Metal-ion induced alignment of an orthogonal anthracene–pyrimidine derivative. Cooperation of metal coordination, hydrogen bonding, and aromatic stacking in the buildup of one-, two- and three-dimensional networks

Abstract

9-(5-Pyrimidinyl)anthracene (1) forms a ternary adduct 1·Cd(NO₃)₂·2(CH₃OH), the crystal structure of which shows a remarkable cooperation of metal coordination, hydrogen bonding and aromatic stacking interactions in the hierarchical formation of one-, two- and three-dimensional networks. Ditopic pyrimidine ligands and cadmium ions form a pyrimidine–Cd²⁺ alternate copolymeric chain. The chains are held together to give a sheet by extensive cross-links via hydrogen bonding between metal-bound nitrate ions of one chain and methanol molecules of the neighboring one. The sheets are self-assembled via stacking, interpenetration or intercalation of the orthogonal anthracene side arms on both sides of a sheet. This gives rise to a layered structure having an alternate arrangement of inorganic and organic sheets; the former contains Cd²⁺ ions two-dimensionally networked by pyrimidine bridges and hydrogen-bonded nitrate–methanol links, while the latter is composed of tightly-packed anthracene columns.