Crystal and molecular structure of DL-serine hydrochloride studied by X-ray diffraction, low-temperature Fourier transform infrared spectroscopy and DFT(B3LYP) calculations.
The structure of dl-serine.HCl was studied by three complementary techniques. Experimental Fourier transform infrared (FT-IR) spectra of pure NH/OH polycrystalline dl-serine.HCl [HO-CH2-CH(NH3+)-COOH.Cl(-)] and the respective deuterated derivatives [ND/ODAlcohol/Acid (<10% and ca. 60% D)] were recorded in the region 4000-400 cm(-1) in the temperature range 300-10 K and interpreted. The assignments were confirmed by comparison with the vibrational spectra of crystalline dl- and l-serine zwitterions [HO-CH 2-CH(NH3+)-COO(-)]. Further insight into the structure of the title compound was provided by theoretical DFT(B3LYP)/6-311++G(d,p) calculations of the infrared spectra and energies of 13 different conformers. Potential energy distributions resulting from normal co-ordinate analysis were calculated for the most stable conformer ( I) in its hydrogenated and deuterated modification. Frequencies of several vibrational modes were used in the estimation of enthalpies of individual H-bonds present in the crystal, using empirical correlations between enthalpy and the frequency shift that occurs as a result of the establishment of the H-bonds. X-ray crystallography data for dl-serine.HCl were recorded for the first time and, together with the experimental vibrational spectra and the theoretical calculations, allowed a detailed characterization of its molecular structure.
Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal. sjarmelo@qui.uc.pt
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S
Jarmelo
I
I
Reva
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M
Rozenberg
M Ramos
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Silva
A M Matos
AM
Beja
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R
Fausto
D018360:Crystallography, X-Ray; D011789:Quantum Theory; D012694:Serine / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014732:Vibration
D012694:Serine