Distinctly different wide-waveband infrared spectra of commercial rare L-fructose and common D-fructose

High-precision mid-infrared (mid-IR, 4000–400 cm–1) and far-infrared (far-IR, 400–40 cm–1) spectra of the name-suggested chiral enantiomers C6H12O6, —namely the rare sugar L-fructose and the common sugar D-fructose, were measured and studied. To the best of our knowledge, this is the first reported IR spectrum of rare L-fructose, and it shows that the most characteristic normal vibration modes of the L-fructose have corresponding values that are identical or nearly identical to, those of D-fructose. The apparent and intrinsic wavenumber differences, especially in the functional group region, may serve as starting points when using the high-precision IR spectroscopy technology as a simple tool for chiral recognition of enantiomeric D- and L-fructose.