Design and synthesis of a squaraine based near-infrared fluorescent probe for the ratiometric detection of Zn~(2+) ions

摘要

A squaraine based ratiometric near-infrared fluorescent probe with bipyridyl binding arms for Zn~(2+) (SQ-1) has been designed and synthesized. SQ-1 exhibits a selective fluorogenic response to Zn~(2+) in acetone by a 22 nm red-shift and a remarkable enhancement of the fluorescence intensity. Further study shows that the calculated detection limit for Zn~(2+) is 6.1 x 10~(-8) M (3σ/k) and the identification for Zn~(2+) will not be impacted by competing ions such as Na~+, K~+, Mg~(2+), Ca~(2+), Pb~(2+), Mn~(2+), Ba~(2+) and Hg~(2+). The binding mode between SQ-1 and Zn~(2+) has also been discussed.