The Study On Photoelectric Properties And Catalytic Application Of Aromatic Triangle [Pd₃]⁺ Complexes

Aromatic triangular metal complexes are widely used in the fields of metal organic synthesis,catalytic reactions and coordination chemistry,and have great potential for development.Aromatic triangular palladium complexes are an important branch.The photochemical and electrochemical studies of such complexes have attracted widespread attention as an important way to understand their electronic properties.The aromatic triangular palladium complexes have shown excellent catalytic performance on the selective hydrogenation of internal alkynes and the cyclization of 1,6-enynes.This paper will explore the photoelectrochemical properties of a series of functional triangular palladium complexes and further expand their applications in catalytic coupling reactions.The work is as follows:1.Four aromatic triangular palladium complexes[Pd₃]⁺were prepared using Pd（dba）₂,diaryldisulfide/selenium compounds and phosphine ligands as raw materials.The photochemical and electrochemical properties of aromatic triangular palladium were explored by fluorescence spectroscopy and cyclic voltammetry.[Pd₃]⁺exhibits luminescence properties close to ratio fluorescence.Under the gradient temperature of77K-298K,the emission peak intensities around 550nm and 780nm show regular changes,reflecting the temperature-sensitive luminescence properties of this type of complex.The cyclic voltammetry test of[Pd₃]⁺in acetonitrile obtained a set of quasi-reversible redox peaks,showing stable redox properties.2.The aromatic triangular palladium complex[Pd₃]⁺was applied to the Suzuki-Miyaura coupling,and excellent reactivity was achieved.By optimizing the reaction conditions（base type,solvent type,reactant ratio,reaction time,temperature）,high-efficiency reaction activity is obtained.In the coupling system involving halogenated aromatic hydrocarbons and substituted phenylboronic acids,the[Pd₃]⁺catalyst exhibits specific and efficient catalysis for iodoaromatics.We have expanded a large number of reaction substrates,and investigated the electronic effects and steric hindrance of the substituents on iodoaromatics and substituted phenylboronic acids.Most of the reaction substrates achieved up to 99%under optimal conditions.We further applied[Pd₃]⁺to catalyze the synthesis of non-steroidal anti-inflammatory drugs（selective COX-2inhibitors）analogs（2-[1,1’-biphenyl]-2-ylbenzothiazole）.An isolated yield of 94%was obtained,which expanded the application in the field of synthesizing vital pharmaceutical intermediates.Based on the high-efficiency reaction activity of this type of complex,we conducted a series of studies on the mechanism of the Suzuki reaction,and speculated that its unique selectivity to iodinated aromatic compounds stems from the selectivity of the iodine atom to the C-S/C-Se bond of the catalyst during the catalytic process.3.We further study the application of aromatic triangular palladium complex[Pd₃]⁺in the coupling reaction of Sonogashira and Glaser.The conditions such as the type of base,solvent type,reactant ratio,reaction time,temperature and other conditions required for the reaction process were explored and optimized,and it was proved that the aromatic triangular complex[Pd₃]⁺as a catalyst is effective for the above two reaction types.