An octapodal corannulene-based supramolecular system has been prepared by introducing eight corannulene moieties in a porphyrin scaffold. Despite the potential of this double picket fence porphyrin for double-tweezer behavior, NMR titrations show exclusive formation of 1:1 adducts. The system exhibits very strong affinity for C₆₀ and C₇₀ (K₁ = (2.71 ± 0.08) × 10⁴ and (2.13 ± 0.1) × 10⁵ M^–1, respectively), presenting selectivity for the latter. Density functional theory (DFT) calculations indicate that, in addition to the four corannulene units, the relatively flexible porphyrin tether actively participates in the recognition process, resulting in a strong synergistic effect. This leads to a very strong interaction with C₆₀, which in turn also induces a large structural change on the other face (second potential binding site), leading to a negative allosteric effect. We also introduced Zn²⁺ in the porphyrin core in an attempt to modulate its flexibility. The resulting metalloporphyrin also displayed single-tweezer behavior, albeit with slightly smaller binding constants for C₆₀ and C₇₀, suggesting that the effect of the coordination of fullerene to one face of our supramolecular platform was still transmitted to the other face, leading to the deactivation of the second potential binding site.

中文翻译：

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基于八足体Corannulene卟啉的程序集：富勒烯寄主中的变构行为

通过在卟啉支架中引入八个香兰素部分，制备了八足体基于香兰素的超分子系统。尽管这种双尖孔栅卟啉具有双镊子行为的潜力，但NMR滴定显示排他形成了1：1加合物。该系统对C ₆₀和C ₇₀表现出非常强的亲和力（K ₁ =（2.71±0.08）×10 ⁴和（2.13±0.1）×10 ⁵ M ^–1，分别表示对后者的选择性。密度泛函理论（DFT）的计算表明，除了四个香兰素单元之外，相对灵活的卟啉链还积极参与识别过程，从而产生了强大的协同效应。这导致与C _60的相互作用非常强，这反过来又在另一面上引起了较大的结构变化（第二个潜在的结合位点），从而导致了负面的变构作用。我们还在卟啉核心中引入了Zn ²⁺，以调节其柔韧性。所得的金属卟啉也表现出单镊子的行为，尽管对于C ₆₀和C _70的结合常数稍小，这表明富勒烯与我们超分子平台的一个表面配位的效果仍会传递到另一表面，从而导致第二个潜在的结合位点失活。