Two-dimensional nano-layered materials as multi-responsive chemosensors constructed by carbazole- and fluorene-based polyaniline-like derivatives

Poly(3-amino-carbazole) derivatives containing 1,10-phenanthroline and 8-hydroxyquinoline ligands: Synthesis, properties and application as ion sensors

As we know, excessive metal ions can even damage human health. Herein, two novel kinds of fluorescent sensing materials Poly(3-amino-carbazole) derivatives containing 1,10-phenanthroline and 8-hydroxyquinoline were synthesized and further applied to fluorescence detection for ions. The results show that Ni²⁺, Cu²⁺, and Pd²⁺ have excellent quenching effects on the fluorescence of Poly[9-(1,10-phenanthroline-2-yl)-9H-carbazol-3-amine] (PPNC), the LOD for these ions reaches 5.2 nM, 12.7 nM, 33.5 nM respectively. In the process of ion response, there is no shift of UV absorption peak, combined with IR spectra and theoretical calculation simulation, the quenching is considered to be caused by the coordination between metal ions and the second amine (-NH-) or 1,10-phenanthroline ligand of PPNC, which leads to the charge transfer from ligands to metal ions. In addition, an acid test was done for PPNC to verify and detect the presence of secondary amine (-NH-), and the results show that PPNC has good acid sensing ability which also supports the secondary amine (-NH-) structure. Finally, the paper test was performed on PPNC, indicating that PPNC has the potential for visual application.

2D polyaniline derivatives as turn-on fluorescent probe for efficient triethylamine detection at room temperature

Due to the severe toxicity of triethylamine (TEA), the preparation of chemsensors with high sensitivity, low cost and visualization for TEA detection has been a research hotspot. However, based on the fluorescence turn-on detection of TEA remains rare. In this work, three two-dimensional conjugated polymers (2D CPs) were prepared by chemical oxidation polymerization. These sensors show a quick response and excellent selectivity toward TEA at room temperature. The minimum limit of detection (LOD) for TEA was 3.6 nM in the range of 10 μM ∼ 30 μM. Interestingly, the paper sensor based on P2-HCl can quantitatively detect TEA gas within 20 s, which showed great application potential in fields of environmental monitoring. Besides, Fourier transform infrared spectra (FT-IR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) data were used to thoroughly interpret the sensing mechanism. This work provided an effective method for the development of 2D fluorescent chemosensors for TEA detection.

Selective photocatalytic oxidation of sulfides with dioxygen over carbazole-fluorene conjugated microporous polymers

One sustainable concept emerges to implement the selective oxidation of sulfides with dioxygen (O₂) at ambient conditions and has received increasing attention. As such, three donor-acceptor (D-A) type conjugated microporous polymers (CMPs) were connected via robust CC bonds prepared from FeCl₃-promoted polymerization of monomers of 3,6-di(9H-carbazol-9-yl)-9H-fluorene with the 9H position of the fluorene moiety occupied by 1,1'-biphenyl-, difluoro-, or keto- group, furnishing 9,9'-(9,9'-spirobi[fluorene]-2,7-diyl)-bis-9H-carbazole-CMP (SFC-CMP), 9,9'-(9,9-difluoro-9H-fluorene-2,7-diyl)bis(9H-carbazole)-CMP (FFC-CMP), and 2,7-di(carbazol-9-yl)-fluoren-9-one-CMP (OFC-CMP), respectively. These three carbazole-fluorene CMPs could implement blue light-driven highly selective oxidation of sulfides into sulfoxides with O₂ in methanol (CH₃OH). Intriguingly, the SFC-CMP imparted the best photocatalytic activity for selective oxidation of sulfides in a broad scope. Besides, the SFC-CMP photocatalyst could be fully recovered even outperforming the fresh one. This work highlights that the properties of CMPs could be regulated by the D-A units like carbazole-fluorene to execute selective chemical transformations ambiently.