Design,Synthesis,and Theoretical Computational Study Of Platinum(Ⅱ) And Iridium(Ⅲ) Complexes Containing Pyridine And Pyridine-Derived Ligands

Organic luminescent materials are known for their low cost,easily modifiable structure,and ease of processing.Transition metal complex materials,have advantages such as broad UV-visible absorption and large Stokes shift.Therefore,domestic and international scholars have widely studied organic-transition metal complex materials.In addition,the quaterpyridine ligand possesses multiple binding sites and is a common ligand in organometallic complexes.With the deepening of research,it has become increasingly common to study the electronic structure,electronic excitation properties,and excited state characteristics of materials through quantum chemistry methods.Theoretical calculations can explain the photophysical properties and luminescence mechanisms of materials more fundamentally.This study synthesized two platinum(Ⅱ)complex molecules([(C^N)Pt(N^N)]Cl)and characterized their spectral properties,focusing on the influence of concentration,solvent,temperature,and oxygen on photophysical properties.The photophysical properties of a series of platinum(Ⅱ)and iridium(Ⅲ)complex molecules were explained through DFT calculations.This provides a theoretical basis for designing transition metal optoelectronic materials.The main research content is summarized as follows:1.Design,synthesis,and photophysical characterization of platinum(Ⅱ)complexes containing quaterpyridineWe designed a series of platinum(Ⅱ)complexes with quaterpyridine ligands.The influence of the external environment on the photophysical properties of platinum(Ⅱ)complexes was investigated by varying the complex concentration,solvent polarity,and oxygen concentration.The results revealed that in solution,the platinum complexes exhibited a tendency to aggregate,as demonstrated by the non-linear relationship between solution concentration and absorbance in dilute solutions,as well as the initial increase and subsequent decrease in emission intensity with increasing concentration.It was also observed that oxygen quenched both types of complexes,with quenching constants of oxygen 1.2× 10-3%-1 and 5.3×10-3%-1,respectively.Through theoretical calculations,the stable planar structure of the molecules in the ground state was simulated,and the absorption spectra of the molecules were also simulated,yielding spectra that closely resembled the experimental results.Excited-state analysis,such as hole-electron analysis,provided a clear understanding of the material’s excitation characteristics and laid a theoretical foundation for the blue shift in luminescence induced by the introduction of fluorine atoms.SOC calculations demonstrated that the material exhibited significant intersystem crossing and displayed excellent phosphorescent properties.2.A theoretical computational study of platinum(Ⅱ)and iridium(Ⅲ)complexes containing violagenWe methylated the tetrapyridine ligand,thus designing three platinum(Ⅱ)complexes containing violagen ligands.By employing density functional theory(DFT)and time-dependent density functional theory(TD-DFT),we investigated the differences in the photoluminescent properties of the quaterpyridine ligand before and after oxidation.The results revealed a significant red shift in the emission of the complexes after methylation.Furthermore,we performed unrestricted density functional theory(UDFT)calculations on the reduced porphyrin dication to examine the changes in dihedral angles of the porphyrin ligand before and after oxidation.Subsequently,we replaced platinum(Ⅱ)with iridium(Ⅲ)to validate the generality of the aforementioned conclusions.The results demonstrate that the same trends hold true in the iridium(Ⅲ)complexes.