Unexpected drastic decrease in the excited-state electronic communication between porphyrin chromophores covalently linked by a palladium(II) bridge.
Chemistry
; 20(40): 12988-3001, 2014 Sep 26.
Article
en En
| MEDLINE
| ID: mdl-25123591
ABSTRACT
A dyad built up of a zinc(II) porphyrin and the corresponding free base, [Zn-Fb], fused to N-heterocyclic carbene (NHCs) ligands, respectively acting as singlet energy donor and acceptor, and a bridging trans-PdI2 unit, along with the corresponding [Zn-Zn] and [Fb-Fb] dimers were prepared and investigated by absorption and emission spectroscopy and density functional computations. Despite favorable structural and spectroscopic parameters, unexpectedly slow singlet energy transfer rates are measured in comparison with the predicted values by the Förster theory and those observed for other structurally related dyads. This observation is rationalized by the lack of large molecular orbital (MO) overlaps between the frontier MOs of the donor and acceptor, thus preventing a double electron exchange through the trans-PdI2 bridge, and by an electronic shielding induced by the presence of this same linker preventing the two chromophores to fully interact via their transition dipoles.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Paladio
/
Zinc
/
Metaloporfirinas
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Chemistry
Asunto de la revista:
QUIMICA
Año:
2014
Tipo del documento:
Article