Novel Cyclometalated Palladium(?) And Platinum(?) Complexes:Synthesis,Photophysical Properties And Liquid Crystalline Characteristics

With the rapid development of organic electroluminescent diode(OLED)in display fields,people have to seek for excellent luminescent materials to meet the demands.Organic metal luminescent materials have been received great attentions due to its good luminescent performance,long service lifetime and simple preparation process.Transition metal complexes,like platinum(?),iridium(?)complexes and so on,can take advantage of their heavy atom effect with intensive spin-orbital coupling,accelerating the fast-intersystem crossing between singlet and triplet states,raising the efficiency of phosphorescence.As a result,there are many reports about related metal complexes.However,because palladium(?)and platinum(?)complexes are attributed to squareplaner coordination complexes,it is easy to form liquid crystalline complexes by simple modification.Recent researches show its potentional applications in PL-LCD(photoluminescence-liquid crystal displays)fields.This dissertation is composed of six chapters.In chapter 1,I mainly introduce the overview and progress of OLED,the mechanism of luminescence;The typical samples of the red luminescent materials,blue luminescent materials and green luminescent materials are summarized;Metal liquid crystalline palladium(?),platinum(?)and iridium(?)complexes are especially discussed;Some copper(?)complexes also are simple introduced;finally,the characteristics of this dissertation are briefly introduced.In chapter 2,A new type of palladium(?)complexes were reported,where 2-(3-iodophenyl)pyridine(HIppy)was used as the main ligand,acetylacetone(acac)as the auxiliary ligand.The quantum efficiency of(Ippy)Pd(acac)is more 15 times higher than(ppy)Pd(acac),indicting that iodine atom in the main ligand could effectively reduce non-radiation decayed rate of the excited state.Therefore,this palladium(?)complexes can be obvious observed luminescence at room temperature.In chapter 3,three new square planar platinum(?)complexes are reported.The complexes with two side long chains display monotropic smectic liquid crystalline behavior.It is discovered in this type of complexes that display different photophysical property in solution and solid state caused by intermolecular associations.In addition,the number of flexible alkoxy chain in cyclometalated ligand can effectively promote and enhance intermolecular Pt···Pt interactions and ?-? interactions.In chapter 4,a series of cyclometalated platinum(?)complexes are successfully obtained,which is firstly reported liquid crystalline behavior by introduction of a very short alkoxy chain or even no alkoxy chain in cyclometalated ligand.On the contrary,with increasing of the length of alkoxy chain,the complexes were not found liquid crystalline property.In addition,all complexes display unique luminescence characteristics caused by intermolecular Pt-Pt interactions and ?-? interactions.In chapter 5,six new cyclometalated platinum(?)complexes were successfully reported,where tetrazole derivatives firstly are used as ligand to synthesized liquid crystalline complexes.The complexes with no any peripheral chains are observed mechanochromism.In addition,the polarized luminescence and carrier moblity are researched.In chapter 6,I summarize the research result of this dissertation and predict the future in this research direction.