New Heterocyclic bridged biphenyls

Abstract

The present invention relates electroluminescent devices, comprising a compound of the formula (I), especially as host for phosphorescent compounds. The hosts may function with phosphorescent materials to provide improved efficiency, stability, manufacturability, or spectral characteristics of electroluminescent devices.

1 . An electroluminescent (EL) device, comprising a compound of the formula 
     
       
         
         
             
             
         
       
     
     wherein A is a 5-, 6-, or 7-membered heteroaromatic ring, containing at least one heteroatom selected from nitrogen, oxygen and sulfur,
 Z 1  is 
 
     
       
         
         
             
             
         
       
        NA 1 A 1′ , —P(═O)A 4 A 4′ , or —SiA 6 A 7 A 8 , 
       Z 2  is 
     
     
       
         
         
             
             
         
       
        —NA 2 A 2′ , —P(═O)A 5 A 5′ , or —SiA 6′ A 7′ A 8′ , 
       Ar and Ar′ are independently of each other C 6 -C 14 aryl which may optionally be substituted by one or more groups selected from C 1 -C 25 alkyl which may optionally be interrupted by —O—, or C 1 -C 25 alkoxy, 
       R 1 , R 2 , R 3 , R 4 , R 5  and R 6  are independently of each other hydrogen, halogen, or an organic substituent, or 
       R 1  and R 2 , R 4  and R 6 , R 2  and R 3 , R 5  and R 3  and/or R 5  and R 6 , which are adjacent to each other, together form an aromatic or heteroaromatic ring or ring system which can optionally be substituted, 
       R 7  is an organic substituent, wherein two or more substituents R 7  in the same molecule may have different meanings, or can form together an aromatic or heteroaromatic ring or ring system, and 
       x is 0, or an integer of 1 to 5; 
       A 1 , A 2 , A 1′  and A 2′  are independently of each other a C 6 -C 24 aryl group, a C 2 -C 30 heteroaryl group, which can optionally be substituted, or a group 
     
     
       
         
         
             
             
         
       
        wherein BU is a bridging unit, A 3  and A 3′  are independently of each other a C 6 -C 24 aryl group or a C 2 -C 30 heteroaryl group, which can optionally be substituted, or A 1  and A 1′  or A 2  and A 2′  or A 3  and A 3′  together with the nitrogen atom to which they are bonded form a heteroaromatic ring or ring system 
       A 4 , A 4′ , A 6 , A 7 , A 8 , A 5 , A 5′ , A 6′ , A 7′ , and A 8′  are independently of each other a C 6 -C 24 aryl group or a C 2 -C 30 heteroaryl group, which can optionally be substituted. 
     
   
   
       2 . The EL device according to  claim 1 , comprising a compound of formula 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       R 1  and R 4  are independently of each other hydrogen, halogen, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, CN, or —CO—R 28 , 
       R 2 , R 3 , R 5  and R 6  are independently of each other H, halogen, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 7 -C 25 aralkyl, CN, or —CO—R 28 , 
       R 8  and R 9  are independently of each other H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 7 -C 25 aralkyl, CN, or —CO—R 28 , or 
       R 8  and R 9  together form a group 
     
     
       
         
         
             
             
         
       
        wherein R 206′ , R 208′  R 205 , R 206 , R 207 , R 208 , R 209  and R 21  are independently of each other H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18 alkoxy, or C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 7 -C 25 aralkyl, CN, or —CO—R 28 , 
       R 10  is H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 7 -C 25 aralkyl, or —CO—R 28 , 
       R 8′  and R 9′  are independently of each other H, CN, —COOR 27 ; —CONR 25 R 26 , C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 7 -C 25 aralkyl, CN, or —CO—R 28 ; 
       R 11  and R 14  are independently of each other hydrogen, halogen, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, CN, or —CO—R 28 , 
       R 12 , R 13 , R 15  and R 16  are independently of each other H, halogen, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, 
       C 7 -C 25 aralkyl, CN or —CO—R 28 , 
       X is O, S, or NR 17 , wherein R 17  is H; C 6 -C 18 aryl; C 2 -C 20 heteroaryl; C 6 -C 18 aryl or C 2 -C 20 heteroaryl which are substituted by C 1 -C 18 alkyl, C 1 -C 18  perfluoroalkyl, or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—; 
       or two substituents R 1  and R 2 , R 4  and R 6 , R and R 12  and/or R 14  and R 6 , R 2  and R 3 , R 5  and R 6 , R 12  and R 13 , and/or R 15  and R 16 , which are adjacent to each other, together form a group 
     
