Synthesis and Supramolecularity of Non-Centrosymmetric Proton Transfer Compound 2-Aminopyridinum Picolinoate

The proton-transfer compound 1 was prepared by mixing equimolar amounts of picolinic acid with 2-aminopyridine. Its crystal structure was determined by single-crystal X-ray diffraction. Compound 1 was ionic, with proton transfer occurring to the aromatic nitrogen of the 2-aminopyridine moiety. Supramolecular synthons including different motifs of hydrogen bonding, ion-pairing interactions, and non-centrosymmetric heteromer existed in the crystal structure were carefully investigated and presented in term of crystal engineering and host-guest chemistry. Compound 1 crystallizes in the space group P2(1)/n of the monoclinic system with unit cell parameters of: a = 8.7714(12) Å, b = 12.1579(17) Å, c = 10.8546(15) Å, with α = 90°, β = 110.100(4)°, and γ = 90°.