Application Of Fused-heterocyclic Compounds And Their Iridium Complexes In OLEDs And Chemosensors

Electroluminescent materials are important pillars to support the field of OLED, but also animportant bottleneck to limit this field. Predecessors have been carried out a considerable part of thesignificant exploratory and synthesized a variety of red phosphorescent materials based onfused-heterocyclic compounds. These phosphorescent materials collect various functional units andhave many advantages.（1） High quantum efficiency;（2） Adjusted the emitted light color;（3）Balanced charge injection and migration. The phosphorescent materials containingfused-heterocyclic ligands have been successfully applied to the devices and made greatcontributions to the development of a red phosphorescent materials. In addition, manyfused-heterocyclic compounds have great conjugate, and a lot of hetero-atoms on thefused-heterocyclic compounds can chelate metal ions to form metal complexes. So,fused-heterocyclic compounds are often used in fluorescent chemical sensors.This thesis synthesized a series of fused-heterocyclic compounds, include phthalazine andquinazoline derivatives. The applications in electroluminescence and fluorescent chemosensors arestudied. We also reported the reactions of them with IrCl3and auxiliary ligands afforded bicycliciridium complexes or ionic iridium complexes. The photophysical, electrochemical andelectrophosphorescent properties of these complexes were investigated. We also synthesizedquinazoline derivative containing phenothiazine and quinazoline-4（3H）-thione. These compoundswere used as chemosensors to detect metal ions. The main contents were shown as follows:First, we synthesized novel iridium （III） complexes using phthalazine derivatives as the ligands.The introduction of carbazole and triphenylamine group into the ligands improved hole-transportingproperty and thermal ability of the corresponding complexes. The red-emitting organiclight-emitting diodes based on these complexes gave a maximum external quantum efficiency of16.8%and a maximum luminance of1484cd/m².Then, two new ligands N, N,2-triphenylquinazolin-4-amine and2-（9-ethyl-9H-carbazol-3-yl）-N, N-diphenylquinazolin-4-amine were prepared, and their corresponding cyclometalted complexeswere synthesized by the reaction of these two ligands with IrCl3and2-pyridine carboxylic acid,acetylacetone, dibenzoylmethane or2-（2-pyridyl）-4-（phenylquinoline）. The UV-vis andphotoluminescence （PL） spectra were determined, and the electrochemical behavious of thecomplexes were studied. The complexes had red photoluminance in dichloromethane. The OLEDdevices with Ir（PQD）₂（acac） and Ir（PQD）₂（pic） as emitting materials and CPB or PBD+PVK as hostmaterial were prepared. The CIE of both two devices are closd to pure red, and the devices based on Ir（PQD）₂（pic）had a maximum external quantum efficiency of18.44%and a maximum Luminanceof7107cd/m².Another part of this thesis was about the application of the quinazolin compounds inchemosensor for metal ions. Because Cu²⁺can oxidate the sulfur in phenothiazine into sulfoxide, sothe quinazolin compound （ECQP） were synthesized by introduce phenothiazine used to detecteCu²⁺. When the concentrations of Cu²⁺increased in the solution of the quinazolin compound, theUV–Vis absorption and photoluminescence spectra of the solution changed observably. The color ofthe solution varied from yellow to colorless. Otherwise, the further research was carried out toinvestigatethe detection of oxidation state ECQPO for Hg²⁺. Upon Hg²⁺dissolved in MeCN wasadded into the solution of ECQPO, The emission of504nm was gradually quenching. But puttingHg²⁺into the solution of ECQP directly, the PL spectra of the solution had no change. This sensorhas the INH effect of logic gate.A highly selective fluorescent probe TPS for Hg²⁺was also designed and characterized. Whenmixing with Hg²⁺, TPS interacts with Hg²⁺in a2:1(TPS-Hg²⁺) stoichiometry via a coordinationbond interaction between the sulfur atom. Upon addition of Hg²⁺, probe TPS showed a remarkabledecrease in fluorescence spectra （468nm） with clear color change from yellow to red, so probe TPScould serve as a “naked-eye” probe for Hg²⁺. Upon addition of KI to the solution of TPS-Hg²⁺species, the spectra can restore to the original spectrum in absorption and phosphorescent andindicates that this probe could be reused. The probe exhibited excellent reproducibility, reversibilityand selectivity.