A comparison of 1D and 2D (unbiased) experimental methods for measuring CSA/DD cross-correlated relaxation

Conventional and enhanced 1D experiments and different NOESY experiments (the 2D unbiased method) were performed for measuring CSA/DD cross-correlated relaxation on trehalose, a compound which could be approximated as a spherical top, and on simple model compounds comprising C3v symmetry (CHCl3, triphenylsilane (TPSi)). The comparison gives experimental evidence for the equivalence of the methods within the limits of the two-spin approach. 1D data are evaluated with both the simple initial rate and the Redfield relaxation matrix approach. The 2D data are obtained from the so-called transfer matrix using the Perrin-Gipe eigenvalue/eigenvector method. For the improved performance of the 2D method, an X-filtered (HHH) NOESY is suggested at the natural abundance of 13C (or other dilute, low gamma species). Also, experimental parameters crucial for reliable CSA data are tested (e. g., the impact of insufficient relaxation delay). Error estimation is carried out for fair comparison of methods. Revised liquid state 1H and 13C (29Si) CSA data are presented for chloroform and TPSi.