Pacella Gianni, Nabatova Maria, Zhang Yuxuan, Picconi David, Weber Roza R, Faraji Shirin, Portale Giuseppe
Zernike Institute for Advanced Materials, University of Groningen, Nijemborg 3, Groningen, 9757AG, Netherlands.
Institute of Theoretical and Computational Chemistry, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany.
Angew Chem Int Ed Engl. 2025 Jul 7;64(28):e202506532. doi: 10.1002/anie.202506532. Epub 2025 May 16.
Efficient photoswitches capable of complete conversion to their metastable isomer are not so common, yet highly desirable for applications in smart materials and devices. Here, we report the photochromic behavior of a series of styryl cyanine photoswitches, all demonstrating high switching efficiency, with some achieving full conversion to the metastable form. Despite structural similarities to spiropyran photoswitches, we demonstrate that the photochemistry of styryl cyanines is fundamentally different. Unlike classical photoswitches that rely on double-bond rotation, these molecules undergo substantial geometric changes via the formation of a spiro carbon. This transformation disrupts conjugation, causing a desirable blue shift in absorbance ideal for creating responsive materials and devices. We further show that the switching kinetics can be finely tuned through electronic effects of various substituents or the choice of surrounding medium. These photoswitches exhibit excellent fatigue resistance and can be easily shifted into the visible region via their acidochromic properties. Taking advantage of their high switching efficiency and affinity for acidic polymers, we finally propose their use as smart dopants to develop light-responsive materials with tunable proton transport properties under visible light irradiation.
能够完全转化为其亚稳态异构体的高效光开关并不常见，但在智能材料和器件应用中却非常理想。在此，我们报道了一系列苯乙烯基花菁光开关的光致变色行为，所有这些光开关都表现出高开关效率，其中一些实现了向亚稳态形式的完全转化。尽管与螺吡喃光开关在结构上有相似之处，但我们证明苯乙烯基花菁的光化学本质上是不同的。与依赖双键旋转的传统光开关不同，这些分子通过形成螺碳经历了显著的几何变化。这种转变破坏了共轭，导致吸光度出现理想的蓝移，这对于制造响应性材料和器件非常有利。我们进一步表明，开关动力学可以通过各种取代基的电子效应或周围介质的选择进行精细调节。这些光开关表现出优异的抗疲劳性，并且可以通过其酸致变色特性轻松转移到可见光区域。利用它们的高开关效率和对酸性聚合物的亲和力，我们最终提出将它们用作智能掺杂剂，以开发在可见光照射下具有可调质子传输特性的光响应材料。
