Through-Space Conjugated Folded Tetraphenylethene Derivatives: Synthesis And Property

Through-space conjugation,which is different from through-bond conjugation,refers to a special electric delocalization manner resulting from π?π interaction between aromatic moieties.They can be applied for constructing novel materials with multidimensional carrier and energy transport.Till now,the most studied through-space conjugated molecules are [2.2]paracyclophane and its derivatives,but novel through-space conjugated systems are still highly desired.Furthermore,understanding of structure-property relationship,and application exploration of through-space conjugated systems are always of high significance.Inspired by our previous works about tetraphenylethene(TPE)derivatives that have interesting aggregation-induced emission(AIE)property,a novel through-space conjugated framework based on TPE was obtained.The studies in this thesis are all based on it,and details are as follows:1)A series of novel TPE derivatives with different planar chromophores were synthesized,and characterized by NMR,MOLDI-TOF,and X-ray single crystallography analyses.And their photophysical properties,including UV absorption and PL emission,were investigated.Besides,theoretical calculations were conducted and the results demonstrated that through-space conjugation could be formed between benzene and these planar units.On the other hand,different aromatic rings led to significant impacts on the intramolecular through-space conjugation,which depended on how suitable the electronic structures and energy levels were between the interacting units.2)By structural modulation of reagents,a series of more complicated folded TPE derivatives containing a pair of π-stacked oligo-p-phenylenes were synthesized and characterized.The folded structures were further confirmed by X-ray diffraction crystallography technique.Besides,unique intramolecular energy transfer process occurred,and was explained by theoretical calculations.More interestingly,Stoke shifts as large as 190–214 nm were also observed for these folded molecules,which were rarely reported in hydrocarbon molecules.3)A series of functionalized folded TPE derivatives,namely f-TPEF,f-TPEC,f-TPEI and f-TPEB were synthesized by introduction of some electron-donating/withdrawing groups.The photophysical properties of these molecules were systematically studied to have a deep insight into the structure-property relationship.On the other hand,the effects of fluoride binding with boron atom(s)on photophysical properties and electronic structures of the molecules were investigated,providing important clues about intramolecular energy transfer.