Based On 1,3,5-tris (1-imidazolyl) Benzene Ligand And Halogen Ion To Build Room Temperature Phosphorescent Zn (Ⅱ) Complex

Phosphorescence is the process in which a substance slowly releases stored energy in the form of light after absorbing.Room temperature phosphorescence（RTP）materials have broad application prospects in organic light-emitting diodes,chemical sensing,and anti-counterfeiting technology due to their high energy utilization and long afterglow under environmental conditions.In recent years,organic RTP materials based on crystallization or host-guest interaction have attracted much attention.However,how to effectively enhance the weak spin-orbit coupling of organic molecules and stabilize high-energy triplet excitons,and obtain efficient and long-lived RTP is still one of the main problems in current research.The crystalline hybrid materials have rich structure and composition based on coordination between organic ligand and metal.Chlorine,bromine and iodine ions can be introduced into the hybrid framework in the form of dissociation or coordination.Its heavy atom effect will enhance the spin-orbit coupling of organic molecules and promote the intersystem crossing to obtain triplet excitons.At the same time,the crystal frame can effectively inhibit the molecular motion stabilize triplet excitons and avoid their rapid deactivation.The construction of this system can effectively improve the quantum efficiency,and show unique advantages in obtaining adjustable phosphorescent color and lifetime.Therefore,in this paper,1,3,5–tris（1-imidazolyl）benzene（tib）with potential luminescence properties is used as a ligand,and a series of hybrid crystalline materials have been constructed with the participation of halogen ions.The RTP properties of this type of material are described in detail.The specific work is as follows:1.Two types of one-dimensional organic-metal halide Zn₃（tib）₂X₆（1,X=Cl/Br/I）and Zn₂（tib）（L）Br₃（2,L=HCOO/CH₃COO for a/b）are designed.The complex 1-Cl/Br/I exhibit RTP characteristics through the influence of crystallization and heavy atoms,and show lifetimes as 54.39,16.28 and 1.51 ms and quantum yields as 2.65,2.12 and 6.44%under environmental conditions,respectively.1-Cl has 5s visible afterglow by naked eye.On this basis,the in-situ introduction of carboxylic acid co-ligands into complex 2,which can change the phosphorescence color by modulating the excitation wavelength,and its quantum yields could reach 14.2%and 13.6%under ambient conditions,respectively.When the excitation wavelength of 2b gradually increased from 280 nm to 420 nm,its phosphorescence emission peak shifted from 483 nm to 558 nm.The phosphorescence color was modulated from blue to yellow at room temperature,which enriched the excitation energy-dependent RTP system;2.Zinc phosphite motifs with cluster,chain,and layer structure may have stronger limiting effect on organic components than the single metal node.Therefore,we prepared two types of hybrid zinc phosphite structures containing halogen ions[Zn₃（HPO₃）₂（tib）₂]·X₂（3,X=Cl/Br/I）and[Zn₄X₄（HPO₃）₂（tib）₂]·4H₂O（4,X=Cl/Br）,in which the halide ion acts as counter anion in 3,and the terminal and bridging coordination mode in 4.Complex 3 shows different phosphorescence emission wavelengths and lifetimes according to varying excitation wavelengths under environmental conditions,and their phosphorescent quantum yields can reach up to 9.1%,8.9%,and 5.8%,respectively.In complex 4,the directional heavy atom effect was caused by the modification of the hybrid skeleton with halogen ions,resulting in quantum yields of 6.3 and 8.7%,and lifetimes of 90.1 and 74.6 ms at room temperature.