RESUMO
A new route to luminescent derivatives of androgenic steroids containing a ketone group in the 3- or 17-position has been developed. Reaction with the fac-Re(CO)(3)Cl complex of 3,3'-diamino-2,2'-bipyridine (complex 1) afforded a cyclic aminal product with different steroids. The rate of reaction and yield varies according to the conjugation or steric hindrance around the ketone group.
Assuntos
Complexos de Coordenação/química , Rênio/química , Esteroides/química , 2,2'-Dipiridil/análogos & derivados , 2,2'-Dipiridil/síntese química , 2,2'-Dipiridil/química , Complexos de Coordenação/síntese química , Cristalografia por Raios X , Diaminas/síntese química , Diaminas/química , Cetonas/química , Conformação Molecular , Teoria Quântica , Espectrometria de FluorescênciaRESUMO
The formation of either dinuclear double-stranded or pentanuclear circular helicates from a ligand containing two tridentate domains separated by a phenylene unit can be controlled by inter-ligand steric interactions which themselves are governed by the size of the metal ion.
Assuntos
Metais Pesados/química , Compostos Organometálicos/síntese química , Cristalografia por Raios X , Ligantes , Substâncias Macromoleculares/síntese química , Substâncias Macromoleculares/química , Modelos Moleculares , Estrutura Molecular , Compostos Organometálicos/química , Tamanho da PartículaRESUMO
The potentially hexadentate ligand L, which contains two terminal coumarin fluorophores, forms dinuclear double-stranded helicates with dicationic metal ions, giving species of the generic form [M(2)L(2)](4+). In solution the free ligand was fluorescent with emission attributed to the coumarin fluorophores (lambda(em) = 437 nm). The luminescent properties of the corresponding dimetallic helicates complexes were examined and revealed that the Zn(2+) complex demonstrates enhanced emission when compared to the parent ligand, whereas Co(2+), Cu(2+), Cd(2+) and Hg(2+) induce varying degrees of fluorescence quenching. In particular, comparative luminescence measurements at 77 K and room temperature showed that the quenching mechanism for [Cu(2)L(2)](4+) can be attributed to a photoinduced electron transfer. ESI-MS selectivity studies showed that in the presence of a mixture of metal dications no preference for any one metal ion was observed.
RESUMO
Linking two isomeric tridentate N-chelates together produces a hetero-ditopic ligand capable of selectively binding Hg2+ and Zn2+ ions in a double-stranded helicate.