“Cage Walking” Synthetic Strategy for Unusual Unsymmetrical Supramolecular Cages

Abstract

Developing novel assembly methods for supramolecular compounds has long been a research challenge. Herein, we describe how to integrate the B–C coupling reaction and “cage walking” process into coordination self-assembly to construct supramolecular cages. In this strategy, dipyridine linkers containing alkynes react with the metallized carborane backbone through B–C coupling and then “cage walking” resulting in metallacages. However, dipyridine linkers without alkynyl groups can form only metallacycles. We can regulate the size of metallacages based on the length of the alkynyl bipyridine linkers. When tridentate-pyridine linkers participate in this reaction, a new type of ravel is formed. The metallization of carboranes, the B–C coupling reaction, and especially the “cage walking” process of carborane cages play a vital role in this reaction. This work provides a promising principle for the synthesis of metallacages and opens up a novel opportunity in the supramolecular field.

Nickelacarborane-Supported Bis-N-heterocyclic Carbenes

“…Upon deprotonation with NaHMDS, 2 provides the N -heterocyclic carbenoids ( 3 ), which serve as a Janus-type bis-carbene ligand to prepare gold complexes ( 4 ) and diselenone ( 5 ). The successful formation of 4 suggests that their potential use in the construction of supramolecular organometallic complexes or heterobimetallic complexes catalyzed tandem processes. ,, The π-accepting ability of the carbene ligands was assessed using diselenone 5 , which could be easily detected by 77 Se NMR. The electronic structures of 3 were also investigated using the theoretical method, revealing relatively high-lying lone-pair orbitals, weak B–H···H–C interactions between BH units and the methyl group, and weak B–H···π interactions between BH groups and the vacant p -orbital of the carbene, intrinsically diminishing its π-accepting properties.…”

Supramolecular Architectures Bearing Half-Sandwich Iridium- or Rhodium-Based Carboranes: Design, Synthesis, and Applications

“…In 2023, Jin et al developed a "cage-walking" strategy for synthesizing nonsymmetric supramolecular cages. 43 In this strategy, the B− C coupling reaction and "cage-walking" process were integrated with coordination-driven self-assembly to construct unusual metallacages. Alkyne-bearing dipyridine linkers react with the metalized carborane backbone via B−C coupling and, subsequently, "cage walking" to produce metallacages (Figure 11).…”

“…Apart from inducing the activation of B–H bonds via supramolecular chemistry, the activation of B–H bonds can induce changes in the supramolecular structures. In 2023, Jin et al developed a “cage-walking” strategy for synthesizing nonsymmetric supramolecular cages . In this strategy, the B–C coupling reaction and “cage-walking” process were integrated with coordination-driven self-assembly to construct unusual metallacages.…”

“…Instead of bifunctional pyridyl linkers, the tridentate linker TPBY (1,3,5-tris­(pyridin-4-ylethynyl)­benzene) was introduced (Scheme ). However, in contrast to the B–C-coupling-induced metallacage formation, M–C and C–C couplings were instead used to obtain metallacage 33 . According to the crystal structure of metallacage 33 , both TPBY linkers cross-linked to form an eight-nucleus metallacage, which appeared as a ravel comprising covalent-bond-linked interlocks (Figure ), which is a molecular architecture that is rarely observed in supramolecular chemistry − and exhibits both intricacy and beauty in its molecular form.…”

Exploration and Insights on Topology Adjustment of Giant Heterometallic Cages Featuring Inorganic Skeletons Assisted by Machine Learning

“…Inspired by the functionality of enzyme pockets in selective catalysis, specific recognition, etc., the chemical synthesis of cage-like compounds has received huge research interests in past decades. − Thanks to the development of the organic synthesis methodology and coordination chemistry, relatively mature design and synthesis methods have been developed for molecular cages with organic , or metal–organic skeletons. − The cage-like assemblies constructed by inorganic skeletons have rigid skeletons and endow the functionality from synergic multimetal centers. − However, despite the possibility of a rational structure design, the poor synthetic controllability and an enormous possible structure space of the coordination components make the precise design and synthesis of them still challenging. As a result, cage-like compounds featuring inorganic skeletons normally come from serendipitous findings via trial-and-error.…”