+ to HPF a color change from yellow to wine-red due to complex formation. The detection limit (5.03 x 10(-8) M) of HPF for Cu2+ ions is much lower than that recommended by WHO in drinking water (31.5 mu M). The sensor shows consistent performance in a pH value range of 4 to 11. Moreover, test strips based on receptor HPF were fabricated, which could act as a handy and efficient Cu2+ test for "in-the-field" measurement of Cu2+.