Hybrid copper(I) halide materials are currently attracting significant attention due to their exceptional luminescence properties, offering great potential for the development of multifunctional emissive materials with, in addition, eco-friendly features. A binuclear copper iodide complex, based on the [Cu₂I₂L₄] motif with phosphite derivatives as ligands, has been synthesized and structurally characterized. Photophysical investigations indicate that this complex displays luminescence thermochromic properties, which are characterized by a temperature-dependent change in the relative intensity of two emission bands. The high-contrast luminescence thermochromism, with an important color variation from purple to cyan, is ascribed to the thermal equilibrium of two different excited states. While thermochromism is relatively known for multimetallic complexes, the perfectly controlled thermochromism of the studied compound is unprecedented for a binuclear complex. From theoretical investigations, this original feature is due to the coordination of phosphite ligands, which induces a specific energy layout of the complex, presenting vacant orbitals of varying nature. This single-component, dual-emissive binuclear complex, displaying relevant sensitivity temperature response, presents great potential for luminescence ratiometric thermometry applications. This study underlines the relevance of the ligand engineering strategy in developing original, emissive, and sustainable copper-based materials.

中文翻译：

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非簇簇碘化铜配合物的发光热致变色


杂化铜 （I） 材料因其卓越的发光性能而目前引起了广泛关注，为开发具有环保特性的多功能发光材料提供了巨大潜力。已经合成了一种基于 [Cu₂I₂L₄] 基序的双核碘化铜络合物，以亚磷酸酯衍生物为配体，并进行了结构表征。光物理研究表明，该复合物表现出发光热致变色特性，其特征是两个发射带的相对强度随温度变化。高对比度发光热致变色具有从紫色到青色的重要颜色变化，归因于两种不同激发态的热平衡。虽然热致变色对于多金属配合物相对已知，但所研究化合物的完美控制热致变色对于双核配合物来说是前所未有的。从理论研究来看，这一原始特征是由于亚磷酸酯配体的配位，它诱导了复合物的特定能量布局，呈现不同性质的空轨道。这种单组分、双发射双核复合物显示出相关的灵敏度温度响应，为发光比例测温应用提供了巨大的潜力。本研究强调了配体工程策略在开发原始、自发光和可持续的铜基材料方面的相关性。