Synthesis And Properties Of Symmetrical/Asymmetrical 9,10-dithienylanthracene Luminescent Small Molecular Compounds

Traditional planar organic luminescent materialsshowed weak fluorescence in solid-state due to the aggregation-caused quenching(ACQ),which greatly limits the development of organic luminescent materials.At the beginning of the 21 st century,Tang's group and Park's group proposed two conceptions,aggregation-induced emission(AIE)and aggregation-induced emission enhancement(AIEE),respectively,which changed the status of ACQ and opened up a new path for the development of OLEDs and MFC materials.In our previous work,we found that 9,10-diheteroarylanthracene compounds(DTA)has a typical AIE behaviors.However,there are few reports on the effect of substituents on the 2-position ofthiophenen ring of DTA.In order to further study the relationship between the structure and properties of these AIE compounds,a series of symmetric / asymmetric DTA compounds with AIE behaviors were designed and synthesized using 9,10-dithienylanthracene as the parent compound and introducing different substituents or heterocyclic aryls into2-position of thiophene ring.The effects of different substitution sites on the luminescence and mechanofluorochromism properties were were systematically studied,and their applications in cell fluorescence imaging were also explored.The specific research contents are as follows:1.Three asymmetric AIE compounds based on 9,10-dithienylanthracene,including DTA-OH,DTA-A and DTA-CN were designed and synthesized.The effects of different electronegative substituents on the photophysical properties of AIE were studied.to These DTA molecules have weak blue emission in pure DMSO solution,while the fluorescence intensity increases sharply when the water ratio reaches 90%,indicating typical AIEE properties.Among them,DTA-OH containing strong electro-donating group hydroxyl group has the strongest fluorescence intensity.Reversible mechanofluorochromic(MFC)experiments found that the fluorescence spectra of them changed from blue to bright cyan after grinding,and XRD analysis indicated that the phase states of these compounds changed from crystal to amorphous under the external forces stimuli.The results clearly demonstrated that the photophysical properties of these DTAs can be effectively regulated by changing the substituents on the 2-positions of thiophene rings.Meanwhile,these DTAs have good biocompatibility and low cytotoxicity,and can be used as fluorescent dye for cell fluorescence imaging.2.Three symmetric AIE compounds based on 9,10-dithienylanthracene,including BHPTA,BYPTA and BSPTA were designed and synthesized.Among them,BYPTA and BSPTA showed good AIE properties because of the interaction of intermolecular N-N bonds,which limits the intramolecular rotation to enhance the fluorescence of the substance,while the BHPTA shows an ACQ effect in solution.All of them showed reversible MFC properties after grinding and fuming,in which the fluorescence intensity of BSPTA in solid powder increased strongly after grinding.These results indicated that different heterocyclic groups have significant effects on the AIE and MFC properties.Furthermore,they can be used as bio-fluorescent dyes to stain He La cells,and have a certain application potential in the field of bioluminescence imaging.3.Based on 9,10-bisthiophenylanthracene,four fluorescent molecules(PCTA,PMTA,PECTA and PEMTA)with regulating fluorescence emission function were designed and synthesized.They show bright yellowish-green,bright yellow,deep yellow and orange-yellow emission in the solid state,respectively.In solution,PMTA,PECTA and PEMTA had significant AIE properties,while PCTA exhibited ACQ effect.In addition,all of them can all penetrate the He La cell membrane for biological imaging.In particular,PMTA and PEMTA have excellent targeting ability to cell lysosomes.