The synthesis and characterization of a CdS-based molecular cluster, [Cd₁₀S₄(SPh)₁₆]^4– (Cd₁₀), with site-specific substitution of Cd²⁺ with Mn²⁺ impurities are reported. The formation of the Cd₁₀ cluster from the smaller [Cd₄(SPh)₁₀]^2– (Cd₄) cluster involves a metastable intermediate cluster, [Cd₈S(SPh)₁₆]^2– (Cd₈), that is detected by electrospray ionization mass spectrometry (ESI-MS). To account for this unexpected intermediate, we propose a complex equilibrium between Cd₄, Cd₈, and Cd₁₀ exists that we exploit to introduce Mn²⁺ impurities at both core and surface cation sites of the Cd₁₀ lattice. We demonstrate through two synthetic procedures that differ only in the sequence in which Mn²⁺ is introduced to the reaction dictates its speciation in the cluster. Introducing dopants at an early stage of the synthesis prevents full conversion of Cd₈ to Cd₁₀; however, it yields core doped Cd₁₀ clusters. Addition of Mn²⁺ ions after the preparation of Cd₁₀ yields only surface doped clusters. The composition of the doped clusters is systematically characterized by ESI-MS and exhibits speciation-dependent peak intensities. Photoluminescence (PL) spectra of the Mn²⁺-centered ⁴T₁ → ⁶A₁ transition also exhibits significant differences in peak position and PL lifetimes that are consistent with the expected variation in ligand field strength experienced by these two metal sites. However, ESI-MS and PL collected on “aged” samples indicate slow displacement of Mn²⁺ from core sites. This study provides new insights to the growth mechanism of clusters that remained rather elusive and demonstrates how the cluster surface dynamics and cluster equilibria can be exploited for precise doping of these well-defined semiconductor analogues.

中文翻译：

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基于CdS的分子簇中Mn ^2+的定点掺杂

报告了基于CdS的分子簇[Cd ₁₀ S ₄（SPh）₁₆ ] ^4–（Cd ₁₀）的合成和表征，其中Cd ²⁺被Mn ²⁺杂质特异性取代。由较小的[Cd ₄（SPh）₁₀ ] ^2–（Cd ₄）团簇形成Cd ₁₀团簇涉及亚稳的中间簇[Cd ₈ S（SPh）₁₆ ] ^2–（Cd ₈），通过电喷雾电离质谱（ESI-MS）检测。为了说明这种意外的中间体，我们建议在Cd ₄，Cd ₈和Cd _10之间存在一个复杂的平衡，我们利用该平衡在Cd ₁₀晶格的核心和表面阳离子位点处引入Mn ²⁺杂质。我们通过两种合成方法证明，它们仅在将Mn ²⁺引入反应的顺序上不同，从而决定了其在簇中的形态。在合成的早期引入掺杂剂会阻止Cd ₈完全转化为Cd ₁₀ ; 但是，它会产生掺杂核心的Cd ₁₀团簇。锰的添加制备Cd ₁₀后的²⁺离子仅产生表面掺杂的簇。掺杂簇的组成通过ESI-MS进行系统表征，并显示出与物种有关的峰强度。以Mn ^2+为中心的⁴ T ₁ → ⁶ A ₁跃迁的光致发光（PL）光谱在峰位和PL寿命方面也显示出显着差异，这与这两个金属位点所经历的配体场强的预期变化相一致。然而，在“老化的”样品上收集的ESI-MS和PL表明Mn ^2+的置换缓慢来自核心网站。这项研究为仍然难以捉摸的团簇生长机制提供了新见解，并展示了如何利用团簇表面动力学和团簇平衡来精确掺杂这些明确定义的半导体类似物。