Trenerry Michael J, Bailey Gwendolyn A
University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
Nanoscale. 2024 Aug 29;16(34):16048-16057. doi: 10.1039/d4nr02615b.
Copper chalcogenide nanoclusters (Cu-S/Se/Te NCs) are a broad and diverse class of atomically precise nanomaterials that have historically been studied for potential applications in luminescent devices and sensors, and for their beautiful, mineral-like crystal structures. By the "cluster-surface" analogy, Cu-S/Se NCs are prime candidates for the development of nanoscale multimetallic catalysts with atomic precision. However, the majority of studies conducted to date have focused exclusively on their solid-state structures and physical properties, leaving open questions as to their solution stability, dynamics, and reactivity. Herein, we report the first detailed interrogation of solution structure, dynamics, electrochemistry, and decomposition of Cu-S NCs. Specifically, we report the detailed NMR spectroscopy, diffusion-ordered spectroscopy, MALDI mass spectrometry, electrochemical and stoichiometric redox reactivity studies, and DFT studies of a series of [CuS] clusters with labile Cu-S bonds supported by monodentate phosphines and ditopic bis(diphenylphosphino)alkane ligands PPhR (R = Et, -(CH)-, -(CH)-). We find that the ligand binding topology dictates the extent of speciation in solution, with complete stability being afforded by the longer octane chelate in dppo (1,8-bis(diphenylphosphino)octane) according to H and DOSY NMR and MALDI-MS studies. Furthermore, a combined electrochemical and computational investigation of [CuS(dppo)] reveals that the intact [CuS] core undergoes a quasireversible one-electron oxidation at mild applied potentials ([CuS]: -0.50 V . Fc). In contrast, prolonged air exposure or treatment with chemical oxidants results in cluster degradation with S atom extrusion as phosphine sulfide byproducts. This work adds critical new dimensions to the stabilization and study of atomically precise metal chalcogenide NCs with labile M-S/Se bonds, and demonstrates both progress and challenges in controlling the solution behaviour and redox chemistry of phosphine-supported copper chalcogenide nanoclusters.
硫族化铜纳米团簇（Cu-S/Se/Te NCs）是一类广泛且多样的原子精确纳米材料，历史上人们对其在发光器件和传感器中的潜在应用以及其美丽的、类似矿物的晶体结构进行了研究。通过“团簇-表面”类比，Cu-S/Se NCs是开发具有原子精度的纳米级多金属催化剂的主要候选材料。然而，迄今为止进行的大多数研究都只专注于它们的固态结构和物理性质，关于它们在溶液中的稳定性、动力学和反应性仍存在未解决的问题。在此，我们报告了对Cu-S NCs溶液结构、动力学、电化学和分解的首次详细研究。具体而言，我们报告了一系列具有不稳定Cu-S键的[CuS]团簇的详细核磁共振光谱、扩散排序光谱、基质辅助激光解吸电离质谱、电化学和化学计量氧化还原反应性研究，以及密度泛函理论研究，这些团簇由单齿膦和双齿双（二苯基膦基）烷烃配体PPhR（R = Et，-(CH₂)₄-，-(CH₂)₆-）支撑。我们发现配体结合拓扑结构决定了溶液中的物种形成程度，根据氢和扩散排序核磁共振以及基质辅助激光解吸电离质谱研究，dppo（1,8-双（二苯基膦基）辛烷）中较长的辛烷螯合物提供了完全的稳定性。此外，对[CuS(dppo)]的电化学和计算联合研究表明，完整的[CuS]核在适度的外加电位下经历准可逆的单电子氧化（[CuS]：-0.50 V vs. Fc）。相比之下，长时间暴露在空气中或用化学氧化剂处理会导致团簇降解，同时以硫化膦副产物的形式挤出硫原子。这项工作为具有不稳定M-S/Se键的原子精确金属硫族化物NCs的稳定化和研究增添了关键的新维度，并展示了在控制膦支撑的硫族化铜纳米团簇的溶液行为和氧化还原化学方面的进展和挑战。
