A new chromenylium-cyanine chemosensor for switch-ON near-infrared copper (II) sensing

A highly selective and sensitive near-IR chemosensor having a chromenylium-cyanine backbone for the detection of Cu2+ in aqueous samples has been designed and synthesized. The sensor has exhibited linear optical response to copper ions at the range of 0–4.9 × 10−6 M in the presence of other competing metal ions, such as Na+, K+, Mg2+, Ca2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, Al3+, Cd2+, Ag+, Sr2+, Pb2+, Hg2+ and Ba2+. The limit of detection (LOD) was calculated as 1.28 × 10−8 M which was lower than that of previously reported analogues. The sensor allows detection of the copper(II) ion through the spirocyclic ring-opening reaction by coordination of Cu2+. [Display omitted] •A new chromenylium-cyanine sensor was designed for coper (II) ion sensing.•Spirocyclic ring-opening reaction by coordination of Cu2+ was observed.•The sensor showed selectivity to copper in the presence of competitive metal ions.