Paramagnetic Proton Nuclear Spin Relaxation Theory of Low-Symmetry Complexes for Electron Spin Quantum NumberS=52

✍ Scribed by Erik Strandberg; P.-O. Westlund

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 137 KB
• Volume: 137
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1998.1696

✦ Synopsis

A generalization of the modified Solomon-Bloembergen-Morgan (MSBM) equations has been derived in order to describe paramagnetic relaxation enhancement (PRE) of paramagnetic complexes characterized by both a transient (⌬ t ZFS ) and a static (⌬ s ZFS ) zero-field splitting (ZFS) interaction. The new theory includes the effects of static ZFS, hyperfine coupling, and angular dependence and is presented for the case of electron spin quantum number S ‫؍‬ 5 2 , for example, Mn(II) and Fe(III) complexes. The model gives the difference from MSBM theory in terms of a correction term ␦ which is given in closed analytical form. The theory may be important in analyzing the PRE of proton spinlattice relaxation dispersion measurements (NMRD profiles) of low-symmetry aqua-metal complexes which are likely to be formed upon transition metal ions associated with charged molecular surfaces of biomacromolecules. The theory has been implemented with a computer program which calculates solvent water proton T 1 NMRD profiles using both MSBM and the new theory.