Study On Synthesis And Optical Properties Of Conjugated Compounds Containing Indole Ring

Because Organic Light-Emitting Diodes（OLEDs） own excellent pr-operties of low driving voltage, small volume, fast response, lightwei-ght, high brightness and potential for fabrication of large-area fullcolor flat-panel display, OLEDs become one of the high-profile leading edge topics of optoelectronic information technology, possess a good market and business prospects. The small organic molecular electroluminescent materials show the properties of easy purification, high chemical mod-ification, high fluorescence quantum yield, production of sanki colored light, and have attracted much attention.Due to electron-rich and benzoheterocycle structure, indole deriva-tives employ not only good capability of high luminous and hole-tras-port, but also good thermal stability and solubility, so it is widely us-ed in OLED devices.In this paper, a series of conjugated compouds containing indole ring were designed and synthesized. The best reaction conditions of s-ome intermediates and target compounds were optimized and the spec-tral property was explored preliminarily.1. Synthesis of conjugated compounds containing indole ring（1） Five phosphonium salts were synthesized by using halogenated hydrocarbon and triphenyl phosphine as raw material:benzyltriphenylp hosphonium chloride （1a）,（naphthalen-l-ylmethyl）triphenylphosphonium chloride （1b）,（4-methylbenzyl）triphenylphosphonium chloride （1c）,（1,4-phenylenebis（methylene））bis（triphenylphosphonium） chloride （1d）,2-ene-1,4-diylbis（triphenylphosphonium） chloride （1e）;（2） Three intermidates:1-p-tolyl-1H-indole （2a）,1H-indole-3-carbaldehyde （2b）,1-p-tolyl-1H-in dole-3-carbaldehyde （3a） were synthesized through Vilsyemer reactiona-nd Ullmann reaction;（3） Five target compounds:3-styryl-1-p-tolyl-1H-indole （4a）,3-（2-（naphthalen-1-yl）vinyl）-1-p-toly1-1H-indole （4b）,3-（4- methylstyryl）-1-p-tolyl-lH-indole （4c）,1,4-bis（2-（1-p-tolyl-1H-indol-3-yl） vinyl）benzene （4d）,1,6-bis（1-p-tolyl-lH-indol-3-yl）hexa-1,3,5-triene （4e） were synthesized through Wittig reaction with3a and4a、4b、4c、4d、4e respectively;（4） The synthetic route of3a was optimized. The bet-ter synthetic route:3a was synthesized through Vilsyemer reaction wit-h indole as raw material first and Ullmann reaction with p-iodotoluene then. The reaction condition of3a was optimized. The best synthesis condition:n （3a）:n （p-iodotoluene）:n （K2CO3）:n （Cu）=1:1.2:1.2:1.2, reactans was heated at20h. The reaction condition of4c was opti-mized. The best synthesis condition was:n （3a）:n （1c）:n （t-BuOK）=1:1.5:3, reactans was heated at20h in absolute ethyl alcohol under using t-BuOK as catalyst. The structure of all the synthesized compo-unds were confirmed by IR,1H NMR and13C NMR.2. Study on the optical property of compoundsThe optical properties of the synthesized compounds3a and4a-4e was studied preliminary.（1） Compared with the UV-vis absorption sp-ectra and fluorescence emission spectra of3a, the λmax of4a-4e （in C H2Cl₂, UV-vis λmax=336～369nm, fluorescence λmax=403～471nm） exhi-bited significant red-shift, because the conjugated system of these co-mpounds increased;（2） Compared with the UV-vis absorption λmax and the fluorescence emission λmax of4a-4e, the result showed λmax（4b）>λ max（4c）λmax（4a）,λmax（4d）>λmax（4e）;（3） Studied the UV-vis and fluore-scence behavior of3a、4a-4e in cyclohexane and dichloromethane, the result indicated that λmaxexhibited small red-shift in strengthen polarity solvent dichloromethane.