     
       
         
         
             
             
         
       
        or two substituents R 15  and R 13 , and/or R 5  and R 3 , which are adjacent to each other, together form a group 
     
     
       
         
         
             
             
         
       
        wherein X 3  is O, S, C(R 119 )(R 120 ), or NR 17 , R 105 , R 106 , R 107 , R 108 , R 106′  and R 108′  are independently of each other H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18 alkoxy, or C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, 
       R 119  and R 120  are independently of each other C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, or C 7 -C 25 aralkyl, or 
       R 119  and R 120  together form a group of formula ═CR 121 R 122 , wherein 
       R 121  and R 122  are independently of each other H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, or C 2 -C 20 heteroaryl, or C 2 -C 20 heteroaryl which is substituted by G, or 
       R 119  and R 120  together form a five or six membered ring, which optionally can be substituted by C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 6 -C 24 aryl, C 6 -C 14 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 7 -C 25 aralkyl, or —C(═O)—R 2 , and 
       R 127  is H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—, 
       D is —CO—; —COO—; —S—; —SO—; —SO 2 —; —O—; —NR 25 —; —SiR 30 R 31 —; —POR 32 —; —CR 23 ═CR 24 —; or —C≡C—; and 
       E is —OR 29 ; —SR 29 ; —NR 25 R 26 ; —COR 28 ; —COOR 27 ; —CONR 25 R 26 ; —CN; or halogen; 
       G is E, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, or C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, 
       wherein R 23 , R 24 , R 25  and R 26  are independently of each other H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—; or 
       R 25  and R 26  together form a five or six membered ring, R 27  and R 28  are independently of each other H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—, 
       R 29  is H; C 6 -C 18 aryl; C 6 -C 18 aryl, which is substituted by C 1 -C 18 alkyl or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—, 
       R 30  and R 31  are independently of each other C 1 -C 18 alkyl, C 6 -C 18 aryl, or C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl, and 
       R 32  is C 1 -C 18 alkyl, C 6 -C 18 aryl, or C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl. 
     
   
   
       3 . The EL device according to  claim 2 , comprising a compound of the formula X, or XI, wherein R and R 4  are hydrogen,
 R 2 , R 3 , R 5  and R 6  are independently of each other H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is interrupted by D, C 7 -C 25 aralkyl, or a group —X 2 —R 18 ,   R 8  and R 9  are independently of each other H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is interrupted by D, or a group —X 2 —R 18 ; or two substituents R and R 3  and/or R 5  and R 6 , which are adjacent to each other, together form a group   
     
       
         
         
             
             
         
       
        or two substituents R 5  and R 3 , which are adjacent to each other, together form a group 
     
     
       
         
         
             
             
         
       
        wherein R 105 , R 106 , R 107  and —R 108  are independently of each other H, or C 1 -C 8 alkyl, or 
       R 8  and R 9  together form a group 
     
     
       
         
         
             
             
         
       
        wherein R 205 , R 206 , R 207 , R 208 , R 209  and R 210  are independently of each other H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 1 -C 18 alkoxy, or C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 1 -C 18  perfluoroalkyl, 
       R 10  is H, C 6 -C 18 aryl, which can be substituted by G, C 2 -C 18 heteroaryl, which can be substituted by G, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, or a group —X 2 —R 18 , 
       wherein X 2  is a C 6 -C 12 aryl, or C 6 -C 12 heteroaryl spacer, which can be substituted one to two times with C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, or C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, 
       and R 18  is H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is interrupted by D, or —NR 25 R 26 ; 
       D is —CO—; —COO—; —S—; —SO—; —SO 2 —; —O—; —NR 25 —; —CR 23 ═CR 24 —; or —C≡C—; wherein 
       R 23 , R 24 , R 25  and R 26  are independently of each other H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 8 alkyl or C 1 -C 8 alkoxy; C 1 -C 8 alkyl; or C 1 -C 8 alkyl which is interrupted by —O—, or R 25  and R 26  together form a five or six membered ring. 
     
