Monosubstituted diazabenzimidazole carbene metal complexes for use in organic light emitting diodes

Abstract

An organic electronic device, preferably an organic light-emitting diode (OLED), comprising at least one metal-carbene complex comprising one, two or three specific bidentate diazabenzimidazole carbene ligands; a light-emitting layer comprising said metal-carbene complex as emitter material, preferably in combination with at least one host material; the use of said metal-carbene complex in an OLED; an apparatus selected from the group consisting of stationary visual display units, mobile visual display units, illumination units, units in items of clothing, units in handbags, units in accessories, units in furniture and units in wallpaper comprising said organic electronic device, preferably said OLED, or said light-emitting layer; the metal-carbene complex comprising one, two or three specific bidentate diazabenzimidazole carbene ligands mentioned above and a process for the preparation of said metal-carbene complex.

Claims

1. An organic electronic device comprising at least one metal-carbene complex, wherein the metal is Ir or Pt, comprising one, two or three bidentate ligands of formula (I) and/or (I′) ##STR00145## wherein R.sup.1 has the following meaning: ##STR00146## wherein: m is 1; ˜ is the bonding site to the ligand of formula (I) or (I′); and the group R.sup.1 has one of the following definitions: TABLE-US-00012 R.sup.6 R.sup.7 R.sup.8 13 iso-butyl methyl hydrogen 14 tert-butyl methyl hydrogen 18 iso-butyl ethyl hydrogen 19 tert-butyl ethyl hydrogen 20 iso-propyl n-propyl hydrogen 22 iso-butyl n-propyl hydrogen 23 tert-butyl n-propyl hydrogen 27 iso-propyl methyl methyl 29 iso-butyl methyl methyl 30 tert-butyl methyl methyl 33 iso-propyl ethyl ethyl 35 iso-butyl ethyl ethyl 36 tert-butyl ethyl ethyl 39 iso-propyl ethyl propyl 41 iso-butyl ethyl propyl 42 tert-butyl ethyl propyl 52 Tolyl hydrogen hydrogen 53 Xylyl hydrogen hydrogen 54 pyridyl hydrogen hydrogen 55 methylpyridyl hydrogen hydrogen 56 pyrimidyl hydrogen hydrogen 57 pyrazinyl hydrogen hydrogen 58 carbazolyl hydrogen hydrogen 59 dibenzofuranyl hydrogen hydrogen 60 dimethylfluorenyl hydrogen hydrogen 61 methylindonyl hydrogen hydrogen 62 —CH.sub.2-tolyl hydrogen hydrogen 63 —CH.sub.2-xylyl hydrogen hydrogen 64 —CH.sub.2-pyridyl hydrogen hydrogen 65 —CH.sub.2-pyrazinyl hydrogen hydrogen 66 —CH.sub.2-methylpyridinyl hydrogen hydrogen 67 —CH.sub.2-dibenzofuranyl hydrogen hydrogen 71 —CMe.sub.2-iso-butyl hydrogen hydrogen 72 cyclopentyl hydrogen hydrogen 73 cyclohexyl hydrogen hydrogen 74 adamantyl hydrogen hydrogen 75 —CH.sub.2-adamantyl hydrogen hydrogen 78 SiMe.sub.3 hydrogen hydrogen 79 SiPh.sub.3 hydrogen hydrogen 80 phenyl methyl methyl 81 tolyl methyl methyl 82 xylyl methyl methyl 83 pyridyl methyl methyl 84 methylpyridyl methyl methyl 85 pyrimidyl methyl methyl 86 pyrazinyl methyl methyl 87 carbazolyl methyl methyl 88 dibenzofuranyl methyl methyl 89 dimethylfluorenyl methyl methyl 90 methylindonyl methyl methyl 91 —CH.sub.2-tolyl methyl methyl 92 —CH.sub.2-xylyl methyl methyl 93 —CH.sub.2-pyridyl methyl methyl 94 —CH.sub.2-pyrazinyl methyl methyl 95 —CH.sub.2-methylpyridinyl methyl methyl 96 —CH.sub.2-dibenzofuranyl methyl methyl 100 —CMe.sub.2-iso-butyl methyl methyl 101 cyclopentyl methyl methyl 102 cyclohexyl methyl methyl 103 CF.sub.3 methyl methyl 104 CF.sub.2CF.sub.3 methyl methyl 105 SiMe.sub.3 methyl methyl 106 SiPh.sub.3 methyl methyl A.sup.1 is CR.sup.2 or N; A.sup.2 is CR.sup.3 or N; A.sup.3 is CR.sup.4 or N; A.sup.4 is CR.sup.5 or N; A.sup.1′ is CR.sup.2′ or N; A.sup.2′ is CR.sup.3′ or N; A.sup.3′ is CR.sup.4′ or N; A.sup.4′ is CR.sup.5′ or N; R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.2′, R.sup.3′, R.sup.4′ and R.sup.5′ are each independently hydrogen; deuterium; a linear or branched, substituted or unsubstituted alkyl radical having 1 to 20 carbon atoms, optionally interrupted by at least one heteroatom, selected from O, S and N; a substituted or unsubstituted cycloalkyl radical having a total of from 3 to 30 carbon atom; a substituted or unsubstituted heterocyclo alkyl radical, interrupted by at least one heteroatom selected from O, S and N and having a total of from 3 to 30 carbon atoms and/or heteroatoms; a substituted or unsubstituted aryl radical, having a total of from 6 to 30 carbon atoms; a substituted or unsubstituted heteroaryl radical, having a total of from 5 to 30 carbon atoms and/or heteroatoms, selected from O, S and N; or a group with donor or acceptor action; or R.sup.2 and R.sup.3, R.sup.3 and R.sup.4 or R.sup.4 and R.sup.5 or R.sup.2′ and R.sup.3′, R.sup.3′ and R.sup.4′ or R.sup.4′ and R.sup.5′ may form, independently of each other, together with the carbon atoms to which they are bonded, a saturated or unsaturated or aromatic, optionally substituted ring, which is optionally interrupted by at least one heteroatom, selected from O, S and N, has a total of from 5 to 18 carbon atoms and/or heteroatoms, and may optionally be fused to at least one further optionally substituted saturated or unsaturated or aromatic ring, optionally interrupted by at least one heteroatom, selected from O, S and N, and having a total of from 5 to 18 carbon atoms and/or heteroatoms; and ˜ in Formula (I) and Formula (I′) is the bonding site to the metal.

2. The organic electronic device according to claim 1, wherein the organic electronic device is selected from organic light-emitting diodes (OLED), light-emitting electrochemical cells (LEEC), organic photovoltaic cells (OPV) and organic field-effect transistors (OFET).

3. The organic electronic device according to claim 1, wherein the metal-carbene complex comprising one, two or three bidentate ligands of formula (I) and/or (I′) is employed as emitter material in OLEDs or a LEECs or absorption dye in OPVs.

4. The organic electronic device according to claim 3, wherein the OLED comprises (a) an anode, (b) a cathode, (c) a light-emitting layer between the anode and the cathode, wherein the metal-carbene complex comprising one, two or three bidentate ligands of formula (I) and/or (I′) is present in the light-emitting layer of the OLED.

5. The organic electronic device according to claim 1, wherein the groups A.sup.1, A.sup.2, A.sup.3, A.sup.4, A.sup.1′, A.sup.2′, A.sup.3′, and A.sup.4′, in the ligands of formulae (I) and (I′) have the following meanings: A.sup.1 is CR.sup.2 or N; A.sup.2 is CR.sup.3 or N; A.sup.3 is CR.sup.4 or N; A.sup.4 is CR.sup.5 or N; A.sup.1′ is CR.sup.2′ or N; A.sup.2′ is CR.sup.3′ or N; A.sup.3′ is CR.sup.4′ or N; A.sup.4′ is CR.sup.5′ or N; R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.2′, R.sup.3′, R.sup.4′ and R.sup.5′ are each independently hydrogen; deuterium; a linear or branched, substituted or unsubstituted alkyl radical having 1 to 20 carbon atoms, optionally interrupted by at least one heteroatom[, selected from O, S and N; a substituted or unsubstituted cycloalkyl radical, having a total of from 3 to 10 carbon atoms; a substituted or unsubstituted heterocyclo alkyl radical, interrupted by at least one heteroatom, selected from O, S and N, and having a total of from 3 to 10 carbon atoms and/or heteroatoms; a group with donor or acceptor action, selected from halogen radicals, CF.sub.3, CN, SiPh.sub.3 and SiMe.sub.3; a substituted or unsubstituted aryl radical, having from 6 to 30 carbon atoms.

6. The organic electronic device according to claim 1, wherein the metal-carbene complex has one of the following formulae (II), (II′) or (II″) ##STR00147## wherein M is Ir; n is 1, 2 or 3; L is a monoanionic bidentate ligand, is 0, 1 or 2, where, when o=2, the L ligands may be the same or different; n′ is 1 or 2; n″ is 1 or 2; wherein the sum of n′+n″ is 2 or 3; o′ is 0 or 1; wherein the sum of n+o in formulae (II) and (II′) and the sum of n′+n″+o′ in formula (II″) is 3, with the proviso that n in formula (II) and (II′) is at least 1 and n′, as well as n″ formula (II″) are at least 1.

7. The organic electronic device according to claim 1, wherein the metal-carbene complex has one of the following formulae (II), (II′) or (II″) ##STR00148## wherein M is Pt; n is 1 or 2; L is a monoanionic bidentate ligand, o is 0 or 1; n′ is 1; n″ is 1; wherein the sum of n′+n″ is 2; o′ is 0; wherein the sum of n+o in formulae (II) and (II″) and the sum of n′+n″+o′ in formula (II″) is 2, with the proviso that n in formula (II) and (II″) is at least 1 and n′, as well as n″ in formula (II″) are both 1.

8. The organic electronic device according to claim 6, wherein n is 3; n′ is 1 or 2, n″ is 1 or 2, wherein the sum of n′+n″ is 3.

