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 (1g) 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 (1g) production in air saturated acetonitrile solutions. Depending on the nature of the Re(I) complex, the excited state responsible for the generation of 1O2 (1g) is either metal-to-ligand charge transfer (3MLCT) or a ligand centered (3LC) excited state. With LS-CO2-Re(CO)3(bpy) complexes, 1O2 (1g) 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 (1g) mainly by oxygen quenching of their 3MLCT luminescence with an efficiency of 1O2 (1g) 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.