Encapsulation of Aromatic Molecules in Hexanuclear Arene Ruthenium Cages: A Strategy to Build Up Organometallic Carceplex Prisms with a Dangling Arm Standing Out

Self-assembly of 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine (tpt) subunits with p -cymene ( p- Pr i C 6 H 4 Me) or hexamethylbenzene (C 6 Me 6 ) ruthenium building blocks and 2,5-dihydroxy-1,4-benzoquinonato (dhbq) or 2,5-dihchloro-3,6-dihydroxy-1,4-benzoquinonato (dchq) bridges affords the triangular prismatic organometallic cations [Ru 6 ( p- Pr i C 6 H 4 Me) 6 (tpt) 2 (dhbq) 3 ] 6+ ([ 1 ] 6+ ), [Ru 6 ( p- Pr i C 6 H 4 Me) 6 (tpt) 2 (dchq) 3 ] 6+ ([ 2 ] 6+ ), [Ru 6 (C 6 Me 6 ) 6 (tpt) 2 (dhbq) 3 ] 6+ ([ 3 ] 6+ ), and [Ru 6 (C 6 Me 6 ) 6 (tpt) 2 (dchq) 3 ] 6+ ([ 4 ] 6+ ). These hexanuclear cationic cages are isolated in good yield as their triflate salts. The assembly of 1 − 4 can also be achieved in the presence of large aromatic molecules such as pyrene, fluoranthene, benzo[ e ]pyrene, triphenylene, or coronene to give the corresponding inclusion systems [aromatic⊂ 1 ] 6+, [aromatic⊂ 2 ] 6+, [aromatic⊂ 3 ] 6+, and [aromatic⊂ 4 ] 6+ . The closed proximity of the encapsulated molecule with the different components of the cage and the carceplex nature of these systems are confirmed by one-dimensional ROESY 1 H NMR experiments, mass spectrometry, and the single-crystal structure analysis of [pyrene⊂ 1 ][O 3 SCF 3 ] 6 and [benzo[ e ]pyrene⊂ 1 ][O 3 SCF 3 ] 6 . Pyrene can be encapsulated even if it contains a functionalized aliphatic substituent; in this case the aromatic moiety is included in the cage, while the functionalized side arm stands out. Thus, methyl 4-(pyren-1-yl)butanoate (pyrene-R) is encapsulated in 1 to give the carceplex [pyrene-R⊂ 1 ] 6+, in which the methyl butyrate arm dangles outside the cage while the pyrene moiety is firmly trapped by the metallo-prismatic cation, as demonstrated by 1 H NMR experiments and ESI-MS.