Synthesis And Properties Of N-hetero Crown Ether Ring Modified [n]Rotaxanes Possessing Fluorescence

Mechanically interlocked molecules (MIMs) such as rotaxanes(pseudorotaxane), catenanes, knots and daisy chains, is a major component of supramolecular chemistry, due to its perfect topology structure and potential application value, which gets gradually the favour of chemists. Rotaxanes become focus of the research due to the uniqueness of structure. Along with their research gradually deepening, innovation and novelty of the structure could not meet the needs of scientists. Therefore, researchers began to link mechanical interlock molecules with special functional groups to realize the application value of them. Recently, chemists gradually applied supramolecular chemistry to molecular recognition, ion recognition, biological sensor, fluorescent sensor, controlled release, drug delivery and so on. Therefore, design and synthesis of novel functional rotaxanes has become significant. In this paper, we designed and constructed a series of dendritic [2] rotaxanes and tetraphenylethene modified [njrotaxanes, along with N-hetero crown ring as host molecular and diverse dialkylammonium salts as guest molecular, by template-directed clipping approach.1. A series of G0-G2[2]rotaxanes with dendritic groups as stoppers have been designed and synthesized, meanwhile the introduction of fluorescent pyrene to rotaxane endows them with specific optical properties. Then we took a research on UV/vis absorption and fluorescence of them. The results indicate that these two rotaxanes possess stronger intermolecular interaction in the solid state than in solution. As a result, solutions of high concentration readily formed the excimer. These special rotaxanes might be applied in dynamic self-assembling fluorescent materials.2. A series of novel Tetraphenylethene (TPE)-based [n]rotaxanes have been elaborately designed and fabricated. Their optical properties, such as UV/vis absorption and fluorescence in acetonitrile/water mixtures with different water fractions, were also investigated. The results indicated that not only the TPE-based dialkylammonium salts but also the corresponding [n]rotaxanes performed excellent AIE properties,[n]rotaxanes with characteristic of N-hetero crown ether ring adjacent to TPE stopper arise aggregation state more easily than their corresponding ammonium salts. Meanwhile,[n]rotaxanes with host macrocircle distant to TPE stopper show same AIE behavior as corresponding ammonium salt. The present results may provide a novel perspective for the design and construct of AIE-active mechanically interlocked molecules.