Coumarin-based luminescent ligand that forms helicates with dicationic metal ions.
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.
Bullock
Sam J
SJ
Department of Chemical and Biological Sciences, University of Huddersfield, Huddersfield HD1 3DH.
Felton
Cara E
CE
Fennessy
Rebecca V
RV
Harding
Lindsay P
LP
Andrews
Michael
M
Pope
Simon J A
SJ
Rice
Craig R
CR
Riis-Johannessen
T
T