   
   
       4 . The EL device according to  claim 2 , comprising a compound having the formula 
     
       
         
         
             
             
         
       
     
     wherein R 10  is H, C 6 -C 18 aryl which can be substituted by G, C 2 -C 18 heteroaryl which can be substituted by G, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, or a group —X 2 —R 18 , wherein X 2  is a C 6 -C 12 aryl or C 6 -C 12 heteroaryl spacer which can be substituted one to two times with C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, or C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, and R 18  is H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is interrupted by D, or —NR 25 R 26 —;
 R 11  and R 14  are hydrogen, 
 R 12 , R 13 , R 15  and R 16  are hydrogen, 
 R 17  is C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl, C 1 -C 18  perfluoroalkyl, or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—; or 
 two substituents R 15  and R 13 , R 12  and R 13  and/or R 15  and R 16 , which are adjacent to each other, together form a group 
 
     
       
         
         
             
             
         
       
        or two substituents R 15  and R 13 , which are adjacent to each other, together form a group 
     
     
       
         
         
             
             
         
       
        wherein R 105 , R 10 , R 107  and R 108  are independently of each other H, or C 1 -C 8 alkyl, 
       D is —S—; —O—; or —NR 25 —; 
       E is —OR 29 ; —SR 29 ; —NR 25 R 26 ; —CN; or F; 
       G is E, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is interrupted by D, C 1 -C 18  perfluoroalkyl, C 1 -C 18 alkoxy, or C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, wherein 
       R 25  and R 26  are independently of each other H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 8 alkyl or C 1 -C 8 alkoxy; C 1 -C 8 alkyl; or C 1 -C 8 alkyl which is interrupted by —O—, or 
       R 25  and R 26  together form 
     
     
       
         
         
             
             
         
       
       R 29  is C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl, or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—. 
     
   
   
       5 . The EL device according to  claim 1 , wherein A 1 , A 2 , A 1′  and A 2′  are independently of each other 
     
       
         
         
             
             
         
       
        or A 1  and A 1′  or A 2  and A 2′  together with the nitrogen atom to which they are bonded form a heteroaromatic ring system 
     
     
       
         
         
             
             
         
       
        m′ is 0, 1, or 2; 
       m can be the same or different at each occurence and is 0, 1, 2, or 3; 
       R 41  can be the same or different at each occurence and is Cl, F, CN, N(R 45 ) 2 , a C 1 -C 25 alkyl group, a C 4 -C 18 cycloalkyl group, a C 1 -C 25 alkoxy group, in which one or more carbon atoms which are not in neighbourhood to each other could be replaced by —NR 45 —, —O—, —S—, or —C(═O)—O—, and/or wherein one or more hydrogen atoms can be replaced by F, a C 6 -C 24 aryl group, or a C 6 -C 24 aryloxy group, wherein one or more carbon atoms can be replaced by O, S, or N, and/or which can be substituted by one or more non-aromatic groups R 41 , or 
       two or more groups R 41  form a ring system; 
       R 45  is H, a C 1 -C 25 alkyl group, a C 4 -C 18 cycloalkyl group, in which one or more carbon atoms which are not in neighbourhood to each other could be replaced by —NR 45″ —, —O—, —S—, —C(═O)—O—, or, —O—C(═O)—O—, and/or wherein one or more hydrogen atoms can be replaced by F, a C 6 -C 24 aryl group, or a C 6 -C 24 aryloxy group, wherein one or more carbon atoms can be replaced by O, S, or N, and/or which can be substituted by one or more non-aromatic groups R 41 , and R 45″  is H, a C 1 -C 25 alkyl group, or a C 4 -C 18 cycloalkyl group, 
       R 116 , R 117  and R 117′  are independently of each other H, halogen, —CN, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 7 -C 25 aralkyl, —C(═O)—R 127 , —C(═O)OR 127 , or —C(═O)NR 127 R 128 , or substituents R 116 , R 117  and R 117′ , which are adjacent to each other, can form a ring, 
       R 119  and R 120  are independently of each other C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, or C 7 -C 25 aralkyl, or 
       R 119  and R 120  together form a group of formula ═CR 121 R 122 , wherein 
       R 121  and R 122  are independently of each other H, C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, or C 2 -C 20 heteroaryl, or C 2 -C 20 heteroaryl which is substituted by G, or 
       R 119  and R 120  together form a five or six membered ring, which optionally can be substituted by C 1 -C 18 alkyl, C 1 -C 18 alkyl which is substituted by E and/or interrupted by D, C 6 -C 24 aryl, C 6 -C 24 aryl which is substituted by G, C 2 -C 20 heteroaryl, C 2 -C 20 heteroaryl which is substituted by G, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, C 1 -C 18 alkoxy, C 1 -C 18 alkoxy which is substituted by E and/or interrupted by D, C 7 -C 25 aralkyl, or —C(═O)—R 127 , and 
       R 126  and R 127  are independently of each other H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—, 
       D is —CO—, —COO—, —S—, —SO—, —SO 2 —, —O—, —NR 65 , —SiR 70 R 71 —, POR 72 —, —CR 63 ═CR 64 —, or —C≡C—, and 
       E is —OR 69 , SR 69 , —NR 65 R 66 , —COR 68 —COOR 67 , —CONR 65 R 66 , —CN, or halogen, 
       G is E, or C 1 -C 18 alkyl, 
       R 63 , R 64 , R 65 , R 65  and R 66  are independently of each other H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—; or 
       R 65  and R 66  together form a five or six membered ring, 
       R 67  and R 68  are independently of each other H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl, or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—, 
       R 69  is H; C 6 -C 18 aryl; C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl or C 1 -C 18 alkoxy; C 1 -C 18 alkyl; or C 1 -C 18 alkyl which is interrupted by —O—, 
       R 70  and R 71  are independently of each other C 1 -C 18 alkyl, C 6 -C 18 aryl, or C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl, and 
       R 72  is C 1 -C 18 alkyl, C 6 -C 18 aryl, or C 6 -C 18 aryl which is substituted by C 1 -C 18 alkyl; or 
       A 1 , A 2 , A 1′  and A 2′  are independently of each other a group 
     