9. The organic electronic device according to claim 6, wherein the monoanionic bidentate ligand L in the metal-carbene complex has following meaning: a ligand of formula (A) ##STR00149## in which R.sup.51 is in each case independently a linear or branched alkyl radical having 1 to 6 carbons atoms; a substituted or unsubstituted aryl radical having 6 to 18 carbon atoms; a substituted or unsubstituted heteroaryl radical having a total of 5 to 18 carbon atoms and/or heteroatoms, R.sup.52 is hydrogen; a linear or branched alkyl radical having 1 to 6 carbon atoms; a substituted or unsubstituted aryl radical having 6 to 18 carbon atoms; or L is a carbene ligand of the general formula (B) ##STR00150## where A.sup.9′ is CR.sup.12′ or N; A.sup.10′ is CR.sup.13′ or N; R.sup.11′ is a linear or branched, substituted or unsubstituted alkyl radical having 1 to 20 carbon atoms, optionally interrupted by at least one heteroatom, selected from O, S and N; a substituted or unsubstituted cycloalkyl radical having 3 to 18 carbon atoms; a substituted or unsubstituted heterocycloalkyl radical interrupted by at least one heteroatom, selected from O, S and N, and having 3 to 18 carbon atoms and/or heteroatoms; a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl radical interrupted by at least one heteroatom, selected from O, S and N and having a total of 5 to 30 carbon atoms and/or heteroatoms; R.sup.12′, R.sup.13′ are each independently hydrogen; deuterium; a linear or branched, substituted or unsubstituted alkyl radical having 1 to 20 carbon atoms, optionally interrupted by at least one heteroatom, selected from O, S and N; a substituted or unsubstituted cycloalkyl radical having 3 to 18 carbon atoms; a substituted or unsubstituted heterocycloalkyl radical interrupted by at least one heteroatom, selected from O, S and N, and having 3 to 18 carbon atoms and/or heteroatoms; a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms; a substituted or unsubstituted heteroaryl radical interrupted by at least one heteroatom, selected from O, S and N and having a total of 5 to 30 carbon atoms and/or heteroatoms; or a group with donor or acceptor action; if A.sup.9′ is CR.sup.12′ and A.sup.10′ is CR.sup.13′, CR.sup.12′ and CR.sup.12′ together may form, a saturated or unsaturated or aromatic, optionally substituted ring, which is optionally interrupted by at least one heteroatom, selected from O, S and N, has a total of from 5 to 18 carbon atoms and/or heteroatoms, and may optionally be fused to at least one further optionally substituted saturated or unsaturated or aromatic ring, optionally interrupted by at least one heteroatom, selected from O, S and N, and having a total of from 5 to 18 carbon atoms and/or heteroatoms; A.sup.5′ is CR.sup.14′ or N; A.sup.6′ is CR.sup.15′ or N; A.sup.7′ is CR.sup.16′ or N; A.sup.8′ is CR.sup.17′ or N; R.sup.14′, R.sup.15′, R.sup.16′, R.sup.17′ are each independently hydrogen; deuterium; a linear or branched, substituted or unsubstituted alkyl radical having 1 to 20 carbon atoms, optionally interrupted by at least one heteroatom, selected from O, S and N; a substituted or unsubstituted cycloalkyl radical having 3 to 18 carbon atoms; a substituted or unsubstituted heterocycloalkyl radical interrupted by at least one heteroatom, selected from O, S and N, and having 3 to 18 carbon atoms and/or heteroatoms; a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms; a substituted or unsubstituted heteroaryl radical interrupted by at least one heteroatom, selected from O, S and N and having a total of 5 to 30 carbon atoms and/or heteroatoms; or a group with donor or acceptor action; or R.sup.14′, and R.sup.15′, R.sup.15′, and R.sup.16′ or R.sup.16′ and R.sup.17′ may form, together with the carbon atoms to which they are bonded, a saturated or unsaturated or aromatic, optionally substituted ring, which is optionally interrupted by at least one heteroatom, selected from O, S and N, has a total of from 5 to 18 carbon atoms and/or heteroatoms, and may optionally be fused to at least one further optionally substituted saturated or unsaturated or aromatic ring, optionally interrupted by at least one heteroatom, selected from O, S and N, and having a total of from 5 to 18 carbon atoms and/or heteroatoms; or if A.sup.9′ is CR.sup.12′, R.sup.12′ and R.sup.17′ together may form a saturated or unsaturated, linear or branched bridge optionally comprising heteroatoms, selected from O, S and N, to which is optionally fused a substituted or unsubstituted, five- to eight-membered ring comprising carbon atoms and/or heteroatoms, and which are optionally substituted with aromatic units, heteroaromatic units or groups with donor or acceptor action; q′ is 0 or 1; or L is a ligand of the general formula (C) ##STR00151## in which the symbols are each defined as follows: D are each independently CR.sup.34′″ or N; W is C or N; E are each independently CR.sup.35′″, N, NR.sup.36′″ or O; I is 1 or 2; R.sup.34′″, R.sup.35′″, R.sup.36′″ are each independently hydrogen; substituted or unsubstituted or branched alkyl; substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl; or in each case two R.sup.34′″, R.sup.35′″ or R.sup.35′″ radicals together form a fused ring which may optionally comprise at least one heteroatom; or R.sup.34′″, R.sup.35′″, R.sup.36′″ or R.sup.37′″ is a radical having donor or acceptor action; where the dotted line means an optional bridge between one of the D groups and one of the E groups; where the bridge may be defined as follows: alkylene, arylene, heteroarylene, alkynylene, alkenylene, NR.sup.38′″, O, S, SiR.sup.41′″R.sup.42′″, and (CR.sup.43′″R.sup.44′″).sub.v, where one or more nonadjacent (CR.sup.43′″R.sup.44′″) groups may be replaced by NR.sup.38′″, O, S, SiR.sup.41′″R.sup.42′″, where v is from 2 to 10; and R.sup.38′″, R.sup.41′″, R.sup.42′″, R.sup.43′″, R.sup.44′″ are each H, alkyl, aryl or heteroaryl.

10. The organic electronic device according to claim 1, wherein the metal-carbene complex is employed in combination with at least one host material.

11. A light-emitting layer comprising at least one metal-carbene complex as defined in claim 1 as emitter material.

12. An OLED comprising the metal-carbene complex as defined in claim 1.

13. An apparatus selected from the group consisting of stationary visual display units, such as visual display units of computers, televisions, visual display units in printers, kitchen appliances, advertising panels, information panels and illuminations; mobile visual display units such as visual display units in smartphones, cellphones, tablet computers, laptops, digital cameras, MP3-players, vehicles, keyboards and destination displays on buses and trains; illumination units; units in items of clothing; units in handbags, units in accessories, units in furniture and units in wallpaper, comprising the organic electronic device of claim 1.

14. A metal-carbene complex, wherein the metal is Ir or Pt, comprising one, two or three bidentate ligands of formula (I) and/or (I′) ##STR00152## wherein R.sup.1 has the following meaning: ##STR00153## wherein: m is 1; ˜ is the bonding site to the ligand of formula (I) or (I′); and the group R.sup.1 has one of the following definitions: TABLE-US-00013 R.sup.6 R.sup.7 R.sup.8 13 iso-butyl methyl hydrogen 14 tert-butyl methyl hydrogen 18 iso-butyl ethyl hydrogen 19 tert-butyl ethyl hydrogen 20 iso-propyl n-propyl hydrogen 22 iso-butyl n-propyl hydrogen 23 tert-butyl n-propyl hydrogen 27 iso-propyl methyl methyl 29 iso-butyl methyl methyl 30 tert-butyl methyl methyl 33 iso-propyl ethyl ethyl 35 iso-butyl ethyl ethyl 36 tert-butyl ethyl ethyl 39 iso-propyl ethyl propyl 41 iso-butyl ethyl propyl 42 tert-butyl ethyl propyl 52 Tolyl hydrogen hydrogen 53 Xylyl hydrogen hydrogen 54 pyridyl hydrogen hydrogen 55 methylpyridyl hydrogen hydrogen 56 pyrimidyl hydrogen hydrogen 57 pyrazinyl hydrogen hydrogen 58 carbazolyl hydrogen hydrogen 59 dibenzofuranyl hydrogen hydrogen 60 dimethylfluorenyl hydrogen hydrogen 61 methylindonyl hydrogen hydrogen 62 —CH.sub.2-tolyl hydrogen hydrogen 63 —CH.sub.2-xylyl hydrogen hydrogen 64 —CH.sub.2-pyridyl hydrogen hydrogen 65 —CH.sub.2-pyrazinyl hydrogen hydrogen 66 —CH.sub.2-methylpyridinyl hydrogen hydrogen 67 —CH.sub.2-dibenzofuranyl hydrogen hydrogen 71 —CMe.sub.2-iso-butyl hydrogen hydrogen 72 cyclopentyl hydrogen hydrogen 73 cyclohexyl hydrogen hydrogen 74 adamantyl hydrogen hydrogen 75 —CH.sub.2-adamantyl hydrogen hydrogen 78 SiMe.sub.3 hydrogen hydrogen 79 SiPh.sub.3 hydrogen hydrogen 80 phenyl methyl methyl 81 tolyl methyl methyl 82 xylyl methyl methyl 83 pyridyl methyl methyl 84 methylpyridyl methyl methyl 85 pyrimidyl methyl methyl 86 pyrazinyl methyl methyl 87 carbazolyl methyl methyl 88 dibenzofuranyl methyl methyl 89 dimethylfluorenyl methyl methyl 90 methylindonyl methyl methyl 91 —CH.sub.2-tolyl methyl methyl 92 —CH.sub.2-xylyl methyl methyl 93 —CH.sub.2-pyridyl methyl methyl 94 —CH.sub.2-pyrazinyl methyl methyl 95 —CH.sub.2-methylpyridinyl methyl methyl 96 —CH.sub.2-dibenzofuranyl methyl methyl 100 —CMe.sub.2-iso-butyl methyl methyl 101 cyclopentyl methyl methyl 102 cyclohexyl methyl methyl 103 CF.sub.3 methyl methyl 104 CF.sub.2CF.sub.3 methyl methyl 105 SiMe.sub.3 methyl methyl 106 SiPh.sub.3 methyl methyl A.sup.1 is CR.sup.2 or N; A.sup.2 is CR.sup.3 or N; A.sup.3 is CR.sup.4 or N; A.sup.4 is CR.sup.5 or N; A.sup.1′ is CR.sup.2′ or N; A.sup.2′ is CR.sup.3′ or N; A.sup.3′ is CR.sup.4′ or N; A.sup.4′ is CR.sup.5′ or N; R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.2′, R.sup.3′, R.sup.4′ and R.sup.5′ are each independently hydrogen; deuterium; a linear or branched, substituted or unsubstituted alkyl radical having 1 to 20 carbon atoms, optionally interrupted by at least one heteroatom, selected from O, S and N; a substituted or unsubstituted cycloalkyl radical having a total of from 3 to 30 carbon atom; a substituted or unsubstituted heterocyclo alkyl radical, interrupted by at least one heteroatom selected from O, S and N and having a total of from 3 to 30 carbon atoms and/or heteroatoms; a substituted or unsubstituted aryl radical, having a total of from 6 to 30 carbon atoms; a substituted or unsubstituted heteroaryl radical, having a total of from 5 to 30 carbon atoms and/or heteroatoms, selected from O, S and N; or a group with donor or acceptor action; or R.sup.2 and R.sup.3, R.sup.3 and R.sup.4 or R.sup.4 and R.sup.5 or R.sup.2′ and R.sup.3′, R.sup.3′ and R.sup.4′ or R.sup.4′ and R.sup.5′ may form, independently of each other, together with the carbon atoms to which they are bonded, a saturated or unsaturated or aromatic, optionally substituted ring, which is optionally interrupted by at least one heteroatom, selected from O, S and N, has a total of from 5 to 18 carbon atoms and/or heteroatoms, and may optionally be fused to at least one further optionally substituted saturated or unsaturated or aromatic ring, optionally interrupted by at least one heteroatom, selected from O, S and N, and having a total of from 5 to 18 carbon atoms and/or heteroatoms; and ˜ is the bonding site to the metal.

