Structure of 6-hydroxy-1-methylquinolinium chloride hydrate studied by X-ray, DFT calculations, FTIR and NMR spectroscopes

The crystal structure of 6-hydroxy-1-methylquinolinium chloride hydrate (1), 6QBWHCl, is monoclinic, space group P2(1)/n and Z = 4. 1-Methyl-6-oxyquinolinium betaine, 6QB, is protonated and its OH group participates in a moderate hydrogen bond with water molecule (O(1)-H center dot center dot center dot O(W1)= 2.636(2) angstrom). The water molecule is further connected by a hydrogen bond to chloride ion (O(W1)-H(W2)center dot center dot center dot Cl(1)= 3.090(3) angstrom). Structures of five complexes (2-6) have been optimized by the B3LYP/6-311G(d, p) level of theory and the results have been compared with the X-ray data of 1. Linear correlations between the experimental H-1 and C-13 NMR chemical shifts (delta(exp)) of complexes 2-5 and the magnetic isotropic shielding constants (sigma(cal)) calculated by the GIAO/B3LYP/6-311G(d, p) approach, using the screening solvation model (COSMO), delta(exp) = a + b sigma(cal), are reported. The probable assignments of the anharmonic experimental solid state vibrational frequencies of anhydrous complex, 6QBHCl, based on the calculated B3LYP/6-311G(d, p) harmonic frequencies have been proposed. (C) 2010 Elsevier B.V. All rights reserved.