Phosphorescent Osmium (II) complexes and uses thereof

Abstract

There is disclosed herein phosphorescent compounds, uses thereof, and devices including organic light emitting diode (OLEDs) including such compounds. Compounds of interest include: wherein A is Os or Ru The anionic chelating chromophores NˆN, which are formed by connecting one pentagonal ring structure containing at least two nitrogen atoms to a hexagonal pyridine type of fragment via a direct carbon-carbon linkage. L is a neutral donor ligand; the typical example includes carbonyl, pyridine, phosphine, arsine and isocyanide; two neutral L's can also combine to produce the so-called chelating ligand such as 2,2′-bipyridine, 1,10-phenanthroline and N-heterocyclic carbene (NHC) ligand, or bidentate phosphorous ligands such as 1,2-bis(diphenylphosphino)ethane, 1,2-bis(diphenylphosphino)benzene. L can occupy either cis or trans orientation. When L occupies the trans position, the preferred structure contains both the hexagonal fragment of NˆN as well as its pentagonal fragment located at the trans position respect to their counterparts of the second NˆN chromophore. When L occupies the cis position, the preferred structure consists of the pentagonal unit of NˆN chromophores residing opposite to the L. X, 1 X 2 and X 3 independently are C or N; when X 2 is N, R 1 is omitted, when X 3 is N, R 2 is omitted, R 1 is H, C1-C8 alkyl, C1-C8 substituted phenyl or C1-C4 perfluoroalkyl, R 2 is H, F or cyano substituent, X 4 is either C or N; X 4 may locate at any position of the hexagonal ring, when X 4 is N and R 3 and R 4 are not linked to X 4 , R 3 is H, methyl or C1-C3 small alkyl, R 4 is H, methyl or C1-C3 small alkyl, or R 3 and R 4 together form an additional conjugated unit with structure

1 . A compound of structure III:  
     
       
         
         
             
             
         
       
       wherein:  
       the anionic chelating chromophores NˆN, are formed by connecting a pentagonal ring structure containing at least two nitrogen atoms to a hexagonal pyridine type of fragment via a direct carbon-carbon linkage;  
       A is Os or Ru;  
       L stands for a neutral donor ligand;  
       L can occupy either cis or trans orientation;  
       X 1 , X 2  and X 3  are independently C or N;  
       when X 2  is N, R 1  is omitted;  
       when X 3  is N, R 2  is omitted;  
       R 1  is H, C1-C8 alkyl, C1-C8 substituted phenyl or C1-C4 perfluoroalkyl;  
       R 2  is H, F and/or a cyano substituent;  
       X 4  of the hexagonal fragment is either C or N;  
       X 4  may located at any position of the hexagonal ring other than at the already present N position when X 4  is N and R 3  and R 4  are not linked to X 4 ; and  
       R 3  is H, methyl or C1-C3 small alkyl;  
       R 4  is H, methyl or C1-C3 small alkyl, or;  
       R 3  and R 4  together form the additional conjugated unit with structure  
       
         
           
           
               
               
           
         
       
     
   
   
       2 . The compound of  claim 1  wherein A is Os.  
   
   
       3 . The compound of  claim 1  wherein A is Ru.  
   
   
       4 . The compound of  claim 1  wherein X 1  is C.  
   
   
       5 . The compound of  claim 1  wherein X 1  is N.  
   
   
       6 . The compound of  claim 1  wherein X 2  is C.  
   
   
       7 . The compound of  claim 1  wherein X 2  is N.  
   
   
       8 . The compound of  claim 1  wherein X 3  is C.  
   
   
       9 . The compound of  claim 1  wherein X 3  is N.  
   
   
       10 . The compound of  claim 1  wherein R 3  is selected from the group consisting of a fluoro substituent and cyano substituent.  
   
   
       11 . The compound of  claim 1  wherein “L” is carbonyl and the remaining substituents are selected to provide structure selected from the group consisting of 1a, 1b, or 1c:  
     
       
         
         
             
             
         
       
     
   
   
       12 . A method of making a compound as set forth in  claim 2  comprising the steps of initiating a condensation reaction of a bidentate chelating ligand having a general formula selected from the group consisting of  
     
       
         
         
             
             
         
       
       together with an osmium metal reagent Os 3 (CO) 12  and in the substantial absence of solvent media or in the presence of a high boiling polar organic solvent at elevated temperature.  
     