15. A process for preparing a metal carbene complex according to claim 14, by contacting suitable compounds comprising Ir or Pt with appropriate ligands or ligand precursors, wherein the ligand precursors are reacted with the suitable Ir or Pt comprising compounds and the carbene can be released from precursors of the carbene ligands by removing lower alcohols, wherein the ligand precursor used is a compound of the general formula (IV) ##STR00154## wherein R.sup.1, A.sup.1, A.sup.2, A.sup.3, A.sup.4, A.sup.1′, A.sup.2′, A.sup.3′ and A.sup.4′ are each as defined in claim 14, and R.sup.12 is independently SiR.sup.13R.sup.14R.sup.15, aryl, heteroaryl, alkyl, cycloalkyl or heterocycloalkyl, R.sup.3, R.sup.4, R.sup.15 are each independently aryl, heteroaryl, alkyl, cycloalkyl or heterocycloalkyl.

16. The metal carbene complex according to claim 14, wherein the group R.sup.1 has one of the following definitions: TABLE-US-00014 R.sup.6 R.sup.7 R.sup.8 52 Tolyl hydrogen hydrogen 53 Xylyl hydrogen hydrogen 54 pyridyl hydrogen hydrogen 55 methylpyridyl hydrogen hydrogen 56 pyrimidyl hydrogen hydrogen 57 pyrazinyl hydrogen hydrogen 58 carbazolyl hydrogen hydrogen 59 dibenzofuranyl hydrogen hydrogen 60 dimethylfluorenyl hydrogen hydrogen 61 methylindonyl hydrogen hydrogen 62 —CH.sub.2-tolyl hydrogen hydrogen 63 —CH.sub.2-xylyl hydrogen hydrogen 64 —CH.sub.2-pyridyl hydrogen hydrogen 65 —CH.sub.2-pyrazinyl hydrogen hydrogen 66 —CH.sub.2-methylpyridinyl hydrogen hydrogen 67 —CH.sub.2-dibenzofuranyl hydrogen hydrogen 71 —CMe.sub.2-iso-butyl hydrogen hydrogen 72 cyclopentyl hydrogen hydrogen 73 cyclohexyl hydrogen hydrogen 74 adamantyl hydrogen hydrogen 75 —CH.sub.2-adamantyl hydrogen hydrogen 78 SiMe.sub.3 hydrogen hydrogen 79 SiPh.sub.3 hydrogen hydrogen 80 phenyl methyl methyl 81 tolyl methyl methyl 82 xylyl methyl methyl 83 pyridyl methyl methyl 84 methylpyridyl methyl methyl 85 pyrimidyl methyl methyl 86 pyrazinyl methyl methyl 87 carbazolyl methyl methyl 88 dibenzofuranyl methyl methyl 89 dimethylfluorenyl methyl methyl 90 methylindonyl methyl methyl 91 —CH.sub.2-tolyl methyl methyl 92 —CH.sub.2-xylyl methyl methyl 93 —CH.sub.2-pyridyl methyl methyl 94 —CH.sub.2-pyrazinyl methyl methyl 95 —CH.sub.2-methylpyridinyl methyl methyl 96 —CH.sub.2-dibenzofuranyl methyl methyl 97 —CMe.sub.2-methyl methyl methyl 98 —CMe.sub.2-ethyl methyl methyl 99 —CMe.sub.2-propyl methyl methyl 100 —CMe.sub.2-iso-butyl methyl methyl 101 cyclopentyl methyl methyl 102 cyclohexyl methyl methyl.

Description

EXAMPLES

(1) The examples which follow, more particularly the methods, materials, conditions, process parameters, apparatus and the like detailed in the examples, are intended to support the present invention, but not to restrict the scope of the present invention.

(2) All experiments are carried out in protective gas atmosphere.

(3) The percentages and ratios mentioned in the examples below—unless stated otherwise—are % by weight and weight ratios.

I Device Examples

(4) Production of an OLED (General Procedure)

(5) The ITO substrate used as the anode is cleaned first with commercial detergents for LCD production (Deconex® 20NS, and 25ORGAN-ACID® neutralizing agent) and then in an acetone/isopropanol mixture in an ultrasound bath. To eliminate possible organic residues, the substrate is exposed to a continuous ozone flow in an ozone oven for a further 25 minutes. This treatment also improves the hole injection properties of the ITO. Next, the hole injection layer (40 nm) AJ20-1000 from Plexcore is spun on from solution. Respectively, in device example 12, the hole injection layer HATCN (10 nm) is applied by vapor deposition. HATCN: Dipyrazino[2,3-f:2′,3′-h]quinoxaline 2,3,6,7,10,11-hexacarbonitrile)

(6) Thereafter, the organic materials specified below are applied by vapor deposition to the cleaned substrate at about 10.sup.−7-10.sup.−9 mbar at a rate of approx. 0.5-5 nm/min. The hole conductor and exciton blocker applied to the substrate is Ir(DPBIC).sub.3 (devices 1 to 6, 9, 10, 11 and 12) respectively Ir(DPABIC).sub.3 (devices 7 or 8 or 9) with a thickness of 20 nm (80 nm in device example 12), of which the first 10 nm (70 nm in device example 12) are doped with MoO.sub.3 (50 wt.-%:50 wt.-%) (90 wt.-% Ir(DPBIC).sub.3: 10 wt.-% MoO.sub.3 in device example 12) to improve the conductivity.

(7) ##STR00086##

(8) (for preparation of Ir(DPBIC).sub.3 see Ir complex (7) in the application WO2005/019373).

(9) ##STR00087##

(10) (described as complex fac-Em1 in WO2012/172182 (synthesis: example 1)).

(11) Subsequently, a mixture of emitter (BE-X), Ir(DPBIC).sub.3 respectively Ir(DPABIC).sub.3, and a host material (the emitter (BE-1, BE-2, BE-3, BE-4, BE-5, BE-6 or BE-7 or BE-9 or BE-10 or BE-11), the host material (SH-1, SH-2, SH-3, SH-4, SH-5 or SH-6) and the relative amounts in % by weight are given in the specific device examples) is applied by vapor deposition with a thickness of 40 nm (devices 1 to 3 and 5 to 12) respectively 60 nm (device 4). Subsequently, the host material is applied by vapor deposition with a thickness of 5 nm as an exciton and hole blocker.

(12) Emitter:

(13) BE-X (X=1, 2, 3, 4, 5, 6, or 7 or 9 or 10):

(14) BE-1:

(15) ##STR00088##
(isomeric mixture of cyclometallation isomers, shown is only one cyclometallation isomer)

(16) BE-2:

(17) ##STR00089##
(isomeric mixture of cyclometallation isomers, shown is only one cyclometallation isomer)

(18) BE-3:

(19) ##STR00090##
(one homoleptic cyclometallation isomer as shown)

(20) BE-4:

(21) ##STR00091##
(one heteroleptic cyclometallation isomer as shown; isomer A)

(22) BE-5:

(23) ##STR00092##
(one heteroleptic cyclometallation isomer as shown; isomer B)

(24) BE-6:

(25) ##STR00093##
(one homoleptic cyclometallation isomer as shown)

(26) BE-7:

(27) ##STR00094##
(and second cyclometallation isomer, shown is only one cyclometallation isomer)

(28) BE-9:

(29) ##STR00095##
(one heteroleptic cyclometallation isomer as shown)

(30) BE-10:

(31) ##STR00096##
(one heteroleptic cyclometallation isomer as shown)

(32) BE-11:

(33) ##STR00097##
(isomeric mixture of cyclometallation isomers, shown are both cyclometallation isomers)

(34) BE-V: Comparative Emitter:

(35) ##STR00098##
fac-Em1 in WO2011/073149

(36) The synthesis of complexes BE-1 to BE-7 and BE-9 and BE-11 is described below.

(37) Host Material:

(38) SH-1:

(39) ##STR00099##
(described in WO2009/008100, example 4)

(40) SH-2:

(41) ##STR00100##
(described as compound “I-1” in WO2011/004639, synthesis described in [0161] to [0163] in WO2011/004639)

(42) SH-3:

(43) ##STR00101##
(compound “3-1” in “Synthetic example 2” in US2009/066226)

(44) SH-4:

(45) ##STR00102##
(“Example 4g” in WO2009/003898)

(46) SH-5:

(47) ##STR00103##
(Compound no. 14 in WO 2010/079051)

(48) SH-6:

(49) ##STR00104##
described in WO2010/079051, structure on page 22 (X═O); synthesis as in example 17 in EP1 885 818 on page 104 in US2013/0119360)

(50) Next, as an electron transporter, a mixture of Liq and ETM (ETM-1 or ETM-2 as specified in the specific device examples) (50 wt.-%:50 wt.-%) is applied by vapor deposition in a thickness of 25 nm; then a 4 nm KF layer is applied; and finally a 100 nm-thick A1 electrode is applied. All components are adhesive-bonded to a glass lid in an inert nitrogen atmosphere.

(51) ##STR00105##

(52) Electron Transport Material:

(53) ETM-1:

(54) ##STR00106##
(compound A-1 in WO 2011/157779)

(55) ETM-2:

(56) ##STR00107##
(compound A1 in WO 2011/157779; compound A-10 in WO2006/128800)

(57) To characterize the OLED, electroluminescence spectra are recorded at different currents and voltages. In addition, the current-voltage characteristic is measured in combination with the light output emitted. The light output can be converted to photometric parameters by calibration with a photometer. The lifetime t.sub.1/2 of the diode is defined by the time taken for the luminance to fall to 50% of its initial value. The lifetime measurement is carried out at a constant current. The CIE.sub.x,y coordinates are extracted from the spectra according to CIE 1931 as known in the art.

