A new carbazole-based colorimetric and fluorescent sensor with aggregation induced emission for detection of cyanide anion

A new carbazole-based naked-eye colorimetric and fluorescent sensor CPPB with aggregation induced emission (AIE) effect was successfully synthesized. The solid powder of CPPB emitted intense yellow fluorescence, and its emission wavelength and fluorescence intensity in DMSO/H2O solution varied with the percentage of water (f(w)). Nano-aggregates of CPPB molecules were prepared by increasing f(w) of DMSO/H2O solution, and the optimal aggregation state of CPPB was reached in 99% aqueous DMSO solution with the maximum fluorescence intensity. Moreover, CPPB displayed high selectivity and sensitivity toward cyanide anions (CN-) in 99% aqueous DMSO solution even in the presence of other competitive anions (CN-, F-, Cl-, AcO-, NO3-, CO32-, HCO3-, HSO3-, SO42-, S-2(-), HS-, OH-, H2PO4- and HPO42-) and the reactive oxygen species (H2O2, O-2(center dot-), O-1(2), t-BuOOH and (OH)-O-center dot). The sensing mechanism for CN- was confirmed by optical spectral studies, H-1 NMR titration, FIRMS spectra, Job's plot analyses and DFT calculations. Sensor CPPB for CN- detection revealed extremely low detection limit (67.4 nM), high anti-interference ability, wide pH response range (3.0-10.0) as well as the immediate response (15 s). Furthermore, the CPPB-based test strips were applied to detect CN- qualitatively and quantitatively in 100% aqueous solution.