Construction and Hierarchical Self-Assembly of Multifunctional Coordination Cages with Triangular Metal–Metal-Bonded Units

Abstract

Herein, a series of face-capped (Tr2M3)4L4 (Tr = cycloheptatrienyl cationic ring; M = metal; L = organosulfur ligand) tetrahedral cages 1–3 functionalized with 12 appended crown ether moieties were designed and synthesized. The reversible binding of ammonium cations with peripheral crown ether moieties to adjust internal guest-binding was realized. Combination of a bisammonium linker and cage 3 led to the formation of a supramolecular gel SPN1 via host–guest interactions between the crown ether moieties and ammonium salts. The obtained supramolecular gel exhibited multiple-stimuli responsiveness, injectability, and excellent self-healing properties and could be further developed to a SPN1-based drug delivery system. In addition, the storage modulus of SPN1 was 20 times higher than that of the model gel without Pd–Pd bonded blocks, and SPN1 had better self-healing properties compared with the latter, demonstrating the importance of such cages in improving mechanical strength without losing the dynamic properties of the material. The cytotoxicity in vitro of the drug-loaded (doxorubicin or methotrexate) SPN1 was significantly improved compared to that of free drugs.

Transformation of Type III to Type II Porous Liquids by Tuning Surface Rigidity of Rhodium(II)‐Based Metal‐Organic Polyhedra for CO2 Cycloaddition

“…Apart from the N-donor molecules mentioned above, the grafting of crown ether attached pyridine complex (N-18-C-6-Py) on neat RhMOP was also carried out to evaluate its influence on the structure of resulting cage. [32] Postgrafting analyses illustrates the robustness of the functionalized cage (a supramolecular system) without any change in its basic structure (Supporting Information, Figures S17-S21). Deemed these as intended properties in the cages, the obtained lucid purple solutions of functionalized RhMOPs in DCM were further mixed with IL-Br.…”

Nested Non-covalent Interactions Expand the Functions of Supramolecular Polymer Networks

“…In searching for a material to demonstrate this idea, we recognized that such a configuration could be achieved with MOC-crosslinked polymers (polyMOCs). [23][24][25][26] MOCs are, in some cases, known to display pronounced host-guest binding ability, [27][28][29][30][31] and a few reports of polyMOCs have leveraged MOCs that can bind guest molecules [32][33][34][35] ; however, no studies have explored how the bulk properties of polyMOCs can be varied by altering guest binding thermodynamics, nor have they leveraged this unique nested junction structure to achieve functions that cannot be obtained with traditional supramolecular networks. For example, we imagined at least three functions that could potentially be uniquely achieved with nested polyMOC networks: (1) guest-induced manipulation of bulk stress-relaxation dynamics, wherein small molecule guests alter the metal-ligand coordination dynamics of the junction; (2) resistance to dissolution under off-stoichiometry network formation conditions or in the presence of competitive reagents due to synergistic stabilization of MOC junctions bound to guests; and (3) the ability to control both percolation (i.e., gelation) and dissolution using selective self-sorting of MOC junctions driven by guest recognition.…”

A dynamic {AuI⋯AuI}-coupling cluster-based coordination capsule for photocatalytic benzylamine oxidation

“…14–18,24 In contrast, polynuclear metal clusters, especially metal–metal bonding cluster assembly motifs, comprehensively enhance the structural diversity, molecular size, and inner cavity of coordination capsules and stimulate more interesting physical and chemical properties. 25–34 In recent years, inter- or intramolecular Au I ⋯Au I bonding interactions, which have similar strengths to hydrogen bonds, 35–41 have been widely utilized in the de novo design and self-assembly of supramolecular aggregates. These aggregates feature various novel structures such as catenanes, 41 polynuclear clusters, 43–46 metallocycles, 47,48 and molecular wires, 49–51 which can potentially be applied in optoelectronic devices and catalytic media.…”