Design,Synthesis And Photophysical Properties Of Perylene Diimide Based Carbon Nanorings

Carbon nanorings(CNRs)have attracted much attention due to their excellent physical and chemical properties which caused by their unique π-bending conjugated structure.In recent years,scientists have developed many carbon nanoring molecules with excellent properties,which have been used in carrier transport and organic light-emitting diodes.The physical and chemical properties of the conjugated carbon nanorings embedded with different functional groups will change obviously.Novel macrorings induce chiral properties due to unique bent π-conjugated structure and geometric distortion of characteristic groups,and exhibit a certain circular polarization luminescence(CPL)response.Perylene diimide(PDI)dyes were a class of high performance luminescent materials.Various optoelectronic materials containing PDI were developed and applied in organic optoelectronic devices.At the same time,the chirality induced by twisted PDI materials attracted a lot of scientists’research interest.This paper focuses on the design,synthesis and properties of carbon nanorings based on PDI.The relevant contents are as follows:1.Three chiral conjugated macrorings(cyclo[n]paraphenylene-1,7-perylene diimide,[n]CPP-PDI1,7,n=6-8)were designed and synthesized via a palladium-catalyzed Suzuki coupling and subsequent reduction aromatization.Compared with the PDI molecule,the conjugate macrorings embedded with PDI have a significant absorption redshift(～110 nm for[6]CPP-PDI1,7).In addition,the chiral enantiomers of(P)/(M)-[6]CPP-PDI1,7 were efficiently separated by high performance liquid chromatography(HPLC),and their chirality were studied by circular dichroism spectroscopy(CD),its absorption asymmetry factor |gabs| can reach 8.87×10-3.In addition,we also designed and synthesized chiral macrocyclic molecules of different sizes,([7]CPP-PDI1,7 and[8]CPP-PDI1,7),and explored the effect of size on the photophysical properties of the macrocyclic molecules.2.Partial and complete cyclization of π-extended PDI derivatives were formed through selective dehydrogenation by Scholl reaction and photocatalysis,and thenπ-extended PDI molecules were coupled to C-type curved cyclophenyl precursor molecules by palladium-catalyzed Suzuki coupling reaction and reduction aromatization reaction.Two conjugated macrocyclic molecules with π-extended PDI embedding were obtained.The successful synthesis of the target products were demonstrated by NMR and high resolution mass spectrometry.Their UV-vis and fluorescence spectra were measured respectively,and compared with the unextended conjugated macroring[7]CPP-PDI1,7.The results show that the fluorescence ofπ-extended molecules 7 and 8 is blue shifted 129 nm and 96 nm,respectively,relative to[7]CPP-PDI1,7.