RESUMO
A new magnetic resonance imaging (MRI) contrast agent based on the trimetallic nitride templated (TNT) metallofullerene Gd(3)N@C(80) was synthesized by a facile method in high yield. The observed longitudinal and transverse relaxivities r(1) and r(2) for water hydrogens in the presence of the water-soluble gadofullerene 2 Gd(3)N@C(80)(OH)(approximately 26)(CH(2)CH(2)COOM)(approximately 16) (M = Na or H) are 207 and 282 mM(-1) s(-1) (per C(80) cage) at 2.4 T, respectively; these values are 50 times larger than those of Gd(3+) poly(aminocarboxylate) complexes, such as commercial Omniscan and Magnevist. This high (1)H relaxivity for this new hydroxylated and carboxylated gadofullerene derivative provides high signal enhancement at significantly lower Gd concentration as demonstrated by in vitro and in vivo MRI studies. Dynamic light scattering data reveal a unimodal size distribution with an average hydrodynamic radius of ca. 78 nm in pure water (pH = 7), which is significantly different from other hydroxylated or carboxylated fullerene and metallofullerene derivatives reported to date. Agarose gel infusion results indicate that the gadofullerene 2 displayed diffusion properties different from those of commercial Omniscan and those of PEG5000 modified Gd(3)N@C(80). The reactive carboxyl functionality present on this highly efficient contrast agent may also serve as a precursor for biomarker tissue-targeting purposes.
Assuntos
Meios de Contraste/síntese química , Fulerenos/química , Gadolínio/química , Compostos Organometálicos/síntese química , Prótons , Animais , Meios de Contraste/química , Difusão , Feminino , Glioma/diagnóstico , Humanos , Imageamento por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Compostos Organometálicos/química , Peróxidos/química , Ratos , Solubilidade , Água/químicaRESUMO
Photochemically generated benzyl radicals react with Sc(3)N@C(80)-I(h) to produce a dibenzyl adduct [Sc(3)N@C(80)(CH(2)C(6)H(5))(2)] in 82% yield and high regioselectivity. The adduct's (1)H spectrum revealed high symmetry: only one AB pattern was observed for the methylene protons. The (13)C NMR spectrum suggested a C(2)-symmetrical structure. DFT calculations reveal that a 1,4-adduct is more favorable than a 1,2-adduct by >10 kcal/mol. The 1,4-structure on [566] ring junctions was unambiguously confirmed by X-ray crystallographic analysis. UV-vis spectra revealed that the removal of two p orbitals from the pi system of the cage together with the benzylic substituents change the electronic properties of the metallofullerene in a manner similar to those reported for disilirane and trifluoromethyl moieties. Under the same conditions from Lu(3)N@C(80)-I(h) we prepared (63% yield) Lu(3)N@C(80)(CH(2)C(6)H(5))(2), which demonstrated properties similar to the 1,4-dibenzyl adduct of Sc(3)N@C(80)-I(h).
Assuntos
Fulerenos/química , Lutécio/química , Compostos de Nitrogênio/química , Compostos Organometálicos/química , Escândio/química , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Processos Fotoquímicos , Espectrofotometria Ultravioleta , Especificidade por SubstratoAssuntos
Fulerenos/química , Hidrocarbonetos Cíclicos/síntese química , Compostos de Nitrogênio/síntese química , Escândio/química , Ciclopropanos/química , Hidrocarbonetos Cíclicos/química , Imageamento por Ressonância Magnética/métodos , Malonatos/química , Modelos Moleculares , Compostos de Nitrogênio/química , Compostos Organometálicos/síntese química , Compostos Organometálicos/químicaRESUMO
Two new 6,6-open phenyl-C(81)-butyric acid methyl ester metallofulleroids, M(3)N@C(80)PCBM (M = Sc, Y), were synthesized by diazoalkane addition reactions and fully characterized. The results demonstrate that the reactive sites are the same for M(3)N@C(80) (M = Sc, Y) but dramatically different from that of C(60).
Assuntos
Compostos Organometálicos/síntese química , Escândio/química , Ítrio/química , Ésteres , Fulerenos/química , Estrutura Molecular , Compostos Organometálicos/químicaRESUMO
This research represents initial functionalization of a Gd3N@C80 metallic nitride fullerene (MNF). Results demonstrate that a bisadduct can be prepared in an isolable yield for this MRI precursor MNF. This Gd3N@C80 bisadduct is synthesized and purified, and preliminary characterization is reported. This is a significant finding as, to date, only MNF monoadducts have been purified.