INIFTA   05425
INSTITUTO DE INVESTIGACIONES FISICO-QUIMICAS TEORICAS Y APLICADAS
Unidad Ejecutora - UE
capítulos de libros
Título:
PHOTOSENSITIZED GENERATION OF SINGLET OXYGEN FROM RE(I) COMPLEXES
Autor/es:
EZEQUIEL WOLCAN
Libro:
Advances in Chemistry Research. Volume 28
Editorial:
NOVA Publishers
Referencias:
Lugar: Nueva York; Año: 2015; p. 231 - 240
Resumen:
In this chapter we give a review of quantum yields of 1O2 (1g) production for a number of Re(I) complexes. Examples found in the literature includes Re(I) tricarbonyl [N,N-bis(quinolin-2-ylmethyl)-amino]-4-butane-1-amine and Re(I) tricarbonyl [N,N-bis(quinolin-2-ylmethyl)amino]-5-valeric acid, i.e. [Re(CO)3(Q-NH2)+] and [Re(CO)3(Q-VA)+], as photodynamic therapy photosensitizers, as well as the tricarbonyl Re(CO)3(phen)CN, and two tetracarbonyl, i.e. [Re(phen)(CO)4+] and Re(bzq)(CO)4 complexes. In particular, [Re(CO)3(Q-NH2)+] and [Re(CO)3(Q-VA)+] proved to be excellent singlet oxygen generators in a lipophilic environment with quantum yields of about 0.75 while Re(phen)CN(CO)3, [Re(phen)(CO)4+] and Re(bzq)(CO)4 showed singlet oxygen efficiencies between 0.50 and 0.70 in acetonitrile media. On the other hand, we have probed two different classes of Re(I) complexes, i.e. LS-CO2-Re(CO)3(bpy) (LS = 2-pyrazine, 2-naphthalene, 9-anthracene, 1-pyrene, 2-anthraquinone) and XRe(CO)3L (X=CF3SO3, py, Cl ; L = bpy, phen or Bathocuproinedisulfonate), as photosensitizers for 1O2 (1g) production in air saturated acetonitrile solutions. Depending on the nature of the Re(I) complex, the excited state responsible for the generation of 1O2 (1g) is either metal-to-ligand charge transfer (3MLCT) or a ligand centered (3LC) excited state. With LS-CO2-Re(CO)3(bpy) complexes, 1O2 (1g) is produced from oxygen quenching of 3LC states of anthracene and pyrene with high quantum yields (Δ between 0.8 and 1.0), while the complexes bearing the ligands LS = 2-anthraquinone, 2-pyrazine and 2-naphthalene did not yield 1O2. XRe(CO)3L complexes generate 1O2 (1g) mainly by oxygen quenching of their 3MLCT luminescence with an efficiency of 1O2 (1g) formation close to unity. Bimolecular rate constants for the quenching of the XRe(CO)3L complexes emission by molecular oxygen range between 1 and 2.5x109 M-1s-1.