Spectroscopic studies, molecular structure and hydrogen bonding in hydrates of Gemini betaines

In the present study, two flexible Gemini betaines are synthesized. N,N'-dicarboxymethyl-N,N,N',N'-tetramethyL-1,3-propanediammonium trihydrate (1) and N,N'-dicarboxymethyl-N,N,N',N'-tetramethylethylenediammonium dihydrate (2). The effect of water molecules on the structure, conformation and hydrogen bonds of the Gemini compounds in solid state and solutions were studied by FTIR, H-1 and C-13 NMR spectra and B3LYP calculations and compared with results of X-ray diffraction. The screening constants for C-13 and H-1 atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. Linear correlations between the experimental H-1 and C-13 chemical shifts and the computed screening constants confirm the optimized geometry. The optimized bond lengths, bond angles and torsion angles calculated by B3LYP/6-31G(d,p) approach have been compared with the X-ray data. A force field calculation was performed on the minimum energy geometry. Vibrational wavenumbers and infrared intensities was predicted. (C) 2010 Elsevier B.V. All rights reserved.