Effect of deuteration on hydrogen bonding: a comparative concentration dependent Raman and DFT study of pyridine in CH₃OH and CD₃OD and pyrimidine in H₂O and D₂O.
The relative effect of hydrogen bonding of pyrimidine (Pyr) in H(2)O/D(2)O and pyridine (Py) in CH(3)OH/CD(3)OD has been analyzed using Raman Difference Spectroscopic (RDS) technique and DFT calculations. This study is focused on analyzing the concentration dependent variation of linewidth, peak position and intensity of ring breathing mode of Py and Pyr. The ring breathing mode of Pyr in H(2)O and D(2)O has three components; due to free Pyr, lighter complexes of mPyr+nH(2)O/D(2)O and heavier complexes of mPyr+nH(2)O/D(2)O. The pyridine molecules, however, show only two components in CH(3)OH and CD(3)OD. Of these two components, one corresponds to free Py and the other inhomogeneously broadened profile corresponds to all mPy+nCH(3)OH/CD(3)OD complexes. The variation of peak position and linewidth establishes the role of dipole moment of complexes and the diffusion in the mixture. In case of CD(3)OD solution splitting was observed in ∼1030 cm(-1) band of Py, where an additional band at ∼1034 cm(-1) appears at x(Py) ≤ 0.4. However, this band remains single at all concentrations in case of CH(3)OH solvent.
Department of Physics, Banaras Hindu University, Varanasi 221 005, India.
Anurag
A
Singh
Debraj
D
Gangopadhyay
Jürgen
J
Popp
Ranjan K
RK
Singh
D003903:Deuterium / Q000737:chemistry*; D006860:Hydrogen Bonding; D000432:Methanol / Q000737:chemistry*; D008958:Models, Molecular; D011725:Pyridines / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D014867:Water / Q000737:chemistry*
D011725:Pyridines; D011743:Pyrimidines; D014867:Water; D003903:Deuterium; C030986:pyrimidine; C023666:pyridine; D000432:Methanol