Asymmetric Boron-Cored Aggregation-Induced Emission Luminogen with Multiple Functions Synthesized through Stepwise Conversion from a Symmetric Ligand.

Multifunction luminogens have emerged as promising candidates in high-performance sensor and imaging systems. Concise approaches to the synthesis of such molecules are urgently required both for fundamental research and technological applications. In this study, a new symmetric ligand of di(2-hydroxyphenyl)phthalazine with multiple binding sites around a phthalazine unit was readily synthesized, which could be converted efficiently into an asymmetric luminogen (OBN-DHPP) through the formation of oxygen-boron-nitrogen bonding. This molecule has a twistable π-extended backbone with a tetracoordinated boron core bearing two bulky phenyl groups, giving it abundant optical properties including a large Stokes shift piezochromism and aggregation-induced emission enhancement. Importantly, the presence of a free phenolic hydroxyl group in the backbone of OBN-DHPP enables the incorporation of various functional moieties into the asymmetric luminogen. As an example, polyethylene glycol (PEG)-modified luminogen (OBN-DHPP-PEG45) was synthesized. In the aqueous medium, OBN-DHPP-PEG45 could self-assemble into spherical nanoparticles with low cytotoxicity and excellent emission performance as well as high solubility. The results of flow cytometry and fluorescence microscopy reveal that these nanoparticles could be internalized successfully by HeLa cells, demonstrating their potential application in bioimaging.

Highly Conjugated Two-dimensional Covalent Organic Frameworks for Efficient Iodine Uptake.

Radioactive iodine in nuclear waste would be harmful to nature and human health. The design of adsorbents for iodine capture with high efficiency still remains a challenge. Herein, two highly conjugated two-dimensional covalent organic frameworks (TFPB-BPTA-COF and TFPB-PyTTA-COF) have been successfully constructed. Both COFs possess high porosity, stability, and a high π-conjugated framework. Impressively, TFPB-PyTTA-COF exhibits an excellent iodine uptake value of up to 5.6 g g-1 , which is superior to most reported COF-based adsorbents for iodine capture.

Reduced graphene oxide promoted assembly of graphene@polyimide film as a flexible cathode for high-performance lithium-ion battery.

Organic carbonyl polymers have been gradually used as the cathode in lithium-ion batteries (LIB). However, there are some limits in most organic polymers, such as low reversible capacity, poor rate performance, cycle instability, etc., due to low electrochemical conductivity. To mitigate the limits, we propose a strategy based on polyimide (PI)/graphene electroactive materials coated with reduced graphene oxide to prepare a flexible film (G@PI/RGO) by solvothermal and vacuum filtration processes. As a flexible cathode for LIB, it provides a reversible capacity of 198 mA h g-1 at 30 mA g-1 and excellent rate performance of 100 mA h g-1 at high current densities of 6000 mA g-1, and even a super long cycle performance (2500 cycles, 70% capacity retention). The excellent performance results in a special layer structure in which the electroactive PI was anchored and coated by the graphene. The present synthetic method can be further applied to construct other high-performance organic electrodes in energy storage.

Three-Dimensional Graphene-based N-doped Carbon Composites as High-Performance Anode Materials for Sodium-ion Batteries.

A nitrogen-doped carbon layer coating on a 3D graphene framework (NCL@GF) was produced by the in-situ polymerization of a uniform polyimide layer on the graphene framework surface and a carbonization process. The NCL@GF exhibited a 3D macroporous structure with uniform N-doped porous carbon layers and a high 5.4 at. % nitrogen content, which not only effectively enhanced the active sites but also facilitated fast ion and electron transport in the 3D pathways. Consequently, the NCL@GF as the anode of a sodium-ion battery (SIB) exhibited a discharge capacity of 357 mAh g-1 at 0.1 A g-1 after 200 cycles, a remarkable rate capability with a capacity of 122 mAh g-1 at 8 A g-1 , and a super long cycle life with a capacity retention of 70 % capacity after 2500 cycles at 0.5 A g-1 . Such performance is superior to that of previously reported carbon or graphene-based composites.