33 Unresolved Questions in Nanoscience and Nanotechnology.

Significant advances in science and engineering often emerge at the intersections of disciplines. Nanoscience and nanotechnology are inherently interdisciplinary, uniting researchers from chemistry, physics, biology, medicine, materials science, and engineering. This convergence has fostered novel ways of thinking and enabled the development of materials, tools, and technologies that have transformed both basic and applied research, as well as how we address critical societal challenges.

Photoinduced Charge Transfer at Discrete Molecular Interfaces in Cocrystals.

Precise construction of molecular heterostructures in organic donor-acceptor (D-A) cocrystals is crucial for understanding charge transfer (CT) dynamics and developing high-performance optoelectronic materials. Although cocrystals with densely packed D-A arrays have been widely investigated, discrete heterojunctions at the molecular scale have been scarcely explored. Herein, we demonstrate an approach to create what we have referred to as discrete molecular interfaces in D-A cocrystals employing a tetracationic naphthalenediimide-based macrocycle () and an electron-rich guest pyrene ().

Chemical and Structural Insights into Nonequilibrium Polyrotaxanes Formed by Molecular Pumps.

Conventionally, the synthesis of polyrotaxanes (PRs) has been constrained by methods that depend on an inherent affinity between the rings and polymer chains. Recently, we reported nonequilibrium polyrotaxanes (NEQ-PRs), where precise numbers of rings (up to 10) can be stored on polymer chains through the action of artificial molecular pumps (AMPs), despite the rings having little to no inherent affinity for the chains. A complete understanding of the intramolecular interactions in such NEQ-PRs is essential for advancing their practical applications but remains largely unexplored.

Mechanical-Bond-Enabled Highly Efficient Charge Separation in a Light-Harvesting Hetero[2]Catenane.

Photodriven charge separation is a key process for converting solar energy into chemical energy. However, it remains a challenge to develop artificial light-harvesting materials that can simultaneously achieve ultrafast charge separation and a long-lived charge-separated state with low energy loss. In contrast to conventional strategies based on covalent or noncovalent interactions, we employed a mechanical bond to forcibly assemble two strongly electron-deficient cationic chromophores ( and ), which have very similar reduction potentials and exhibit limited noncovalent interactions, into a hetero[2]catenane ().

Controlled assembly of rotaxane translational isomers using dual molecular pumps.

The ability to control the relative motion between different components of molecules with precision is a cornerstone of synthetic nanotechnology. Mechanically interlocked molecules such as rotaxanes offer a platform for exploring this control by means of the positional manipulation of their components. Here, we demonstrate the use of a molecular dual pump to achieve the assembly of translational isomers with high efficiency and accuracy.