Aluminum chelate complex for organic el material

Abstract

This invention provides an organic EL material useful for the emissive layer of an organic EL element which deteriorates little in luminance when operated over a prolonged period of time and shows excellent durability. The material is an aluminum chelate complex which is represented by general formula (1) in which Ar 1 is a mono- or bicylic arylene group, Ar 2 is a mono- or bicyclic aryl group, R 1 —R 6 are hydrogen or hydrocarbon groups containing 1-8 carbon atoms and contains a compound represented by general formula (1) in which Ar 2 is a halogen as an impurity in an amount of 350 wt ppm or less.

1 . An aluminum chelate complex for an organic EL element represented by general formula (1) which contains less than 350 wt ppm of a compound represented by general formula (2) as an impurity:  
     
       
         
         
             
             
         
       
     
     in general formulas (1) and (2), Ar 1  is a bicyclic arylene group, Ar 2  is a mono- or bicyclic aryl group, the total number of aromatic rings in Ar 1  and Ar 2  is 3 to 4 and these aromatic rings may be condensed; R 1 —R 6  are independently hydrogen or hydrocarbon groups containing 1-8 carbon atoms.  
   
   
       2 . An aluminum chelate complex as described in  claim 1  wherein Ar 1  is naphthylene, Ar 2  is naphthyl or phenyl and X is Br, Cl or I in general formulas (1) and (2).  
   
   
       3 . A method for preparing an aluminum chelate complex described in  claim 2  by reacting aluminum isopropoxide successively with a quinolinol derivative and a phenolic compound represented by HO—Ar 1 —Ar 2  which comprises purifying the quinolinol derivative and the phenolic compound in such a manner as to reduce the amount of a compound contained therein and represented by HO—Ar 1 —X to 350 wt ppm or less and then submitting them to the reaction.  
   
   
       4 . A method for preparing an aluminum chelate complex described in  claim 1  by reacting aluminum isopropoxide successively with a quinolinol derivative and a phenolic compound represented by HO—Ar 1 —Ar 2  which comprises purifying the quinolinol derivative and the phenolic compound in such a manner as to reduce the amount of a compound contained therein and represented by HO—Ar 1 —X to 350 wt ppm or less and then submitting them to the reaction.  
   
   
       5 . A method for preparing an aluminum chelate complex described in  claim 1  by reacting aluminum isopropoxide successively with a quinolinol derivative and a phenolic compound represented by HO—Ar 1 —Ar 2  which comprises purifying by sublimation the crude aluminum chelate complex containing 350 wt ppm or more of a compound represented by general formula (2) after washing with or recrystallization from an organic solvent until the amount of said halogen-containing compound becomes 350 wt ppm or less.  
   
   
       6 . A method for preparing an aluminum chelate complex as described in  claim 4  or  5  which comprises reacting a compound represented by HO—Ar 1 —X with a compound represented by (Ar 2 ) a —Y (wherein Y is Cu, X, Li, B(OH) 2 , MgX, ZnX and SnMe 3 , X is a halogen and a is an integer of 1-10) to form the phenolic compound represented by HO—Ar 1 —Ar 2 .  
   
   
       7 . A method for preparing an aluminum chelate complex as described in  claim 6  which comprises purifying by recrystallization the phenolic compound obtained by the reaction and represented by HO—Ar 1 —Ar 2  and purifying by sublimation the aluminum chelate complex obtained from said phenolic compound.  
   
   
       8 . An organic EL element containing an emissive layer of an organic compound between the anode and the cathode wherein the emissive layer comprises an aluminum chelate complex described in  claim 1  as a host material and a phosphorescent organic complex of a noble metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold as a guest material.  
   
   
       9 . An aluminum chelate complex for an organic EL material as described in  claim 1  wherein quality control is exercised to keep the amount of a compound represented by general formula (2) at 350 ppm or less and this amount is determined and controlled in the stage for production, shipping or use.