title: A new metallostar complex based on an aluminum(III) 8-hydroxyquinoline core as a potential bimodal contrast agent.
abstract: A ditopic DTPA monoamide derivative containing an 8-hydroxyquinoline moiety was synthesized and the corresponding gadolinium(III) complex ([Gd(H5)(H(2)O)](-)) was prepared. After adding aluminum(III), the 8-hydroxyquinoline part self-assembled into a heteropolymetallic triscomplex [(Gd5)(3)Al(H(2)O)(3)](3-). The magnetic and optical properties of this metallostar compound were investigated in order to classify it as a potential in vitro bimodal contrast agent. The proton nuclear magnetic relaxation dispersion measurements indicated that the relaxivity r(1) of [Gd(H5)(H(2)O)](-) and [(Gd5)(3)Al(H(2)O)(3)](3-) at 20 MHz and 310 K equaled 6.17 s(-1) mM(-1) and 10.9 s(-1) mM(-1) per Gd(III) ion respectively. This corresponds to a relaxivity value of 32.7 s(-1) mM(-1) for the supramolecular complex containing three Gd(III) ions. The high relaxivity value is prominently caused by an increase of the rotational tumbling time τ(R) by a factor of 2.7 and 5.5 respectively, in comparison with the commercially used MRI contrast agent Gd(III)-DTPA (Magnevist®). Furthermore, upon UV irradiation, [(Gd5)(3)Al(H(2)O)(3)](3-) exposes green broad-band emission with a maximum at 543 nm. Regarding the high relaxivity and the photophysical properties of the [(Gd5)(3)Al(H(2)O)(3)](3-) metallostar compound, it can be considered as a lead compound for in vitro bimodal applications.
authors: KU Leuven, Department of Chemistry, Celestijnenlaan 200F, B-3001 Heverlee, Belgium.
authors: Elke
authors: E
authors: Debroye
authors: Geert
authors: G
authors: Dehaen
authors: Svetlana V
authors: SV
authors: Eliseeva
authors: Sophie
authors: S
authors: Laurent
authors: Luce
authors: L
authors: Vander Elst
authors: Robert N
authors: RN
authors: Muller
authors: Koen
authors: K
authors: Binnemans
authors: Tatjana N
authors: TN
authors: Parac-Vogt
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D003287:Contrast Media / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry; D015125:Oxyquinoline / Q000737:chemistry*; D004369:Pentetic Acid / Q000737:chemistry
chemical_list: D003287:Contrast Media; D056831:Coordination Complexes; D015125:Oxyquinoline; D004369:Pentetic Acid; D005682:Gadolinium; D000535:Aluminum