Two-dimensional carbazole-based derivatives as versatile chemosensors for colorimetric detection of cyanide and two-photon fluorescence imaging of viscosity in vitro

Abstract

A pair of carbazole-based derivatives with two-dimensional chromophore structures was designed and employed for the measurement of cyanide and viscosity, respectively. We investigated the ability of hydrazone derived from 2,4-dinitrophenylhydrazine to detect CN− by UV–vis spectroscopy involving the NH proton abstraction by cyanide ions. With addition of CN− to the solution of the 2,4-dinitrophenylhydrazine derived chemosensor, color changes from yellow to violet were observed, accompanied by 60 nm red-shift of the maximum absorption wavelength. Absorbance ratio (A500/A440) of this chemosensor had a good linear relationship with the concentration of CN− ranging from 0 to 30 μM. Meanwhile, the carbazole-based chemosensor containing a 4-nitrophenylhydrazone unit exhibited a “turn on” fluorescence response to changes in viscosity by increasing the viscosity of methanol-polyethyleneglycol system or reducing the temperature of testing environment. The good linear relationships can be found between the logarithmic relations of viscosity and one/two-photon fluorescence intensity. Confocal fluorescence imaging experiments indicated the latter chemosensor could be applied for visualizing viscosity in living cells and fresh liver tissues under the two-photon excitation.