Guest-induced (crystal-to-crystal) transformation, i.e., periodic flexibility, is a typical feature of molecule-based crystalline porous materials, but its role for adsorptive separation is controversial. On the other hand, aperiodic flexibility is rarely studied. This work reports a pair of isomeric Cu(I) triazolate frameworks, namely, α-[Cu(fetz)] (MAF-2Fa) and β-[Cu(fetz)] (MAF-2Fb), which show typical periodic and aperiodic flexibility for CO chemical adsorption, respectively. Quantitative mixture breakthrough experiments show that, while MAF-2Fa exhibits high adsorption capacity at high pressures but negligible adsorption below the threshold pressure and with leakage concentrations of 3–8%, MAF-2Fb exhibits relatively low adsorption capacity at high pressures but no leakage (residual CO concentration <1 ppb). Tandem connection of MAF-2Fa and MAF-2Fb can combine their advantages of high CO adsorption capacities at high and low pressures, respectively. MAF-2Fa and MAF-2Fb can both keep the separation performances unchanged at high relative humidities, but only MAF-2Fb shows a unique coadsorption behavior at a relative humidity of 82%, which can be used to improve purification performances.

中文翻译：

---

异构多孔三唑酸铜 (I) 框架显示出有效 CO 分离的周期性和非周期性灵活性


客体诱导（晶体到晶体）转变，即周期性柔性，是分子基结晶多孔材料的典型特征，但其在吸附分离中的作用尚存在争议。另一方面，非周期性柔性却很少被研究。这项工作报道了一对同分异构的 Cu(I) 三唑盐骨架，即 α-[Cu(fetz)] (MAF-2Fa) 和 β-[Cu(fetz)] (MAF-2Fb)，它们表现出典型的周期性和非周期性。 CO 化学吸附的灵活性。定量混合物突破性实验表明，MAF-2Fa 在高压下表现出较高的吸附能力，但在阈值压力以下且泄漏浓度为 3%~8% 时吸附量可以忽略不计，而 MAF-2Fb 在高压下表现出相对较低的吸附能力，但没有泄漏（残留 CO 浓度 <1 ppb)。 MAF-2Fa和MAF-2Fb的串联可以结合它们分别在高压和低压下高CO吸附能力的优点。 MAF-2Fa和MAF-2Fb都可以在高相对湿度下保持分离性能不变，但只有MAF-2Fb在相对湿度82%时表现出独特的共吸附行为，可用于提高净化性能。