Swinkels P J M, Stuij S G, Gong Z, Jonas H, Ruffino N, Linden B van der, Bolhuis P G, Sacanna S, Woutersen S, Schall P
Institute of Physics, University of Amsterdam, Amsterdam, The Netherlands.
Molecular Design Institute, Department of Chemistry, New York University, New York, NY, USA.
Nat Commun. 2021 May 14;12(1):2810. doi: 10.1038/s41467-021-23144-6.
Colloids have a rich history of being used as 'big atoms' mimicking real atoms to study crystallization, gelation and the glass transition of condensed matter. Emulating the dynamics of molecules, however, has remained elusive. Recent advances in colloid chemistry allow patchy particles to be synthesized with accurate control over shape, functionality and coordination number. Here, we show that colloidal alkanes, specifically colloidal cyclopentane, assembled from tetrameric patchy particles by critical Casimir forces undergo the same chemical transformations as their atomic counterparts, allowing their dynamics to be studied in real time. We directly observe transitions between chair and twist conformations in colloidal cyclopentane, and we elucidate the interplay of bond bending strain and entropy in the molecular transition states and ring-opening reactions. These results open the door to investigate complex molecular kinetics and molecular reactions in the high-temperature classical limit, in which the colloidal analogue becomes a good model.
胶体作为“大原子”有着丰富的历史，被用于模拟真实原子来研究凝聚态物质的结晶、凝胶化和玻璃化转变。然而，模拟分子动力学仍然难以实现。胶体化学的最新进展使得人们能够精确控制形状、功能和配位数来合成补丁粒子。在这里，我们表明，由临界卡西米尔力从四聚体补丁粒子组装而成的胶体烷烃，特别是胶体环戊烷，会经历与其原子对应物相同的化学转变，从而可以实时研究它们的动力学。我们直接观察到胶体环戊烷中椅式和扭式构象之间的转变，并阐明了分子过渡态和开环反应中键弯曲应变和熵的相互作用。这些结果为研究高温经典极限下的复杂分子动力学和分子反应打开了大门，在这种情况下，胶体类似物成为一个很好的模型。
