Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Ciudad de México, Mexico.
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 Ciudad de México, Mexico.
J Org Chem. 2022 Mar 4;87(5):2255-2266. doi: 10.1021/acs.joc.1c01334. Epub 2022 Feb 15.
This work describes the synthesis and aggregation behavior of a dimeric bile acid derivative in which two steroid cores are bridged by a -di(phenylethynyl)phenylene fluorophore. The studied compound contains three key characteristics: (a) restricted conformational equilibrium in solution, (b) efficient fluorescence conferred by the bridge, and (c) medium responsiveness encoded in the steroid fragments. The incorporation of the three components afforded a compound that generates nano- and micrometric spherical particles with aggregation-responsive fluorescence emission. The observed self-assembly process of the featured molecule was induced by the gradual addition of water to the tetrahydrofuran (THF) solution. This aggregation led to significant changes in fluorescence that went from two bands at λ values of 370 and 390 nm in pure THF to a new spectrum with two maxima at λ values of 395 and 418 nm at high water contents, without a decrease in emission. The observed changes can be ascribed to weakly coupled aggregation, a hypothesis supported by multiscale molecular modeling, which sheds light on the mechanism of the self-assembly of this unconventional amphiphile.
这项工作描述了一种二聚胆酸衍生物的合成和聚集行为，其中两个甾体核心通过一个 - 二（苯乙炔基）苯并芴荧光团桥接。所研究的化合物具有三个关键特征：（a）在溶液中受限的构象平衡，（b）桥赋予的高效荧光，以及（c）甾体片段中编码的介质响应性。三个组件的组合提供了一种化合物，该化合物生成具有聚集响应荧光发射的纳米级和微米级球形颗粒。观察到的特征分子的自组装过程是通过向四氢呋喃（THF）溶液中逐渐添加水来诱导的。这种聚集导致荧光发生显著变化，从纯 THF 中 λ 值为 370 和 390nm 的两个带变为在高含水量时 λ 值为 395 和 418nm 的新光谱，而发射强度没有降低。观察到的变化可以归因于弱耦合聚集，这一假设得到了多尺度分子建模的支持，该模型揭示了这种非常规两亲分子自组装的机制。
