[1] Because VCD is sensitive to the mutual orientation of distinct groups in a molecule, it provides three-dimensional structural information.
Among such quantum computations of VCD spectra resulting from the chiral properties of small organic molecules are those based on density functional theory (DFT) and gauge-including atomic orbitals (GIAO).
Measurements of vibrational optical activity (VOA) have thus numerous applications, not only for small molecules, but also for large and complex biopolymers such as muscle proteins (myosin, for example) and DNA.
The published reports over the last 22 years have established VCD as a powerful technique with improved results over those previously obtained by visible/UV circular dichroism (CD) or optical rotatory dispersion (ORD) for proteins and nucleic acids.
The effects due to solvent on stabilizing the structures (conformers and zwitterionic species) of amino acids and peptides and the corresponding effects seen in the vibrational circular dichroism (VCD) and Raman optical activity spectra (ROA) have been recently documented by a combined theoretical and experimental work on L-alanine and N-acetyl L-alanine N'-methylamide.
[17] VCD spectra of nucleotides, synthetic polynucleotides and several nucleic acids, including DNA, have been reported and assigned in terms of the type and number of helices present in A-, B-, and Z-DNA.
An example is that of a Bomem model MB-100 FTIR interferometer equipped with additional polarizing optics/ accessories needed for recording VCD spectra.
FT-VCD spectra accumulation of the selected sample solution is then carried out, digitized and stored by an in-line computer.