Combinatorial Self-Assembly of Coordination Cages with Systematically Fine-Tuned Cavities for Efficient Co-Encapsulation and Catalysis.

Controllable arrangement of different ligands in a single assembly will not only bring increased complexity but also offers a new route to fine-tune the function of the designed architecture. We report here a combinatorial self-assembly with enPd(NO 3 ) 2 and three different ligands (L 1-3 ), which gave rise to a family of six palladium-organic cages (C1-6) with systematically varied shapes and cavities, including three new heteroleptic (Pd 5 L 1 2 L 2 , Pd 5 L 1 2 L 3 , Pd 4 L 2 L 3 ), one new homoleptic (Pd 4 L 3 2 ) cages, and two known homoleptic (Pd 6 L 1 4 , Pd 4 L 2 2 ) cages. Emergent functions due to the fusion of two half cavities on the heteroleptic cages from their parent homoleptic cages have been observed: the heteroleptic cages can form ternary complexes by co-encapsulation of both aromatic and aliphatic guests, while their homoleptic counterparts can only form binary complexes. Such a forced co-encapsulation effect endows the heteroleptic cages with enhanced catalytic power for the Knoevenagel condensation.