光动力疗法对肿瘤细胞具有良好的选择性，但已临床应用和正在研究阶段的光动力试剂主要基于单重态氧机制（II型机制），由于该机制对细胞内的氧浓度高度依赖，难于有效光动力灭活乏氧肿瘤细胞。利用乏氧肿瘤细胞高谷胱甘肽浓度这一微环境特征，我们拟设计合成氯甲基/溴甲基修饰的钌（II）多吡啶配合物，借助由谷胱甘肽到激发态钌（II）配合物的光诱导电子转移作用，引发卤甲基基团的还原脱卤反应，利用反应过程中产生的活泼自由基对乏氧肿瘤细胞实施自由基机制（I型机制）的光动力灭活，为发展基于I型机制的新型光动力试剂提供新策略，为有效杀灭对传统放化疗具有高耐受性且易转移的乏氧肿瘤细胞提供新手段。

Photodynamic therapy (PDT) is a highly selective treatment modality against many types of tumors, however, the most PDT agents either in clinical use or under preclinical evaluation rely on singlet oxygen mechanism (Type II mechanism) and therefore cannot photo-inactivate hypoxic tumor cells effectively due to their high dependence on cellular O2. Taking advantage of the high concentration of glutathione (GSH) in hypoxic tumor cells, we will design and synthesize a series of chloromethyl/bromomethyl modified Ru(II) polypyridyl complexes. It is envisioned that active free radicals may be generated by way of reductive dehalogenation of the chloromethyl/bromomethyl groups upon photoinduced electron transfer from GSH to the complexes, and the free radicals may inactivate hypoxic tumor cells by free radical mechanism (Type I mechanism). We hope our studies may open a new avenue for the development of Type I mechanism-based PDT agents and provide a new strategy against hypoxic tumor cells which can be the most resistant to radiotherapy and chemotherapy and susceptible toward metastasis.