Lanthanide Paramagnetic Probes for NMR Spectroscopic Studies of Fast Molecular Conformational Dynamics and Temperature Control. 18-Crown-6 Intramolecular Reorientation in Complexes of Cerium(III) Chelates

By 1 Н dynamic NMR method the conformational reorientation of the 18-crown-6 ether molecules in [(Ce(ptfa) 3 ) 2 (18crown-6)] complexes has been experimentally studied in the CDCl 3 solution.The results of the present work demonstrate that there is a conformational dynamic processes in [(Ce(ptfa) 3 ) 2 (18-crown-6)] complex (with the activation free energy ∆G ‡ (320K) = 49 ± 4 kJ/mol ).It is conditioned by conformational reorientation of 18-crown-6 molecule.These complexes are promising to be subnanoscale NMR spectroscopic probes to determine the temperature in nonaqueous media.