| 曹洪玉,王梦妍,马子辉,唐乾,王立皓,郑学仿.化学通报,2021,84(9):926-931. |
| 光激发四苯基卟啉钴氧化还原反应机理研究 |
| Photo-Induced Redox Reaction Mechanism of Cobalt Tetraphenylporphyrin |
| 投稿时间：2020-12-18 修订日期：2021-04-01 |
| DOI： |
| 中文关键词: 四苯基卟啉钴 光激发氧化还原 紫外可见光谱 瞬态吸收光谱 |
| 英文关键词:Cobalt-Coordinated Tetraphenylporphyrin, Photo-Induced Redox, Uv-visible Absorption Spectrum, Transient Absorption Spectrum |
| 基金项目:国家自然科学基金项目(21601025,21571025,21601024)和大连市高层次创新人才项目(2017Q156)资助 |
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| 中文摘要: |
| 金属卟啉在光激发条件下会呈现出重要催化特性和光学性质。四苯基卟啉亚钴CoⅡTPP性质稳定，难以通过强氧化剂氧化至四苯基卟啉钴CoⅡITPP。本文分别利用全波长氙灯与355 nm激光脉冲诱导四苯基卟啉亚钴CoⅡTPP，探究其分子内的氧化还原过程。研究结果发现CoⅡTPP 的Soret带最大吸收峰随光照时长的递增出现红移，且吸收强度呈现先下降后上升的趋势，最大吸收峰位置由415 nm逐渐红移至433 nm，其Q带最大吸收峰位置由532 nm逐渐红移至545 nm。两种光源诱导CoⅡTPP均出现稳态吸光度的降低，分子内的活性中心钴离子由Co2+氧化到Co3+。咪唑使得CoⅡTPP受光诱导后更易出现稳态吸收峰红移。CoⅡTPP的瞬态吸收光谱有3个瞬态吸收峰，激光激发含咪唑的CoⅡTPP溶液仅在396nm出现单个瞬态吸收峰。数据表明光激发时，电子从卟啉的π成键分子轨道向具有配体特征的π*反键分子轨道迁移，发生金属对配体的电荷迁移，生成稳定高价态CoIII。 |
| 英文摘要: |
| Photo-excited metalloporphyrins exhibit important catalytical and optical properties. The center metal cobalt(Ⅱ) of CoⅡTPP is hard to be oxidized to cobalt (III) by strong oxidant because of the low valence cobalt ion stability. A full-wavelength light from xenon lamp and 355 nm laser pulse were applied to irradiate CoⅡTPP for exploring the photo-induced redox process. Based on the UV-Visible spectra, the maximum Soret band absorption peaks of the CoⅡTPP red shifted with the irradiation time. The absorption peak at 415 nm of the Soret band gradually red-shifted to 433 nm, while the Q band peak gradually red shifted from 532 nm to 545 nm. The steady absorbance intensity of CoⅡTPP induced by the two light sources decreased obviously. The center metal cobalt ion in the molecule was oxidized to CoIII. As a ligand of the center metal, imidazole promoted the red-shifted rate of the steady absorption peaks of photo-induced CoⅡTPP. Three transient absorption peaks of laser excited CoⅡTPP could be observed in the transient absorption spectra, while only one single transient absorption peak at 396nm appeared in the laser excited CoⅡTPP spectra with imidazole. The above data illustrated that electrons migrated from the π bonding molecular orbital to the ligand characteristic π* anti-bonding molecular orbital in the laser excited CoⅡTPP. The metal-ligand charge transfer resulted in a stable high-valence state CoIII coordinated complex. |
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