In the design of self-assembled compounds, small variations in the linkers connecting the coordinating moieties can produce large differences in the obtained structures. Here, we report three novel zinc(II) complexes with phenanthroline-derived ligands as building blocks (L1-L3): A mononuclear complex, a bimetallic helicate, and a trimetallic circular helicate. The even-number spacer in L2 promotes the formation of a bimetallic helicate stabilized by π-π interactions of adjacent phenanthrolines. The addition of an extra methylene in L3 increases the distance between where the phenanthrolines can stack, and CH-π noncovalent interactions give stability to the circular helicate. When irradiated at 308 nm in acetonitrile, long-lived excited states are formed with all three complexes, which are able to participate in oxidation of 2-propanol and in reduction of methylviologen, MV2+. While the overall behavior of the three complexes is similar, the bimetallic helicate is able to form a ground-state adduct with MV2+, while the trimer reaches the excited state to form an exciplex with MV2+.

中文翻译：

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Zn（II）邻菲咯啉衍生的配合物的结构和光化学性质：从单核到双金属和环状三金属螺旋。

在自组装化合物的设计中，连接配位部分的接头的微小变化会在获得的结构中产生很大的差异。在这里，我们报告三种新颖的锌（II）配合物与菲咯啉衍生的配体作为构建基块（L1-L3）：单核配合物，双金属螺旋和三金属环状螺旋。L2中的偶数间隔基促进了通过相邻菲咯啉的π-π相互作用稳定的双金属螺旋的形成。在L3中添加额外的亚甲基会增加菲咯啉可堆叠的位置之间的距离，并且CH-π非共价相互作用可为环状螺旋结构提供稳定性。当在乙腈中以308 nm照射时，所有三种配合物均会形成长寿命的激发态，能够参与2-丙醇的氧化和甲基紫精MV2 +的还原。尽管三种配合物的总体行为相似，但双金属螺旋体能够与MV2 +形成基态加合物，而三聚体达到激发态则与MV2 +形成激基复合物。