(58) For the different emitters, different host materials and different electron transport materials in the above-described OLED structure, the following electrooptical data are obtained:

(59) All data are obtained at 300 nits.

(60) Device 1:

(61) Compound BE-1 and BE-2 with SH-1

(62) 40 nm HIL Plexcore AJ20-1000-10 nm Ir(DPBIC).sub.3:MoO.sub.3 (50:50)—10 nm Ir(DPBIC).sub.3—40 nm BE-X/Ir(DPBIC).sub.3/SH-1 (10:15:75)—5 nm SH-1-25 nm ETM-X:Liq (50:50)—4 nm KF—100 nm Al

(63) TABLE-US-00003 Voltage LumEff EQE Example BE-X ETM-X [V] [lm/W] [%] CIE x, y Device 1.1 BE-V ETM-1 5.6 15.4 15.5 0.16; 0.29 (comparative) Device 1.2.sup.[1] BE-1 ETM-1 4.0 21.2 17.7 0.15; 0.25 Device 1.3 BE-2 ETM-2 4.1 18.1 16.1 0.15; 0.23 .sup.[1]40 nm BE-1/Ir(DPBIC).sub.3/SH-1 (30:5:65)

(64) Result: Inventive devices 1.2 and 1.3 show better color (CIE.sub.y), luminous efficacy, lower voltage and better EQE compared with comparative device 1.1 (BE-V).

(65) Device 2:

(66) Compound BE-1 and BE-2 with SH-2

(67) 40 nm HIL Plexcore AJ20-1000-10 nm Ir(DPBIC).sub.3:MoO.sub.3 (50:50)—10 nm Ir(DPBIC).sub.3—40 nm BE-X/Ir(DPBIC).sub.3/SH-2 (10:10:80)—5 nm SH-2-25 nm ETM-X:Liq (50:50)—4 nm KF—100 nm Al

(68) TABLE-US-00004 Voltage LumEff EQE Example BE-X ETM-X [V] [lm/W] [%] CIE x, y Device 2.1 BE-V ETM-1 3.9 21.2 15.0 0.16; 0.29 (comparative) Device 2.2 BE-1 ETM-1 3.9 23.3 18.4 0.15; 0.25

(69) Result: Inventive device 2.2 shows better color (CIE.sub.y) and better EQE and better luminous efficacy compared with comparative device 2.1 (BE-V).

(70) Device 3

(71) Compound BE-2, Compound BE-4 and Compound BE-5 with SH-3

(72) 40 nm HIL Plexcore AJ20-1000-10 nm Ir(DPBIC).sub.3:MoO.sub.3 (50:50)—10 nm Ir(DPBIC).sub.3—40 nm BE-X/Ir(DPBIC).sub.3/SH-3 (10:15:75)—5 nm SH-3-25 nm ETM-2:Liq (50:50)—4 nm KF—100 nm Al

(73) TABLE-US-00005 Voltage LumEff EQE relative Example BE-X [V] [lm/W] [%] CIE x, y LT Device 3.1 BE-V 4.1 15.8 11.7 0.15; 0.26 100 (comparative) Device 3.2 BE-2 3.8 21.0 17.5 0.14; 0.23 164 Device 3.3.sup.[1] BE-4 4.0 16.5 13.4 0.15; 0.21 136 Device 3.4.sup.[2] BE-5 3.9 16.4 12.5 0.15; 0.22 212 .sup.[1]EML: 40 nm BE-4/Ir(DPBIC).sub.3/SH-3 (20:10:70), EB .sup.[2]EML: 40 nm BE-5/Ir(DPBIC).sub.3/SH-3 (20:10:70)

(74) Result: Inventive devices 3.2, 3.3 and 3.4 show better color (CIE.sub.y), luminous efficacy, better EQE and better lifetime compared with comparative device 3.1 (BE-V).

(75) Device 4

(76) Compound BE-1 with SH-4

(77) 40 nm HIL Plexcore AJ20-1000-10 nm Ir(DPBIC).sub.3:MoO.sub.3 (50:50)—10 nm Ir(DPBIC).sub.3—60 nm BE-X/Ir(DPBIC).sub.3/SH-4 (10:5:85)—5 nm SH-4-25 nm ETM-1:Liq (50:50)—4 nm KF—100 nm Al

(78) TABLE-US-00006 LumEff Example BE-X Voltage [V] [Im/W] CIE x, y Device 4.1 (comparative) BE-V 7.5 10.4 0.16; 0.26 Device 4.2 BE-1 5.0 15.0 0.16; 0.26

(79) Result: Inventive device 4.2 shows better voltage and better luminous efficacy by constant color (CIE) compared with comparative device 4.1 (BE-V).

(80) Device 5

(81) Compound BE-2, compound BE-4 and compound BE-5 with SH-5

(82) 40 nm HIL Plexcore AJ20-1000-10 nm Ir(DPBIC).sub.3:MoO.sub.3 (50:50)—10 nm Ir(DPBIC).sub.3—40 nm BE-X/Ir(DPBIC).sub.3/SH-5 (10:5:85)—5 nm SH-5-25 nm ETM-2:Liq (50:50)—4 nm KF—100 nm Al

(83) TABLE-US-00007 Voltage Lum Eff EQE Example BE-X [V] [Im/W] [%] CIE x, y Device 5.1 (comparative) BE-V 5.5 14.6 15.5 0.16; 0.27 Device 5.2 BE-2 4.3 17.9 18.7 0.14; 0.20 Device 5.3.sup.[1] BE-4 3.9 18.7 18.4 0.14; 0.16 Device 5.4.sup.[2] BE-5 3.8 15.7 15.8 0.14; 0.15 .sup.[1]EML: 40 nm BE-4/Ir(DPBIC).sub.3/SH-5 (5:15:80); .sup.[2]EML: 20 nm BE-5/Ir(DPBIC).sub.3/SH-5 (5:10:85)

(84) Result: Inventive devices 5.2, 5.3 and 5.4 show better color (CIE.sub.y), luminous efficacy and better EQE compared with comparative device 5.1 (BE-V).

(85) Device 6

(86) Compound BE-2 and compound BE-4 with SH-6

(87) 40 nm HIL Plexcore AJ20-1000-10 nm Ir(DPBIC).sub.3:MoO.sub.3 (50:50)—10 nm Ir(DPBIC).sub.3—40 nm BE-X/Ir(DPBIC).sub.3/SH-6 (10:15:75)—5 nm SH-6-25 nm ETM-2:Liq (50:50)—4 nm KF—100 nm Al

(88) TABLE-US-00008 Voltage LumEff EQE Example BE-X [V] [Im/W] [%] CIEx, y Device 6.1 (comparative) BE-V 4.1 17.3 14.4 0.15; 0.25 Device 6.2 BE-2 3.6 22.8 18.8 0.14; 0.21 Device 6.3.sup.[1] BE-4 3.8 18.7 17.2 0.14; 0.17 .sup.[1]EML: 40 nm BE-4/Ir(DPBIC).sub.3/SH-6 (5:5:90)

(89) Result: Inventive devices 6.2 and 6.3 show better color (CIEw) and better EQE compared with comparative device 6.1 (BE-V).

(90) Device 7

(91) Compound BE-5 with SH-5 and with Ir(DPABIC).sub.3

(92) 40 nm H IL Plexcore AJ20-1000 10 nm Ir(DPABIC).sub.3:MoO.sub.3 (50:50)—10 nm Ir(DPABIC).sub.3—40 nm BE-X/Ir(DPBIC).sub.3/SH-5 (10:5:85)—5 nm SH-5-25 nm ETM-2:Liq (50:50)—4 nm KF—100 nm Al

(93) TABLE-US-00009 Voltage Lum Eff Example BE-X M [Im/W] CIEx, y Device 7.1 (comparative) BE-V 5.0 17.0 0.15; 0.26 Device 7.2.sup.[1] BE-5 3.5 20.5 0.15; 0.20 .sup.[1]40 nm BE-5/Ir(DPBIC).sub.3/SH-5 (15:35:50)

(94) Result: Inventive device 7.2 shows better color (CIE.sub.y) and better luminous efficacy compared with comparative example device 7.1 (BE-V).

(95) Further Device (Device 8) Comprising Compound BE-4 with SH-5 and with Ir(DPABIC).sub.3

(96) Same device setup as device 7, only BE-X=BE-4 and using 60 nm BE-4/Ir(DPBIC).sub.3/SH-5 (5:10:85) shows even better CIE coordinates: (0.14; 0.15).

(97) Further Device (Device 9) Comprising Compound BE-7

(98) By replacement of the emitter materials mentioned in devices 1 to 7 by the emitter material BE-7 luminescent organic light-emitting devices emitting blue light having a high color purity are obtained.

(99) Device 10:

(100) Compound BE-9 and BE-10 with SH-3

(101) 40 nm HIL Plexcore AJ20-1000-10 nm Ir(DPBIC).sub.3:MoO.sub.3 (50:50)—10 nm Ir(DPBIC).sub.3—40 nm BE-X/Ir(DPBIC).sub.3/SH-3 (10:15:75)—5 nm SH-3-25 nm ETM-2:Liq (50:50)—4 nm KF—100 nm Al

(102) TABLE-US-00010 Voltage LumEff EQE relative Example BE-X [V] [lm/W] [%] CIE x, y LT Device 9.1.sup.[1] BE-V 4.1 15.8 11.7 0.15; 0.26 100 (comparative) Device 9.2 BE-9 4.4 17.1 15.1 0.15; 0.21 170 Device 9.3 BE-10 4.3 18.4 15.6 0.15; 0.22 180 .sup.[1]EML: 40 nm BE-V/Ir(DPBIC).sub.3/SH-3 (10:15:75)

(103) Result: Inventive devices 9.2 and 9.3 show better color (CIEw), luminous efficacy, better EQE and better lifetime compared with comparative device 9.1 (BE-V).

(104) Further Device (Device 11) comprising Compound BE-11 By replacement of the emitter materials mentioned in device 10 by the emitter material BE-11 luminescent organic light-emitting devices emitting blue light having a high color purity are obtained.

