A novel conformationally adaptive macrocyclic tetramaleimide with flipping pyrene sidewalls

The synthesis,structure,and properties of pyrene-based conformationally adaptive macrocycles are described.This new type of conformationally adaptive macrocycle was constructed through Perkin reaction,followed by imidization.By changing the condensation partner as the linking unit,a family of conjugated macrocycles with different sizes of the cavity was synthesized,which provide a simple and modular synthetic strategy towards the conformationally adaptive macrocycles.Furthermore,the macrocycles provide two well-defined conformations through flipping pyrene subunit,which were unambiguously determined by single-crystal X-ray diffraction analysis.The conformational interconversion barrier was determined by density functional theory(DFT)calculations.This new macrocycle also demonstrated unique properties,such as vapochromic behavior and aggregation emission enhancement effect.Furthermore,we have also investigated the effect of the linker on the shape and photophysical properties of the resulting macrocyclic products.