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-ete(2)H(+))(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 x 36.7 Angstrom 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 x 7.5 Angstrom 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.