Photofunctional ionic crystals have become more and more appealing in the applications of light-emitting devices, optical imaging, and anti-counterfeiting. However, it is still limited to achieve ultralong room temperature phosphorescence (RTP) and stimuli-responsive property in ionic crystals due to the lack of valid design principles. Herein, we developed a new class of organic ionic crystals (sodium o-, m-, p-carboxyphenylborate, o-, m-, p-Nacpb) by a structural isomerization strategy, which could exhibit ultralong RTP and mechanochromic emission. Among the three isomers, m-Nacpb crystal exhibits the longest RTP lifetime up to 732.8 ms, which is ca. 120 times longer than that (6.1 ms) of o-Nacpb crystal. Interestingly, o-Nacpb could display mechano-responsive luminescence with tunable fluorescence-phosphorescence emissions and longer phosphorescence lifetime (increased by about 20-fold). Both experimental and theoretical studies indicate that the distinct RTP and mechanochromic luminescence properties of the organic ionic crystals are attributed to the alternation of molecular conformations and spatial packing modes. Moreover, potential applications including data encryption and decoration are demonstrated, benefiting from the varied phosphorescence lifetimes and good processability. Therefore, this work not only provides a rational isomerization route to prepare various organic ionic crystals with ultralong RTP and stimuli-responsive emission, but also supplies a facile way to develop the advanced information encryption applications.

光功能离子晶体在发光器件、光学成像和防伪等领域的应用越来越受到关注。然而，由于缺乏有效的设计原则，在离子晶体中实现超长室温磷光（RTP）和刺激响应性能仍然有限。在此，我们通过结构异构化策略开发了一类新的有机离子晶体（o-、m-、p-羧基苯基硼酸钠、o-、m-、p -Nacpb），该晶体具有超长的RTP和机械致变色发射。在三种异构体中，m -Nacpb 晶体的 RTP 寿命最长，可达 732.8 ms，即约 比o -Nacpb 晶体长 120 倍（6.1 ms） 。有趣的是，o-Nacpb 可以显示出具有可调荧光-磷光发射和更长磷光寿命（增加约 20 倍）的机械响应发光。实验和理论研究都表明，有机离子晶体独特的 RTP 和机械致变色发光特性归因于分子构象和空间堆积模式的交替。此外，还展示了包括数据加密和装饰在内的潜在应用，这得益于不同的磷光寿命和良好的可加工性。因此，该工作不仅为制备各种具有超长RTP和刺激响应发射的有机离子晶体提供了合理的异构化途径，也为开发先进的信息加密应用提供了一条捷径。