ORD accessory – MOS-500 – Spectroscopy – Application Note 11

Abstract

Optical Rotatory Dispersion (ORD) is closely related to Circular Dichroism (CD) and is used extensively in the characterization of chiral molecules. Instead of measuring the differential absorption of circularly polarized light as is the case with CD, ORD measures the wavelength dependence of rotation by a chiral molecule of plane-polarized light. In fact, it has been well established that when a sample is optically active near a chiral center, an anomalous ORD spectrum is obtained displaying a Cotton effect and the two spectra, CD and ORD, can be transformed into one another using the Kronig-Kramers relationship. This application note describes the use of the MOS 500 with an ORD accessory to obtain the CD, ORD, and absorption spectra of CSA (1S)-(+)-10-camphorsulphonic acid. Hardware reconfiguration is done within minutes and spectra can be obtained without the need to purge the optics down to 200 nm nitrogen purging because of the isolation of the optics from the light source eliminating the need to obtain yet another spectropolarimeter for the lab.

Introduction

Optical Rotation is used extensively in the quantification and characterization of chiral molecules (such as sugars and polymers) for many years [1,2]. Optical Rotation depends on the wavelength of the irradiating light. The wavelength dependence of the optical rotation is called Optical Rotatory Dispersion (ORD). The effect results in a rotation of the polarization plane of linearly polarized light after passing through a sample…

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