Double Orthogonal Sample Design Scheme and Corresponding Basic Patterns in Two-Dimensional Correlation Spectra for Probing Subtle Spectral Variations Caused by Intermolecular Interactions

Abstract

This paper introduces a new approach named double orthogonal sample design scheme (DOSD) to probe intermolecular interactions based on a framework of two-dimensional (2D) correlated spectroscopy. In this approach, specifically designed concentration series are selected according to the mathematical analysis on orthogonal vectors to generate useful 2D correlated spectra. As a result, the interfering portion can be completely removed from both synchronous and asynchronous spectra, and complementary information concerning intermolecular interactions can be obtained from the set of 2D spectra. A model system, where intermolecular interactions occur between two solutes in a solution, is used to investigate the behavior of 2D correlated spectra generated by using the DOSD approach. Simulation results demonstrate that the resultant spectral patterns can reflect subtle spectral variation in bandwidths, peak positions, and absorptivities brought about by intermolecular interaction, which are hardly visualized in conventional 1D spectra because of the severe band-overlapping problem. The ability to reveal a subtle variation in a characteristic peak in detail by using the DOSD approach provides a new opportunity to understand the nature of intermolecular interactions from a molecular structural point of view. Intermolecular interactions between iodine and benzene in CCl(4) solutions were investigated by using the proposed DOSD approach to prove the applicability of the DOSD method in real chemical systems.