Efficient Route to Organometallic Cage Formation via C–H Activation-Directed Muticomponent Assembly Accompanying Aromatic Guest Encapsulation

Driven by C–H activation-directed self-assembly, a series of organometallic cages, 4a–4e, was obtained from the reaction of [Cp*IrCl2]2 (1) and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpt) (2) with terephthal-bis-aromatic imine ligands 3a–3e in the presence of AgOTf (Tf = O2SCF3). The 1H NMR spectra of 4a–4d revealed that two isomers of the organometallic cages (symmetrical isomer SI-4 and asymmetrical isomer ASI-4) are formed. Pure isomer can be isolated from their chloroform solution of the product mixture by crystallization at low temperature. In the resulting supramolecular assemblies, the two central triazine units are very close, and the centroid···centroid distance between the two triazine moieties is only 3.3 Å. These discrete cages can form complexes with a wide variety of π-donor substrates, including Pt(acac)2, pyrene, and coronene. The transannular separation between the centers of the triazine rings in the host–guest complex is now enlarged to about 6.66 Å. The preparation of host–guest systems in a one-pot procedure was accomplished. The 1:1 complexation between the guest and host was confirmed by 1H NMR, elemental analyses and single-crystal X-ray diffraction analyses (6⊂SI-4b, 7⊂SI-4b, and 6⊂SI-4c).