Solution Dynamics and Stability of Lanthanide(III) (S)-2-(p-Nitrobenzyl)DOTA Complexes

• Published in: Inorganic chemistry Vol. 43; no. 9; pp. 2845 - 2851
• Main Authors: Woods, Mark, Kovacs, Zoltan, Kiraly, Robert, Brücher, Ernö, Zhang, Shanrong, Sherry, A. Dean
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03.05.2004
• Subjects: Chelating Agents - chemistry; Heterocyclic Compounds, 1-Ring - chemistry; Isomerism; Kinetics; Magnetic Resonance Spectroscopy; Metals, Rare Earth - chemistry; Molecular Structure; Solutions; Thermodynamics; Water - chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic0353007

Addition of a benzyl substituent to the macrocyclic ring of DOTA has a substantial impact on the conformational ring flipping motion of the macrocycle in the resulting LnDOTA complexes. The p-NO2-benzyl substituent in the Ln(p-NO2-Bn-DOTA)- complexes lies in an equatorial position and effectively “locks” the conformation of the ring into the δδδδ configuration. The presence of the p-NO2-benzyl group also increases the population of the square antiprismatic (SAP) coordination isomer for all Ln(p-NO2-Bn-DOTA)- complexes relative to that seen for the respective LnDOTA- complexes. Despite this increase in SAP isomer population, the rate of water exchange in these complexes remains comparatively fast. The kinetic and thermodynamic stabilities of the Ln(p-NO2-Bn-DOTA)- complexes are also slightly lower than the corresponding LnDOTA- complexes but appear to be sufficiently high for in vivo use.