A highly selective copper fluorescent indicator based on aminoquinoline substituted BODIPY

A highly selective fluorescent indicator for copper, substituted with an aminoquinoline group at the position 3 or 5 of the BODIPY has been synthesized. The indicator has very low fluorescence quantum yield in acetonitrile with emission maxima at 580 nm. Upon binding copper it shows 50 nm bathochromic shifts with a change of solution color and a large increase in the fluorescence intensity. The fluorescence lifetime in acetonitrile was too short and could not be determined; whereas fluorescence decay profile of the copper complex was described by a mono-exponential decay with the lifetime of 4.38 ns. ESI-MS enabled detection of a Cu·1 CN complexes which was fromed by C–C bond cleavage of acetonitrile.

► An aminoquinoline substituted BODIPY dye 1 was synthesis and got its crystal structure. ► 1 shows bathochromic shifts with a large increase in the fluorescence intensity upon binding copper. ► Cu·1 adduct suggest the presence of CN complexes which is from C–C bond cleavage of acetonitrile. ► Fluorescence lifetime of 1 in acetonitrile could not be determined while Cu·1 was described by a mono-exponential decay.