Recent advances in organic pressure-responsive luminescent materials

Pressure is a powerful tool to regulate the molecule aggregation and intermolecular interactions. Organic luminescent materials under high pressure can produce rich phenomena,which have many potential applications.     

Piezochromism in Dynamic Three-Dimensional Covalent Organic Frameworks

Piezochromic materials with pressure-dependent photoluminescence tuning properties are important in many fields, such as mechanical sensors, security papers, and storage devices. Covalent organic frameworks (COFs), as an emerging class of crystalline porous materials (CPMs) with structural dynamics and tunable photophysical properties, are suitable for designing piezochromic materials, but there are few related studies. Herein, we report two dynamic three-dimensional COFs based on aggregation-induced emission (AIE) or aggregation-caused quenching (ACQ) chromophores, termed JUC-635 and JUC-636 (JUC=Jilin University China), and for the first time, study their piezochromic behavior by diamond anvil cell technique. Due to the various luminescent groups, JUC-635 has completely different solvatochromism and molecular aggregation behavior in the solvents. More importantly, JUC-635 with AIE effect exhibits a sustained fluorescence upon pressure increase (≈3 GPa), and reversible sensitivity with high-contrast emission differences (Δλ_em=187 nm) up to 12 GPa, superior to other CPMs reported so far. Therefore, this study will open a new gate to expand the potential applications of COFs as exceptional piezochromic materials in pressure sensing, barcoding, and signal switching.     

基于含蒽荧光配体的层柱型金属有机框架的合成及压致变色研究

利用含蒽荧光配体9,10-双[(E)-2-(吡啶-4-基)乙烯基]蒽(BP4VA)分别与2种不同长度的二羧酸配体反应,合成了层柱型的金属有机框架(MOFs)材料FDM-26和具有dia拓扑的三维材料FDM-27,并解析了其单晶结构.此外,对含有配位键断裂缺陷的基于BP4VA配体的层柱型MOFs材料FDM-22晶体施加外界压力,研究了压力刺激对FDM-22结构和荧光性质的影响.结果表明,在压力作用下,FDM-22能够保持结构稳定,但其荧光发射波长出现红移.经分析发现,此压致变色性能是由于结构内压力诱导生成的配位缺陷数目增加所致.