Lanthanide Complexes as NMR Paramagnetic Probes for Fast Molecular Dynamics and Relaxation Contrast Reagents for in Situ Control of Temperature

Abstract

Studies of the paramagnetic lanthanide-induced shifts and relaxation rate enhancements (RRE) in NMR spectra allow to gain quantitative information about the molecular structure as well as the kinetic and thermodynamic stability of paramagnetic complexes in solutions. Several types of molecular dynamics were found by the dynamic NMR in the complexes investigated (e.g. interconversion of complex enantiomeric forms, pseudorotation of a macrocycle molecule, macrocycle molecule inversion and exchange of ligands). Valuable dependence of RRE of lanthanide complexes on the temperature was found. We found experimentally by the paramagnetic NMR that Ln complexes are quite appropriate nano-sized probes for in situ temperature determination in solutions.