(105) Device 12:

(106) Mixture of compounds BE-3 to BE-6 with SH-3

(107) 10 nm HIL HATCN—70 nm Ir(DPBIC).sub.3:MoO.sub.3 (90:10)—10 nm Ir(DPBIC).sub.3—40 nm BE-X/Ir(DPBIC).sub.3/SH-3 (10:20:70)—5 nm SH-3-25 nm ETM-2:Liq (50:50)—4 nm KF—100 nm Al

(108) TABLE-US-00011 Voltage LumEff EQE Example BE-X [V] [Im/W] [%] CIEx, y Device 12 BE-3 to BE-6 3.8 17.4 13.5 0.15; 0.21

(109) Result: Replacing the solution processed HIL (Plexcore AJ20-1000) and optimizing the HTL thickness gives similar color (CIE.sub.y), voltage and EQE as device 3.4, having now all steps processed in vacuum.

(110) The inventive compounds can be used in a pure isomeric form or as mixture of cyclometalation isomers without significant impact on the device performance.

II Synthesis of Complexes BE-1 to BE-11

(111) General Aspects

(112) Determination of the photoluminescence Spectra

(113) The photoluminescence (PL) spectra of the complexes are measured on thin polymer films doped with the respective complexes. The thin films are prepared by the following procedure: a 10%-w/w polymer solution is made by dissolving 1 g of the polymer “PMMA 6N” (Evonik) in 9 g of dichloromethane, followed by stirring for one hour. 2 mg of the respective complexes are added to 0.098 g of the PMMA solution, and stirring continued for one minute. The solutions are casted by doctor-blading with a film applicator (Model 360 2082, Erichsen) with a 60 μm gap onto quartz substrates providing thin doped polymer films (thickness ca. 6 μm). The PL spectra and quantum-yields (Q.Y.) of these films are measured with the integrating-sphere method using the Absolute PL Quantum Yield Measurement System (Hamamatsu, Model C9920-02) (excitation wavelength: 400 nm).

(114) Determination Oft the Lifetime τ.sub.v

(115) The lifetime (τ.sub.v) of the luminescence of the complexes in the prepared films are measured by the following procedure: For excitation of the emission a sequence of short laser pulses (THG Nd-YAG, 355 nm, 1 nsec pulse length, 1 kHz repetition rate) is used. The emissions are detected by the time-resolved photon-counting technique in the multi-channel scaling modus using a combination of photomultiplier, discriminator and a multiscaler card (FAST ComTec GmbH, Model P7888). The λ.sub.max, CIE x,y, Q.Y., and iv values of the photoluminescence measurements, and the full width of half maxima (FWHM) of the emission spectra values are included in the following experimental part.

i) Synthesis of Complexes BE-1 and BE-2

Synthesis of BE-1

a) Synthesis of 5-bromopyrazin-2-amine

(116) ##STR00108##

(117) A light yellow solution of 19.0 g (0.20 mol) of 2-aminopyrazine in 40 ml of DMF and 120 ml of acetonitrile, and a light yellow solution of 30.0 g (0.10 mol) of 1,3-dibromo-5,5-dimethylhydantoin (DBH) in 20 ml of DMF and 180 ml of acetonitrile are simultaneously added during 30 minutes under argon from two dropping funnels at −5° C. to pre-cooled 20 ml of acetonitrile. After addition the resulting brown solution is treated with 40 ml of a 10%-solution of sodium thiosulfate at −5° C. providing a brown suspension and stirring continued until room temperature is reached. The reaction mixture is concentrated under vacuum and 180 ml of aqueous 2%-solution of sodium carbonate added, followed by the addition of 10 g of Hyflo® filter aid. The mixture is stirred for 30 minutes, filtered, and four times extracted with a 3:2-mixture of ethyl acetate and hexane. The combined organic phases are dried over sodium sulfate and concentrated under vacuum, providing a dark oil which is further suspended in hexane and filtered giving a tacky solid. After drying under vacuum at 60° C. a viscous oil is obtained which is dissolved in 100 ml of ethyl acetate and the resulting suspension filtered through a 5 cm layer of silica gel followed by rinsing the silica gel with 200 ml of ethyl acetate. The reddish brown solution is treated with activated charcoal DARCO® KB-G and stirred at room temperature during 24 hours followed by filtration and concentration under vacuum, giving the title product as light yellow viscous oil (yield: 25.0 g (72%)). .sup.1H-NMR (400 MHz, d.sub.6-DMSO): δ=6.64 (s, 1H), 7.68 (s, 1H), 8.03 (s, 1H).

b) Synthesis of 5-ethylpyrazin-2-amine

(118) ##STR00109##

(119) 28.7 g (165 mmol) of 5-bromopyrazin-2-amine and 1.78 g (3.28 mmol) of [1,3-bis(diphenylphosphino)propane]dichloronickel(II) are suspended in 400 ml of dioxane at room temperature under argon. 300 g of a 15 wt %-solution (1.1 M) of diethylzinc in toluene are slowly added at 12° C. during 90 minutes giving a turbid brown solution. The reaction temperature is raised to 21° C. during one hour and the reaction completed by stirring at 21° C. for an 90 minutes. 30 ml of methanol are slowly added by controlling the temperature to 21° C. by cooling. The resulting solution is concentrated under vacuum and further suspended in 600 ml of toluene followed by the addition of 50 g of Hyflo® filter aid. The mixture is stirred during 30 minutes and filtered over a layer of Hyflo® filter aid. The solid filter residue is washed first with 1000 ml of toluene and 1000 ml of ethyl acetate and the combined filtrates concentrated under vacuum. An additional amount of crude product is obtained by washing the solid filter residue with 1500 ml of a 90:10-mixture of dichloromethane/methanol and concentrating the filtrate under vacuum. The concentrated fractions are each suspended in dichloromethane followed by filtration and concentration of the filtrates under vacuum giving the title product as light beige viscous oil (yield: 20.1 g (99%)). .sup.1H-NMR (400 MHz, CDCl.sub.3): δ=1.26 (t, 3H), 2.70 (q, 2H), 4.36 (br. s, 2H), 7.88 (s, 1H), 7.99 (s, 1H).

c) Synthesis of 3-bromo-5-ethyl-pyrazin-2-amine

(120) ##STR00110##

(121) 21.0 g (0.171 mol) of 5-ethylpyrazin-2-amine and 14.3 g (0.181 mol) of pyridine are dissolved in 600 ml of dioxane. 27.35 g (0.171 mol) of bromine are slowly added at room temperature during 30 minutes during which the temperature rises to 39° C. The brown reaction mixture is further stirred during 20 minutes and quenched with 20 ml of water and cooled down under stirring to 28° C. during 15 minutes. The organic phase is separated and filtered through silica gel (4 cm layer). The organic phase is separated and filtered through a 4 cm layer of silica gel followed by rinsing with 50 ml of dioxane. The filtrate is concentrated under vacuum giving the title product as colorless oil (yield: 18.3 g (53%)). .sup.1H-NMR (400 MHz, d.sub.6-DMSO): δ=1.23 (t, 3H), 2.65 (q, 2H), 5.16 (br. s, 2H), 7.78 (s, 1H).

d) Synthesis of 5-ethyl-N2,N3-diphenyl-pyrazine-2,3-diamine

(122) ##STR00111##

(123) 10.1 g (50.0 mmol) of 3-bromo-5-ethyl-pyrazin-2-amine and 465 g of aniline are heated under argon at 146° C. during 28 hours. The brown suspension is concentrated under vacuum and the residue treated with water followed by acidification with aqueous HCl giving a dark suspension which is vigorously stirred during 15 minutes. The mixture is treated with 200 ml of hexane and stirring vigorously continued during one hour. The liquid phase is separated and the tacky residue taken up in dichloromethane and extracted two times with 100 ml of water. The organic layer is concentrated under vacuum and the residue dissolved in toluene followed by filtration through a 4 cm layer of silica gel and additional rinsing of the silica gel layer with plenty of toluene. The combined organic phases are concentrated under vacuum and further purified by chromatography (silica gel, toluene/hexane). The title product is obtained as light brown clear viscous oil (yield: 6.1 g (42%)).

(124) .sup.1H-NMR (400 MHz, ds-DMSO): δ=1.22 (t, 3H), 2.57 (q, 2H), 6.92-7.02 (m, 2H), 7.26-7.37 (m, 4H), 7.48 (s, 1H), 7.61 (dd, 2H), 7.74 (dd, 2H), 8.42 (s, 1H), 8.51 (s, 1H).

e) Synthesis of 5-ethyl-1,3-diphenyl-imidazo[4,5-b]pyrazin-3-ium tetrafluoroborate

(125) ##STR00112##

(126) 6.8 g (23.4 mmol) of 5-ethyl-N2,N3-diphenyl-pyrazine-2,3-diamine are suspended under argon in 80 ml of acetonitrile and cooled down to ice-bath temperature. 7.5 g (58.5 mmol) of (chloromethylene)dimethylammonium chloride (Vilsmeier reagent) are added in small portions during under cooling at 0° C. and stirring continued for two hours. Stirring is continued over an ice-bath for a further 20 hours during which the temperature slowly reached 21° C. The brown solution is treated with 10.3 g (93.8 mmol) of sodium tetrafluoroborate and stirring continued at 21° C. during 20 hours providing a light brown suspension. The suspension is filtered and the solid washed with 20 ml of acetonitrile. The filtrate is concentrated under vacuum giving 16.3 g of a brown viscous oil which is heated up with 30 ml of ethanol. The brown solution is cooled down and the resulting suspension further stirred at 0° C. during 30 minutes followed by filtration and washing with 20 ml of cold ethanol. The solid is dried under vacuum giving the title product as beige solid (yield: 4.8 g (72%)). .sup.1H-NMR (400 MHz, d.sub.6-DMSO): δ=1.36 (t, 3H), 3.12 (q, 2H), 7.73-7.87 (m, 6H), 8.00-8.08 (m, 4H), 9.01 (s, 1H), 11.07 (s, 1H).

f) Synthesis of 2-ethoxy-5-ethyl-1,3-diphenyl-2H-imidazo[4,5-b]pyrazine

(127) ##STR00113##

(128) 4.7 g (12.1 mmol) of 5-ethyl-1,3-diphenyl-imidazo[4,5-b]pyrazin-3-ium tetrafluoroborate are suspended under argon in 40 ml of ethanol and cooled down to ice-bath temperature. 3.93 g (12.1 mmol) of a 21 wt % solution of sodium ethoxide in ethanol are slowly added under cooling during 15 minutes. The ice-bath is removed and stirring continued during 30 minutes giving a light beige suspension. The suspension is filtered and the solid washed with a small amount of ethanol. The filtrate is concentrated under vacuum giving the title product as beige viscous oil (yield: 4.2 g (quantitative). .sup.1H-NMR (400 MHz, d.sub.6-DMSO): δ=0.90 (t, 3H), 1.25 (t, 3H), 2.61 (q, 2H), 3.17 (q, 2H), 7.17 (q, 2H), 7.41 (s, 1H), 7.47 (q, 4H), 7.73 (s, 1H), 8.05 (d, 2H), 8.10 (d, 2H).

