Naphthalenediimide-based coordination compound with air-stable organic radicals and photochromism

Abstract

In general, the formation of air-stable radicals in crystalline functional materials is difficult to realize because of their transient nature of organic radicals, which can be quickly quenched by oxygen in air. Here, an inimitable naphthalenediimide-based coordination compound with radical-doped nature and photochromic behavior was successfully obtained. Importantly, the significant photochromic behavior for this crystalline material can be facilely realized by extra blue-light stimulus. The radical-doped nature, photochromic behavior and color changing mechanism for the crystalline material were thoroughly unearthed by single-crystal structural analysis, electron paramagnetic resonance (EPR), powder X-ray diffraction (PXRD), in-situ UV–Vis–NIR absorption and infrared (IR) spectroscopies. Studies of such a light-stimulus responsive material with air-stable radicals will not only help to understand the radical-doped nature, but also offer in-depth insight to the mainly determining factors and intrinsic mechanisms of photochromic behavior, which provide guidance for the design and synthesis of radical-doped functional materials.