Perfect Separation\nof <i>n</i>‑Pentane\nand <i>Iso</i>-pentane by Nonporous Adaptive Crystals of\nPerethylated Pillar[5]arene

The separation of <i>n</i>-pentane (<b><i>n</i>-PT</b>) and <i>iso</i>-pentane (<b><i>iso</i>-PT</b>) mixtures represents a significant challenge\nin the petrochemical\nindustry. In this study, we propose an innovative, efficient, and\nenergy-saving method for the adsorptive separation of <b><i>n</i>-PT</b> and <b><i>iso</i>-PT</b> mixtures\nusing nonporous adaptive crystals (NACs) based on perethylated pillar[5]arene\n(<b>EtP5</b>), achieving 100% purity. The single crystal structure\nsuggests that the high selectivity is due to multiple noncovalent\ninteractions between <b>EtP5</b> and <b><i>n</i>-PT</b> as well as the formation of newly stable crystals of <b><i>n</i>-PT</b>@<b>EtP5</b>. Density functional\ntheory demonstrates that the host–guest interaction of <b><i>n</i>-PT</b>@<b>EtP5</b> is mainly concentrated\nin the cavity center of <b>EtP5</b>, and the aromatic area of <b>EtP5</b> contributes the most. Additionally, NACs of <b>EtP5</b> exhibit recyclability due to the reversible transformation between\nthe guest-free and guest-loaded structures.