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Reaction monitoring using mid-infrared laser-based vibrational circular dichroism

: Rüther, A.; Pfeifer, M.; Lórenz-fonfría, V.A.; Lüdeke, S.


Chirality 26 (2014), Nr.9, S.490-496
ISSN: 0899-0042
ISSN: 1520-636X
International Conference on Chiroptical Spectroscopy <14, 2013, Nashville/Tenn.>
Zeitschriftenaufsatz, Konferenzbeitrag
Fraunhofer IPM ()

Changes in vibrational circular dichroism (VCD) were recorded on-line during a chemical reaction. The chiral complex nickel-(-)-sparteine chloride was hydrolyzed to free (-)-sparteine base in a biphasic system of sodium hydroxide solution and chloroform (CHCl3). Infrared (IR) and VCD spectra were iteratively recorded after pumping a sample from the CHCl3 phase through a lab-built VCD spectrometer equipped with a tunable mid-IR quantum cascade laser light source, which allows for VCD measurements even in the presence of strongly absorbing backgrounds. Time-dependent VCD spectra were analyzed by singular value decomposition and global exponential fitting. Spectral features corresponding to the complex and free (-)-sparteine could be clearly identified in the fitted amplitude spectrum, which was associated with an exponential decay with an apparent time constant of 127 min (t1/2 = 88 min).