Seven new nitrogen-donor ligands that contain a photoactive nitrophenyl group within the ligand backbone have been prepared and evaluated for their binding affinity for copper(II) and zinc(II). Among this series, the ligand 3Gcage (pyridine-2-carboxylic acid 1-(2-nitro-phenyl)-3-[(pyridin-2-ylmethyl)-amino]-propyl}-amide) has the best affinity for copper(II), with an apparent dissociation constant at pH 7.4 of 0.18 fM. Exposure of buffered aqueous solutions of 3Gcage or Cu(II)-bound 3Gcage to UV light induces bond cleavage in the ligand backbone, which reduces the denticity of the ligands. The quantum yields of photolysis for 3Gcage in the absence and presence of Cu(II) are 0.66 and 0.43, respectively. Prior to photolysis, the 3Gcage ligand inhibits copper from generating hydroxyl radicals in the presence of hydrogen peroxide and ascorbic acid; however, hydroxyl radical formation increases by more than 300% following light activation, showing that the reactivity of the copper center can be triggered by light.
我们制备了
配体骨架中含有光活性
硝基苯基团的七种新的氮供体
配体,并评估了它们与
铜(II)和
锌(II)的结合亲和力。在这一系列
配体中,3Gcage(
吡啶-2-
羧酸 1-(2-
硝基苯基)-3-[(
吡啶-2-基甲基)-
氨基]-丙基}-酰胺)对
铜(II)的亲和力最好,在 pH 值为 7.4 时的表观解离常数为 0.18 fM。将 3Gcage 或与
铜(II)结合的 3Gcage 的缓冲
水溶液暴露在紫外线下,会导致
配体骨架中的键裂解,从而降低
配体的牙齿强度。在没有 Cu(II)和有 Cu(II)的情况下,3Gcage 的光解量子产率分别为 0.66 和 0.43。在光解之前,3Gcage
配体会抑制
铜在
过氧化氢和
抗坏血酸存在下产生羟基自由基;然而,在光激活后,羟基自由基的形成会增加 300% 以上,这表明
铜中心的反应性可以由光引发。