Supramolecular Coordination Cages Based on N‐Heterocyclic Carbene‐Gold(I) Ligands and Their Precursors: Self‐Assembly, Structural Transformation and Guest‐Binding Properties.

The incorporation of functional groups into the cavity of discrete supramolecular coordination cages (SCCs) will bring unique functions and applications. Here, three dicarboxylate ligands (H2L1Cl, H2L2Cl and H2L3Cl) containing N‐heterocyclic carbene (NHC) precursors as linkers were introduced to construct SCCs by combining with two C3‐symmertic (CpZr)3(μ3‐O)(μ2‐OH)3 clusters as three‐connect vertices, resulted in a series of rugby‐like V2E3 (V=vertex, E=edge) type homoleptic cages (SCC‐1, SCC‐2 and SCC‐3). However, V4E6‐type tetrahedral cages (SCC‐4 and SCC‐5), incorporating six Au‐NHC moieties, were obtained when the corresponding NHC‐gold(I) functionalized ligands (H2L1Au, H2L2Au) were applied. For the first time, we present a trackable CpZr‐involved cage to cage conversion to generate a heteroleptic V2E3 cage (SCC‐6) from two homoleptic cages (SCC‐2 and SCC‐5) with different geometries of V2E3 and V4E6. The heteroleptic assembly SCC‐6 can also be formed upon a subcomponent displacement strategy. The structural transformation and reassembly processes were detected and monitored by 1H NMR spectroscopy and electrospray‐ionization mass spectrometry. The formation of heteroleptic assembly was further supported by single crystal X‐ray diffraction analysis. Moreover, homoleptic cage SCC‐2 possesses a trigonal bipyramidal cationic cavity allowing the encapsulation of a series of sulfonate anionic guests. [ABSTRACT FROM AUTHOR]