Supramolecular aggregation of two hydroxy­carboxylic acid derivatives

The crystal structures of 7,7‐dicyclo­but­yl‐5‐hydroxy­meth­yl‐6‐oxabicyclo­3.2.1]octa­ne‐1‐carboxylic acid, C₁₇H₂₆O₄, (I), and 1‐(hydroxy­meth­yl)‐7‐oxaspiro­bicyclo­3.2.1]octa­ne‐6,1′‐cyclo­penta­ne]‐5‐carboxylic acid, C₁₃H₂₀O₄, (II), determined at 170 K, show that the conformation of the hydroxy­meth­yl group (anti or gauche) affects the dimensionality (one‐ or two‐dimensional) of the supramolecular structures via O—H⋯O hydrogen bonds. In (I), the carbox­yl and hydroxy­meth­yl groups inter­act with themselves, forming a one‐dimensional step‐ladder, while in (II), a two‐dimensional structure is made up of carboxylic acid centrosymmetric R₂²(8) dimers connected by hydrox­yl‐to‐ether contacts.