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⁻.