Well-defined fullerene-PEG conjugates, C₆₀-PEG (1) and two C₇₀-PEG (2 and 3 with the addition sites on ab-[6,6] and cc-[6,6]-junctions), were prepared from their corresponding Prato monoadduct precursors. The resulting highly water-soluble fullerene-PEG conjugates 1–3 were evaluated for their DNA-cleaving activities and reactive oxygen species (ROS) generation under visible light irradiation. Unexpectedly, photoinduced cleavage of DNA by C₆₀-PEG 1 was much higher than that by C₇₀-PEG 2 and 3 with higher absorption intensity, especially in the presence of an electron donor (NADH). The preference of photoinduced ROS generation from fullerene-PEG conjugates 1–3 via the type II (energy transfer) or the type I (electron transfer) photoreaction was found to be dependent on the fullerene core (between C₆₀ and C₇₀) and functionalization pattern of C₇₀ (between 2 and 3). This was clearly supported by the electron transfer rate obtained from cyclic voltammetry data and computationally estimated relative rate of each step of the type II and the type I reactions, with the finding that type II energy transfer reactions occurred in the inverted Marcus regime while type I electron transfer reactions proceeded in the normal Marcus regime. This finding on the disparity in the pathways of photoinduced reactions (type I versus type II) provides insights into the behavior of photosensitizers in water and the design of photodynamic therapy drugs.

中文翻译：

---

水中 C60 和 C70 的光致反应与 O2•– 或 1O2 的生成存在意外差异

明确定义的富勒烯-PEG缀合物，C ₆₀ -PEG（1）和两个C ₇₀ -PEG（2和3与在添加位点AB- [6,6]和CC- [6,6] -junctions），分别为由其相应的普拉托单加合物前体制备。将所得的高水溶性富勒烯-PEG偶联物1 - 3分别为在可见光照射下它们的DNA切割活性和反应性氧物质（ROS）的产生进行评价。出乎意料的是，C ₆₀ -PEG 1对 DNA 的光诱导切割远高于 C ₇₀ -PEG 2和3具有更高的吸收强度，尤其是在有电子供体 (NADH) 的情况下。光敏反应ROS产生的从富勒烯-PEG偏好缀合物1 - 3经由式II（能量转移）或I型（电子转移）光反应被认为是依赖于（C之间的富勒烯芯₆₀和C ₇₀和官能化） C _{70 的}模式（在2和3之间）。从循环伏安法数据中获得的电子转移率和计算估计的II 型和I型每一步的相对速率清楚地支持了这一点反应，发现II 型能量转移反应发生在反马库斯机制中，而I 型电子转移反应发生在正常马库斯机制中。这一关于光诱导反应途径差异的发现（I 型与II 型）提供了对光敏剂在水中的行为和光动力治疗药物设计的见解。