-symmetric aromatic triimides as useful building blocks for supramolecular chemistry and advanced materials.

-symmetric aromatic triimides (ATIs) represent an interesting class of electron-deficient molecular backbones, characterized by π-conjugated aromatic cores symmetrically substituted with three imide groups. Their unique structural and electronic features, combined with exceptional stability and straightforward -functionalization at three imide sites, make ATIs promising as versatile building blocks for applications in supramolecular chemistry and materials science. Despite their promising attributes, research on ATIs remains underexplored compared to the extensively studied aromatic imides and diimides, largely due to the synthetic challenges involved in constructing three imide groups on the aromatic frameworks.

Internal and External Pockets in Pillar[]arene Sheets and Their Host-Guest Binding Beyond Cavity Volume Limitations.

Constructing binding pockets by hierarchically assembling tailored building blocks and understanding structure-property relationships are challenging goals. Herein, amphiphilic pillar[5]arene and pillar[6]arene were prepared and used to construct 2D sheets, which consisted of well-defined hydrophobic and hydrophilic interlayers. In the hydrophobic interlayers, internal hydrophobic pockets were created by packing pairs of pillar[]arenes, and external hydrophobic pockets were simultaneously generated from gaps between pillar[]arenes due to electrostatic attractions.

Helical-Sense Matching Facilitates Supramolecular Copolymerization of Helical-Chiral Pillar[5]arenes.

Supramolecular polymerization using two-dimensional π-conjugated chiral monomers has been mainly demonstrated because the supramolecular polymerization can be controlled by stereocommunication through π-π stacking between the two-dimensional chiral monomers. We herein report supramolecular copolymerization utilizing three-dimensional pentahedrons with twisted helical chirality through different combinations of helical-chiral acidic and basic pillar[5]arenes as comonomers. In this case, helical-sense matching is key to facilitating the supramolecular copolymerization.

Anion-Carbonyl Interactions.

Presented herein is the exploration of a novel non-covalent anion-carbonyl (X···C═O) interaction using aromatic imides as receptors and halides as lone pair donors. Combined theoretical calculations and experimental methods including C NMR, IR, and crystallographic analyses were performed to provide the physical origin and experimental evidence of anion-carbonyl interactions. The EDA analysis (energy decomposition analysis) based on DFT calculation indicates that electrostatic terms are the dominant contributions for the binding energy while electron delocalization also significantly contributes alongside the electrostatic attraction.

Chiral Benzene Triimide (BTI) Radical Anions for Probing the Interplay of Unpaired Electron Spin and Chirality.

Herein a series of chiral BTI radical anions bearing different chiral substituents were efficiently prepared by chemical reduction. X-ray crystallography revealed finely-tuned packing and helix assemblies of the radicals by the size of chiral substituents in crystalline state. In accordance with the crystalline-state packing, the powder ESR spectra indicate that 4 a ⋅CoCp and 4 c ⋅CoCp π-dimers exhibit thermally excited triplet states arising from strong spin-spin interactions, while discrete 4 b ⋅CoCp shows a broad doublet-state signal reflecting weak spin-spin interactions.

Magnetic Multistability in an Anion-Radical Pimer.

Radical pimers are the simplest and most important models for studying charge-transfer processes and provide deep insight into π-stacked organic materials. Notably, radical pimer systems with magnetic bi- or multistability may have important applications in switchable materials, thermal sensors, and information-storage media. However, no such systems have been reported.

Benzene Triimide Cage as a Selective Container of Azide.

Benzene triimide (BTI, or mellitic triimide) is a -symmetric backbone with a highly electron-deficient, extended π surface and three easy functionalization sites. Here, we report the first BTI-based cage composed of two face-to-face BTIs pillared by three -xylylene spacers and efficient and selective binding of azide through cooperative anion-π interactions. The cage was easily synthesized in two steps from benzene triimide.

Macrocycle-Directed Construction of Tetrahedral Anion-π Receptors for Nesting Anions with Complementary Geometry.

Manipulation of the emerging anion-π interactions in a highly cooperative manner through sophisticated host design represents a very challenging task. In this work, unprecedented tetrahedral anion-π receptors have been successfully constructed for complementary accommodation of tetrahedral and relevant anions. The synthesis was achieved by a macrocycle-directed approach by using large macrocycle precursors bearing four reactive sites, which enabled a kinetic-favored pathway and afforded the otherwise inaccessible tetrahedral cages in considerable yields.

Toward Anion-π Interactions Directed Self-Assembly with Predesigned Dual Macrocyclic Receptors and Dianions.

Realizing anion-π interaction induced self-assembly with charge-neutral π receptors as building components is extremely challenging. We designed and synthesized a series of bisoxacalix[2]arene[2]triazines 7-11 in which two macrocyclic motifs are linked in diverse branching angle and rigidity. Crystal structures showed the use of rigid linkers is able to control the orientation of the two macrocyclic cavities.

Vesicles Constructed with Chiral Amphiphilic Oxacalix[2]arene[2]triazine Derivatives for Enantioselective Recognition of Organic Anions.

Chiral amphiphilic oxacalix[2]arene[2]triazine derivatives 1-3 bearing l-prolinol moieties were synthesized. The self-assembly behavior of the chiral macrocyclic amphiphiles was investigated. SEM, TEM, and DLS measurements demonstrated that 1 formed stable vesicles (size of ∼90 nm), whereas 2 and 3 formed micelles.