Host-in-Host Complexation: Activating Classical Hosts through Complete Encapsulation within an ML Coordination Cage.

This study reports a method for enhancing the functions and properties of traditional organic macrocyclic hosts by fully encapsulating them within a large ML cage to form host-in-host complexes. Within the cage host, the macrocyclic organic hosts with electron-rich aromatic rings, such as cyclotriveratrylene and calix[8]arene, adopt specific orientations enhancing their inherent molecular recognition abilities. Due to the high crystallinity of the ML cage, the guest encapsulation behavior of the host-in-host complexes can be observed by X-ray structural analysis.

Template and Solid-State-Assisted Assembly of an ML Expanded Coordination Cage for Medium-Sized Molecule Encapsulation.

The ML cage, self-assembling from six Pd(II) or Pt(II) 90-degree blocks and four triazine-cored triangular ligands, has an effective hydrophobic cavity of about 450 Å capable of encapsulating one or more small molecules. Here, from the same components, we successfully constructed an ML cage with an internal volume expanded to 1540 Å via the self-assembly of an ML precursor using pillar[5]arene as a template. This cage retains the high molecular recognition ability of the ML cage while recognizing medium-sized guest molecules with molecular weights of up to ∼1600.

Selective Synthesis and Functionalization of an Acyclic Methylene-Bridged-Arene Trimer in a Cage.

Arene-formaldehyde condensation is a versatile reaction for producing various oligomeric/polymeric materials. However, the precise control of oligomerization degree is still challenging because the starting materials and intermediates have similar reactivities. Here, we demonstrate the selective synthesis of a methylene-bridged arene trimer using the confined cavity of a coordination cage.

Mathematical Model for Estimating the Sound Absorption Coefficient in Grid Network Structures.

Although grid network structures are often not necessarily intended to absorb sound, the gaps between the rods that make up the grid network are expected to have a sound absorption effect. In this study, the one-dimensional transfer matrix method was used to develop a simple mathematical model for accurately estimating the sound absorption coefficient of a grid network structure. The gaps in the grid network structure were approximated as the clearance between two parallel planes, and analysis units were derived to consider the exact geometry of the layers.