| 荧光素-纳米二氧化钛表面复合及光诱导电子转移 |
| Fluorescein-Nano TiO2 Interface Complexion and Photo-Induced Electron Transfer |
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| 摘要: 本文研究了中性条件下TiO2纳米粒子与双阴离子态荧光素F2-的结合能力，发现所形成的复合物与文献报道的强酸性条件下TiO2-质子化荧光素H3F+复合物相比，结构与性能均很不同，F2--TiO2复合物吸收光谱红移30 nm以上且发射荧光。用UV-vis吸收光谱测定了复合物的结合常数、用稳态和瞬态荧光光谱测定了复合物的荧光效率和寿命分别为0.14和1.08 ns，与相应自由态F2-的测定值0.92和4.68 ns相比，复合物荧光效率和寿命都有很大的降低，这是由于复合物内部光诱导电子转移所致，因这一电子转移是热力学上非常有利的过程，其自由能变化达1.1 eV。光致电子转移的速率常数为7.1×108 s-1，是其它竞争过程的3倍以上，复合物内光诱导电子转移效率达77%。 |
| 关键词: 荧光素 纳米TiO2 二氧化钛胶体 光诱导电子转移 |
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| Abstract: This paper reports the complexion of TiO2 with fluorescein dianion (F2-) in ethanol-water under neutral pH condition. We found that F2--TiO2 complex showed very different spectral behavior from that of H3F+-TiO2 formed under strong acidic system. F2--TiO2 is 30 nm red shifted in absorption, it also emits fluorescence. The binding constant of the complex was measured to be 470 L·mol-1 by UV-Vis absorption spectrum. The fluorescence quantum yield (Φf) and fluorescence lifetime (τf) of F2- moiety in the complex were measured to be 0.14 and 1.08 ns by steady state and time-resolved fluorescence spectrometer, respectively, remarkably reduced from that of free F2-(Φf=0.92, τf=4.68 ns) due to photo-induced electron transfer (PET) within the complex. PET is highly favored by the thermodynamic driving force (ΔG=-1.1 eV). The rate constant of PET is 7.1×108 s-1, which is three times larger than other competitive processes. PET efficiency is calculated to be 77%. |
| Keywords: fluorescein nano TiO2 TiO2 colloid photo-induced electron transfer |
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| 刘苏平,张先付.荧光素-纳米二氧化钛表面复合及光诱导电子转移[J].无机化学学报,2012,28(10):2139-2147. |
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