The Aggregation-Annihilation Circular Dichroim Property Of Tetraphenylethylene

Tetraphenylethylene(TPE)is a typical Aggregation-Induced Emission molecule with simple structure and various modifiability,which has attracted wide attention.When the benzene ring twists in one diretation,TPE can adopt two chiral conformations,including the P-order(right-handed propeller)and M-order(left-handed propeller).How to construct chiral TPE molecules and the relationship between chirality and aggregation luminescence is of great research value.This paper summarized different kinds of chiral TPE,which includs chiral aggregates,chiral single crystals and chiral organic small molecules.In the second chapter,the compounds R-BINOL-TPE and S-BINOL-TPE were obtained by modifying the α sites of two benzene rings of the same double-bond carbon of TPE with BINOL.In aggregate state likeTetrahydrofuran-water mxtures(fw-90%),the fluorescence intensities were enhanced significantly,while the Circular Dichroism signals sharply collapsed,showing abnormal Aggregation-Annihilation Circular Dichroism(AACD)phenomenon,therefore no obvious circularly polarized luminescence signals were observed.In high viscosity solution,compounds emitted strong fluorescence and the Circular Dichroism signals remained with signals of R-BINOL-TPE and S-BINOL-TPE with mirror image were observed.The R-BINOL-TPE showed the positive signal,and the S-BINOL-TPE showed the opposite one.This work proves that TPE has the AACD property,and it will be of benefit to the research of chiral TPE and chiral aggregates luminescence.In the third chapter,we modified four α sites of TPE benzene ring with two BINOL,made precursor compound S-BINOL-BP and hoped to obtain the target compound S-S-TPE by McMurry coupling.However,only the substituted tetraphenylethane S-S-TDE was obtained.Then,a series of experiments were carried out like oxidation dehydrogenation by DDQ and diazo compound coupling reaction,but the compound could not be obtained.The fluorescence properties of S-S-TDE were studied,and it showed obvious AIE effect of tetraphenylethane.In addition,by changing the fw,the fluorescence of BINOL and tetraphenylethane can be retained at the same time,resulting in a mixed luminescence.In the fourth chapter,we further explored the previous achievement and found that there are two types of C-H/π interactions in TPE-C4.One is within the same cell(Type Ⅰ),and the other is between adjacent cell(Type Ⅱ).