Halogen atoms induced reversible supramolecular assembly and pH-response of the fluorescence properties: Low driving force triggered fluorescence switch with high SNR and high stability
Jiajun Xu, Meifen Huang, Tianyu Li, Haijun Pang, Xun Ma, Xindi Xu, Liang Jiao, Hui Tian, Rui Duan, Yu Guojun, Qiong Wu
Abstract
With the aim to investigate the influence of halogens on electronic structures and fluorescence properties, a new Salen type hetero-halogenated lanthanide complex [Ce IV ((±)3Br5Cl-salmen) 2 ] (Ce-χ-L) was synthesized, and a set of optical properties were investigated. The complex was characterized by FT-IR, elemental analysis, UV and single-crystal X-ray diffraction, and structural analysis revealed that halogen atoms plays a significant role in inducing the complex into a special intramolecular ‘X’ structure as well as supramolecular dimer assemblies. Theoretical calculations revealed that the introduction of halogen atoms is important for lowering the energy level of HOMO-LUMO the lanthanide complexes Schiff base complexes and also increase pathways of intermolecular interactions. pH stability test revealed the supramolecular assemblies of Ce-χ-L is sensitive to the variation of pH environment, and the accompanied assemble and disassemble behaviors are closely related to the substitution of halogen atoms.