Chiroptical spectroscopy exploring the interaction of matter with polarized light provides many tools for molecular structure and interaction studies. Here, some recent discoveries are reviewed, primarily in the field of vibrational optical activity. Technological advances results in the development of more sensitive vibrational circular dichroism (VCD), Raman optical activity (ROA) or circular polarized luminescence (CPL) spectrometers. Significant contributions to the field also come from the light scattering and electronic structure theories, and their implementation in computer systems. Finally, new chiroptical phenomena have been observed, such as enhanced circular dichroism of biopolymers (protein fibrils, nucleic acids), plasmonic and resonance chirality‐transfer ROA experiments. Some of them are not yet understood or attributed to instrumental artifacts so far. Nevertheless, these unknown territories also indicate the vast potential of the chiroptical spectroscopy, and their investigation is even more challenging.
Protein
fibrils are involved in a number of biological processes.
Because their structure is very complex and not completely understood,
different spectroscopic methods are used to monitor different aspects
of fibril structure. We have explored circularly polarized luminescence
(CPL) induced in lanthanide compounds to indicate fibril growth and
discriminate among fibril types. For hen egg-white lysozyme and polyglutamic
acid-specific CPL, spectral patterns were obtained and could be correlated
with vibrational circular dichroism (VCD) spectra and thioflavin T
fluorescence. The CPL spectra were measured on a Raman optical activity
spectrometer, and its various polarization modes are discussed. The
experiments indicate that the induced CPL is sensitive to more local
aspects of the fibril structure than VCD. For CPL, smaller amounts
of the sample are required for the analysis, and thus this method
appears to be a good candidate for future spectroscopic characterization
of these peptide and protein aggregates.
Vibrational circular dichroism (VCD) spectroscopy has been widely used to study (bio)molecules in solution. However, its solid-state applications have been restricted due to experimental limitations and artifacts. Having overcome some of them, the first VCD study of nucleoside crystals is now presented. A two-orders-of-magnitude enhancement of VCD signal was observed due to high molecular order in the crystals and resulting supramolecular chirality. This allowed to obtain high-quality VCD spectra within minutes using minute amounts of samples. The VCD technique is extremely sensitive in detecting changes in a crystal order and is able to distinguish different hydration states of crystals. This elevates it to a new level, as a fast and efficient tool to study chiral crystalline samples. This study demonstrates that VCD is capable of near-instantaneous detection of hydration polymorphs and crystal degradation, which is of substantial interest in pharmaceutical industry (quality and stability control).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.