Redox-switchable self-assembly of a thia-cage with Bipyridiniums

We report a redox-active molecular cage 1 incorporating two dibenzo[24]-crown-8 ether (DB24C8) units and two thianthrene (TA) moieties, which enables reversible complexation with pyridinium guests. Cage 1 forms stable 1:1 complexes with methyl viologen (MV²⁺) and 1,2-bis(4-pyridinium)ethane (DPE²⁺), as confirmed by NMR spectroscopy, UV – vis analysis, and single-crystal X-ray diffraction. The association constants were determined to be (4.2 ± 0.8) × 10⁵ M^{− 1} for MV²⁺ and (3.0 ± 0.6) × 10⁵ M^{− 1} for DPE²⁺. Cyclic voltammetry revealed that 1 undergoes reversible two-electron oxidation (<i>E</i>_₁/₂ = 0.384 V) and reduction, with guest release occurring upon oxidation to 1²⁺ and re-encapsulation upon reduction to the neutral state. Redox-switchable complexation was observed for both MV²⁺ and DPE²⁺, evidenced by characteristic shifts in redox potentials and restoration of binding. These results highlight cage 1 as a versatile redox-responsive host, providing a promising platform for the design of stimuli-controlled molecular devices and adaptive supramolecular systems.

我们报道了一种氧化还原活性分子笼1，其包含两个二苯并[24]-冠-8醚（dibenzo[24]-crown-8 ether，DB24C8）单元和两个噻蒽（thianthrene，TA）片段，可与吡啶鎓客体发生可逆络合。通过核磁共振波谱（NMR spectroscopy）、紫外-可见分析（UV-vis analysis）和单晶X射线衍射（single-crystal X-ray diffraction）证实，分子笼1与甲基紫精（methyl viologen，MV²⁺）和1,2-双(4-吡啶鎓)乙烷（1,2-bis(4-pyridinium)ethane，DPE²⁺）形成稳定的1:1络合物。MV²⁺和DPE²⁺的结合常数分别测定为(4.2±0.8)×10⁵ M⁻¹和(3.0±0.6)×10⁵ M⁻¹。循环伏安法（cyclic voltammetry）显示，分子笼1发生可逆双电子氧化（E₁/₂=0.384 V）和还原反应：氧化为1²⁺时释放客体，还原至中性状态时重新包封客体。MV²⁺和DPE²⁺均观察到氧化还原可控的络合行为，这可通过氧化还原电位的特征偏移和结合作用的恢复得以证明。这些结果表明分子笼1是一种多功能氧化还原响应主体，为刺激可控分子器件和自适应超分子系统的设计提供了前景广阔的平台。