2H QUOSY 2D-NMR Experiments in Weakly Aligning Systems: From the Conventional to the Ultrafast Approach

We describe three anisotropic ultrafast (UF) QUadrupolar Ordered SpectroscopY (QUOSY) 2D-NMR experiments (referred to as ADUF 2D NMR spectroscopy) designed for recording the ²H homonuclear 2D spectra of weakly aligned (deuterated) solutes in sub-second experiment times. These new ADUF 2D experiments derive from the Q-COSY, Q-resolved and Q-DQ 2D pulse sequences (J. Am. Chem. Soc. 1999 , 121, 5249) and allow the correlation between the two components of each quadrupolar doublet, and then their assignment on the basis of ²H chemical shifts. The UF 2D pulse sequences are analyzed by using the Cartesian spin-operator formalism for spin I=1 nuclei with a small quadrupolar moment. The optimal experimental/practical conditions as well as the resolution, sensitivity and quantification issues of these ADUF 2D experiments are discussed on comparison to their conventional 2D counterparts and their analytical potentialities. Illustrative ADUF 2D experiments using deuterated achiral/prochiral/chiral solutes in poly-γ-benzyl-L-glutamate based chiral liquid crystals are presented, as well as the first examples of natural abundance deuterium (ANADUF) 2D spectrum using 14.1 T magnetic field and a basic gradient unit (53 G.cm^?1) in oriented solvents.