Self-assembly of grid and helical hydrogen-bonded arrays incorporating bowl-shaped receptor sites that bind globular molecules

1,2-Dicarbadodecaborane(12) (o-carborane) and bowl-shaped cyclotriveratryle ne (CTV) self-assemble through bifurcated C-H-carborane...(O)(2) hydrogen b onds into infinite arrays with two-dimensional (2D) hexagonal grid or helic al chain topologies. The in-built shape-specific receptor sites bind o-carb orane or fullerene C-70. The structures of two such supramolecular systems in the solid state were established: (o-carborane)(2)(CTV) features hydroge n-bonded carborane ... CTV hexagonal grids as well as CTV ... carborane hos t-guest interactions, while a helical hydrogen-bonded carborane ... CTV cha in is formed in the quaternary system (C-70)(o-carborane)(CTV)(1,2-dichloro benzene) in addition to CTV ... C-70 host-guest interactions. The bifurcate d C-H-carborane...(O)(2) hydrogen bonding interaction common to both these structures was studied on the model system (o-carborane)(1,2-dimethoxybenze ne) using ab initio calculations and found to be energetically favoured by 5.48 kcal mol(-1), whereas a B-H-carborane...(O)(2) bifurcated hydrogen bon ding was less favoured at 1.13 kcal mol(-1).