Low-dimensional nanostructures fabricated from bis(dioxaborine) carbazole derivatives as fluorescent chemosensors for detecting organic amine vapors

New triphenylamine functionalized bis(dioxaborine) carbazole derivatives (BDOBCn, n = 4, 8, 16) have been synthesized, and low-dimensional nanostructures with different morphologies have been fabricated from BDOBCn with carbon chains of different lengths. For example, 1D single-crystalline nanowires are generated from BDOBC4 via a reprecipitation approach, 1D nanofibers based on BDOBC16 are prepared through an organogelation process, and amorphous nanoparticles are obtained from BDOBC8. It is interesting that the films formed from the obtained nanostructures can give strong fluorescence emission under irradiation and can act as fluorescent chemosensors for probing aniline vapors, with different response rates and different sensitivity controlled by their morphologies. The mesh-like film obtained from the BDOBC16-based gel exhibits faster fluorescent response in milliseconds and higher sensitivity than the nanoparticle- and nanowire-based films, because the supramolecular objects primarily formed in the gelling process percolate and fill the entire volume at a low-over all-volume fraction, and the entangled piling of the fibers leads to increased porosity. Thus, it not only provides a large surface for enhanced adsorption and accumulation of gaseous molecules but also enables expedient cross-film diffusion of gaseous species. Notably, the organogel fibers of BDOBC16 allow high selectivity for probing aniline vapor, and the detection limit reaches 8.6 ppm.