g) Synthesis of Complex BE-1

(129) ##STR00114##

(130) 4.0 g (11.6 mmol) of 2-ethoxy-5-ethyl-1,3-diphenyl-2H-imidazo[4,5-b]pyrazine and 0.97 g (1.4 mmol) of chloro(1,5-cyclooctadiene)iridium(I) dimer are suspended under argon in 30 ml of o-xylene. The suspension is four times evacuated and backfilled with argon, followed by heating at 134° C. during 140 minutes. The dark brown clear solution is cooled down to room temperature and diluted with 40 ml of hexane followed by filtration and washing with 100 ml of hexane. The solid is three times suspended with 20 ml of ethanol followed by filtration and washing with 20 ml of ethanol. The solid is further suspended in hexane followed by filtration and washing four times with 20 ml of methanol and drying under vacuum. The resulting grey powder is dissolved in 10 ml of dichloromethane and filtered through a 4 cm layer of silica gel followed by rinsing with 80 ml of dichloromethane under the exclusion of light. The combined filtrate is diluted with 30 ml of ethanol and concentrated under vacuum to one fifth of the volume giving a light yellow suspension which is filtered, and the resulting solid further washed with ethanol. The solid is heated up in a mixture of 30 ml of 2-butanone and 5 ml of toluene and stirring continued for 30 minutes. The yellow suspension is cooled down to room temperature, filtered, and the resulting solid further dried under vacuum giving the title product as a light yellow powder (yield: 1.33 g (42%)). .sup.1H-NMR (400 MHz, CDCl.sub.3): 3=1.20-1.34 (m, 6H), 1.44-1.62 (m, 6H), 2.70-2.84 (m, 3H), 2.96-3.11 (m, 3H), 6.21-7.27 (2 m and br. s, 24H), 7.90-8.00 and 8.15-8.25 (2 m, 3H), 8.71-8.80 and 8.81-8.90 (2 m, 3H). APCI-LC-MS (positive, m/z): exact mass of C.sub.57H.sub.45IrN.sub.12=1090.35; found 1091.2 [M+1].sup.+.

(131) Photoluminescence data (2% film in PMMA): λ.sub.max=471 nm, CIE x,y=(0.15, 0.22), Q.Y.=96%, τ.sub.v=3.3 μs.

Synthesis of BE-2

a) Synthesis of 5-isobutylpyrazin-2-amine

(132) ##STR00115##

(133) 14.59 g (0.60 mol) of magnesium shavings are suspended under argon in 50 ml of tetrahydrofuran. 91.35 g (0.66 mol) of 1-bromo-2-methylpropane in 200 ml of tetrahydrofuran are slowly added during 45 minutes by carefully regulating the exothermy of the Grignard reaction by cooling with an ice-bath keeping the reaction temperature at a maximum of 54° C. The grey suspension is further stirred during 30 minutes and allowed to cool down to room temperature. A colorless solution of 40.89 g (0.30 mol) of anhydrous zinc chloride in 200 ml of tetrahydrofuran is added during 10 minutes and the released exothermy carefully regulated with an ice-bath keeping the temperature at a maximum of 48° C. The resulting grey thick suspension is further stirred during 75 minutes until the temperature reaches 25° C. A solution of 17.4 g (0.10 mol) of 2-bromo-5-aminopyrazine in 200 of tetrahydrofuran and 1.08 g (2.0 mmol) of [1,3-bis(diphenylphosphino)propane]dichloronickel(II) are sequentially added and the temperature increased up to 48° C. during 45 minutes giving a light brown solution. Stirring is continued for 15 minutes at the same temperature and the solution cooled down to room temperature. The solution is slowly treated with 25 ml of water and 40 ml of concentrated HCl followed by stirring and dilution of the mixture with 300 ml of water. Aqueous ammonia solution is added until basic pH is reached and the resulting suspension further stirred together with 400 ml of toluene and 40 g of Hyflo® filter aid followed by filtration. The organic phase is separated and three times extracted with 250 ml of water, followed by drying over sodium sulfate and concentration under vacuum giving the title product as a light yellow oil (yield: 12.4 g (82%)). .sup.1H-NMR (400 MHz, CDCl.sub.3): δ=0.89 (d, 6H), 1.92-2.04 (d, 1H), 2.49 (d, 2H), 4.59 (br. s, 2H), 7.79 (s, 1H), 7.94 (s, 1H).

b) Synthesis of 3-bromo-5-isobutyl-pyrazin-2-amine

(134) ##STR00116##

(135) 12.38 g (81.9 mmol) of 5-isobutylpyrazin-2-amine and 6.86 g (86.7 mmol) of pyridine are dissolved under argon in 100 ml of dioxane. 13.08 g (81.8 mmol) of bromine are slowly added at a temperature of 21° C. during 45 minutes, controlling the temperature by the use of an ice-bath. The brown biphasic solution is vigorously stirred during 50 minutes and treated with 75 ml of water. The resulting brown suspension is extracted with 200 ml of ethyl acetate and the organic phase washed three times with 100 ml of water, followed by drying over sodium sulfate, filtration and concentration under vacuum. The resulting dark oil is further purified by chromatography (silica gel, heptane/ethyl acetate) giving the title product as a light yellow solid (yield: 14.5 g (77%)). .sup.1H-NMR (400 MHz, d.sub.6-DMSO): δ=0.86 (d, 6H), 1.81-1.97 (m, 1H), 2.40 (d, 2H), 6.44 (s, 2H), 7.82 (s, 1H).

c) Synthesis of 5-isobuty-N2,N3-diphenyl-pyrazine-2,3-diamine

(136) ##STR00117##

(137) 12.4 g (53.9 mmol) of 3-bromo-5-isobutyl-pyrazin-2-amine and 250 g of aniline are heated under argon at 152° C. during 28 hours. The brown suspension is diluted with 200 ml of toluene and extracted three times with 200 ml of water, and the organic phase concentrated under vacuum. The residue is stirred with aqueous 5% solution of HCl giving a precipitate which is filtered and washed with water and diluted aqueous ammonia solution. The sticky solid is dissolved in 300 ml of toluene and extracted with diluted ammonia solution and three times with 200 ml of water. The organic phased is dried over sodium sulfate and concentrated under vacuum. The dark viscous oil is purified by chromatography (silica gel, hexane/ethyl acetate) giving the title product as light yellow solid (yield: 8.9 g (52%)). .sup.1H-NMR (400 MHz, d.sub.6-DMSO): δ=0.92 (d, 6H), 1.95-2.11 (m, 1H), 2.41 (d, 2H), 6.92-7.02 (m, 2H), 7.26-7.36 (m, 4H), 7.44 (s, 1H), 7.62 (dd, 2H), 7.71 (dd, 2H), 8.39 (s, 1H), 8.47 (s, 1H).

d) Synthesis of (3-anilino-6-isobutyl-pyrazin-2-yl)-phenyl-ammonium chloride

(138) ##STR00118##

(139) A yellow suspension of 8.30 g (26.1 mmol) of 5-isobutyl-N2,N3-diphenyl-pyrazine-2,3-diamine and 100 ml of 37% hydrochlorid acid is stirred at room temperature during two hours providing a yellow-brownish solution. The solution is filtered and poured slowly into 300 ml of water leading to a yellow precipitate which is filtered off and washed with plenty of water. The solid residue is dried under vacuum giving the title product as a yellow powder (yield: 9.1 g (99%)).

(140) .sup.1H-NMR (400 MHz, d.sub.6-DMSO): δ=0.92 (d, 6H), 1.96 (m, 1H), 2.41 (d, 2H), 6.94-7.07 (m, 2H), 7.27-7.42 (m, 5H), 7.65 (d, 2H), 7.78 (d, 2H), 8.96 (br. s, 1H), 9.06 (br. s, 1H).

e) Synthesis of 2-ethoxy-5-isobutyl-1,3-diphenyl-2H-imidazo[4,5-b]pyrazine

(141) ##STR00119##

(142) 4.50 g (12.7 mmol) of (3-anilino-6-isobutyl-pyrazin-2-yl)-phenyl-ammonium chloride and 56.5 g (0.38 mol) of triethyl orthoformate are heated up under argon at 120° C. for one hour. The light brown solution is concentrated under vacuum giving the title product as brown viscous oil (yield: 4.75 g (quantitative)). .sup.1H-NMR (400 MHz, d.sub.6-DMSO): δ=0.85-0.99 (m, 9H), 1.99-2.14 (m, 1H), 2.37-2.50 (m, 2H), 3.17 (q, 2H), 7.13-7.22 (m, 2H), 7.43-7.52 (m, 5H), 7.73 (s, 1H), 8.03-8.12 (m, 4H).

f) Synthesis of Complex BE-2

(143) ##STR00120##

(144) 4.50 g (12.0 mmol) of 2-ethoxy-5-isobutyl-1,3-diphenyl-2H-imidazo[4,5-b]pyrazine and 1.01 g (1.5 mmol) of chloro(1,5-cyclooctadiene)iridium(I) dimer are suspended under argon in 60 ml of o-xylene. The suspension is four times evacuated and backfilled with argon, followed by heating at 122° C. during 23 hours. The brown solution is cooled down to 40° C., filtered, and diluted with 100 ml of heptane, filtered, and the solution concentrated under vacuum giving a brown viscous oil. Purification by chromatography (silica gel, heptane/dichloromethane) delivers a yellow powder which is further dissolved in 10 ml of dichloromethane and 50 ml of ethanol. Dichloromethane is stripped off under vacuum and the resulting yellow suspension filtered. The solid is dissolved in 10 ml of dichloromethane and 50 ml of acetonitrile. Dichloromethane is stripped off under vacuum and the light turbid solution further cooled down over an ice-bath. The thick suspension is filtered and the solid washed with a small amount of acetonitrile first, followed by washing with 30 ml of ethanol and 30 ml of hexane. The same dissolution and precipitation procedure is repeated once and the resulting solid dried under vacuum giving the title product as a light yellow solid (yield: 1.56 g, 44%). .sup.1H-NMR (400 MHz, CDCl.sub.3): δ=0.88-0.99 (m, 12H), 1.05-1.15 (m, 6H), 1.90-2.03 and 2.28-2.41 (2 m, 3H), 2.54-2.65 and 2.81-2.90 (2 m, 6H), 6.22-7.27 (br. s+2 m, 24H), 7.85-7.91 and 8.11-8.20 (2 m, 3H), 8.73-8.80 and 8.80-8.88 (2 m, 3H). APCI-LC-MS (positive, m/z): exact mass of C.sub.63H.sub.57IrN.sub.12=1174.45; found 1175.3 [M+1].sup.+.

