Hashimoto Sigma, Iwamoto Takahiro, Kurachi Daisuke, Kayahara Eiichi, Yamago Shigeru
Institute for Chemical Research, Kyoto University, Kyoto, 611-0011, Japan.
Chempluschem. 2017 Jul;82(7):1015-1020. doi: 10.1002/cplu.201700097. Epub 2017 Apr 6.
The host-guest chemistry of cycloparaphenylenes (CPPs) of different sizes is described. [n]CPPs (n=5, 6, 7, 8, and 10) selectively interact with [n+5]CPPs, forming complexes [n+5]CPP⊃[n]CPP, which are the shortest double-walled armchair carbon nanotubes. The size selectivity is dictated by the difference in diameters of the CPPs (that is, 0.34-0.35 nm), which maximizes attractive van der Waals interactions. Theoretical calculations suggest that the orbital energies of the CPPs become perturbed upon complex formation, and orbital mixing between the two CPPs is predicted for large CPP pairs. The association constants in 1,1,2,2-[D ]tetrachloroethane, estimated by H NMR titration, are approximately 10 mol L at 50 °C. Van't Hoff plot analysis reveals that complexation is driven mainly by entropy owing to desolvation of the CPPs. [13]CPP also forms a complex with [4]cyclo-2,7-pyrenylene ([4]CPY), which is a π-extended [8]CPP. Theoretical calculations suggest that the formation of [13]CPP⊃[4]CPY is more exothermic than that of [13]CPP⊃[8]CPP. A ternary complex, [15]CPP⊃[10]CPP⊃C , is also formed by mixing [15]CPP and [10]CPP⊃C .
描述了不同尺寸的环对亚苯基（CPPs）的主客体化学。[n]CPPs（n = 5、6、7、8和10）与[n + 5]CPPs选择性相互作用，形成复合物[n + 5]CPP⊃[n]CPP，它们是最短的双壁扶手椅型碳纳米管。尺寸选择性由CPPs直径的差异（即0.34 - 0.35 nm）决定，这使范德华吸引力相互作用最大化。理论计算表明，CPPs的轨道能量在形成复合物时会受到扰动，并且对于大的CPP对，预测两个CPP之间会发生轨道混合。通过1H NMR滴定法估计，在50 °C下，在1,1,2,2-[D]四氯乙烷中的缔合常数约为10 mol L。范特霍夫图分析表明，由于CPPs的去溶剂化，络合作用主要由熵驱动。[13]CPP还与[4]环-2,7-芘撑（[4]CPY）形成复合物，[4]CPY是一种π扩展的[8]CPP。理论计算表明，[13]CPP⊃[4]CPY的形成比[13]CPP⊃[8]CPP的形成放热更多。通过混合[15]CPP和[10]CPP⊃C还形成了三元复合物[15]CPP⊃[10]CPP⊃C。
