Preparation And Structure-activity Relationship Of New Delay Fluorescence Materials

Delayed fluorescence(DF)generated from the radiative transition of the singlet S1 state regenerated from the first excited triplet T1 state.Unlike general fluorescent materials,the fluorescent lifetime is different from that of nanometers.The delayed fluorescent material can radiate microseconds or even milliseconds under certain conditions.Delayed fluorescence is divided into E-type delayed fluorescence,P-type delayed fluorescence and compound fluorescence.This article systematically studied the properties of two types of delayed fluorescent materials.Study on E-type delayed fluorescence1.A series of "D-A","D-A-D" configurations of E-type delayed fluorescent material molecules,sulfone derivatives,were prepared herein.Due to the presence of delocalized triple bonds in the molecules of the three compounds,the molecules are prone to photoexcite from the phenyl carbazolyl group “D” or phenothiazine group “D” to the thiophene sulfone group.The intramolecular charge transfer between "A",the corresponding absorption band undergoes a significant red shift.Since DBTO-2Cz has one more electron donating carbazole substituent than DBTO-Cz,the intramolecular charge separation is stronger,the ICT absorption band is red shifted,and the fluorescence peak appears a large red shift of 12 nm.Because DBTO-2PTZ has a low degree of molecular space distortion,its longwavelength absorption peak is blue shifted compared with DBTO-2Cz.2.In this paper,the absorption and fluorescence spectra of sulfone derivatives were studied.Unlike DBTO-Cz and DBTO-2Cz,DBTO-2PTZ is virtually non-fluorescent in toluene.This is due to the butterfly-like structure of the molecule.Its PTZ group is free to rotate in solution,resulting in a higher molecular twist.Therefore,the energy of molecular excited state is further dissipated through the non-radiative transition channel,making DBTO-2PTZ less fluorescent in solution.While in the aggregation state,DBTO-2PTZ is greatly enhanced,while the fluorescence of DBTO-Cz and DBTO-2Cz decreases in a cliff-like manner because of the vibration of the phenothiazine group and the rotation of the benzene ring in dibenzothiophene.Limited so non-radiative attenuation is blocked,resulting in AIE effects.3.A series of E-type delayed fluorescent light-emitting materials based on phthalocyanine-based carbazole derivatives were tested herein,with carbazolyl as "D" and phthalocyanine as "A".The spectral behavior of the comparative molecules can be found that the introduction of more carbazole donor groups will increase their ability to donate electrons,which can lead to increased absorbance of the material.At the same time,the increase in molecular structure distortion leads to a blue shift in the ICT absorption band and a long wavelength emission peak.Different position of carbazole group leads to its gradual increase of electron donating ability,and the degree of charge separation in the molecule is further enlarged.The ICT absorption band of 4CZIPN and 4CZTPN is largely red shifted,and the red shift of fluorescence emission peak is also greater.It depends on the electron donating and accepting ability of the peripheral carbazole group and the central benzocyanobenzene unit,respectively.4.In this paper,the delayed fluorescence lifetimes of sulfone derivatives and carbazole derivatives under light excitation are studied.The measured lifetimes are all in the microsecond order,which indicates that the RISC of the molecules is activated under light excitation,and the triplet excited state returns to the singlet excited state and delays.Fluorescence.This is due to the fact that the carbazolyl units are significantly distorted from the phthalocyanine plane by steric hindrance.The highest occupied molecular orbital and the lowest unoccupied molecular orbital of these fluorescent materials are located on the donor and acceptor moieties,respectively,resulting in very small(35)ES-T.Study on p-type delayed fluorescence1.In this paper,we designed and prepared 8 kinds of anthracene derivatives by modifying reactive groups at the 9,10-position of anthracene ring;prepared 5,10,15,20-tetraphenylporphyrin palladium as photosensitizer;passed 1HNMR spectroscopy,ESI-MS structure characterization,UV-Vis absorption spectra,fluorescence emission spectra,transient fluorescence emission lifetime were measured,and the fluorescence quantum yield was calculated.2.By comparing the absorption and emission spectra of different molecules,the effect of substituent position on its spectral properties was discussed.The hydroxymethyl phenyl-substituted stilbene organisms contain an electron-donating substituent(-OH),the charge transfer within the molecule increases,the steric hinderance of the meta-and parasubstitution structures formyl with hydrazine hosts is small,and more molecules are in coplanar.The state is conducive to increasing the mobility of the ytterbium electrons in the molecule,so that the conjugation effect is strengthened,resulting in the enhancement of fluorescence;at the same time,since the m-substitution and p-substitution structure is close to the anthracene body due to the formation of the m-substitution and p-substitution,the effect on the intramolecular charge transfer is great larger,more significant blue shift than p-substitution.3.The UV-Vis absorption,fluorescence emission,and phosphorescence emission spectrum of 2,3,7,8,12,13,17,18-octaethyl-porphyrin palladium,5,10,15,20-tetraphenylporphyrin palladium was investigated for two different photosensitizers.4.Pd OEP and Pd TPP were used as photosensitizers,respectively,and the self-made quencher 9,10-substituted anthracene derivatives were compounded to perform a series of upconversion related tests.The different photosensitizer/quencher ratios in the two-component upconversion system were studied(see Table 5-1),and the logarithmic relationship between the power density of the incident excitation light source and the upconversion intensity was tested.5.In this paper,the different up-conversion abilities of the meta-and para-formylphenyl-substituted hydrazine molecules in different solvents are studied in order to provide potential applications in bioimaging,environmental testing and other fields.