PHOTOREDUCTION OF 1,10-PHENANTHROLINE
PHOTOREDUCTION OF 1,10-PHENANTHROLINE
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DOI：
10.1039/f19777300663
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发表时间：
1977-01-01
期刊：
影响因子：
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通讯作者：
HARRIMAN, A
中科院分区：
文献类型：
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作者：
BANDYOPADHYAY, BN;HARRIMAN, A
溶剂极性对1,10-菲罗啉光物理性质的影响表明，在所有溶剂中，（n, π*）和（π, π*）激发单重态非常接近，而最低的三重态是（π, π*）。在烃类溶剂中，第一激发态具有（n, π*）特征，而在水中，a （π, π*）位于该状态下~ 700 cm-1处。即使在水中，（n, π*）态也能从溶剂中抽出一个氢原子，形成中间的半中间自由基。自由基可以通过闪光光解和e.s.r.技术检测，并且在有机溶剂中，由于歧化反应，它以二级动力学衰变。反应的主要产物是二氢菲罗啉，在烃溶剂中形成的量子效率为~ 25%。在水溶液中，半中间自由基的产率和衰变速率与pH有关，自由基质子化的pK为7.3。因此，在pH为5的水中辐照会形成稳定的双质子化自由基阳离子。
The effects of solvent polarity on the photophysical properties of 1,10-phenanthroline indicate the close proximity of (n, π*) and (π, π*) excited singlet states, whilst the lowest triplet state is (π, π*) in all solvents. In hydrocarbon solvent, the first excited singlet state is of (n, π*) character but in water a (π, π*) is situated ∼ 700 cm–1 below this state. Even in water, the (n, π*) state is capable of abstracting a hydrogen atom from the solvent forming an intermediate semidiaza radical. The radical can be detected by flash photolysis and e.s.r. techniques and, in organic solvents, it decays with second order kinetics due to a disproportionation reaction. The major product of reaction is dihydrophenanthroline which, in hydrocarbon solvents, is formed with a quantum efficiency of ∼ 25 %. In aqueous solvent, the yield and rate of decay of the semidiaza radical are pH dependent, and the pK for protonation of the radical is 7.3. Thus, irradiation in water at pH 5 results in formation of the stable diprotonated radical cation.