Further Understanding on the Measurement Methods for Solid-State Circular Dichroism Spectroscopy-Discussion on Concentration Effects

In this paper, the recent developments in measurement methods of solid-state circular dichroism (CD) spectroscopy were summarized and discussed, especially the effects of concentration on solid-state CD spectral distortions. By reinspection and introspection of the solid-state CD spectra of four reported compounds, concentration gradient measurements were proved to be necessary for appropriate concentrations, which are greatly related to the chiroptical properties. The thin film solid-state CD measurements of the inherently chiral atropisomer (S)-1,1'-bi-2-naphthol (S-BINOL) were carried out with concentration gradient measurements. Using this film-state technique for the first time, the results show some subtle correlations between the CD curves and the special concentrations.