Synthesis And Luminescent Properties Of Small Molecules Based On Phenothiazine Derivatives

Luminescent organic small molecules were widely used in many fields because of their wide color gamut and easy modification of their structure and many other advantages.However,planar small-molecule luminescent materials were prone to produce strong?-?interactions between molecules,which affected the luminescence performance,thus restricting their development to a certain extent.The phenothiazine(PTZ)group exhibits a butterfly-shaped non-planar structure,which can effectively inhibit the?-?stacking of the intermolecular surface and the surface.Therefore,in this thesis,the phenothiazine matrix was modified to prepare a new type of phenothiazine non-planar luminescent material,and its luminescent properties were studied.In the second chapter,phenothiazine was connected with planar groups(quinoline,pyrene and carbazole)to obtain small molecule luminescent materials PZQ,PZPR,PZCEt,then PZPR and PZCEt were oxidized to obtain corresponding compounds POPR and POCEt,and their luminescence properties were studied.The fluorescence emission spectrum of PZQ compound and the relationship diagram of??-?f showed that with the increase of solvent polarity,the emission peak was accompanied by 99 nm red-shift,showing obvious ICT characteristics.In addition,PZQ also exhibited piezochromic properties.The original solid emission peaks of PZQ were located at approximately 418 nm and 520 nm,respectively.Although the position of the emission peak of the solid remained unchanged after grinding,the relative intensity has changed significantly.The lifetime of the PZQ solid at 418 nm was in the order of nanoseconds,and the lifetime at 520 nm was in the order of microseconds.A further study of this property indicated that the ground solid could be self-recovered to its original state.Analysis of the crystal structure showed that the non-planar structure of PZQ can effectively inhibit the strong?-?interaction between the molecular surface and the surface.The luminescence properties of PZPR,PZCEt,POPR,and POCEt were studied.The results showed that in the solid state,the fluorescence emission spectra of POPR and POCEt were blue-shifted compared with those of PZPR and PZCEt,indicating that the oxidation of phenothiazine has a greater impact on the fluorescence emission behavior.In the third chapter,oxidized phenothiazine was used as the electron withdrawing group,carbazole was used as the electron donating group.Benzene ring,pyridine,and pyrimidine were used as the bridging group,respectively.The D-?-A structure compounds POPC,POPYC and POPMC were designed and synthesized,their luminescence properties were studied.The results showed that by introducing different bridging groups,the charge transfer and phosphorescence emission of the molecule could be effectively regulated.With the increase of solvent polarity,the emission peaks of POPC,POPYC and POPMC were red-shifted by 65 nm,42 nm,and 60 nm,respectively.Their slopes were 11249.02 cm^-1,7193.23 cm^-1 and 10798.05 cm^-1,respectively.The above results indicated that the charge transfer ability of POPC was stronger than the other two compounds.In the solid state,the fluorescence emission peak of POPC was located at 370 nm,the main room temperature phosphorescence emission peak was at 511 nm(2.70 ms);the fluorescence emission peak of POPYC solid was located at 401 nm and 421 nm,the main room temperature phosphorescence emission peak was at 516 nm(36.15 ms);The fluorescence emission peaks of POPMC solid were located at 397 nm and 492 nm,respectively,the main peak of room temperature phosphorescence emission was at 492 nm(2.63 ms).In the fourth chapter,designed and synthesized phenothiazine compounds PZCOC,PZCOPF,POCOC,and POCOPF with carbonyl as the bridging group.The structure of four compounds was characterized and their luminescence properties were studied.The results showed that with the increase of solvent polarity,the fluorescence emission peak of PZCOC and PZCOPF exhibited ICT characteristics.The calculation results showed that the HOMO of PZCOC was mainly concentrated on the carbazole ring,and the LUMO was mainly concentrated on the carbonyl group.The measured fluorescence and room temperature phosphorescence spectra in the solid state showed that the fluorescence emission peaks of PZCOC were located at 347 nm,383 nm,and 406 nm,respectively,and the room temperature phosphorescence emission peaks were located at 529 nm and 656 nm(10.49 ms).The fluorescence emission peaks of PZCOPF were located at 446 nm and 509 nm,and the room temperature phosphorescence emission peaks were located at 509 nm(15.81 ms).