Conjugated microporous organic polymer as fluorescent chemosensor for detection of Fe3+ and Fe2+ ions with high selectivity and sensitivity.

A conjugated microporous organic polymer (TPA-Bp) comprised of triphenylamine (TPA) and 2,2'-bipyridine-5,5'-diformaldehyde (Bp) was prepared via the Schiff-base reaction under ambient conditions. TPA-Bp is an amorphous and microporous spherical nanoparticle with very high stability. TPA-Bp suspension in DMF displayed strong fluorescence emission and selective fluorescence quenching response towards Fe3+ and Fe2+ ions. The fluorescence intensity of TPA-Bp at 331 nm presents linear relationship with the concentrations of both Fe3+ and Fe2+ with low detection limits of 1.02 × 10-5 M for Fe3+ and 5.37 × 10-6 M for Fe2+. The results of X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR) confirm the selective coordination of N atoms of pyridine unit with Fe ions. The fluorescence quenching of TPA-Bp upon the addition of Fe3+/Fe2+ ions can be attributed to the absorption competition quenching (ACQ) mechanism and the energy transfer between TPA-Bp and Fe3+/Fe2+ ions. This work demonstrates that the conjugated microporous polymers are promising candidates as luminescent sensor for detection of the special analytes in practical applications.

A tetraphenylethylene-based aggregation-induced emission sensor: Ultrasensitive "turn-on" fluorescent sensing for phosphate anion in pure water.

A new fluorescent sensor of tetraphenylethylene (TPE) derivate with four dimethylformamidine and four chloride anions, sensor 1, was resoundingly synthesized. Meanwhile, the structure of sensor 1 has been characterized by 1H NMR, 13C NMR, FT-IR and mass spectrum. Sensor 1 can dissolve in water completely and showed significant fluorescence enhancement response towards PO43- with selectivity and sensitivity in pure water. The results of fluorescence spectra, turbidity measurement, dynamic light scattering (DLS) and fluorescent micrographs elucidated that the distinct fluorescence enhancement of sensor 1 with PO43- anion can be attributed to the aggregation-induced emission (AIE) of TPE. The AIE of sensor 1 with PO43- anion was reversible, proved by the alternate addition of PO43- anion and calcium ion. The fluorescence intensity of sensor 1 at 510 nm gradually increased and was obviously augmented by 266% when the added concentration of PO43- was 150 µmol L-1 (15 equiv. of sensor 1). In addition, the fluorescence intensity also displayed a good linear relationship with PO43- ions in the large concentration range of 10-150 µmol L-1 with very low detection limit for PO43- of 6.56 × 10-8 mol L-1. Furthermore, sensor 1 also presented the semi-quantitative visual detection ability for PO43- in solutions and test paper mode via the fluorescence changes and quantitative detection potential for PO43- in actual water sample.

Iron oxides nanobelt arrays rooted in nanoporous surface of carbon tube textile as stretchable and robust electrodes for flexible supercapacitors with ultrahigh areal energy density and remarkable cycling-stability.

We report a significant advance toward the rational design and fabrication of stretchable and robust flexible electrodes with favorable hierarchical architectures constructed by homogeneously distributed α-Fe2O3 nanobelt arrays rooted in the surface layer of nanoporous carbon tube textile (NPCTT). New insight into alkali activation assisted surface etching of carbon and in-situ catalytic anisotropic growth is proposed, and is experimentally demonstrated by the synthesis of the Fe2O3 nanobelt arrays/NPCTT. The Fe2O3/NPCTT electrode shows excellent flexibility and great stretchability, especially has a high specific areal capacitance of 1846 mF cm-2 at 1 mA cm-2 and cycling stability with only 4.8% capacitance loss over 10,000 cycles at a high current density of 20 mA cm-2. A symmetric solid-state supercapacitor with the Fe2O3/NPCTT achieves an operating voltage of 1.75 V and a ultrahigh areal energy density of 176 µWh cm-2 (at power density of 748 µW cm-2), remarkable cycling stability, and outstanding reliability with no capacity degradation under repeated large-angle twisting. Such unique architecture improves both mechanical robustness and electrical conductivity, and allows a strong synergistic attribution of Fe2O3 and NPCTT. The synthetic method can be extended to other composites such as MnO nanosheet arrays/NPCTT and Co3O4 nanowire arrays/NPCTT. This work opens up a new pathway to the design of high-performance devices for wearable electronics.