Two viologen-like macrocyclic receptors, [1]²⁺ and [2]²⁺, merging a bent oligophenylene loop with a (para-xylylene)bispyridinium moiety were designed and synthesized. Both dications were derived from the same precursor: the more strained cycloparaphenylene analogue [1]²⁺ was obtained using a reductive aromatization, whereas the less curved, meta-phenylene-containing [2]²⁺ was generated using a double eliminative rearrangement. [1]²⁺ is active as a receptor toward pyrene-1,3,6,8-tetrasulfonate, displaying a 2 : 1 binding interaction, with K₁₁ = 7.4(3) × 10³ M⁻¹. In the solid state, [1][TFA]₂ shows differential sorption of C₆ hydrocarbons and shows reversible sorption of water. [1]²⁺ displays yellow emission in solution (λ^em_max = 544 nm in DMF), which is considerably red shifted in the solid state (λ^em_max = 644 nm for dry samples). Both [1]²⁺ and [2]²⁺ undergo electrochemical reduction, yielding transient viologen-like radical cations and diradicals.

中文翻译：

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Viologen-cycloparaphenene 杂化物：用于阴离子结合和特异性蒸汽吸附的发光分子纳米碳


设计并合成了两个紫精样大环受体 [1]²⁺ 和 [2]²⁺，它们合并了一个弯曲的寡苯环和一个（对二甲苯）双吡啶部分。两种离子都来自相同的前体：更应变的环对苯类似物 [1]²⁺ 是使用还原芳构化获得的，而弯曲程度较低、含有间苯烯的 [2]²⁺ 是使用双消除重排产生的。[1]²⁺ 作为芘-1,3,6,8-四磺酸盐的受体具有活性，显示出 2 ： 1 结合相互作用，K₁₁ = 7.4（3） × 10^{3 M-1}。在固态下，[1][TFA]₂ 显示 C₆ 烃的差异吸附，并显示水的可逆吸附。[1]²⁺ 在溶液中显示黄色发射（DMF 中的 λ^em_max = 544 nm），在固态中红移很大（干燥样品的 λ^em_max = 644 nm）。[1]²⁺ 和 [2]²⁺ 都经历电化学还原，产生瞬态紫精样自由基阳离子和双自由基。