Formation kinetics of europium(III) complexes of DOTA and its bis(phosphonate) bearing analogs

Lanthanide(III) complexes with tridentate Schiff base ligand, antioxidant activity and X-ray crystal structures of the Nd(III) and Sm(III) complexes

“…The analyses for carbon, hydrogen and nitrogen were carried out using a LECO CHNS-932 instrument. 1 H and 13 C spectra of the compounds were recorded in DMSO-d 6 with TMS as internal reference on a Bruker Advance operating at 250 MHz. The IR spectra were recorded as KBr discs on a Bruker IFS-66 V spectrophotometer (4000-400 cm -1 ).…”

“…[1][2][3] The intriguing structures [4][5][6] and the potential uses in a wide variety of areas as diagnostic tools in biology 7 catalysis, 8 luminescence 9 and magnetism 10 reinforce the interest of chemists in these areas of research. A few years ago our research group initiated a project concerning rare earth metal chemistry 11 in a search for unusual molecular materials.…”

DOTA analogues with a phosphinate-iminodiacetate pendant arm: modification of the complex formation rate with a strongly chelating pendant

“…The formation of the complexes of DOTA-like ligands is mostly described as a two-step process. [8][9][10][11][12][13][14][15][16][17] An out-of-cage complex (indicated in formulas below with superscript "oc") is swiftly formed in the first step. In the complex, donor atoms of the pendant arms are coordinated and two macrocyclic amines are protonated and the protons block the macrocyclic cavity.…”

“…Recently, we have shown that different types of the out-of-cage complexes are formed if ligand or metal ion excesses are used in the reaction of lanthanide(III) ions and H 4 dota. 14 With metal ion excess, the out-ofcage complex has the structure discussed above where oxygen atoms of four acetate pendant arms are bound together with some water molecules. However with the ligand excess, two ligand molecules are coordinated through their pendant arms to the metal ion in the out-of-cage complex.…”

“…The complexation of DOTA-like ligands is commonly described as a two-step process. [8][9][10][11][12][13][14] In the first step, the metal ion is swiftly coordinated by the pendant arm oxygen atoms forming an outof-cage complex. In such an intermediate, the macrocycle amino groups are protonated and the rate-determining step of the complexation is the deprotonation of the ring nitrogen atoms and the transfer of the metal ion into the central ligand cavity which results in the formation of an in-cage complex with the metal ion coordinated by the four nitrogen and four oxygen atoms.…”