Co-crystalline hydrogen bonded solids based on the alcohol–carboxylic acid–alcohol supramolecular motif

Abstract

The helical tubuland diol 4 forms 1 ∶ 1 hydrogen bonded co-crystalline adducts with 2-propanol and propanoic acid in space group P2₁/c, and with benzoic acid in C2/c. In the first of these compounds, the 2-propanol molecules contribute one hydroxy group to the intermolecular ⋯O–H⋯O–H⋯O–H⋯ hydrogen bond repeat unit. The co-crystals formed with propanoic acid and benzoic acid both contain a ⋯O–H⋯OC(R)–O–H⋯O–H⋯ repeat unit with the hydrogen bonds surrounding a pseudo-threefold screw axis, and where the carboxylic acid group functions like an extended alcohol hydroxy group. Aromatic offset face–face associations also play a significant role in the crystal structure of the benzoic acid compound.