ICT-based Cu(II)-sensing 9,10-anthraquinonecalix[4]crown

A series of calix[4]arene-based chromogenic sensors bearing the 9,10-anthraquinone moiety have been synthesized and examined for their abilities to recognize various cations such as Li+, Na+, K+, Rb+, Cs+, Ag+, Cd2+, Mg2+, Ca2+, Sr2+, Ba2+, Zn2+, Hg2+, Pb2+, Co2+, and Cu2+ by UV-vis spectroscopy. In acetonitrile, the presence of Cu2+ induces the formation of the 1:1 ligand/metal complex, which exhibits a new absorption band centered at 450 nm, and leads to an obvious color change from yellow to red.