Wenlong Yang

Design and Assembly of Rotaxane-Based Molecular Switches and Machines

Mechanically interlocked molecules, such as catenanes and rotaxanes, are at the heart of the development of molecular machines chemistry. They are able to self-organize, self-assemble, and self-control themselves into new materials with potential application as molecular devices. In this review, an overview of some recent progress on molecular machines is given, including new methodologies for their synthesis and self-assembly and their recent applications as dual or multilevel fluorescent molecular switches, as potential sensors, and even as a molecular-level transporter. In one development, a molecular machine containing a charge-transfer chromophore was designed to generate controllable aggregate structures through the reversible movement of a macrocycle over a thread; this was done in order to better understand the application of a molecular shuttle in solid state. Light is shed on how the novel properties and functions of molecular machines are extended, and examples of the ways in which molecular machines have been applied to the design and process of intelligentized systems are provided.

An Unusual Addition Reaction for Constructing a Novel pH-Controlled Fluorescence Switch

A pH-controlled fluorescence switch based on a core-substituted naphthalenediimide compound (NDI-DBU) was constructed. The novel pentacyclic compound (NDI-DBU) was derived from naphthalenediimide (NDI) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in only one synthetic operation, catalysized by CuI.

Amidetriazole: A Versatile Building Block for Construction of Oxyanion Anion Receptors

The design and synthesis of efficient receptors for tetrahedral oxyanions is an emerging field in supramolecular chemistry. Herein, we have developed a urea-like anion-recognizing motif, amidetriazole, which can be easily synthesized and derived and shows good solubility. A series of simple acyclic receptors were designed and synthesized to confirm the potential of amidetriazole for the construction of tetrahedral oxyanion receptors. This molecular platform can be used extensively for the construction of numerous receptor systems appended with functional groups, which opens the way to many applications in the field of supramolecular chemistry.

Directed synthesis of [2]catenanes incorporating naphthalenediimide and crown ethers by associated interactions of templates.

In this paper, we introduce a simple one-step method to synthesize [2]catenanes incorporating naphthalenediimide and crown ethers by associated interactions of templates. In this functional supermolecular system, the combined hydrogen-bond and π-donor/π-acceptor interactions led production of the [2]catenanes which exhibit reversible moving of the crown ether macrocycle on the big ring between two stations via de/reprotonation. This movement on the big ring can change the electron interaction, resulting in strong quenching of the emission of naphthalene diimide.

A Controllable Chiral Molecular Machine: Movement on Molecular Level

With the view to develop new chiral molecular switches, a new pH-controlled bistable chiral [3]rotaxane with a binaphthalene as chiral moiety is synthesized and characterized. The movement of the macrocycle DB24C8 along the thread tunes the dihedral angle between the two naphthalene rings and supplies tunable circular dichroism output signals.