     
       
         
         
             
             
         
       
        wherein BU is 
     
     
       
         
         
             
             
         
       
     
     or 
   
   
       6 . The EL device according to  claim 1 , comprising a compound selected from 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
   
   
       7 . Electroluminescent device according to  claim 1 , comprising a cathode, an anode, and therebetween a light emitting layer containing a host material and a phosphorescent light-emitting material, wherein the host material is a compound of formula I. 
   
   
       8 . A compound of the formula 
     
       
         
         
             
             
         
       
     
     wherein
 A, Z 1 , Z 2 , R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7  and x are as defined in  claim 1 , with the proviso that phenazine compounds expressed by formula 
 
     
       
         
         
             
             
         
       
     
     are excluded, wherein each R 1 -R 4  is an H atom, a (substituted)alkyl group, aralkyl group, aryl group, or heterocyclic group, wherein R 1  and R 2 , and R 3  and R 4  may form a 5-7 membered ring together with an N atom, respectively; each R 5 -R 7  is an H atom, (substituted)alkyl group, alkoxy group, halogen atom or nitro group. 
   
   
       9 . Solar cells, dye lasers or electroluminescent devices comprising a compound of formula I according to  claim 8 . 
   
   
       10 . A process for the preparation of compounds of the formula Ia or Ib according to  claim 12 , wherein Z 1  and Z 2  are independently of each other —NA 1 A 1′ , or 
     
       
         
         
             
             
         
       
     
     m′ is 0, 1, or 2; which comprises reacting a compound of formula 
     
       
         
         
             
             
         
       
     
     wherein X 10  stands for halogen, with a compound of formula HNA 1 A 1′ , or 
     
       
         
         
             
             
         
       
     
     in the presence of a base and a catalyst in a solvent. 
   
   
       11 . An electroluminescent (EL) device according to  claim 1 , comprising a compound of the formula 
     
       
         
         
             
             
         
       
       wherein A is a 5-, 6-, or 7-membered heteroaromatic ring, containing one nitrogen atom and at least one further heteroatom selected from nitrogen, substituted nitrogen, oxygen and sulfur, 
       Ar and Ar′ are independently of each other phenyl or naphthyl, which may optionally be substituted by one or more groups selected from C 1 -C 25 alkyl which may optionally be interrupted by —O— or C 1 -C 25 alkoxy, 
       A 1 , A 2 , A 1′  and A 2′  are independently of each other a C 6 -C 24 aryl group, a C 2 -C 30 heteroaryl group, which can optionally be substituted, or a group 
     
     
       
         
         
             
             
         
       
        wherein BU is 
     
     
       
         
         
             
             
         
       
       A 3  and A 3′  are independently of each other a C 6 -C 24 aryl group or a C 2 -C 30 heteroaryl group, which can optionally be substituted, 
       or A 1  and A 1′  or A 2  and A 2′  or A 3  and A 3′  together with the nitrogen atom to which they are bonded form a heteroaromatic ring system 
     
