Empirical and Theoretical Insights into the Structural Features and Host-guest Chemistry of M₈L₄ Tube Architectures

Meng, W.; League, A. B.; Ronson, T. K.; Clegg, J. K.; Isley, W. C., III; Semrouni, D.; Gagliardi, L.; Cramer, C. J.; Nitschke, J. R.
J. Am. Chem. Soc. 2014, 136, 3972 (doi:10.1021/ja412964r).

We demonstrate a general method for the construction of M₈L₄ tubular complexes via subcomponent self-assembly, starting from Cu^I or Ag^I precursors together with suitable elongated tetraamine and 2-pyridine-carboxaldehyde subcomponents. The tubular architectures were often observed as equilibrium mixtures of diastereomers having two different point symmetries (D_2d or D₂ ⇄ D₄) in solution. The equilibria between diastereomers were influenced through variation in ligand length, substituents, metal ion identity, counter-anion, and temperature. In the presence of dicyanoaurate(I) and Au^I, the D₄-symmetric hosts were able to bind linear Au(Au(CN)₂)^2– (with two different configurations) as the best-fitting guest. Substitution of dicyanoargentate(I) for dicyanoaurate(I) resulted in the formation of Au(Au(CN)₂)^2– as the optimal guest through transmetalation. Density functional theory was employed to elucidate the host-guest chemistries of the tubes.