image: Time-step VCD measured monitoring in situ the progress of chirality amplification from microscopic to supramolecular scales.
Vibrational circular dichroism (VCD) spectroscopy is an extension of circular dichroism spectroscopy into the infrared and near-infrared regions where vibrational transitions occur in the ground electronic state of a molecule. The method offers the advantage of studying the chiroptical properties of a wide range of molecules in non-crystalline states. However, due to the weakness of the signals, one measurement requires several hours to yield reliable results. Accordingly, its target was limited to a stable molecule in a solution. To overcome this difficulty, our group applied the VCD method to supramolecular systems. In this article, we report a new horizon for VCD spectroscopy. Solid state and time-step VCD methods were developed in determining the mechanism of chirality amplification from the microscopic to supramolecular scales. The VCD signals were enhanced in the following three cases: (i) chiral gels with hundreds of molecules arranged in stereoregularity, (ii) chiral metal complexes with low-lying excited states in the IR region, and (iii) a molecular pair interacting stereoselectively on a solid surface. Finally, we describe an on-going project involving the construction of a multi-dimensional VCD system.