Nanodimentional thermometric NMR sensors on the basis of double-decker paramagnetic lantanide(III) complexes with porphyrins for solution temperature measurements

Abstract

Earlier temperature dependencies of NMR spectra of asymmetric double-decker complexes of [LnH(oep)(tpp)], where Ln is Yb, Dy and Lu, tpp is tetraphenylporphyrin, and oep is octaethylporphyrin, have been analyzed by us [Babailov S.P., Coutsolelos A.G., Dikiy A., Spyroulias G.A., Eur. J. Inorg. Chem. 2001, 1, 303-306]. The NMR signal assignment has been done by 1D NOE as well as on 2D NOESY, ROESY, TOECSY and COSY experiments. The kinetic and thermodynamic parameters for intramolecular phenyl ring rotations have been determined by dynamic NMR. The results obtained using pseudo-contact shifts and lanthanide-induced enhancement of longitudinal relaxation rates experienced by some protons of paramagnetic [DyH(oep)(tpp)] and [YbH(oep)(tpp)] revealed that the structure of the complexes are very similar, with only slight decrease in distance between the planes of porphyrin ligands upon increase in the atomic number of the lanthanide ions. This result has been interpreted as being due to lanthanide contraction. Nevertheless, paramagnetic properties of these complexes were investigated insufficiently. In the paper the 1H NMR method is used to study the features of paramagnetic properties of complexes [DyH(oep)(tpp)]. The temperature dependencies of the lanthanide-induced shifts in NMR spectra of asymmetric double-decker complexes of [DyH(oep) (tpp)] are analyzed. The obtained results indicate that complexes [DyH(oep)(tpp)] are promising compounds as in situ NMR thermosensors for temperature determination in solution. © ISUCT Publishing.