铝和镓叶啉的基态和激发态动力学。
Ground- and excited-state dynamics of aluminum and gallium corroles.
机构信息
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, Canada.
出版信息
Inorg Chem. 2009 Mar 16;48(6):2670-6. doi: 10.1021/ic900056n.
The steady-state absorption and emission spectra and the temporal fluorescence decay profiles of two metallocorroles, Al(tpfc)(py)(n) and Ga(tpfc)(py)(n) (n = 1,2), have been measured in a noncoordinating solvent, benzene, in a coordinating solvent, pyridine, and in mixed benzene-pyridine solutions. The ground-state spectra reveal that an equilibrium between the pentacoordinate corrole (n = 1) and the hexacoordinate corrole (n = 2) is established in the mixed benzene-pyridine solutions. The ground-state equilibrium constants are 135 M(-1) and 1.0 M(-1) at 295 K for the Al and Ga species, respectively. The excited-state radiative and nonradiative decay constants of the pentacoordinate and the hexacoordinate species have been obtained from measurements of the fluorescence quantum yields and monoexponential fluorescence decay times in pure benzene and pure pyridine. Temporal fluorescence decays of the gallium system in a mixed benzene-pyridine solution are biexponential due to dissociation of the hexacoordinate species in the excited state leading to the establishment of a dissociation-association equilibrium. The rate constants for the pyridine association and dissociation processes for the gallium corrole in the excited state have been measured, k(a)* = 2.3 x 10(8) M(-1) s(-1) and k(d)* = 2.9 x 10(8) s(-1), respectively, leading to a value for the excited-state association equilibrium constant of K(a)* = 0.78 M(-1).
在非配位溶剂苯、配位溶剂吡啶以及混合的苯-吡啶溶液中,测量了两种金属卟啉,Al(tpfc)(py)(n)和 Ga(tpfc)(py)(n)(n = 1,2)的稳态吸收和发射光谱以及瞬态荧光衰减曲线。基态光谱表明,在混合的苯-吡啶溶液中,五配位卟啉(n = 1)和六配位卟啉(n = 2)之间达到了平衡。在 295 K 时,Al 和 Ga 物种的基态平衡常数分别为 135 M(-1)和 1.0 M(-1)。从纯苯和纯吡啶中荧光量子产率和单指数荧光衰减时间的测量中,获得了五配位和六配位物种的激发态辐射和非辐射衰减常数。由于激发态中六配位物种的解离导致形成解离-缔合平衡,因此在混合的苯-吡啶溶液中,镓体系的瞬态荧光衰减呈双指数衰减。已经测量了处于激发态的镓卟啉的吡啶缔合和解离过程的速率常数,k(a)* = 2.3 x 10(8) M(-1) s(-1)和 k(d)* = 2.9 x 10(8) s(-1),导致激发态缔合平衡常数 K(a)* = 0.78 M(-1)。