     
       
         
         
             
             
         
       
        m′ is 0, 1, or 2; 
       R 41  can be the same or different at each occurence and is Cl, F, CN, NR 45 R 45′ , a C 1 -C 25 alkyl group, a C 4 -C 18 cycloalkyl group, a C 1 -C 25 alkoxy group, in which one or more carbon atoms which are not in neighbourhood to each other could be replaced by —NR 45 —, —O—, —S—, —C(═O)—O—, or —O—C(═O)—O—, and/or wherein one or more hydrogen atoms can be replaced by F, a C 6 -C 21 aryl group, or a C 6 -C 24 aryloxy group, wherein one or more carbon atoms can be replaced by O, S, or N, and/or which can be substituted by one or more non-aromatic groups R 41 , or two or more groups R 41  form a ring system; 
       R 45  and R 45′  are independently of each other H, a C 1 -C 25 alkyl group, a C 4 -C 18 cycloalkyl group, in which one or more carbon atoms which are not in neighbourhood to each other could be replaced by —NR 45 —, —O—, —S—, —C(═O)—O—, or, —O—C(═O)—O—, and/or wherein one or more hydrogen atoms can be replaced by F, a C 6 -C 24 aryl group, or a C 6 -C 24 aryloxy group, wherein one or more carbon atoms can be replaced by O, S, or N, and/or which can be substituted by one or more non-aromatic groups R 41 , and 
       R 45″  is H, a C 1 -C 25 alkyl group or a C 4 -C 18 cycloalkyl group, 
       m can be the same or different at each occurence and is 0, 1, 2, or 3. 
     
   
   
       12 . A compound according to  claim 8 , of the formula 
     
       
         
         
             
             
         
       
       wherein A is a 5-, 6-, or 7-membered heteroaromatic ring, containing one nitrogen atom and at least one further heteroatom selected from nitrogen, substituted nitrogen, oxygen and sulfur, 
       Ar and Ar′ are independently of each other phenyl or naphthyl, which may optionally be substituted by one or more groups selected from C 1 -C 25 alkyl which may optionally be interrupted by —O— or C 1 -C 25 alkoxy, 
       A 1 , A 2 , A 1′  and A 2′  are independently of each other a C 6 -C 24 aryl group, a C 2 -C 30 heteroaryl group, which can optionally be substituted, or a group 
     
     
       
         
         
             
             
         
       
        wherein BU is 
     
     
       
         
         
             
             
         
       
       A 3  and A 3′  are independently of each other a C 6 -C 24 aryl group or a C 2 -C 30 heteroaryl group, which can optionally be substituted, 
       or A′ and A 1′  or A 2  and A 2′  or A 3  and A 3′  together with the nitrogen atom to which they are bonded form a heteroaromatic ring system 
     
     
       
         
         
             
             
         
       
        m′ is 0, 1, or 2; 
       R 41  can be the same or different at each occurence and is Cl, F, CN, NR 45 R 45′ , a C 1 -C 25 alkyl group, a C 4 -C 18 cycloalkyl group, a C 1 -C 25 alkoxy group, in which one or more carbon atoms which are not in neighbourhood to each other could be replaced by —NR 45 —, —O—, —S—, —C(═O)—O—, or —O—C(═O)—O—, and/or wherein one or more hydrogen atoms can be replaced by F, a C 6 -C 24 aryl group, or a C 6 -C 24 aryloxy group, wherein one or more carbon atoms can be replaced by O, S, or N, and/or which can be substituted by one or more non-aromatic groups R 41 , or two or more groups R 41  form a ring system; 
       R 45  and R 45′  are independently of each other H, a C 1 -C 25 alkyl group, a C 4 -C 18 cycloalkyl group, in which one or more carbon atoms which are not in neighbourhood to each other could be replaced by —NR 45″ —, —O—, —S—, —C(═O)—O—, or, —O—C(═O)—O—, and/or wherein one or more hydrogen atoms can be replaced by F, a C 6 -C 24 aryl group, or a C 6 -C 24 aryloxy group, wherein one or more carbon atoms can be replaced by O, S, or N, and/or which can be substituted by one or more non-aromatic groups R 41 , and 
       R 45″  is H, a C 1 -C 25 alkyl group or a C 4 -C 18 cycloalkyl group, 
       m can be the same or different at each occurence and is 0, 1, 2, or 3.