Multiple-Quantum NMR Spectra of Partially Oriented Indene: A New Approach to Estimating Order in a Nematic Phase

Abstract

Multiple-quantum proton NMR spectra of the 8-spin system of indene partially oriented in a nematic mesophase were acquired using a magnetic field gradient (MFG) method. Six-, seven- and eight-quantum spectra were solved to yield all intramolecular dipolar couplings (Dij) which were used to determine the molecular shape. The spectral widths of multiple-quantum spectra are dependent on molecular orientation and geometry and a novel method was developed to estimate the Saupe order parameters from the observed spectral widths of the high-order multiple-quantum spectra.