Distance measurements between 13C nuclei in singly labeled p-xylene/Dianin's inclusion compound by 2D-RFDR

Two-dimensional magnetization exchange experiments, with the radio-frequency-driven recoupling pulse sequence in the mixing time, have been performed for the detection of homonuclear 13C-13C distances between the singly 13C labeled methyl carbon of p-xylene and the natural abundant 13C nuclei of the host molecules in p-xylene/Dianin's complex. The intensities of the cross peaks between the methyl carbon and six host carbons were measured as function of the length of the mixing time and normalized by the intensities of their diagonal peaks. The results were compared with simulations based on the known distances in the complex. Good agreement was obtained, without taking the homonuclear zero-quantum linewidth (1/piTZQ2) into account. This can be understood by realizing that in this complex the 13C carbon pairs are significantly diluted.