A Comparison of 1D and 2D (Unbiased) Experimental Methods for Measuring CSA/DD Cross-Correlated Relaxation

✍ Scribed by Gy. Batta; K.E. Kövér; J. Kowalewski

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 130 KB
• Volume: 136
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1998.1620

✦ Synopsis

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 C 3v symmetry (CHCl 3 , 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 13 C (or other dilute, low ␥ 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 1 H and 13 C ( 29 Si) CSA data are presented for chloroform and TPSi.