Citric acid: A powerful biomass-derived host doped with diverse guests for green room-temperature phosphorescence materials

Abstract

Guest-host doping is a strongly preferred strategy for organic room-temperature phosphorescence (RTP). Exploring nontoxic, low-cost and versatile host is highly desirable for green RTP materials and ultimate practical applications. Herein the edible biomass-derived citric acid (CA) is developed as a novel green and biorenewable host to achieve the persistent RTP of a wide range of aromatic guests including simple arene, boronic acid, carboxylic acid, aldehyde, phenol, alcohol, halohydrocarbon and alkaloid. Totally 20 representative RTP samples were fabricated by a simple and green process. They show colorful afterglow, part of which could be directly observed under natural light. The RTP lifetime ranges widely from 0.092 to 2.15 s. Experimental and theoretical results reveal that CA molecules could not only provide a rigid matrix by virtue of a large number of hydrogen bonds, but also considerably promote the intersystem crossing of the guest molecule. These RTP materials show promising applications in anticounterfeiting, three-mode latent fingerprint visualization, rewritable luminescent paper and stimuli-responsive fields. This study develops a powerful biomass-derived host for green and sustainable RTP materials. Based on its excellent versatility, CA could be a promising alternative to traditional fossil fuel-derived hosts.