Multifunctional Crystalline Coordination Polymers Constructed from 4,4′-Bipyridine-N,N′-dioxide: Photochromism, White-Light Emission, and Photomagnetism

Abstract

Multifunctional photochromic coordination polymers (CPs) have shown great potential in many areas, like molecular switches, anticounterfeiting, magnetics, and optoelectronics. Although multifunctional photochromic CPs can be obtained by introducing photoresponsive functional units or by exploiting the synergy effect of each component, relatively limited photochromic ligands hinder the development of various multifunctional photochromic CPs. In this work, we reported two multifunctional coordination polymers {[Zn­(bpdo)­(fum)­(H2O)2]} n (1) and {[Mn­(bpdo)­(fum)­(H2O)2]} n (2) based on an easily accessible but underestimated photoactive molecule 4,4′-bipyridine-N,N′-dioxide (bpdo). Compound 1 exhibits photochromism and white-light emission with an ultra-high color rendering index (CRI) of 92.1. Interestingly, compound 1 could emit intrinsic white light in the crystalline state upon UV irradiation both before and after photochromism. Meanwhile, compound 2 displays photochromic and photomagnetic properties, induced by the photogenerated radicals via a photoinduced electron transfer mechanism.

Photochromism and single-component white light emission from a metalloviologen complex based on 1,5-naphthyridine

“…From the perspective of structure, both the electron transfer and charge transfer from chlorine atoms to ND molecules are produced by the D–M–A assembly mode, which implies that the D–M–A assembly mode of metalloviologen is not only helpful in producing photochromism, but also beneficial for creating white-light emission. 24…”