Carbazole based new organic dye recognizes hydrazine and hydrogen sulfide via signal difference protocols

Signal change strategy plays a primary role in the development of sensitive assay system. Deep insights into multiple signal responses will benefit the assembly of efficient sensors. Herein, we have developed a multi-functional fluorescent probe 24(5-(9-phenyl-9H-carbazol-3-yethiophen-2-yemethylene)malononitrile (SO-CN) for the detection of N2H4 and H2S with different emission channels. Initially, a broad band at 604 nm has been monitored and an orange-yellow fluorescence has been observed in DMSO/PBS system (3/2, v/v, pH 7.4). After treating with hydrazine (N2H4), only N2H4 can give rise to the special changes of SO-CN by the signals of ratiometric fluorescence (F-442/F-604) and colorimetric signals (bright yellow to colorless) with a low detection limit (42.5 nM). Moreover, the fluorescence intensity ratio F-532/F-604 of SO-CN exhibits an excellent linear equation with the concentration range (NaHS) from 0 to 400 mu M (detection limit = 0.77 mu M). In this way, SO-CN can be employed to recognize N2H4 and hydrogen sulfide (H2S) via the same excitation wavelength and different emission performance. The discriminative sensing behaviors of SO-CN for N2H4 and H2S are assigned to two mechanisms, which can be verified by H-1 NMR spectra, HR-MS spectra and density functional theory (DFT) calculation. Therefore, this molecular framework has pave new way for the detection of new target species with functional group controls.