Yan-Song Zheng

Molecular cages with an adjustable cavity have great potential in selective separation, adsorption, drug releasing etc. But to construct resizable cages is highly challenging. Here, retractable cages with a continually change of cavity size are found for the first time. The as‐prepared 2 + 3 cages are highly compressed with only 2.83 Å height of cavity. However, the cage is prolonged to 12.88 Å by crystalizing from CHCl ₃ /CH ₃ OH and encapsulating six methanol molecules while it is transferred into half‐expanded state with 7.50 Å cavity if it is immersed in methanol and includes three methanol molecules. Interestingly, using CHCl ₃ /CH ₃ CN mixed solvent, compressed cages with both 2.83 and 5.29 Å cavity are obtained by rapid crystallization, whereas expanded cage with 12.12 Å height of cavity is got by slow crystallization. Furthermore, with acid treatment, the compressed cage is expanded to 12.29 Å height. Consequently, the cage's cavity could be continually and precisely adjusted between 12.88, 12.29, 12.12, 7.50, 5.29, and 2.83 Å. This cage change could be easily monitored by ¹ H NMR, CPL, and visual color change etc. Due to adaptive adsorption, the scalable cage exhibits very high iodine uptake capacity of up to 6.02 g/g in iodine vapor and 3.70 g/g in water. Exceptionally, by reducing the rigid imine cage into the flexible amine cage, iodine uptake is enhanced by 37% in vapor and 91% in solution, giving an unprecedented example of organic adsorbents with high capacity from flexible cavity.

Conformation-immobilized tetraphenylethylene is exploited, for the first time, as chiral lid in construction of chiral molecular cages. The prepared chiral cages display potential in CPL switch, chiral analysis, chiral transfer, and energy transfer.

Hindered tetraphenylethylene (hTPE) helicates are resolved into two left-handed (M) and right-handed (P) isomers by linkage and removal of chiral auxiliary (1R,2S,5R)-menthol, furnishing gram-scale hTPE enantiomers via flash silica column chromatography. hTPE helicate enantiomers bearing electron-accepting cyano and electron-donating triphenylamine groups can emit deep-blue CPL signals with a fluorescence quantum yield surpassing 50%. Full-color and white-light emission were achieved by blending them with dyes in a poly(methyl methacrylate) (PMMA) film.

New chiral TPE bimacrocycles exhibit helical self-inclusion in crystals, strong CD (>7000 mdeg) and CPL (absolute g_lum 0.062) signals, and significant potential in enantiomer analysis for diverse chiral molecules.

Macrocycle-to-macrocycle conversion is an effective strategy to construct new macrocyclic arenes with specific structures. Herein, a new class of chiral macrocyclic arene, namely, octopus[5]arenes (Oc5s), cannot be synthesized by the direct approach from the corresponding chiral monomers but can be successfully achieved by a macrocycle-to-macrocycle conversion strategy utilizing racemic pagoda[5]arenes as the starting materials. It was found that enantiomeric Oc5s showed fixed conformations and stable chiral structures and exhibited significant chiral recognition toward chiral diamines.

Aggregation‐induced emission (AIE) and aggregation‐caused quenching (ACQ) are two classes of opposite luminescence phenomena. It is almost impossible to show both AIE and ACQ effect simultaneously by the same molecule. However, here we report that a simple TPE derivative TAP‐TPE grows into both AIE crystals and ACQ ones. It is found that equatorial, contact distance‐longer and weak ArH‐π interactions exist in AIE crystals while vertical, contact distance‐shorter and strong ArH‐π interactions appear in ACQ crystals. Theoretical calculation of electron density on the interaction atoms unveils that ACQ crystals have much larger change in electron density than AIE ones, suggesting that the intermolecular electron transfer aroused by the strong ArH‐π hydrogen bonds leads to ACQ phenomenon. This result provides a new insight into the emission mechanism in aggregation state. Interestingly, due to the ArH‐pi interactions difference, only one of five kinds of crystals shows rapid photochromism, and can act as multimode anti‐counterfeiting materials. Very exceptionally, for the first time we find that the photochromic micrometric rod‐like crystal even makes forward rolling movement as it repeatedly bends and straightens by responding to on and off of the ultraviolet light irradiation, displaying potential for photo‐actuator and light‐driven micro‐vehicle.

Tetraphenylethylene (TPE) helicates with single helical handedness not only owe high fluorescence quantum yield but also possess good helical chirality, showing an excellent circularly polarized luminescence active material. In this work, a new method for directly obtaining single-handed TPE helicates has been developed. By using chiral p-phenylenediamine derivatives as an intramolecular cyclization reagent of TPE, the single-handed propeller-like conformation and stable helical chirality of the TPE unit were obtained, avoiding complicated and expensive HPLC chiral column separation. The as-prepared chiral TPE helicates displayed strong emission with an almost quantitative fluorescence quantum yield (Φ_f) and strong circularly polarized luminescence (CPL). In addition, the chirality and CPL signals of the TPE helicates could be significantly magnified by the helical arrangement together with 4'-pentyl-4-biphenylcarbonitrile (5CB) liquid crystal molecules. Moreover, full-color CPL emissions with both a high absolute CPL dissymmetrical factor up to 0.43 and high Φ_f were afforded.