Tailoring the aggregation-induced emission (AIE) characteristics of well-defined metal nanoclusters (MNCs) is highly sought after for numerous practical applications. Studies have primarily focused on assembling AIE-type MNCs using monomorphic molecules. Achieving polymorphic assemblies, with different molecular arrangements could provide valuable insights into the role of external molecular matrices on the photoluminescence (PL) behaviour of these NCs. In this study, by mimicking biomineralisation, we successfully embedded an AIE-type Au22SG18 NCs within different polymorphic environments of CaCO3. Upon incorporation into CaCO3 matrices such as, calcite, vaterite and a mixture of both, the PL was enhanced in all the inorganic composites accompanied by a significant blue shift. In the metastable vaterite matrix, Au22SG18 NCs exhibited the highest blue shift in the PL spectrum while in the stable crystalline matrix of calcite, the NCs showed the highest PL intensity as well as excited state lifetime. Time-resolved spectroscopic and single-molecule Raman studies revealed that variations in the PL of NCs are linked to the stability of their polymorphic structures, progressing from vaterite to a vaterite/calcite mixture, and finally to calcite. These findings shed light on the crucial role of external molecular arrangement in the AIE behaviour of MNCs.

中文翻译：

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通过生物矿化启发的多态性定制 AIE 型金纳米簇的光致发光


定制定义明确的金属纳米团簇 （MNC） 的聚集诱导发射 （AIE） 特性在许多实际应用中备受追捧。研究主要集中在使用单晶性分子组装 AIE 型 MNC 上。实现具有不同分子排列的多晶型组装可以为外部分子基质对这些 NC 的光致发光 （PL） 行为的作用提供有价值的见解。在这项研究中，通过模拟生物矿化，我们成功地将 AIE 型 Au22SG18 NCs 嵌入到 CaCO3 的不同多晶型环境中。在掺入 CaCO3 基质（如方解石、瓦特石和两者的混合物）中后，所有无机复合材料的 PL 都得到了增强，并伴有明显的蓝移。在亚稳态方解石基体中，Au22SG18 NCs 在 PL 光谱中表现出最高的蓝移，而在方解石的稳定结晶基体中，NCs 表现出最高的 PL 强度和激发态寿命。时间分辨光谱和单分子拉曼研究表明，NC 的 PL 变化与其多晶型结构的稳定性有关，从 vaterite 发展到 vaterite/方解石混合物，最后发展到方解石。这些发现阐明了外部分子排列在 MNC 的 AIE 行为中的关键作用。