Relaxometry, Luminescence Measurement, Electrophoresis, and Animal Biodistribution of Lanthanide(III) Complexes of Some Polyaza Macrocyclic Acetates Containing Pyridine

Complexation Properties of N,N′,N″,N′′′‐[1,4,7,10‐Tetraazacyclododecane‐1,4,7,10‐tetrayltetrakis(1‐oxoethane‐2,1‐diyl)]tetrakis[glycine] (H4dotagl). Equilibrium, Kinetic, and Relaxation Behavior of the Lanthanide(III) Complexes

“…It seems that a ring N-atoms cannot act as an anchor N-atom, likely due to the rigid structure of the macrocycle. Similarly to [Cu(dotagl) [21]. The relaxivities of [Gd(dotagl)] are constant in the pH range 5 ± 9.…”

Impact of rigidification on relaxometric properties of a tricyclic tetraazatriacetic gadolinium chelate

“…Although PCTA12 is a heptadentate macrocyclic ligand, its gadolinium complex is characterized by a high thermodynamic stability (logK Gd 3þ ¼ 20.8) (25). Consequently, the decrease in denticity allowing the presence of two inner-sphere molecules in the Gd-PCTA12 scaffold results in a sufficient stability to avoid the toxicity of free gadolinium in vivo, considering that for gadolinium chelates used in clinical practice a thermodynamic stability constant of 10 17 appears to be a minimum requirement (26). It therefore appeared that the PCTA12 scaffold may be of interest in finding more effective derivatives.…”

“…The residence lifetime of the inner-sphere water molecules, t M , was determined by analysis of the transverse relaxation rate of the oxygen-17 NMR water signal assuming two inner-sphere molecules for both Gd-PCTA12 and Gd-cyclo-PCTA12 as both corresponding ligands are heptadentate. Unfortunately, this assumption could not be checked by luminescence lifetime measurement of europium and terbium complexes (26)(27)(28) owing to the small quantities of cyclo-PCTA12 ligand obtained after a fairly long and time-consuming chemical synthesis (29). The fitted value of t M obtained by oxygen-17 NMR for Gd-PCTA12 (82 ns at 310 K, i.e.…”

Solid‐State and Solution Structure of Lanthanide(III) Complexes with a Flexible Py‐N6 Macrocyclic Ligand

“…The overall freeenergy variations have negative values in vacuo, and the values range from -88. 8 + complexes are observed in the solid state for Ln = Nd-Lu).…”

“…Pyridine-based macrocyclic ligands were also shown to bind efficiently Ln III ions, 12-membered rings bearing acetate or phosphonate pendant arms to yield very stable complexes. [8] Moreover, 18-membered hexaaza macrocycles such as L 1 (Scheme 1) derived from the condensation of 2,6-pyridinedicarbaldehyde or 2,6-diacetylpyridine and diamines provide a relatively large cavity that allows efficient complexation of lanthanide(III) ions. [9] This macrocyclic platform may be easily functionalized with pendant arms containing additional donor atoms, which allows the cation binding ability of the parent hexaaza macrocycle to be enhanced.…”