Synthesis,Photophysical Properties And Bioimaging Of Chalcone Derivatives And Terpyridine Iridium Complexes

Iridium(Ⅲ)complexes have been extensively used in energy,nonlinear optical materials and biomedical fields due to their long-lived luminescence,large Stokes shift,good photostability and biocompatibility.As a kind of ideal candidate for chelating ligands,terpyridine and its derivatives are ideal ligands for complexes assembling due to their strong coordination ability and easy modification mode.In this dissertation,a series of novel iridium(Ⅲ)complexes was constructed based on functionalized terpyridine ligands,which expected to provide new ideas for multi-photon absorption and biological applications.The main work of this dissertation are as follows:1.Synthesis,structure,optical properties and bioimaging of chalcone derivatives of terpyridine precursorsTwo series of compounds L1～L3 and L1-1～L3-1 were designed and synthesized with alkyl chain modified carbazole as electron donor and chalcone pyridine or dicyanopyridine as electron acceptor.The crystal structure analysis exhibited that the pyridyl compounds have good planarity,and the intermolecular force of biscyanopyridyl compounds is stronger,which is conducive to electron delocalization.The effects of different pushing and pulling electron groups and halogen atoms on the photophysical properties of the compounds were studied systematically.The intramolecular charge transfer was enhanced with the introduction of the strong electron-pulling dicyanide group.The absorption and emission peaks of the compounds had obvious red-shift.With the introduction of halogen atoms,the delayed fluorescence properties of the compounds are improved.D-π-A structure makes the six compounds possess good nonlinear optical properties.Simultaneously,the steric effect of the dicyanide group destroyed the planarity of the molecules,which made the compounds L1-1～L3-1 exhibit twisted intramolecular charge transfer(TICT)and aggregation-induced emission(AIE)properties.Biological studies have shown that six chalcone derivatives can specifically target subcellular organelle lipid droplets.L1-1,which has the best luminescence performance,can be used for monitoring lipid droplets under multi-photon confocal microscope and super-resolution microscope and hold broad application prospects in the field of biomedicine.2.Assembly and photophysical properties of long-chain modified terpyridine iridium complexesOn basis of chalcone derivatives,a series of terpyridyl compounds were further synthesized.Three "3+3" type iridium(Ⅲ)complexes Ir-Kt1-8OC,Ir-Kt2-8OC and Ir-Kt3-8OC were assembled based on terpyridines which had strong coordination ability.By studying the optical properties of the three complexes,it was found that the introduction of halogen atom(-Br,-I)improved the two-photon absorption activity,showing good third-order nonlinear optical properties.Meanwhile,with the introduction of halogen atom,the singlet oxygen yield of the complex was enhanced significantly,and the yield of Ir-Kt3-8OC was up to 0.83.Due to good biocompatibility,the complex also shows certain photodynamic activity in cells,which has potential applications in cancer diagnosis and treatment.3.Design and synthesis of terpyridine iridium complexes with lipid droplet targeting and two photons photodynamic activityOn the basis of halogen-modified carbazole terpyridine ligand,the Ir-C bond was introduced to synthesize three "3+3" type cyclometalated iridium(Ⅲ)complexes Ir-Kt1-CNC,Ir-Kt2-CNC and Ir-Kt3-CNC.By studying the photophysical properties,it revealed that the introduction of Ir-C bond makes complexes exhibit good near-infrared luminescence properties.With the introduction of halogen atom(-Br,I),the two-photon absorption of the complexes was optimized,and the singlet oxygen production rate was also increased.Based on the good lipid solubility and biocompatibility of the complexes,confocal experimental studies have found that the complexes can specifically target intracellular lipid droplets.It showed good intracellular photodynamic effect under light,and it is expected to realize the two-photon photodynamic therapy with subcellular organelle targeting.4.Design,synthesis,photophysical properties and organelle specificity of different lipid soluble iridium terpyridine complexesFour "3+2+1" type cyclometalated iridium(Ⅲ)complexes,Ir-Kt1-Cl,Ir-Kt1-CN,Ir-8OC-Cl and Ir-8OC-CN,were assembled by different electron-donating abilities of terpyridine or solvent molecules as ligand.The photophysical properties of the four complexes have been studied systematically.It is found that the complexes exhibit high fluorescence quantum yield,long-lived luminescence and large two-photon absorption cross section.The four complexes are responsive to temperature and viscosity due to their larger conjugated system and long flexible chains.Biological experiments have shown that iridium complexes with different lipid solubility can target different subcellular organelles in cells,which provides an idea for designing different subcellular organelles targeted iridium complexes.