One-Pot Synthesis and Structure–Property Relationship of Aminomaleimides: Fluorescence Efficiencies in Monomers and Aggregates Easily Tuned by Switch of Aryl and Alkyl

Organic fluorophores have attracted great interest owing to their wide applications. They usually contain an electron-conjugated system with an aromatic moiety and show high emission in dilute solutions but weaker or even no emission upon aggregation. Here, a simple one-pot, three-component reaction (3CR) (method I) for the synthesis of various di- and monosubstituted aminomaleimides (DAMIs and MAMIs) has been developed, and the reported 3CR (method II) has been found to be efficient only for the synthesis of MAMIs with R² = alkyl. Twelve AMIs were designed and synthesized for investigation of the influence of structures on their optical properties in monomers and aggregates. It was found that alkyl MAMIs, alkyl DAMIs, and aryl AMIs/DAMIs show very different fluorescence efficiencies in different solvents, and only MAMIs with butyl and oleyl show high emissions in powders similar to those in nonpolar solutions. Single-crystal structures indicate that their fluorescence efficiencies in aggregates mainly correlate with molecular packing modes. The efficient synthesis method, the sensitive fluorescence on–off response to protic solvents or polar solvents, and the unusual high emissions of AMI without any aromatic moiety in both monomer and aggregates are expected to attract great interest in the fields of application and theory

A Method for Promoting Assembly of Metallic and Nonmetallic Nanoparticles into Interfacial Monolayer Films

Two-dimensional metal nanoparticle arrays are normally constructed at liquid–oil interfaces by modifying the surfaces of the constituent nanoparticles so that they self-assemble. Here we present a general and facile new approach for promoting such interfacial assembly without any surface modification. The method use salts that have hydrophobic ions of opposite charge to the nanoparticles, which sit in the oil layer and thus reduce the Coulombic repulsion between the particles in the organic phase, allowing the particles to sit in close proximity to each other at the interface. The advantage of this method is that because it does not require the surface of the particles to be modified it allows nonmetallic particles including TiO₂ and SiO₂ to be assembled into dense interfacial layers using the same procedure as is used for metallic particles. This opens up a route to a new family of nanostructured functional materials

Making 2‐D Materials Mechanochemically by Twin‐Screw Extrusion: Continuous Exfoliation of Graphite to Multi‐Layered Graphene

Mechanochemistry has developed rapidly in recent years for efficient chemicals and materials synthesis. Twin screw extrusion (TSE) is a particularly promising technique in this regard because of its continuous and scalable nature. A key aspect of TSE is that it provides high shear and mixing. Because of the high shear, it potentially also offers a way to delaminate 2‐D materials. Indeed, the synthesis of 2‐D materials in a scalable and continuous manor remains a challenge in their industrialization. Here, as a proof‐of‐principle, the automated, continuous mechanochemical exfoliation of graphite to give multi‐layer graphene (MLG, ≈6 layers) by TSE is demonstrated. To achieve this, a solid‐and‐liquid‐assisted extrusion (SLAE) process is developed in which organic additives such as pyrene are rendered liquid due to the high temperatures used, to assist with the exfoliation, and simultaneously solid sodium chloride is used as a grinding aid. This gave MLG in high yield (25 wt%) with a short residence time (8 min) and notably with negligible evidence for structural deterioration (defects or oxidation).</p