Fig. 2.

(a) Proton longitudinal relaxivity (20 °C, pH = 7.4) of biphenyl-functionalized cryptate 1 in the absence (○) and presence (□) of HSA as a function of magnetic field strength. (b) Proton longitudinal relaxivity (37 °C, pH = 7.4) of biphenyl-functionalized cryptate 1 in the absence (○) and presence (□) of HSA as a function of magnetic field strength. Simulated relaxivity values (■) of a slowly rotating Eu²⁺-containing complex at 37 °C. Values at 1.4, 3, 7, and 11.7 T without HSA are from reference 6. HSA concentration was 4.5% (w/v). Error bars represent standard error of the mean of 3–9 independently prepared samples.