A method based on the DAOSD approach to estimate the variation of the peak position and bandwidth caused by intermolecular interactions

Subtle spectral variations caused by intermolecular interactions, which are hardly observed in the original one-dimensional spectra or the second derivative spectra, can be distinctly visualized via spectral patterns in two-dimensional spectra generated by using double asynchronous orthogonal sample designed scheme (DAOSD). If intermolecular interaction only brings about band-shift on a characteristic peak, a pair of cross peaks appears in the corresponding near diagonal region. If intermolecular interaction induces variation of bandwidth only, a cluster of cross peaks forms a diamond pattern in the near diagonal region. In both cases, the variation of peak position or bandwidth can be deduced quantitatively from the pattern of cross peaks. If intermolecular interaction causes variations on both peak position and bandwidth, four cross peaks form a butterfly pattern. In this case, however, it is not straightforward to estimate the variation of peak position and bandwidth directly from the patterns of the cross peaks. In this paper, we propose an algorithm to estimate the variations of peak position and bandwidth of a characteristic peak caused by intermolecular interactions. The validity of this approach was confirmed by computer simulation on several model systems.