Design,Synthesis And Properties Of Phosphorescent Platinum/Manganese Complexes

Due to the heavy atom effect of the metal center of phosphorescent transition metal complexes,the orbital coupling effect is enhanced,and singlet excitons and triplet excitons can be used at the same time,which greatly increases the quantum efficiency of phosphorescence.Thus,phosphorescent transition metal complexes have become a research hotspot in the field of organic optoelectronics.In addition,the phosphorescent transition metal complex also has the following characteristics:1)The heavy atom effect of the metal center enables the intersystem crossing from singlet to triplet state to occur effectively,achieving a long phosphorescent lifetime from triplet radiation relaxation;2)The ligand structure is easy to be modified,by changing the position and number of electron donating/electron-withdrawing groups.Thus,the emission wavelength,lifetime,and quantum efficiency of the transition metal complex can be effectively adjusted;3)Excellent photophysical properties,such as large stokes shift,high phosphorescence efficiency and excellent photo stability,etc.,can be obtained.This thesis focuses on the development of new functional phosphorescent metal complexes.The main research contents are shown as follows:1. Design,synthesis and circular polarized luminescence properties of chiral platinum（Ⅱ）complex based on binaphthyl isonitrile.Nowadays,circularly polarized luminescent materials,such as organic small molecules,polymers,liquid crystals,and supramolecular self-assembly,etc.,are difficult to possess both high asymmetric factors(g_lum)and high luminescent efficiency for electroluminescent devices.This challenge hinders the application of circularly polarized luminescent materials in the field of organic optoelectronics.Phosphorescent metal complexes,such as iridium（Ⅱ）and platinum（Ⅱ）,can utilize both singlet and triplet excitons through the spin-orbit coupling effect of the heavy atom leading to highly efficient phosphorescence emission.In this work,we chose C^N^N as the tridentate chelating ligand,and introduced R/S-1,1’-bi-2-naphthol as the chiral generation unit on the auxiliary ligand isonitrile structure to synthesize a pair of ionic phosphorescent platinum（Ⅱ）complexes under mild reaction conditions.Studies on their photophysical properties in different aggregation states revealed that this pair of enantiomers exhibited red light emission.Compared with the emission measured on the film,the emission of the solid powder exhibited an obvious red shift.This may be due to different intermolecularπ-π/Pt-Pt interaction in different aggregation states.A study of their circularly polarized luminescence properties revealed that both have obvious chiral optical activity,and their asymmetry factors(g_lum)are 0.65×10^-3 and-0.36×10^-3,respectively.Finally,we explored the self-assembly morphology of this pair of complexes in mixed solutions of DMSO and water in different proportions,and found that they can form nanosheets with lengths of tens of microns in pure DMSO solution.In addition,we also found that the morphology of the complexes is related to the aging time in pure DMSO.2. Design,synthesis and application of manganese（Ⅱ）complex based on phosphine oxide ligand.The currently developed phosphorescent metal complexes are mainly based on precious metal elements such as iridium and platinum.Manganese is a cheap and easily obtained metal,and the manganese（Ⅱ）complex has the characteristics of high luminescence quantum efficiency and long phosphorescent lifetime.Therefore,it is very important to exploitt low cost manganese（Ⅱ）complexes for optoelectronic field.In this work,we prepared four phosphorescent manganese（Ⅱ）complexes by using phosphine oxide ligand.Crystal structure studies show that the crystals of Mn1b and Mn2b grown in methanol have four-coordinated metal centers,while those of Mn1a and Mn2a grown in ethanol and dichloromethane have both four-coordinated and six-coordinated metal centers.Subsequently,we studied the photophysical properties of these four manganese（Ⅱ）complexes,and realized the tuning of the emission color from yellow-green light to orange-red light,while the emission lifetime can be as long as 20 ms.Finally,we used an ethanol solution containing Mn Br₂ as an ink and a commercial printer to print information on security paper coated with phosphine oxide ligand.The information cannot be read under natural light,but can be identified under the 254 nm ultraviolet light,realizing the information encryption.