Unexpected organic hydrate luminogens in the solid state
Feng Zhou1,6, Peiyang Gu1,6, Zhipu Luo2, Hari Krishna Bisoyi 3, Yujin Ji4, Youyong Li 4, Qingfeng Xu1 , Quan Li 3,5,*& Jianmei Lu 1,*（路建美）
1 College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, Jiangsu 215123, China.
2 Institute of Molecular Enzymology, School of Biology and Basic Medical Sciences, Soochow University, Suzhou, China.
3Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, USA.
4 Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu, China.
5 Institute of Advanced Materials and School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu, China.
6 These authors contributed equally: Feng Zhou, Peiyang Gu.
NATURE COMMUNICATIONS , (2021) 12:2339
Developing organic photoluminescent materials with high emission efficiencies in the solid state under a water atmosphere is important for practical applications. Herein, we report the formation of both intra- and intermolecular hydrogen bonds in three tautomerizable Schiffbase molecules which comprise active hydrogen atoms that act as proton donors and acceptors, simultaneously hindering emission properties. The intercalation of water molecules into their crystal lattices leads to structural rearrangement and organic hydrate luminogen formation in the crystalline phase, triggering significantly enhanced fluorescence emission. By suppressing hydrogen atom shuttling between two nitrogen atoms in the benzimidazole ring, water molecules act as hydrogen bond donors to alter the electronic transition of the molecular keto form from nπ* to lower-energy ππ* in the excited state, leading to enhancing emission from the keto form. Furthermore, the keto-state emission can be enhanced using deuterium oxide (D2O) owing to isotope effects, providing a new opportunity for detecting and quantifying D2O.