A second archetypal example is adamantane-1,3,5,7-tetracarboxylic acid (ADTA, Fig. ), which was reported in 1988 by Ermer to form a 5-fold interpenetrated diamondoid hydrogen-bonded net. Broadly speaking, the molecular assembly followed the intuitive design rules; that is, the tetrahedral node led to a 3-D diamondoid net. However the 5-fold interpenetration could (presumably) not have been predicted a priori, although an analysis of crystal density did show that a 5-fold form matched experiment (1.65 g cm -3 ), while a hypothetical non-interpenetrated diamondoid net was suggested to have a density of just 0.336 g cm - 3 . To modulate the interpenetration, Ermer later functionalized the adamantane core with dioxo or dimethylidene groups to sterically direct the formation of 3-fold and 2-fold interpenetrated networks, respectively. In this study, we use CSP calculations to uncover the underlying structural landscapes for carboxylic acid-bearing molecules, using the classic TMA and ADTA systems as examples. This introduces a new challenge: unlike the triptycene benzimidazalones in our previous study, which can be considered as rigid molecules with a single conformation, the carboxylic acids in TMA and ADTA can adopt different possible conformations that must be accounted for in the CSP search.