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United States Department of Agriculture

Agricultural Research Service

Title: Application of Raman Spectroscopy to Analysis of Interactions Between Enantiomers

Authors
item Schmidt, Walter
item Jayasundera, Shalini - UNIV MD
item Adar, Fran - JOBIN YVON HORIBA

Submitted to: Annual Experimental Nuclear Magnetic Resonance Conference
Publication Type: Abstract Only
Publication Acceptance Date: December 30, 2000
Publication Date: N/A

Technical Abstract: Detailed interactions between molecular functional groups are known to control bio-activity and environmental fate. The specificity and activity of molecules containing chiral centers markedly change with conformation and configuration. Vibrational spectra obtained using Raman instrumentation include large amounts of structural information, but the bands are often difficult to assign to specific particular functional groups. Identifying the specific sites at which the largest vibrational interactions occur helps reveal important mechanisms essential for the specificity and selectivity in molecule-molecule interactions. Mixtures of L-Aspartic acid (L-Asp) and D-Aspartic acid (D-Asp) can serve as less complicated model compounds to better understand the structural basis behind interactions between and among chiral sites. Two molecules of L-Asp form dimers apparently as the zwitter ion pairs; correspondingly, L-Asp forms dimers with D-Asp. In the solid state at a ratio of 3/1, both L/L and L/D dimers form, but the packing is nearly the same for the L/L dimer. Although one D-Asp molecule of four Asp molecules does not significantly alter the crystal lattice packing, two D-Asp molecules in four Asp molecules do. Identifying the structural criteria for such conformational changes from Raman spectral data is essential for interpreting similar conformational changes in more complicated molecules.

Last Modified: 8/21/2014
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