Effects Of Ligands On The Properties Of Transition Metal Os(?)and Ru(?) Complexes And Their Applications

As a kind of phosphorescence materials with excellent properties,transition metal complexes have been widely used in the fields of OLED,photodynamic therapy,photocatalysis and triplet-triplet annihilation?TTA?upconversion,and have become one of the research hotspots in recent years.This is mainly because the transition metal complexes have a long lifetime of triple excited states and complex and diverse excited state properties,which makes this kind of topic of great significance in the study of theoretical and application value.However,how to regulate the photophysical and electrochemical properties of transition metal complexes through ligands to obtain the desired excellent properties is still a very important research topic.The research content of this thesis is mainly carried out by using two transition metals of the same main group,Os???and Ru???.Through the regulation of ligands,the photophysical and electrochemical properties of transition metal osmium and ruthenium complexes are studied,and the applications of all transition metal complexes are studied.The main contents are as follows:We selected different types of polypyridyl ligands or modified on bipyridine ligands to synthesize four Os???complexes?Os-1,Os-2,Os-3,Os-4?with direct S₀?T₁absorption.The effects of the configuration of Os???complexes based on tridentate ligands and bidentate ligands on their photophysical properties were studied by means of UV-Vis,emission spectra,transient absorption spectra and DFT/TDDFT theoretical calculations.It is found that the excited state lifetime of the Os-2 complex??=281 ns?formed with the2,2'-bipyridine ligand is longer than that of the Os-1 complex??=71 ns?formed by the2-bipyridine ligand.The great difference in the excited state lifetimes of the two Os???complexes is due to the strong effect of the space interaction on the field strength of the ligands,resulting in the increase of the energy gap between the ³MLCT and ³MC states.Furthermore,we introduced organic chromophore pyrene to modify Os-2,which has the best photophysical properties,and synthesized the complex Os-4.Compared with the unmodified Os-2,the luminescence quantum efficiency of Os-4 is increased by 6 times.The application of Os???complex as triplet photosensitizer in TTA upconversion was also studied,and the upconversion from red light to blue-green light was realized,and the anti-Stoke shift was as high as 160 nm.The upconversion quantum yields of Os-2 and Os-4 were 1.4%and 1.2%,respectively.In addition,we chose[Ru?bpy?₃]PF₆?Ru-0?as the parent complex,and two Ru???complexes Ru-1 and Ru-2 were synthesized by introducing electron withdrawing group-CF₃and donor group-OCH₃,into the ligand.It was found that the oxidation potential of Ru-1increased to 1.41 e V compared with that of the parent complex Ru-0,while the oxidation potential of Ru-2 increased to 1.05 e V.Then it was applied to the photocatalytic organic synthesis reaction,and the photocatalytic properties of Ru?II?complexes with different redox potentials were investigated,and we realized the phosphonylation of alkyl tertiary amines by photocatalysis for the first time.It was found that under the same experimental conditions,the photocatalysts of Ru-0,Ru-1 and Ru-2.The yields of Ru-0 and Ru-2 are 23%and 70%respectively,but the target product can not be obtained in the reaction of Ru-1 catalyst with the highest oxidation potential,which indicates that the appropriate redox potential is an important parameter for the smooth progress of photocatalytic reaction.Finally,the substrate expansion study was carried out with Ru-2 catalyst,and it was found that the photocatalyst had high universality and the yield of each product was more than 50%.