Nanoencapsulation-Induced Second Harmonic Generation in Pillararene-Based Host-Guest Complex Cocrystals.

The features of molecularly preferable centrosymmetric arrangements exclude organic nonlinear optical (NLO) materials for second harmonic generation (SHG) when used in the solid and crystalline states, which greatly limits their applications in optoelectronic devices. Herein, a pillar[5]arene () is used as the macrocyclic host to encapsulate NLO molecules, 4-[4'-methoxystyryl]-1-methylpyridinium iodide (), 4-[2'-(5'-(dimethylamino)thiophen-2'-yl)vinyl]-1-methylpyridinium iodide (), and 4-methoxy-β-nitrostyrene (), to alter the solid-state packing of these NLO molecules and manipulate their centrosymmetric arrangements. forms 2:1 host-guest complexes with and , while it forms a 1:1 host-guest complex with .

Pillararene-Based Variable Stoichiometry Co-Crystallization: A Versatile Approach to Diversified Solid-State Superstructures.

Variable stoichiometry co-crystals are important in solid-state supramolecular chemistry as they allow studies of structure-property relationships while permitting the synthesis of new scaffolds using identical synthons. In this work, we extend the concept of variable stoichiometry co-crystals into the realm of pillararene chemistry and show that this permits the rational construction of a diverse set of supramolecular structures in the solid state. Specifically, we report a series of variable stoichiometry co-crystals based on pillar[]arenes and tetracyanobenzene () and show that the combination of in-cavity complexation by pillar[]arenes ( = 5,6) and outside binding with allows several types of co-crystals with different self-assembled superstructures to be isolated.

Macrocycle-Based Solid-State Supramolecular Polymers.

Supramolecular polymers, generated by connecting monomers through noncovalent interactions, have received considerable attention over the past years, as they provide versatile platforms for developing diverse aesthetically pleasing polymeric structures with promising applications in a variety of fields, such as medicine, catalysis, and sensing. In the development of supramolecular polymers, macrocyclic hosts play a very important role. Benefiting from their abundant host-guest chemistry and self-assembly characteristics, macrocycles themselves or their host-guest complexes can self-assemble to form well-ordered supramolecular polymeric architectures including pseudopolyrotaxanes and polyrotaxanes.

Supramolecular Tessellations via Pillar[]arenes-Based Exo-Wall Interactions.

Supramolecular tessellation is a newly emerging and promising area in supramolecular chemistry because of its unique structural aesthetics and potential applications. Herein, we investigate the "exo-wall" interactions of pillar[]arenes and prepare fantastic hexagonal supramolecular tessellations based on perethylated pillar[6]arenes () with electron-deficient molecules 1,5-difluoro-2,4-dinitrobenzene () and tetrafluoro-1,4-benzoquinone (). The crystal structures clearly confirm that can form highly ordered hexagonal 2D tiling patterns with / as linkers through cocrystallization.

Acid/Base-Tunable Unimolecular Chirality Switching of a Pillar[5]azacrown [1]Catenane.

Stimuli-responsive unimolecular chirality switching is a highly intriguing topic because the molecular structure as well as its function can be adjusted simultaneously by a switching process. Herein, a novel acid/base-tunable unimolecular chirality switching system based on a pillar[5]azacrown [1]catenane is reported. The bicyclic pillar[5]azacrown [1]catenane is synthesized through fusing an azacrown ring onto one repeating unit of a pillar[5]arene.

Host-Guest Complexation of Perethylated Pillar[6]arene toward Ferrocene Derivatives Both in Solution and Solid State: Different Binding Modes Induced by Minor Structural Changes of Guests.

Herein, novel host-guest properties between perethylated pillar[6]arene and four kinds of ferrocene derivatives were fully investigated. NMR titrations, 2D NOESY NMR spectroscopy, and ESI-MS are used to confirm that they indeed formed stable inclusion complexes. Two precious single-crystal structures were obtained and showed that ferrocene derivatives with different chemical structures exhibit different binding modes with perethylated pillar[6]arenes.