Light-harvesting macroring accommodating a tetrapodal ligand based on complementary and cooperative coordinations
Light-harvesting macroring accommodating a tetrapodal ligand based on complementary and cooperative coordinations
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DOI：
10.1021/ja048118t
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发表时间：
2004-07-21
影响因子：
15
通讯作者：
Kobuke, Y
中科院分区：
文献类型：
--
作者：
Kuramochi, Y;Satake, A;Kobuke, Y
通过在分子两端与咪唑取代基自组装三卟啉锌(II)络合物，合成了一种模拟紫光细菌捕光络合物的卟啉大分子。咪唑基与锌(II)的很强的互补配位作用，在27℃的稀溶液中，在CHCl3/MeOH=9/1(v/v)的条件下，生成了三卟啉的环状三聚体。核磁共振氢谱表明存在两个拓扑异构体，一个对称，一个不对称。使用三个非配位的卟啉锌(II)位点允许一个四足配体被结合到宏环的空腔中。UV-−-Vis滴定的工作图和清晰的弯曲行为表明，该化合物形成了1：1的络合物；没有观察到两种拓扑异构体的异质性，两种异构体都类似地容纳了四足配体。通过曲线拟合分析得到甲苯中的缔合常数为8×108m-1。这一较大的缔合常数反映了三个配位的协同性质。
A porphyrin macroring, mimicking the light-harvesting complex of photosynthetic purple bacteria, was synthesized by self-assembling trisporphyrinatoZn(II) complexes with imidazolyl substituents at both molecular terminals. Very strong complementary coordination of imidazolyl to Zn(II) afforded exclusively the cyclic trimer of trisporphyrin under dilute conditions at 27 °C in CHCl3/MeOH = 9/1 (v/v).1H NMR spectra of the macroring indicate the existence of two topological isomers, one symmetric and one asymmetric. Use of three noncoordinated porphyrinatoZn(II) sites allows a tetrapodal ligand to be incorporated into the cavity of the macroring. A Job plot and the clear bending behavior on UV−vis titration indicated the formation a 1:1 complex; the heterogeneity of two topological isomers was not observed, and both isomers similarly accommodated the tetrapodal ligand. The association constant obtained by curve fitting analysis was 8 × 108M-1in toluene. This large association constant reflects the cooperative nature of three coordination sites.