Controlled Hierarchical Self-Assembly of Catenated Cages

Abstract

Constructing hierarchical superstructures to achieve comparable complexity and functions to proteins with four-level hierarchy is challenging, which relies on the elaboration of novel building blocks with complex structures. We present a series of catenated cages with unique structural complexity and tailorability. The rational design was realized as such: A catenane of two symmetric cages (CSC), CSC-1, with all rigid imine panels was converted to a catenane of two dissymmetric cages (CDC), CDC-1, with two exterior flexible amine panels, and CDC-5 was tailored from CDC-1 by introducing an additional methyl group on each blade to increase lateral hindrance. CDC-1s with the most irregular and flexible configuration formed supramolecular dimers, which self-organized into 3D continuous wavelike plank with a three-level hierarchy, previously undiscovered by conventional building blocks. A drastically different 3D triclinic crystalline phase with a four-level hierarchy and trigonal phase with a three-level hierarchy were constructed of distorted CSC-1s and the most symmetric CDC-5s, respectively. The wavelike plank exhibited the lowest order, and the triclinic phase had a lower order than the trigonal phase which had the highest order. It correlates with the configuration of the primary structures, namely, the most disordered shape of CDC-1, the low-order configuration of CSC-1, and the most ordered geometry of CDC-5. The catenated cages with subtle structural differences therefore provide a promising platform for the search of emerging hierarchical superstructures that might be applied to proton conductivity, ferroelectricity, and catalysis.

A class of organic cages featuring twin cavities

“…Our group has been focusing on the elaboration 16,17 and hierarchical self-assembly 18,19 of covalent organic cages prepared by dynamic covalent chemistry (DCC) 7,8 . Due to the dynamic and reversible nature of DCC, it allows error correction to yield the thermodynamic products 20,21 .…”

High Fluorescence Porous Organic Cage for Sensing Divalent Palladium Ion and Encapsulating Fine Palladium Nanoparticles

“…[ 10 ] The smart dynamic covalent chemistry enables the easy fabrication route of discrete POCs by rationally choosing organic building blocks. [ 11 ] In this direction, imine chemistry has been widely studied by means of reversible connection nature to direct the construction of the target thermodynamic preferred stable product. Introduction of imine nitrogen atoms could serve as effective binding sites and nucleation site for the metal ions and metal nanoparticles, respectively.…”

A Size-Matching Strategy to Differentiate Flexible Conformers for the Discovery of Novel Cages with Twin Cavities

“…These molecules include cages with two different pockets, denoted Janus diphanes, which we will report in due course. These molecules with unique shapes and configurations can also be used novel supramolecular synthons for the construction of hierarchical superstructures 13,19 with the potential application of proton conductivity, ferroelectricity, catalysis, and so on, which are the ongoing endeavors within our laboratories.…”