Williamson Curtis B, Nevers Douglas R, Nelson Andrew, Hadar Ido, Banin Uri, Hanrath Tobias, Robinson Richard D
Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA.
Science. 2019 Feb 15;363(6428):731-735. doi: 10.1126/science.aau9464.
Structural transformations in molecules and solids have generally been studied in isolation, whereas intermediate systems have eluded characterization. We show that a pair of cadmium sulfide (CdS) cluster isomers provides an advantageous experimental platform to study isomerization in well-defined, atomically precise systems. The clusters coherently interconvert over an ~1-electron volt energy barrier with a 140-milli-electron volt shift in their excitonic energy gaps. There is a diffusionless, displacive reconfiguration of the inorganic core (solid-solid transformation) with first order (isomerization-like) transformation kinetics. Driven by a distortion of the ligand-binding motifs, the presence of hydroxyl species changes the surface energy via physisorption, which determines "phase" stability in this system. This reaction possesses essential characteristics of both solid-solid transformations and molecular isomerizations and bridges these disparate length scales.
分子和固体中的结构转变通常是孤立进行研究的，而中间体系的表征一直难以实现。我们表明，一对硫化镉（CdS）团簇异构体为研究定义明确、原子精确的体系中的异构化提供了一个有利的实验平台。这些团簇在约1电子伏特的能垒上相干地相互转化，其激子能隙有140毫电子伏特的位移。无机核心存在无扩散的位移重排（固-固转变），具有一级（类异构化）转变动力学。受配体结合基序畸变的驱动，羟基物种的存在通过物理吸附改变表面能，这决定了该体系中的“相”稳定性。该反应兼具固-固转变和分子异构化的基本特征，并架起了这些不同长度尺度之间的桥梁。
