The controlled switching of fluorophores between non-fluorescent and fluorescent states is central to every super-resolution fluorescence microscopy (nanoscopy) technique, and the exploration of radically new switching mechanisms remains critical to boosting the performance of established, as well as emerging super-resolution methods. Photoactivatable dyes offer substantial improvements to many of these techniques, but often rely on photolabile protecting groups that limit their applications. Here we describe a general method to transform 3,6-diaminoxanthones into caging-group-free photoactivatable fluorophores. These photoactivatable xanthones (PaX) assemble rapidly and cleanly into highly fluorescent, photo- and chemically stable pyronine dyes upon irradiation with light. The strategy is extendable to carbon- and silicon-bridged xanthone analogues, yielding a family of photoactivatable labels spanning much of the visible spectrum. Our results demonstrate the versatility and utility of PaX dyes in fixed and live-cell labelling for conventional microscopy, as well as the coordinate-stochastic and deterministic nanoscopies STED, PALM and MINFLUX.

荧光团在非荧光状态和荧光状态之间的受控切换是每项超分辨率荧光显微镜（纳米）技术的核心，探索全新的切换机制对于提高已建立和新兴超分辨率的性能仍然至关重要方法。可光活化染料对这些技术中的许多技术进行了重大改进，但通常依赖于限制其应用的光不稳定保护基团。在这里，我们描述了一种将 3,6-二氨基氧杂蒽酮转化为无笼组的可光活化荧光团的一般方法。这些可光活化的呫吨酮 (PaX) 在光照射后迅速而干净地组装成高度荧光、光和化学稳定的吡咯宁染料。该策略可扩展到碳和硅桥接的呫吨酮类似物，产生一系列覆盖大部分可见光谱的光活化标签。我们的结果证明了 PaX 染料在常规显微镜的固定和活细胞标记以及坐标随机和确定性纳米显微镜 STED、PALM 和 MINFLUX 中的多功能性和实用性。