Skip to main content
. 2021 Oct 18;64(20):15250–15261. doi: 10.1021/acs.jmedchem.1c01286

Figure 4.

Figure 4

1H NMRD profiles showing the millimolar relaxivity per gadolinium r1p of Gd-TESMA (2.3 mM, solid symbols) and Gd4-TESMA (1.3 mM, open symbols) in the HEPES buffer (pH 7.2) at 298 K (circles) and 310 K (squares). The solid line represents the best fitting of the experimental points at 310 K to the SBM and Freed theory of paramagnetic relaxation. The following parameters were kept fixed: water diffusion coefficient (D) = 3.1 10–5 cm2 s–1; distance between Gd(III) and the inner sphere water protons (r) = 3.1 Å; number of inner sphere water molecules (q) = 1; and distance of the closest approach of outer-sphere water protons = 3.8 Å. Curve fitting converged to the following: correlation time for molecular reorientation (τR) = 170 ps; residence lifetime of the inner sphere water molecule (τM) = 460 ns; correlation time for electronic relaxation (τv) = 47 ps; and zero-field splitting energy (Δ2) = 1.3 1019 s–2.