Hydrogen-bonded networks formed from tri- and tetra-substituted adamantanes bearing dimethoxyphenol moieties and their 1,3,5-trinitrobenzene complexes via charge-transfer interactions

Adamantane derivatives represent valuable scaffolds for the generation of interesting supramolecular architectures in the crystalline state because of their high symmetry and the facile attachment of functional groups. Tri- and tetrasubstituted adamantanes with dimethoxyphenol moieties were designed and prepared as novel hydrogen-bonded (H-bonded) electron-donor molecules with the aim of introducing donor-acceptor interactions into the H-bonded structures. Single-crystal X-ray analysis of ternary molecules based on adamantane (1) revealed the creation of one-dimensional (1D) ladders through H-bonding between methoxy and hydroxyl groups of dimethoxyphenol units. Individual ladders assembled into three-dimensional (3D) networks via multiple C-H center dot center dot center dot O interactions. In the crystals of tetrasubstituted adamantane (2), H-bonded 1D polymers composed of a cyclic framework were produced, which were aligned into a 3D network structure through C-H center dot center dot center dot O interactions. In the 1,3,5-trinitrobenzene (3) charge-transfer complex of trisubstituted adamantane, infinite H-bonded two-dimensional (2D) sheets were sustained by the formation of multiple H-bonds. The 2D sheets were observed to stack with guest molecules via charge-transfer interactions. The complexation of 3 with 2 led to the formation of H-bonded 2D sheets possessing two types of cavities, which were intermolecularly interdigitated via donor-acceptor interactions, resulting in the construction of a 3D network structure.