   
   
       13 . The compound of  claim 2  wherein substituents are selected to provide a structure selected from the group consisting of 3a, 3b, or 3c;  
     
       
         
         
             
             
         
       
     
   
   
       14 . The compound of  claim 2  wherein substituents are selected to provide a structure selected from the group consisting of 4a, 4b or 4c:  
     
       
         
         
             
             
         
       
       wherein the phosphine donor ligand is selected from the group consisting of PPh 3 , PPh 2 Me, PPhMe 2 , PMe 3 , PPh 2 (C 2 F 5 ), PPh(C 2 F 5 ) 2 , PPh 2 Et, PPhEt 2 , PEt 3 , PPh 2 (CH═CH 2 ) and PPh(CH═CH 2 ) 2 , and the phosphite ligand is selected from the group consting of P(OPh) 3 , P(OMe) 3  and P(OEt) 3 , and the arsine ligand is selected from the group consisting of AsPh 3  and AsMe 3 .  
     
   
   
       15 . A method of making a compound of  claim 14  comprising initiating a condensation reaction of a bidentate chelating ligand having a general formula selected from the group consisting of;  
     
       
         
         
             
             
         
       
       together with an osmium carbonyl reagent Os 3 (CO) 12  and in the presence of a high boiling polar organic solvent at elevated temperature, followed by treatment of the resulting reaction mixture with a freshly sublimed decarbonylation reagent Me 3 NO or Et 3 NO, and the phosphine donor ligand.  
     
   
   
       16 . The compound of  claim 2  wherein substituents are selected to provide structures selected from the group consisting of 5a, 5b or 5c:  
     
       
         
         
             
             
         
       
       wherein chelating diphosphine ligand R 5   2 PˆPR 5   2  are selected from the group consisting of 1,2-bis(dimethylphosphino)ethane, 1,2-bis(diphenylphosphino)ethane, 1,2-bis(diphenylphosphino)benzene, 1,2-bis(diethoxylphosphino)benzene, cis-1,2-bis(diphenylphosphino)ethylene, bis(dipentafluoroethylphosphino)ethane 1,2-bis(dipentafluorophenylphosphino)ethane, 1,3-bis(dimethylphosphino)propane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(dimethylphosphino)butane and 1,4-bis(diphenylphosphino)butane, for which the carbon spacer linking the phosphorous donor group is considerably lengthened to increase the chelating bite angle at the Os(II) metal center.  
     
   
   
       17 . The compound of  claim 1  and wherein the 2-pyridyl unit of the pyrazolate, triazolate and tetrazolate ligands contains an aromatic heterocycle molecule and the pyrazolate fragment of the anionic ligand is replaced with at least one of an imidiazolate or indazolate unit.  
   
   
       18 . The compound of  claim 17  wherein the aromatic hetercycle molecule is selected from the group consisting of:  
     
       
         
         
             
             
         
       
     
   
   
       19 . The compound of  claim 17  wherein the aromatic heterocycle molecule is selected from the group consisting of pyrazine, pyrimidine, pyridazine, quinoline and isoquinoline.  
   
   
       20 . A light emitting device comprising a pair of electrodes, a substrate, at least one organic layer on said substrate forming a light emitting structure, said at least one organic layer including as a functional phosphorescent component a compound of structure III:  
     
       
         
         
             
