1,10-菲咯啉-5,6-醌水溶液的γ辐解

GAMMA RADIOLYSIS OF AQUEOUS SOLUTIONS OF 1,10-PHENANTHROLINE-5,6-QUINONE

采用60Coγ辐解，以异丙醇自由基为还原剂，研究了1，10－菲咯啉－5，6－醌（PQ）水溶液的单电子还原性质，获得了pH分别为9、≈7和≈4的水溶液幅照后的紫外、可见吸收光谱。pH9时吸收谱呈现出一个中心在490nm的宽吸收带，低于pH7，这个490nm附近的吸收要小得多，而且随溶液pH值的降低而下降。60Coγ辐解实验的观察与脉冲辐解结果一致。由此建议60Coγ辐解观察到的可见范围的吸收和脉冲辐解微秒范围所观察到的结果均由辐解终产物引起。质谱研究表明：pH3．3的水溶液经γ辐解生成一个质量数大于PQ的终产物。此终产物假定为由中性PQ半醌自由基歧化作用产生的PQH2．

One-electron reduction of 1, 10-phenanthroline-5, 6-quinone(PQ)in aqueous solutions was studied by 6oCo γ-radiolysis using isopropanol free radical as a reductant. The UV/vis absorption spectrum obtained after irradiation at pH9 showed a new broad band centered at 490 nm. Different absorption spectra were obtained at pH≈7 and≈4. Below pH 7, the increase in the absorption around 490nm was much small and decreased with decreasing pH. These observations agree with that in pulse radiolysis experiments where a residual absorption at about 490nm remained constant for several milliseconds,and this residual absorption increased with increasing pH[1~3]. It is suggested that the absorption in the visible region observed after the γ-irradiation and millisecond after pulse radiolysis is caused by the same species, a final product. MS analysis indicates that a final product with more mass number that PQ was produced after γ-irradiation at pH 3.3. This final product was assumed to be PQH2 produced by the disproportionation of PQ semiquinone neutral radical.