Adsorption and Removal of 2,4,6-Trinitrotoluene by a Glycoluril-Derived Molecular-Clip-Based Supramolecular Organic Framework

A glycoluril-derived molecular-clip-based supramolecular organic framework (clip-SOF) with intrinsic porosity was prepared. The clip-SOF was used for the adsorption and removal of 2,4,6-trinitrotoluene (TNT) driven by noncovalent interactions. The efficiency of TNT removal by clip-SOFs is up to 88.5% in adsorption equilibrium, and the TNT adsorption capacity of clip-SOFs is about 40.2 mg/g at 25.0 °C. Clip-SOFs have good reusability, exhibiting almost no loss in performance in ten consecutive recycling tests. This work not only provides a new method for adsorbing energetic materials, but also promotes the application of supramolecular hosts in crystal engineering.

Intercage Polymerization of Postfunctionalized Phosphine Organic Prisms into Cage-Based Assemblies with Tunable Morphologies

Great effort has been dedicated to the engineering of porous organic cages (POCs) in geometry and topology. Yet, harnessing these cage-like entities as premade building units to construct infinite cage-based superstructures remains elusive. In this study, we design a type of vertex-modified phosphine organic prism by a postfunctionalized approach and use it as a ditopic cage monomer to achieve an intercage supramolecular polymerization via the synergy of metal coordination and π-π dimerization. The resulting cage-by-cage polymers can further hierarchically organize into superstructures of diverse morphologies and dimensionalities, including 1D fibers, 2D lamellae, and 3D vesicles. Control over the cosolvents is capable of well regulating their structural hierarchies and self-assembled shapes. This would pave a way for the creation of cage-based supramolecular assemblies and nanomaterials.

Host-guest system of a phosphorylated macrocycle assisting structure determination of oily molecules in single-crystal form

X-ray crystallography is the most reliable method for structure elucidation and absolute configuration determination of organic molecules based on their single-crystal forms. However, many analytes are hard to crystallize because of their low melting points (an oily state at room temperature) or conformational flexibility. Here, we report the crystallization of a macrocycle, CTX[P(O)Ph] (host), which is a cyclotrixylohydroquinoylene (CTX) derivative, with 26 oily organic molecules (guests), which is applied for the structural determination of the guest with X-ray crystallography. With the aid of the host, CTX[P(O)Ph], the guest molecules were well-ordered with full occupancy in crystal structures. In most cases, at least one guest structure without any disorder could be observed; solvent masking was not necessary for the single crystal X-ray structural analysis, and thus the structures of the guests could be successfully determined, and the absolute configuration could be assigned reliably for chiral guests with this method. The crystallization mechanism was further discussed from theoretical and experimental perspectives, suggesting that the negative electrostatic potential surface of CTX[P(O)Ph] and noncovalent interactions between the host and guest were crucial for the ordered arrangements of the guest.

Accurate Analysis of Anisotropic Carrier Mobility and Structure-property Relationships in Organic BOXD Crystalline Materials

Charge mobility is an essential factor of organic crystalline materials. Although many investigators have made important progress, the exact relationship between the crystal structure and carrier mobility remains to be clarified. Fortunately, a series of bis-1,3,4-oxadiazole derivatives have been successfully prepared and reported. They have similar main molecular fragments but different crystal packing modes, which provide an ideal research objective for studying the effect of molecular packing on charge mobility in organic photoelectric conversion systems. In this work, the charge mobilities of these molecules are systematically evaluated from the perspective of first-principles calculation, and the effect of a molecular overlap on orbital overlap integral and final charge carrier mobility is fully discussed. It can be seen that the small intermolecular distance (less than 6 Å) is the decisive factor to achieve high electron mobility in π stacking, and better mobility can be obtained by increasing the hole migration distance appropriately. A larger dihedral angle of anisotropy is an important point limiting the charge mobility in the herringbone arrangement. It is hoped that the correlation results between the crystal structure and mobility can assist the experimental study and provide an effective way to improve the photoelectric conversion efficiency of the organic semiconductor devices and multiple basis for multiscale material system characterization and material information.

Fluorescence Response and Self-Assembly of a Tweezer-Type Synthetic Receptor Triggered by Complexation with Heme and Its Catabolites

There is increasing interest in the development and applications of synthetic receptors that recognize target biomolecules in aqueous media. We have developed a new tweezer-type synthetic receptor that gives a significant fluorescence response upon complexation with heme in aqueous solution at pH 7.4. The synthetic receptor consists of a tweezer-type heme recognition site and sulfo-Cy5 as a hydrophilic fluorophore. The receptor-heme complex exhibits a supramolecular amphiphilic character that facilitates the formation of self-assembled aggregates, and both the tweezer moiety and the sulfo-Cy5 moiety are important for this property. The synthetic receptor also exhibits significant fluorescence responses to biliverdin and bilirubin, but shows very weak fluorescence responses to flavin mononucleotide, folic acid, and nicotinamide adenine dinucleotide, which contain smaller π-scaffolds.

Azobenzene-Based Macrocyclic Arenes: Synthesis, Crystal Structures, and Light-Controlled Molecular Encapsulation and Release

Azobenzene (azo)-based macrocycles are highly fascinating in supramolecular chemistry because of their light-responsiveness. In this work, a series of azo-based macrocyclic arenes 1, 2, 3, and 4, distinguished by the substituted positions of azo groups, is rationally designed and synthesized via a fragment-cyclization method. From the crystal and computed structures of 1, 2, and 3, we observe that the cavity size of these azo-macrocycles decreases gradually upon E→Z photoisomerization. Moreover, light-controlled host-guest complexations between azo-macrocycle 1 and guest molecules (7,7,8,8-tetracyanoquinodimethane, terephthalonitrile) are successfully achieved. This work provides a simple and effective method to prepare azo-macrocycles, and the light-responsive molecular-encapsulation systems in this work may further advance the design and applications of novel photo-responsive host-guest systems.