More generally, hydrogen bonding has been used to control the supramolecular assembly of a huge range of organic building blocks, most commonly using carboxylic acid groups. The study of hydrogen bonded nets can be traced back to 1969, when Duchamp et al. reported the 'α-polymorph' of trimesic acid (TMA; Fig. ), which comprises triply interlocked pleated hexagonal networks of TMA molecules. Seventeen years later, Herbstein reported the first non-catenated hexagonally arranged networks of TMA, which were stabilized in an offset arrangement by disordered alkane guests. Herbstein also showed that TMA can be crystallized from the vapor, by condensation onto a cold surface, to produce a γ-polymorph, which was recently shown to adsorb acetic acid reversibly after activation. Zaworotko reported a 2:1 TMA:acetic acid solvate, which features triply inclined interpenetration between truncated 1D and hexagonal 2D nets. The 2-D ordering of TMA on metal surfaces has also been investigated, and TMA is an archetypal ligand for MOF synthesis (e.g., HKUST-1). As such, TMA has been widely studied by the crystal engineering community for decades. The continued fascination with this molecule results from the complexity of its solid form landscape and the large number of competing structures that can be produced.