(145) Photoluminescence data (2% film in PMMA): λ.sub.max=470 nm, CIE x,y=(0.15, 0.21), Q.Y.=99%, τ.sub.v=3.4 μs).

ii) Synthesis of Complexes BE-3, BE-4, BE-5 and BE-6

Synthesis of Intermediate A

(146) ##STR00121##

(147) A mixture of 32.2 g (0.18 mol) 1-bromopinacolon and 20.5 g (0.22 mol) in acetonitrile (225 ml) is stirred at 55° C. for 20 h. The reaction mixture is allowed to cool to room temperature and the solid is filtered off, washed and discarded. The solvent of the filtrate is removed and the resulting solid is taken up in a mixture of 5% HCl in 2-propanol (450 ml). The reaction mixture is stirred for 48 h, then the solid is removed. Diethyl ether is added and the resulting solid is isolated by filtration and dried under vacuum to give the title product (yield: 26.2 g (96%)). .sup.1H-NMR (400 MHz, CDCl.sub.3): δ=1.21 (s, 9H), 4.32 (q, 2H), 8.4 (br. s, 3H).

Synthesis of Intermediate B

(148) ##STR00122##

(149) A mixture of 24.0 g (0.16 mol) intermediate A in water (115 ml) is added in small portions to a suspension of 91 g (0.91 mol) calcium carbonate in chloroform (300 ml). The reaction mixture is cooled to 5° C., and then a solution of 32.3 ml (0.36 mol) 2-bromoacetylbromide in chloroform (225 ml) is quickly added. The resulting mixture is stirred for 1.5 h, the solid is filtered off, washed with chloroform and discarded. The filtrate is sequentially washed with a 2N aqueous HCl solution, a sodium carbonate solution and water. The solvent of the separated organic phase is removed and the resulting solid is dried under vacuum to give the title product (yield: 34.5 g (93%)). .sup.1H-NMR (500 MHz, CD.sub.2Cl.sub.2): δ=1.21 (s, 9H), 3.91 (s, 2H), 4.30 (d, 2H), 7.3 (br. s, 1H).

Synthesis of Intermediate C

(150) ##STR00123##

(151) A mixture of 34.1 g (0.15 mol) intermediate B and 4.26 g (28 mmol) sodium iodide in a solution of 2M ammonia in ethanol (500 ml) is stirred at 40° C. for 48 h. The solvent of the reaction mixture is removed and ethyl acetate is added to the residue. The organic phase is washed with water and then dried over sodium sulfate. The solvent of the separated organic phase is removed and the resulting residue is dried under vacuum to give the title product (yield: 18.6 g (84%)). .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.26 (s, 9H), 7.12 (s, 1H), 8.16 (s, 1H), 12.5 (br. s, 1H).

Synthesis of Intermediate D

(152) ##STR00124##

(153) A solution of 12.5 g (78 mmol) bromine in chloroform (60 ml) is slowly added at 0° C. to a mixture of 12.5 g (82 mmol) intermediate C and 6.8 g (86 mmol) pyridine in chloroform (350 ml). The resulting mixture is stirred for a further 60 min at 0° C. Methylene chloride (400 ml) is added and then a 10% aqueous sodium thiosulfate solution. The organic layer is separated, extracted with a 1 M aqueous sodium hydroxide solution and discarded. The aqueous solution is neutralized with 2 M hydrochloric acid and extracted with methylene chloride. The organic phase is dried over sodium sulfate. The solvent of the organic phase is removed and the resulting residue is dried under vacuum to give the title product (yield: 8.7 g (46%)). .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.27 (s, 9H), 7.22 (s, 1H), 12.7 (br. s, 1H).

Synthesis of Intermediate E

(154) ##STR00125##

(155) A mixture of 8.7 g (38 mmol) intermediate D, 18.0 g (0.19 mol) trimethylammonium chloride and 57 g (0.37 mol) POCl.sub.3 are stirred at 110° C. for 20 h. After cooling to room temperature the remaining liquid is removed and the residue is taken up in methylene chloride. The mixture is poured in ice water and the phases are separated. Water is added to the organic phase and the liquid is brought to pH 11 by adding 25% aqueous sodium hydroxide. The organic layer is separated and dried over sodium sulfate. The solvent of the organic phase is removed and the resulting residue is dried under vacuum to give the title product (yield: 5.5 g (71%)). .sup.1H-NMR (500 MHz, CD.sub.2Cl.sub.2): δ=1.37 (s, 9H), 8.33 (s, 1H).

Synthesis of Intermediate F

(156) ##STR00126##

(157) A solution of 9.2 g (45 mmol) intermediate E and 63 g (68 mmol) aniline in o-xylene (25 ml) is stirred at 160° C. for 20 h. After cooling to room temperature the remaining liquid is removed and the residue is taken up in methylene chloride. The organic phase is sequentially washed with 20% hydrochloric acid, 25% aqueous sodium hydroxide and water. The organic phase is dried over sodium sulfate. The solvent of the organic phase is removed and the resulting residue is purified by column chromatography (silica, eluent: cyclohexane/ethyl acetate) to give the title product (yield: 11.3 g (79%)). .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.36 (s, 9H), 6.06 (s, 1H), 6.47 (s, 1H), 6.99 (m, 2H), 7.16 (d, 2H), 7.29 (m, 4H), 7.49 (d, 2H), 7.78 (s, 1H).

Synthesis of Intermediate G

(158) ##STR00127##

(159) A solution of 11.2 g (35 mmol) intermediate F in a 1M solution of HCl in methanol (250 ml) is stirred at room temperature for 20 h. The solvent is removed and the resulting residue is dried under vacuum. Triethylorthoformiate (250 ml) is added and the mixture is stirred at 100° C. for 1 h. The solvent is removed and the resulting residue is dried to give the title product (yield: 12.5 g (98%)). .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.04 (t, 3H), 1.38 (s, 9H), 3.30 (q, 2H), 7.12-7.19 (m, 2H), 7.26 (s, 1H), 7.41-7.48 (m, 4H), 7.55 (s, 1H), 8.07 (d, 2H), 8.17 (d, 2H).

Synthesis of BE-3, BE-4, BE-5 and BE-6

(160) ##STR00128##

(161) A mixture of 5.0 g (13 mmol) intermediate G and 0.9 g (1.3 mmol) [Ir(cod)Cl].sub.2 in o-xylene (300 ml) is stirred at reflux for 5 h. The solvent is removed, the residue is taken up in a 1:1 mixture of acetonitrile and acetone (100 ml) and stirred for 16 h. The solid (containing BE-3-BE-5) is isolated by filtration and and the isomers are separated and purified by column chromatography on silica. The solvent of the acetonitrile/acetone filtrate is removed and the residue (containing BE-5-BE-6) is purified by column chromatography on silica.

(162) BE-3

(163) ##STR00129##

(164) Yield: 155 mg (5%). .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.30 (s, 27H), 6.2-7.1 (br. m, 12H), 6.65 (d, 3H), 6.72-6.82 (m, 6H), 7.13 (t, 3H), 8.39 (s, 3H), 8.74 (d, 3H). PL (2% in PMMA): λ.sub.max=468 nm, CIE x,y=(0.14, 0.20), Q.Y.=89%, τ.sub.v=2.9 μs.

(165) BE-4

(166) ##STR00130##

(167) Yield: 730 mg (23%). .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.29 (s, 9H), 1.30 (s, 9H), 1.55 (s, 9H), 6.2-7.2 (m, 24H), 8.09 (s, 1H), 8.38 (s, 1H), 8.40 (s, 1H), 8.71 (d, 1H), 8.74 (d, 1H), 8.82 (d, 1H).

(168) PL (2% in PMMA): λ.sub.max=467 nm, CIE x,y=(0.14, 0.19), Q.Y.=99% τ.sub.v=2.9 μs.

(169) BE-5

(170) ##STR00131##

(171) Yield: 750 mg (24%). .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.30 (s, 9H), 1.55 (s, 9H), 1.56 (s, 9H), 6.2-7.3 (m, 24H), 8.09 (s, 1H), 8.10 (s, 1H), 8.39 (s, 1H), 8.72 (d, 1H), 8.79 (d, 1H), 8.83 (d, 1H).

(172) PL (2% in PMMA): λ.sub.max=466 nm, CIE x,y=(0.14, 0.18), Q.Y.=99% τ.sub.v, =2.8 μs.

(173) BE-6

(174) ##STR00132##

(175) Yield: 180 mg (6%). .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): d=1.55 (s, 27H), 6.1-7.3 (m, 24H), 8.10 (s, 3H), 8.82 (d, 3H).

(176) PL (2% in PMMA): λ.sub.max=466 nm, CIE x,y=(0.15, 0.18), Q.Y.=96% τ.sub.v=2.8 μs.

iii) Synthesis of BE-8, BE-9 and BE-10

a) Synthesis of Intermediate B

(177) ##STR00133##

(178) Reagent A: A solution of Isopropenylmagnesiumbromide (0.5 M in THF, 32.1 mL) is slowly added to a mixture of 3.4 g (32 mmol) Trimethylborate in dry THF (20 mL) at −78° C. The reaction is stirred overnight to room temperature. The resulting suspension is poured into 50 mL saturated ammonium chloride solution between −10 and 0° C. The clear aqueous solution is extracted three times with diethyl ether (65 mL). The organic layer is then washed once with saturated sodium chloride solution (25 mL) and then this organic layer is dried over magnesium sulfate. The solvent is removed under vacuum and the white solid is stored under argon. .sup.1H-NMR (400 MHz, DMSO): δ=1.72 (s, 3H), 5.45 (s, 1H), 5.60 (s, 1H), 7.58 (s, 2H).

(179) Intermediate B: Then a mixture of 1.44 g (8.02 mmol) 2-Amino-5-brompyrazine 97%, the in advance prepared reagent A (raw product) and 6.81 g (32.1 mmol) potassium phosphate in 100 mL dry toluene is purged with argon for 10 minutes. Then, 147 mg (0.160 mmol) Tris(dibenzylidenacetone)dipalladium(0) and 180 mg (0.642 mmol) Tricyclohexylphosphine are added. The reaction is stirred under reflux overnight. After cooling to room temperature, the suspension is filtered. The solvent of the filtrate is removed and the resulting residue is purified by column chromatography (silica, eluent: toluene/ethyl acetate) to give the intermediate B (yield: 1.01 g (94%)).

