A self-complementary macrocycle by a dual interaction system

Solid-State Self-Assembly: Exclusive Formation and Dynamic Interconversion of Discrete Cyclic Assemblies Based on Molecular Tweezers

In contrast to self-assembly in solution systems, the construction of well-defined assemblies in the solid state has long been identified as a challenging task. Herein, we report the formation of tweezers-shaped molecules into various assemblies through a solid-state self-assembly strategy. The relatively flexible molecular tweezers undergo exclusive and quantitative assembly into either cyclic hexamers or a porous network through classical recrystallization or the exposure of powders to solvent vapor, despite the fact that they form only dimers in solution. The cyclic hexamers have high thermal stability and exhibit moderate solid-state fluorescence. The formation of heterologous assemblies consisting of different tweezers allows for tuning these solid-state properties of the cyclic hexamer. Furthermore, (trimethylsilyl)ethynyl-substituted tweezers demonstrate solvent-vapor-induced dynamic interconversion between the cyclic hexamer and a pseudocyclic dimer in the solid state. This assembly behavior, which has been studied extensively in solution-based supramolecular chemistry, had not been accomplished in the solid state so far.

Intramolecular Cation-π Interactions Organize Bowl-Shaped, Luminescent Molecular Containers

Molecules with nonplanar architectures are highly desirable due to their unique topological structures and functions. We report here the synthesis of two molecular containers (1 ⋅ 3Br- and 1 ⋅ 3Cl-), which utilize intramolecular cation-π interactions to enforce macrocylic arrangements and exhibit high binding affinity and luminescent properties. Remarkably, the geometry of the cation-π interaction can be flexibly tailored to achieve a precise ring arrangement, irrespective of the angle of the noncovalent bonds. Additionally, the C-H⋅⋅⋅Br- hydrogen bonds within the container are also conducive to stabilizing the bowl-shaped conformation. These bowl-shaped conformations were confirmed both in solution through NMR spectroscopy and in the solid state by X-ray studies. 1 ⋅ 3Br- shows high binding affinity and selectivity: F->Cl-, through C-H⋅⋅⋅X- (X=F, Cl) hydrogen bonds. Additionally, these containers exhibited blue fluorescence in solution and yellow room-temperature phosphorescence (RTP) in the solid state. Our findings illustrate the utility of cation-π interactions in designing functional molecules.

Single-layer semiconductor-decorated flexible 2D protein nanosheets by engineered anchoring for efficient photocatalytic hydrogen production

Protein self-assembly can be accurately manipulated to form ordered nanostructures through various supramolecular forces. This strategy is expected to make significant breakthroughs in the field of new biomimetic functional materials. Specifically, the construction of photocatalytic systems on two-dimensional (2D) flexible protein nanosheets meets a great challenge. We introduce a synthetic methodology for creating single-layer semiconductor-decorated protein 2D materials under mild conditions with enhanced light-driven hydrogen production. This approach employs a bioengineered green fluorescent protein (E4P) with the addition of a Cd-binding peptide, enabling precise control of the assembly of CdS quantum dots (QDs) on the protein's surface. Consequently, we obtained 4.3 nm-thin single-layer 2D protein nanosheets with substantial surface areas ideal for accommodating CdS QDs. By orthogonal incorporation of metal-binding peptides and supramolecular coordination, significantly enhancing the overall photocatalytic efficiency. Our findings demonstrate the potential for stable and efficient hydrogen production, highlighting the adaptability and biocompatibility of protein scaffolds for photocatalysis.