By integrating a tailor-made donor–acceptor (D–A) ligand in a metal–organic framework (MOF), a material with unprecedented features emerges. The ligand combines a pair of cyano groups as acceptors with four sulfanylphenyls as donors, which expose each a carboxylic acid as coordination sites. Upon treatment with zinc nitrate in a solvothermal synthesis, the MOF is obtained. The new material combines temperature-assisted reverse intersystem crossing (RISC) and intersystem crossing (ISC). As these two mechanisms are active in different temperature windows, thermal switching between their characteristic emission wavelengths is observed for this material. The two mechanisms can be activated by both, one-photon absorption (OPA) and two-photon absorption (TPA) resulting in a large excitement window ranging from ultraviolet (UV) over visible light (VL) to near infrared (NIR). Furthermore, the emission features of the material are pH sensitive, such that its application potential is demonstrated in a first ammonia sensor.

中文翻译：

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金属有机框架中磷光或热激活延迟荧光的热控制

通过将定制的供体-受体（D-A）配体整合到金属有机框架（MOF）中，一种具有前所未有特性的材料出现了。该配体将一对作为受体的氰基与四个作为供体的硫烷基苯基结合在一起，每个硫基苯基都暴露出一个作为配位位点的羧酸。在溶剂热合成中用硝酸锌处理后，获得 MOF。这种新材料结合了温度辅助逆向系间跨越（RISC）和系间跨越（ISC）。由于这两种机制在不同的温度窗口中活跃，因此观察到这种材料的特征发射波长之间的热切换。这两种机制可以被单光子吸收 (OPA) 和双光子吸收 (TPA) 激活，从而产生从紫外线 (UV) 到可见光 (VL) 到近红外 (NIR) 的大激发窗口。此外，该材料的发射特性对 pH 值敏感，因此其应用潜力在第一个氨传感器中得到了证明。