(180) .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=2.13 (s, 3H), 4.62 (s, 2H), 5.11 (s, 1H), 5.72 (s, 1H), 7.94 (s, 1H), 8.16 (s, 1H).

b) Synthesis of Intermediate C

(181) ##STR00134##

(182) 1.01 g (7.47 mmol) of compound B are dissolved in ethyl acetate (50 ml). The reaction is purged with nitrogen, and then Pd/C 10% (84 mg) is added to the clear, yellow solution. The suspension is stirred at room temperature overnight at a constant hydrogen atmosphere. After 12 h hydrogenation there is still starting material detectable in the reaction mixture, so after filtration of the reaction mixture over a filter, the filtrate is treated a second time with Pd/C, 10% (84 mg) and hydrogen at room temperature overnight. Then the suspension is filtered and the filtrate is concentrated. The title product C is obtained in quantitative yield.

(183) .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.23 (d, 3H), 1.24 (d, 3H), 2.93 (sept, 1H), 4.45 (s, 2H), 7.84 (d, 1H), 7.91 (d, 1H).

c) Synthesis of Intermediate D

(184) ##STR00135##

(185) 3.59 g (26.17 mmol) of intermediate C and 2.17 g (27.48 mmol) of pyridine are dissolved in 180 mL of chloroform. The solution is cooled to 0° C. Then, a solution of 3.97 g (24.86 mmol) of bromine in 35 mL chloroform is slowly added over 1.5 h. The mixture is stirred for 1.5 h at 0° C. The reaction was then allowed to warm to room temperature and to stir overnight.

(186) The brown reaction mixture is slowly quenched with 150 mL of saturated sodium thiosulfate solution. This mixture is then stirred for 30 minutes. Then the mixture is separated in a separation funnel. The organic layer is washed with water and dried over sodium sulfate. The filtrate is concentrated and the residue is filtered over silica with toluene/ethyl acetate. The fractions with product are collected and concentrated to give the title product D as brown oil in 79.3% yield (4.26 g).

(187) .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.23 and 1.24 (2d, 6H), 2.86-2.98 (m, 1H), 4.89 (s, 2H), 7.82 (s, 1H).

d) Synthesis of Intermediate E (and F1)

(188) ##STR00136##

(189) 4.26 g (19.7 mmol) of intermediate D are stirred in 210 ml of aniline under argon atmosphere. The reaction is heated to reflux and stirred overnight. After cooling to room temperature, the reaction mixture is filtered under vacuum. The filtrate is concentrated. After removal of aniline (50° C., 3*10.sup.−2 mbar), the brown residue is suspended in a mixture of dichloromethane (100 ml) and cyclohexane (300 ml). The suspension is filtered and the solid is washed with cyclohexane (2×100 ml). The solid was washed with water (50 ml, 12 h stirring) and dried to give the title product F1 (yield: 2.4 g (31%)).

(190) The dichloromethane/cyclohexane filtrate is concentrated and the residue is purified via column chromatography (silica, CH/EE) to obtain intermediate E (1.5 g, 25%).

(191) Intermediate E: .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.29 and 1.30 (2d, 6H), 2.92-3.02 (sept, 1H), 6.06 (s, 1H), 6.46 (s, 1H), 7.00 (q, 2H), 7.16 (d, 2H), 7.29 (q, 4H), 7.65 (s, 1H), intermediate F1: .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.21 and 1.22 (2d, 6H), 2.81-2.97 (sept, 1H), 5.04 (s, 1H), 6.94-7.09 (m, 2H), 7.34 (t, 4H), 7.41 (s, 1H), 7.60 (d, 2H), 7.78 (d, 2H), 8.18 (s, 1H), 8.70 (s, 1H).

e) Synthesis of Intermediate F2

(192) ##STR00137##

(193) 0.65 g (2.1 mmol) of intermediate E are suspended in 17 ml of hydrochloric acid (32%) at room temperature. The mixture is stirred overnight under nitrogen atmosphere. The brown lump is treated in an ultrasonic bath until a green precipitate is formed. This is filtered and washed with water. The solid is dried at 40° C. overnight. The desired product F.sub.2 is obtained as light yellow solid (0.73 g, 78%).

(194) .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.21 and 1.22 (2d, 6H), 2.81-2.95 (m, 1H), 3.95 (s, 1H), 6.93-7.07 (m, 2H), 7.33 (t, 4H), 7.39 (s, 1H), 7.63 (d, 2H), 7.84 (d, 2H), 9.02 (s, 1H), 9.16 (s, 1H).

f) Synthesis of Intermediate G

(195) ##STR00138##

(196) 589 mg (1.73 mmol) of intermediate F2 are suspended in 24 ml of triethyl orthoformate. The suspension is stirred at room temperature overnight. Then the reaction is heated to 70° C. for 2 h. The brown suspension is filtered under vacuum and the residue is washed with ethanol. The filtrate is concentrated under vacuum to give the title product G in 91% yield (0.57 g).

(197) .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.04 (t, 3H), 1.31 and 1.32 (2d, 6H), 2.88 (sept, 1H), 3.29 (q, 2H), 7.10-7.20 (m, 2H), 7.24 (s, 1H), 7.37-7.49 (m, 5H), 8.06 (d, 2H), 8.13 (d, 2H).

g) Synthesis of BE-8, BE-9 and BE-10

(198) ##STR00139##

(199) 500 mg (1.39 mmol) of intermediate G are suspended in 10 ml of anhydrous o-xylene under argon atmosphere. The mixture is purged 10 minutes with argon. Then 93 mg (0.14 mmol) [Ir(cod)Cl].sub.2 are added. The reaction is heated to reflux and stirred overnight. After cooling to room temperature, the mixture is concentrated under vacuum. The brown residue is suspended in ethanol and then filtered under vacuum. The solid is washed a few times with ethanol. After drying at 40° C. overnight, the solid is purified via column chromatography (silica, eluent: cyclohexane/ethyl acetate) to yield BE-8, BE-9 and BE-10.

(200) BE-8

(201) ##STR00140##

(202) 30 mg (10%) BE-8

(203) .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.20 (d, 6H), 1.23-1.30 (m, 12H), 3.04 (sept, 3H), 6.48 (m, 7H), 6.63 (d, 4H), 6.73-6.82 (q, 7H), 7.13 (t, 3H), 7.13-7.52 (m, 3H), 8.23 (s, 3H), 8.74 (d, 3H).

(204) PL (2% PMMA): λ.sub.max=469 nm, CIE(x;y)=0.15; 0.21, QY=88%, τ.sub.v=3.3 μs

(205) BE-9

(206) ##STR00141##

(207) 89 mg (28%) BE-9

(208) .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.20 (m, 6H), 1.25-1.50 (m, 12H), 2.97-3.10 (m, 2H), 3.22-3.34 (septet, 1H), 6.25-7.32 (m, 10H), 6.65 (d, 4H), 6.72-6.84 (m, 7H), 7.09-7.19 (m, 4H), 7.92 (s, 1H), 8.22 and 8.23 (2s, 2H), 8.73 (t, 2H), 8.83 (d, 1H).

(209) PL (2% PMMA): λ.sub.max=468 nm, CIE(x;y)=0.15; 0.21, QY=86%, τ.sub.v=3.2 μs

(210) BE-10

(211) ##STR00142##

(212) 78 mg (25%) BE-10

(213) .sup.1H-NMR (400 MHz, CD.sub.2Cl.sub.2): δ=1.25-1.50 (m, 18H), 2.97-3.10 (septet, 1H), 3.22-3.34 (m, 2H), 6.25-7.42 (m, 10H), 6.65 (d, 4H), 6.72-6.84 (m, 6H), 7.09-7.19 (m, 4H), 7.92 (d, 2H), 8.23 (s, 1H), 8.73 (d, 1H), 8.83 (t, 2H).

(214) PL (2% PMMA): λ.sub.max=467 nm; CIE(x;y)=0.15; 0.19; QY=89%; τ.sub.v=3.1 μs.

iv) Synthesis of BE-11 and BE-7

a) Synthesis of BE-11

(215) ##STR00143##

(216) A mixture of 0.55 g (1.47 mmol) 2-ethoxy-5-isobutyl-1,3-diphenyl-2H-imidazo[4,5-b]pyrazine and 0.55 g (1.47 mmol) Pt(cod)C.sub.2 in 20 ml o-xylene is heated to 110° C. for 2 hours. 0.30 g (1.47 mmol) silver acetylacetonate is added and the resulting reaction mixture is heated to 110° C. for a further 16 hours. After cooling to RT, the solvent is removed under vacuum. The residue is taken up in dichloromethane, and silica is added. The mixture is stirred for 30 min, then the solid is filtered off. The solvent of the filtrate is removed, and the residue is purified by chromatography (silica gel, toluene), yielding both isomers as yellow solids.

(217) Isomer 1 (yield: 67 mg, 7%).

(218) .sup.1H-NMR (CD.sub.2Cl.sub.2): δ=0.93 (d, 6H), 1.36 (s, 3H), 2.02 (s, 3H), 2.06 (sept, 1H), 2.69 (d, 2H), 5.37 (s, 1H), 7.09 (dt, 1H), 7.19 (dt, 1H), 7.56-7.67 (m, 5H), 7.75-7.90 (m, 1H), 8.18-8.25 (m, 1H), 8.29 (s, 1H).

(219) PL (2% in PMMA): λ.sub.max=487 nm, CIE x,y=(0.22, 0.36), Q.Y.=67% τ.sub.v=3.5 μs.

(220) Isomer 2 (yield: 53 mg, 6%).

(221) .sup.1H-NMR (CD.sub.2Cl.sub.2): δ=1.01 (d, 6H), 1.36 (s, 3H), 2.02 (s, 3H), 2.28 (sept, 1H), 2.84 (d, 2H), 5.37 (s, 1H), 7.09 (dt, 1H), 7.20 (dt, 1H), 7.56-7.71 (m, 5H), 7.73-7.90 (m, 1H), 8.16 (s, 1H), 8.26-8.34 (m, 1H).

(222) PL (2% in PMMA): λ.sub.max=482 nm, CIE x,y=(0.21, 0.33), Q.Y.=52% τ.sub.v=3.1 μs.

b) Synthesis of BE-7

(223) ##STR00144##

(224) BE-7 is prepared in the same manner as BE-11 with the only difference that 2-ethoxy-5-isoproyl-1,3-diphenyl-2H-imidazo[4,5-b]pyrazine is employed instead of 2-ethoxy-5-isobutyl-1,3-diphenyl-2H-imidazo[4,5-b]pyrazine.