A benzimidazole functionalised DO3A chelator showing pH switchable coordination modes with lanthanide ions.
The synthesis of a new macrocyclic chelator incorporating a benzimidazole heterocycle is reported. Lanthanide complexes with macrocyclic chelators based on 1,4,7,10-tetra(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DOTA) and 1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO3A) are of interest in luminescent, radiopharmaceutical and magnetic resonance (MR) biomedical imaging applications. The benzimidazole DO3A chelator allows for sensitisation of europium(iii), terbium(iii) and ytterbium(iii) luminescence by the heterocycle and also shows a pH dependent coordination change due to protonation of the chelator (pKa = 4.1 for the europium(iii) complex). The thermodynamic stability of the complexes has been investigated by potentiometric titration with the gadolinium(iii) complex showing significantly higher stability than the zinc(ii) complex, where log βZnLH = 28.1 and log βGdLH = 32.1.
Department of Chemistry, The University of Hull, Cottingham Road, Hull, HU6 7RX, UK. s.j.archibald@hull.ac.uk.
Christopher M
CM
Fisher
Euan
E
Fuller
Benjamin P
BP
Burke
Vijetha
V
Mogilireddy
Simon J A
SJ
Pope
Amanda E
AE
Sparke
Isabelle
I
Déchamps-Olivier
Cyril
C
Cadiou
Françoise
F
Chuburu
Stephen
S
Faulkner
Stephen J
SJ
Archibald
D001562:Benzimidazoles / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D005063:Europium / Q000737:chemistry; D005682:Gadolinium / Q000737:chemistry; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D049449:Luminescence; D008279:Magnetic Resonance Imaging; D008956:Models, Chemical; D013725:Terbium / Q000737:chemistry; D013816:Thermodynamics; D015018:Ytterbium / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
C520644:1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid; D001562:Benzimidazoles; D002614:Chelating Agents; D056831:Coordination Complexes; D006573:Heterocyclic Compounds, 1-Ring; D028581:Lanthanoid Series Elements; D013725:Terbium; D005063:Europium; D005682:Gadolinium; C031000:benzimidazole; D015032:Zinc; D015018:Ytterbium