Design,synthesis,Crystal Structure And Biological Imaging Of Multiphoton Active Quinolinyl Iridium Complexes

In recent years,photoelectric functional complex materials were widely used in the fields of microelectronics,chemical sensing,and biomedicine.Furthermore,iridium complexes have bright application prospects in biomolecular recognition and cell imaging due to their excellent nonlinear optical properties and good biocompatibility.In this dissertation,a series of new cyclometalated iridium complexes were constructed by quinoline derivatives,Schiff and?-diketones bases derivatives acting as bioactive ligands,respectively.By combined photophysical properties and structures-property correlation of these complexes are systematically studied,in addition,the application in biology is explored.The main results are as follows:1.Design,synthesis,crystal structure and biological application of highly selective recognition of histidine/BSA series iridium complexesHerein,two cyclometalated solvent molecules iridium(III)complexes B1 and B2were synthesized by quinoline derivatives and acetonitrile solvent molecules acting as ligands.The single crystals of the complexes were obtained.The results of the photophysical properties investigation showed that the addition of His and BSA to the complex B2 triggered the fluorescence enhancement,fluorescence lifetime extension and quantum yield improvement.In addition,the experimental phenomenon combined with the crystal structure expounded the structure-activity relationship of the complexes.Through selective experiments with biomolecules,it is found that B2 has a higher selectivity and sensitivity to His/BSA.NMR spectra and high-resolution mass spectrometry further demonstrated that the recognition site and reaction mechanism with BSA/His.Then,the nonlinear optical properties study revealed that B2 has excellent two-photon and three-photon activity after adding His and BSA.The results of biological imaging showed that the complex B2 realized the visual imaging of exogenous histidine in cells.2.Design,synthesis,crystal structure and application of Schiff base series iridium complexes in photodynamic therapyFour Schiff base iridium complexes with multiphoton activity and excellent active oxygen generation ability were synthesized by N,N-diethyl/hydroxyethylaniline Schiff base and quinoline derivatives acting as ligands.Four single crystals of iridium complexes were obtained.Among them,F1 and F2 belong to the triclinic system and the center-symmetric P?space group,and F3 and F4 belong to the monoclinic system and the center-symmetric P2₁/c space group.Crystal structure analysis can find that these complexes have a lot of intermolecular interactions,moreover,F1 and F2exhibited aggregation-induced emission behavior in ethanol/water,and the change of solvent polarity has a significant impact on the emission of F3 and F4.The introduction of Schiff base ligands increases the conjugation system of the entire complex,which is conducive to the charge flow in the molecule,therefore enhancing the nonlinear optical effect of the complex.All four complexes can produce effective singlet oxygen,which lays the foundation for further research on multiphoton photodynamic therapy.3.Design,synthesis,crystal structure and application of?-diketone series iridium complexes in kinetic therapyFour iridium complexes NY-1?NY-4 of?-diketone base were synthesized from HTTA and ferrocene diketone acting as ligands.Four single crystals of the complexes were obtained.In addition,except NY-3,which belongs to triclinic and center symmetric P?space group,the other three iridium complex belong to monoclinic and the center symmetric P2₁/c space group.The Ir-N and Ir-C bond length data in the crystal indicate that the coordination environment of iridium presents a deformed octahedral configuration.Moreover,the nonlinear optical properties showed that the four complexes have excellent two-photon absorption activity at 720 nm,and NY-3 has the largest two-photon absorption cross section.In order to study the influence of kinetic treatment,the generated singlet oxygen and hydroxyl radicals were further confirmed by the probe ABDA and terephthalic acid.The study results displayed that the complex NY-3 can produce singlet oxygen at the same time through the Fenton reaction of ferrous ions to produce hydroxyl radicals,Furthermore,ESR trapping measurements were carried out to further distinguish two kinds of ROS species.MTT test and confocal imaging experiments showed that the complex NY-3 has high phototoxicity and can quickly promote cancer cell apoptosis.Therefore,the result of synergistic treatment of photodynamics and chemotherapy is achieved.4.Design,synthesis,crystal structure and photophysical properties of?-diketone series iridium complexes with specific recognition of lecithinOn the third chapter?-diketone,four iridium complexes NW-1?NW-4 were synthesized by introducing different push-pull electronic groups(acetylacetone/hexafluoroacetylacetone)on the auxiliary ligand to adjust their biocompatibility.The single crystal structures of the four complexes were obtained and analyzed.The optical properties of the target complexes were systematically studied.The transition mechanism in the spectra was explained by theoretical calculation,and the influence of different push-pull electronic groups on the photophysical properties was clarified.Biomolecular selectivity experiments showed that the introduction of acetylacetone ligands in NW-1/NW-2 made the two complexes highly specific to lecithin,and the reaction mechanism with lecithin was proved by low temperature spectra and viscosity experiments.The results of unveiled that all the four complexes possessed considerable multiphoton absorption properties.The biological experiments showed that the complexes can specifically recognize lysosomes,which could be employed as two-photon fluorescence probes to monitor the dynamic changes of lysosomes in cells.