Solvent-Directed Rhenium(I) Metallocyclic Tubes, Dimeric Capsule, and Intercalated Dimers

Neutral flexible bidentate nitrogen donor ligands L-n (L-bim and L-nim) were designed, synthesized, and utilized as structural frameworks to construct solvent-directed rhenium(I) metallocyclic tubes, dimeric capsules, and intercalated dimers in the solid state. The combination of Re-2(CO)(10), 6,11-dihydroxy-5,12-naphthacenedione (H-2-dhnq) or 1,4-dihydroxyanthraquinone (H-2-dhaq), and L-bim or L-nim in the presence of benzene (Bz), mesitylene (Mes), or p-xylene (p-xyl) resulted in neutral heteroleptic metallocyclic tubes fac-[{(CO)(3)Re(mu-dhnq)Re(CO)(3)}(mu-L-bim)] (1), fac-[{(CO)(3)Re(mu-dhnq)Re(CO)(3)}(mu-L-nim)] (2), or fac-[{(CO)(3)Re(mu-dhaq)Re(CO)(3)}(mu-L-nim)] (3) with/without encapsulated guest solvent(s) depending on the nature of the solvent. Metallocyclic tubes 1 and 3 crystallized with solvent guest molecule(s) as (Bz)(2)@1, (Mes)(2)@1, (Bz)@3, and (p-xyl)(2)@3. On the other hand, metallocyclic tube 1 crystallized as a dimeric capsule (p-xyl)@1(2) in the presence of p-xylene, which acts as a glue between the two metallocyclic tubes stabilized via noncovalent interactions in the solid state. Metallocyclic tubes 2 and 3 in the presence of the mesitylene solvent crystallized as an intercalated dimeric assembly 2(2)4(Mes) and 3(2)4(Mes) in the solid state. The results reveal that along with the ligand motifs, the size and shape of methyl- and nonmethyl-substituted aromatic solvents influence the formation of the tubular architecture, dimeric capsule, or intercalated dimers. All of the compounds were confirmed by single-crystal X-ray diffraction analysis and characterized by various analytical and spectroscopic methods. The thermal stability of the assembled host-guest structures was studied by thermogravimetric analysis.