Intra- and Intermolecular Photochemical Properties of Poly(amidoamine) Dendrons with an Anthracene at Focal Point
作者:Mamoru Fujitsuka、Osamu Ito、Yutaka Takaguchi、Tomoyuki Tajima、Kazuchika Ohta、Jiro Motoyoshiya、Hiromu Aoyama
DOI:10.1246/bcsj.76.743
日期:2003.4
Photophysical and photochemical properties of poly(amidoamine) dendrons containing an anthracene at the focal point have been studied by the steady-state and transient spectroscopic methods in solution. The fluorescence lifetime of the anthracene moiety in the higher generation dendron (G3.5) is slightly shorter than that of the lower generation homologue (G0.5). On the other hand, the triplet lifetime of G3.5 is longer than that of G0.5. The bimolecular rate constants for energy transfer from the triplet states of the anthracene moiety to O2 (kO2) and for T–T annihilation (kTT) were almost the same for the anthryl dendrons, G3.5 and G0.5, suggesting that the dendron groups do not hinder the approach of O2 or the anthracene moiety. Photodimerization of G3.5 took place at a similar rate to G0.5, while the photodissociation rates of these anthracene dimers increase in the order of anthracene > G0.5 > G3.5, suggesting the presence of some attractive forces between dendron wedges.
通过溶液中的稳态和瞬态光谱方法研究了焦点处含有蒽的聚(酰胺胺)树枝的光物理和光化学性质。较高代树枝状基团 (G3.5) 中蒽部分的荧光寿命略短于较低代同系物 (G0.5) 的荧光寿命。另一方面,G3.5的三重态寿命比G0.5长。对于蒽基树枝状分子 G3.5 和 G0.5,从蒽部分的三重态到 O2 (kO2) 的能量转移和 T-T 湮灭 (kTT) 的双分子速率常数几乎相同,表明树枝状分子基团不会阻碍 O2 或蒽部分的接近。 G3.5 的光二聚化速率与 G0.5 相似,而这些蒽二聚体的光解离速率按蒽 > G0.5 > G3.5 的顺序增加,表明树枝状分子楔之间存在一些吸引力。