Synthesis and application of a new class of D-π-A type charge transfer probe containing imidazole-naphthalene units for detection of F- and CO2

Abstract

A new class of D-π-A type charge transfer probe, 3 and 4, containing imidazole-naphthalene moieties as donor and acceptor, respectively, has been synthesized via a Suzuki coupling reaction. Probe 3, upon interaction with different classes of anions, showed high selectivity toward fluoride with a detection sensitivity of 4 ppb (0.22 μM). The in situ generated imidazolyl ion (3 + F-) enables the detection of CO2 with the restoration of the original absorption and emission properties of 3. The mode of interaction has been confirmed by 1H NMR and DFT studies which suggested the deprotonation of the -NH fragment of the imidazolyl unit in the presence of F-.