Cocrystals of 1,3,5-Cyclohexanetricarboxylic Acid with 4,4‘-Bipyridine Homologues: Acid···Pyridine Hydrogen Bonding in Neutral and Ionic Complexes

cis, cis -1,3,5-Cyclohexanetricarboxylic acid (H 3 CTA) is crystallized with bipyridine bases 1,2-bis(4-pyridyl)ethane (bipy-eta), 1,4-bis(4-pyridyl-2-ethyl)benzene (bipy-etabz), 1,2-bis(4-pyridyl)ethylene (bipy-ete), and 1,4-bis(2-(4-pyridyl)ethenyl)benzene (bipy-etebz) to afford molecular complexes (H 3 CTA)·(bipy-eta) 1.5 1, (H 3 CTA)·(bipy-etabz) 2, (H 2 CTA - )·(bipy-ete2H + ) 0.5 3, and (H 2 CTA - )·(bipy-etebz2H + ) 0.5 4 . Cocrystal 1 has a super honeycomb hydrogen bond network stabilized by carboxylic acid-bipyridine O−H···N synthon Va . The hexagonal cavity of 34.1 × 36.7 Å is filled by parallel triple interpenetration of independent networks. 2 has zigzag chains of synthon Va connected via O−H···O hydrogen bonds. Carboxylic acid to pyridine proton transfer occurs in 3 and 4 . These structures have undulated and flat 2D layers of O−H···O - and O−H···O hydrogen bonds that are connected to bipyridinium via N + −H···O - hydrogen bond Vb . H 2 CTA - anions in 4 form a porous parquet grid of 14.5 × 7.5 Å with the channels accommodating two molecules of bipy-etebz2H + . Supramolecular organization and 3D architecture in H 3 CTA crystal structures is compared with bipyridine adducts of trimesic acid.