title: Reaction monitoring using mid-infrared laser-based vibrational circular dichroism.
abstract: 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 (CHCl(3)). Infrared (IR) and VCD spectra were iteratively recorded after pumping a sample from the CHCl(3) 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 (t(½) = 88 min).
authors.affiliation: Institute of Pharmaceutical Sciences, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Rüther
authors.forename: Marcel
authors.initials: M
authors.lastname: Pfeifer
authors.forename: Víctor A
authors.initials: VA
authors.lastname: Lórenz-Fonfría
authors.forename: Steffen
authors.initials: S
authors.lastname: Lüdeke
mesh_terms: D002942:Circular Dichroism; D007834:Lasers; D014732:Vibration
keywords: flow-through setup; global exponential fitting; hydrolytic reaction; matrix least squares fitting; quantum cascade laser; time-resolved spectroscopy; vibrational circular dichroism