Owing to their high tunability and predictable structures, metal–organic materials offer a powerful platform to study glass formation and crystallization processes and to design glasses with unique properties. Here, we report a novel series of glass-forming metal–ethylenebis(acetamide) networks that undergo reversible glass and crystallization transitions below 200 °C. The glass-transition temperatures, crystallization kinetics, and glass stability of these materials are readily tunable, either by synthetic modification or by liquid-phase blending, to form binary glasses. Pair distribution function (PDF) analysis reveals extended structural correlations in both single and binary metal–bis(acetamide) glasses and highlights the important role of metal–metal correlations during structural evolution across glass–crystal transitions. Notably, the glass and crystalline phases of a Co–ethylenebis(acetamide) binary network feature a large reflectivity contrast ratio of 4.8 that results from changes in the local coordination environment around Co centers. These results provide new insights into glass–crystal transitions in metal–organic materials and have exciting implications for optical switching, rewritable data storage, and functional glass ceramics.

中文翻译：

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设计金属-双（乙酰胺）网络的玻璃相和晶相以促进高光学对比度

由于其高度可调性和可预测的结构，金属有机材料为研究玻璃形成和结晶过程以及设计具有独特性能的玻璃提供了一个强大的平台。在这里，我们报告了一系列新型玻璃形成金属-乙撑双（乙酰胺）网络，这些网络在 200 °C 以下经历可逆玻璃化和结晶转变。这些材料的玻璃化转变温度、结晶动力学和玻璃稳定性很容易通过合成改性或液相混合进行调节，以形成二元玻璃。对分布函数 (PDF) 分析揭示了单一和二元金属-双（乙酰胺）玻璃中的扩展结构相关性，并强调了金属-金属相关性在玻璃-晶体转变的结构演化过程中的重要作用。尤其，Co-亚乙基双（乙酰胺）二元网络的玻璃相和结晶相具有 4.8 的大反射率对比度，这是 Co 中心周围局部配位环境变化的结果。这些结果为金属-有机材料中的玻璃-晶体转变提供了新的见解，并对光开关、可重写数据存储和功能性玻璃陶瓷具有令人振奋的意义。