             
         
       
       wherein:  
       the anionic chelating chromophores NˆN, are formed by connecting a pentagonal ring structure containing at least two nitrogen atoms to a hexagonal pyridine type of fragment via a direct carbon-carbon linkage;  
       A is Os or Ru;  
       L stands for a neutral donor ligand;  
       L can occupy either cis or trans orientation;  
       X 1 , X 2  and X 3  are independently C or N;  
       when X 2  is N, R 1  is omitted;  
       when X 3  is N, R 2  is omitted;  
       R 1  is H, C1-C8 alkyl, C1-C8 substituted phenyl or C1-C4 perfluoroalkyl;  
       R 2  is H, F and/or a cyano substituent;  
       X 4  of the hexagonal fragment is either C or N;  
       X 4  may located at any position of the hexagonal ring other than at the already present N position when X 4  is N and R 3  and R 4  are not linked to X 4 ; and  
       R 3  is H, methyl or C1-C3 small alkyl;  
       R 4  is H, methyl or C1-C3 small alkyl, or;  
       R 3  and R 4  together form the additional conjugated unit with structure  
       
         
           
           
               
               
           
         
       
     
   
   
       21 . The light-emitting device of  claim 20  wherein said compound of structure III is disposed in a substantially non-ionic environment.  
   
   
       22 . The light-emitting device of  claim 20  and wherein said light-emitting diode is at least one of an Organic Light Emitting Diode (OLED), a Polymer Light Emitting Diode (PLED), or said at least one functional layer is formed from small molecules including oligomers and other of said at least one functional layers are formed from polymers or polymer/small molecule composite materials.  
   
   
       23 . The device of  claim 20  where some of said at least one functional layers can be made of small molecules including oligomers and other of said at least one functional layers can be made of polymers or polymer/small molecule composite materials.  
   
   
       24 . The device of  claim 20  further including a second phosphorescent material.  
   
   
       25 . A light-emitting device comprising an anode and a cathode, a hole transport layer, an electron transport layer, and wherein at least one of said hole transport layer and said electron transport layer comprises either alone or in combination an active material of structure III:  
     
       
         
         
             
             
         
       
       wherein:  
       the anionic chelating chromophores NˆN, are formed by connecting a pentagonal ring structure containing at least two nitrogen atoms to a hexagonal pyridine type of fragment via a direct carbon-carbon linkage;  
       A is Os or Ru;  
       L stands for a neutral donor ligand;  
       L can occupy either cis or trans orientation;  
       X 1 , X 2  and X 3  are independently C or N;  
       when X 2  is N, R 1  is omitted;  
       when X 3  is N, R 2  is omitted;  
       R 1  is H, C1-C8 alkyl, C1-C8 substituted phenyl or C1-C4 perfluoroalkyl;  
       R 2  is H, F and/or a cyano substituent;  
       X 4  of the hexagonal fragment is either C or N;  
       X 4  may located at any position of the hexagonal ring other than at the already present N position when X 4  is N and R 3  and R 4  are not linked to X 4 ; and  
       R 3  is H, methyl or C1-C3 small alkyl;  
       R 4  is H, methyl or C1-C3 small alkyl, or;  
       R 3  and R 4  together form the additional conjugated unit with structure  
       
         
           
           
               
               
           
         
       
     
   
   
       26 . The light-emitting device of  claim 24  wherein the compound of structure III is located in a substantially non-ionic environment.  
   
   
       27 . The light-emitting device of  claim 24  and further comprising a hole injection promotion layer and at least one hole transport layer, said hole injection promotion layer is adjacent to said at least one hole transport layer.  
   
   
       28 . The light-emitting device of  claim 24  and further including an electron injection promotion layer and at least one electron transport layer, said electron injection promotion layer is adjacent said at least one electron transport layer.  
   
   
       29 . The light-emitting device of  claim 27  and further including an electron promotion layer, said electron promotion layer is LiF.  
   
   
       30 . The light-emitting device of  claim 26  and wherein said hole promotion layer is [Poly (ethylene dioxythiophene: polystryrene sulfonate)] (PEDOT-PSS).  
   
   
       31 . The light emitting device of  claim 20  and wherein said at least one organic layer is deposited by one of a dry deposition method or a wet thin film processing method.  
   
   
       32 . The light-emitting device of  claim 31  wherein the dry deposition method is selected of the group consisting of thermal deposition and sputtering deposition and PECVD deposition and MOCVD deposition.  
   
   
       33 . The light-emitting device of  claim 31  and wherein the wet thin film processing method is selected of the group of Langmuir-Blodgett, screen printing, and ink-jet printing, and solution dipping and spin-coating.