Using mixed metal clusters in the reductive synthesis of doped ZnO nanocrystals

描述（由申请人提供）：开发用于早期疾病检测和诊断的新工具对于改善公众健康和降低医疗保健成本至关重要。半导体纳米晶体，也被称为量子点，其光学特性使其在荧光成像、生物传感和诊断领域具有巨大的潜力。然而，为了提高纳米晶体在这些应用中的有效性，必须扩大其物理性质的范围，包括：1)调节荧光发射和增加寿命2)对电场或磁场的敏感性和3)抑制闪烁。目前的一种方法是在晶格中掺入金属杂质或掺杂。掺杂纳米晶体是一个相对未开发的领域，尽管近年来掺杂Mn2+、Cu2+和镧系元素的纳米晶体因其独特的光学和磁性而得到了研究。控制掺杂剂在纳米晶体中的掺入量和位置对于控制这些新的物理性质非常重要。不幸的是，这种水平的合成控制一直具有挑战性，并且掺杂剂掺入纳米晶体的机制仍未完全了解。本研究的总体目标是开发新的合成方法，以改善对掺杂剂密度和分布的控制。具体来说，本提案描述了混合金属羧酸支持的多核锌簇的设计和合成，配位金属氧酸盐配体作为掺杂ZnO纳米晶体的可溶性单源前驱体。这些团簇的合成为研究可能作为成核团簇中间体的多核锌配合物的溶液态团簇降解和聚集提供了机会。本研究计划的第二个方面是开发一种在ZnO晶格生长过程中基于原位还原金属氧酸阴离子合成掺杂纳米晶体的新方法。通过这种方法，将观察到不同的成核和生长动力学，这可能提供新颖的和光谱上独特的纳米结构。这些结果将允许设计不同类型的掺杂纳米晶体，以特定的光学和磁性为目标。拟议项目的广泛和长期目标是提供获取这些材料的途径，以扩大可用于生物医学应用的化学工具包。

DESCRIPTION (provided by applicant): The development of new tools for early disease detection and diagnosis is essential to improving public health and lowering healthcare costs. Semiconductor nanocrystals, also known as quantum dots, display optical properties that give them enormous potential in the fields of fluorescence imaging, biosensing, and diagnostics. To advance the effectiveness of nanocrystals in these applications, however, the range of their physical properties must be broadened to include: 1) tuning of fluorescence emission and increased lifetimes 2) sensitivity to electric or magnetic fields and 3) suppression of blinking. One current approach has been the incorporation of metal impurities in the crystal lattice, or doping. Doped nanocrystals comprise a relatively unexplored field, although in recent years nanocrystals with Mn2+, Cu2+, and lanthanide dopants have been studied for their unique optical and magnetic properties. Controlling the amount and location of dopant incorporation within the nanocrystal is important for controlling these new physical properties. Unfortunately, this level o synthetic control has been challenging to achieve, and the mechanisms of dopant incorporation in nanocrystals are still not completely understood. The overall objective of the proposed research is to develop new synthetic methods for doped zinc oxide (ZnO) nanocrystals with improved control over dopant density and distribution. Specifically, this proposal describes the design and synthesis of mixed metal carboxylate-supported multinuclear zinc clusters with coordinated oxometallate ligands as soluble single-source precursors of doped ZnO nanocrystals. The synthesis of these clusters affords the opportunity to study solution-state cluster degradation and aggregation of multinuclear zinc complexes that may serve as intermediates for nucleation clusters. A second aspect of this research plan is to develop a novel approach for the synthesis of doped nanocrystals based upon in situ reduction of oxometallate anions during ZnO lattice growth. With this approach, different nucleation and growth dynamics will be observed that may afford novel and spectroscopically unique nanostructures. These results will allow the design of different types of doped nanocrystals that target specific optical and magnetic properties. The broad, long-term goal of the proposed project is to provide access to these materials to expand the chemical toolkit available for biomedical applications.