Table 2.
System | r1p (mM−1 s−1) | Δ2 (s−2)[b] | τV (ps)[c] | τR (ps)[e] | |||
---|---|---|---|---|---|---|---|
Gd-DOTA-L6-(2Nal)2 | 1 mg/mL | 7.3 | 1.02 × 1019 | 50 | 184 | ||
25 mg/mL | 12.3 | 8.10 × 1018 | 43 | τR l | τR g | S2 | |
423 | 4800 | 0.23 | |||||
Gd-DOTA-L6-F2 | 1 mg/mL | 5.7 | 2.97 × 1019 | 28 | 120 | ||
25 mg/mL | 6.0 | 2.28 × 1019 | 35 | 127 |
[a]On carrying out the fitting procedure, some parameters were fixed to reasonable values: rGd-H (distance between Gd and protons of the inner sphere water molecule) = 3.1 Å; a (distance of minimum approach of solvent water molecules to Gd3+ ion) = 3.8 Å; D (solvent diffusion coefficient) = 2.2∙10−5 cm2 s−1. [b]Squared mean transient zero-field splitting (ZFS) energy. [c]Correlation time for the collision-related modulation of the ZFS Hamiltonian. [d]Electronic relaxation time at zero field (calculated as 1/τs0 = 12Δ2 × τv). [e]Reorientational correlation time.