Crystal structures and Hirshfeld surface analyses of seven 7-aryl-4,7-dioxoheptanoic acids: differing carboxylic acid interactions leading to dimers, chains and three-dimensional arrays

Crystal structures and Hirshfeld surface analysis are reported of seven aryl-CO-CH2CH2COCH2CH2CO2H derivatives, namely aryl = 4-ClC6H4 , 1: 2-HOC6H4, 2: (2,4-(MeO)(2)C6H3, 3: 3,5-Me 2 -4-MeOC6H2, 4: 4-MeC6H4, 5: C6H5 , 6: 2,4-(HO)(2)C6H3, 7. There are significant differences in their molecular conformations and their crystal packing. Within the group of compounds, three different types of carboxylic acid intermolecular interactions are exhibited, all involving O-H center dot center dot center dot O hydrogen bonds. These three types are (i) symmetric R-2(2)(8) dimers formed from pairs of O-H center dot center dot center dot O hydrogen bonds in compounds 1-5, (ii) infinite 1D homo-assemblies of carboxylic groups (homoAA,A catemers), and (iii), a 3-D array, in which there are no direct carboxylic acid-carboxylic acid interactions, generated from O-H center dot center dot center dot O interactions of each carboxylic acid group with the hydroxyl and carbonyl groups of other molecules in 7. Each of the carboxylic acid groups in the catemer exhibit anti arrangements with all the carboxylic acid oxygen atoms lying in a plane. Disorder is exhibited in the carboxylic acid groups in 2 and 6. With the variety of oxygen substituents present in 1-7, a large number of O-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds are exhibited, resulting in all cases in three dimension assemblies. In 1 5, interlayer contacts between the carboxylic acid R-2(2)(8) dimers in rows, with differing sets of weaker C-H center dot center dot center dot O and/or C-H center dot center dot center dot pi interactions, result in the formation of two-molecular wide columns and/ or infinite sheets. While column and sheet sub structures can also be designated in compound 6, on linking the carboxylic acid groups with other substituents via C-H center dot center dot center dot O, C-H center dot center dot center dot pi and C-H center dot center dot center dot pi interactions, these differ from those in 1-5 due to the different arrangements of the CO2H groups.