Structural Transformations of Group III-V and II-VI Magic-Sized Clusters Driven by Atomic-Bond Exchanges

Multistep nucleation and growth of quantum dots (QDs) involves the utilization of kinetically persistent, small inorganic clusters, specifically magic-sized clusters (MSCs), as intermediates. Therefore, understanding and control of the reactivity (or stability) of MSCs is essential to such non-classical QD synthesis. In this talk, using <i>ab initio</i> molecular dynamics (AIMD) simulations, we reveal the destabilization process of a carboxylate-ligated In₃₇P₂₀ MSC, induced by a surface ligand network modification beyond a critical limit.¹ At elevated temperatures, the release of three In(O₂CR)₃ subunits triggers the sudden loss of stability in the remaining In₃₄P₂₀ core, leading to structural transformations through In–P bond breaking and rearrangement. This isomerization manifests as an In–P bond exchange between a pair of In atoms, resulting in a “rupture” on the cluster surface. The structural disruption in the InP cluster causes noticeable changes in the simulated UV–vis absorption spectra and XRD patterns, which agree well with experimental findings² on MSC destabilization induced by reactions with primary amines at low temperatures. Our analysis elucidates that the MSC instability is driven by the intricate interactions between the surface ligand network and the inorganic core of the group III-V MSC. Finally, we discuss the fundamental differences in the isomerization of the InP MSC and a related CdS cluster of similar size,^3,4 highlighting the distinct nature of surface ligand networks in the group III–V and II–VI cluster systems.<br/><br/>1. D. Shim and J. Kang, <i>Chem. Mater</i>. <b>2023</b>, <i>35</i>, 700–708.<br/>2. D. C. Gary, A. Petrone, X. Li, and B. M. Cossairt, <i>Chem. Commun.</i> <b>2017</b>, <i>53</i>, 161–164.<br/>3. C. B. Williamson et al., <i>Science</i> <b>2019</b>, <i>363</i>, 731–735.<br/>4. D. Shim, J. Lee, and J. Kang, <i>Chem. Mater.</i> <b>2022</b>, <i>34</i>, 9527–9535.