Crystal structure and spectroscopic properties of the 1:1 complex of pyridine betaine with p-hydroxybenzoic acid

Crystal structure of the 1:1 complex of pyridine betaine (PyB) with p-hydroxybenzoic acid (HBA) has been determined by X-ray diffraction. The crystals are monoclinic, space group P2(1)/c with the unit cell parameters a = 11.9009(4), b = 10.3283(3), c = 11.0616(4) angstrom and beta = 104.252(4)degrees, Z = 4. R = 0.038. Both oxygen atoms of the carboxylate group of PyB are linked with the carboxylic and hydroxyl groups of HBA of the neighboring molecules, through two O-H center dot center dot center dot O hydrogen bonds of 2.589(1) and 2.588(2) angstrom, respectively. The PyB and HBA molecules are connected into infinite chains parallel to the x-axis. The FTIR spectrum of the solid complex is consistent with the X-ray results. H-1 and C-13 chemical shifts of the title complex in D2O and DMSO-d(6) and the GIAO/B3LYP/6-31G(d,p) calculated magnetic isotropic shielding tensors ((T) using the screening solvation model (COSMO),delta(exp) = a + b sigma, are reported. In the theoretically optimized Structures of the complex investigated the O center dot center dot center dot O distances between PyB and HBA are not the same. (c) 2009 Elsevier B.V. All rights reserved.