NMR thermosensing properties on binuclear triple-decker complexes of terbium(III) and dysprosium(III) with 15-crown-5-phthalocyanine

• Trisphthalocyaninates of lanthanides as temperature sensors (303–323 K). • Analysis of the lanthanide-induced chemical shifts and relaxation data. • Terbium complex has the highest sensitivity among the published in organic media. • NMR determination of local temperature in aqueous media. In this paper, we have firstly demonstrated the thermosensing properties of binuclear triple-decker terbium(III) and dysprosium(III) complexes with 15-crown-5-phthalocyanine Tb 2 [(15C5) 4 Pc] 3 ( I ) and Dy 2 [(15C5) 4 Pc] 3 ( II ) in the physiological temperature range (303–323 K). Measuring the LIS values for I and II in CDCl 3 has revealed high temperature sensitivity for the signals of the aromatic protons of the inner deck of the complexes: ∂ δ/ ∂ T = 1.1 and 0.55 ppm/K for I and II , respectively. Terbium-containing complex I has the highest sensitivity of the LIS among the published complexes of 4f and d elements with polydentate ligands in organic media. A significant impact of the Curie-spin contribution to the paramagnetic spin–spin relaxation rate enhancement has been found, which has a pronounced temperature dependence. The results obtained for kinetically and thermodynamically stable Ln 2 [(15C5) 4 Pc] 3 complexes allow one to consider them pronounced NMR thermosensors in nonpolar solutions. The possibility of the solubilization of complex I in aqueous media due to the presence of crown ether moieties has been also demonstrated.