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  • H10K85/346—Transition metal complexes, e.g. Ru(II)polypyridine complexes comprising platinum
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  • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
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  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
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  • H10K85/342—Transition metal complexes, e.g. Ru(II)polypyridine complexes comprising iridium
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  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/917—Electroluminescent

Definitions

• the present invention relates to light-emitting devices, and more particularly to organic light-emitting devices (OLEDs).
• OLEDs organic light-emitting devices
• the invention relates to the use of luminescent biphenyl metal complexes as monomer and oligomer emitters in such devices.
• OLEDs Organic Light Emitting Devices or Organic Light Emitting Diodes
• OLEDs represent a new technology that will dramatically change the screen and lighting technology.
• OLEDs consist mainly of organic layers, which are also flexible and inexpensive to manufacture.
• OLED components can be designed over a large area as lighting fixtures, but also as small pixels for displays.
• OLEDs Compared to conventional technologies, such as liquid crystal displays (LCDs), plasma displays or cathode ray tubes (CRTs), OLEDs have many advantages, such as low operating voltage, thin structure, high-efficiency self-luminous pixels, high contrast and a good resolution as well as the possibility to display all colors. Furthermore, an OLED emits light when being touched electrical voltage instead of just modulating it. While many applications have already been developed for the OLED and also new fields of application have been opened up, there is still a need for improved OLEDs and in particular for improved triplet emitter materials. In the previous solutions, in particular problems in the long-term stability, the thermal stability and the chemical stability to water and oxygen occur. Furthermore, many emitters show only low sublimability. Furthermore, often important emission colors are not available with previously known emitter materials. Often, high efficiencies at high current densities or high luminances are not achievable. Finally, there are problems with many emitter materials in terms of manufacturing reproducibility.
• LCDs liquid crystal displays
• CRTs cathode ray tubes
• WO 03/087258 describes OLEDs comprehensively organometallic compounds, which are in particular five-coordinate 16- or six-coordinate 18 valence electron complexes.
• EP 1 191 614 A2 US2002 / 0034656 A1 and WO 00/57676 A1 describe platinum compounds which contain both a biphenyl and a bipyridine group as ligands.
• An object of the present invention was to provide new emitter materials, in particular for OLEDs and new light-emitting devices, which at least partially overcome the disadvantages of the prior art and which in particular have a high chemical stability.
• a light emitting device comprising (i) an anode, (ii) a cathode and (iii) an emitter layer disposed between and in direct or indirect contact with the anode and the cathode comprising at least one complex of the formula (I) (S-BPH) ML,
• M represents Pt (II), Rh (I), Ir (I), Pd (II) or Au (III), especially Pt (II), L represents a bidentate ligand or
• L X 2 , wherein each X independently represents a monodentate ligand and s-bph represents a ligand having an Ar-Ar moiety, wherein Ar represents an aromatic ring system, eg, especially biphenyl or substituted biphenyl.
• the use according to the invention of the complexes of the formula (I) in the emitter layer makes it possible to obtain light-emitting devices which have outstanding properties.
• the compounds used according to the invention show high quantum yields.
• the complexes can be varied by substitution and / or modification of the ligands, resulting in a variety of possibilities for modifying or controlling the emission properties. By suitable choice of the ligands also compounds with high sublimability can be obtained.
• the device comprises at least one anode, a cathode and an emitter layer.
• one or both of the electrodes used as the cathode or anode is made transparent, so that the light can be emitted by this electrode.
• Indium tin oxide (ITO) is preferably used as the transparent electrode material.
• a transparent anode is used.
• the other electrode may also be formed of a transparent material, but may also be formed of another material with suitable electron work function, if light is to be emitted only by one of the two electrodes.
• the second electrode in particular the cathode, made of a metal with high electrical conductivity, for example of aluminum, or silver, or a Mg / Ag or a Ca / Ag alloy.
• an emitter layer is arranged between the two electrodes. This may be in direct contact with the anode and the cathode, or in indirect contact, where indirect contact means that further layers are included between the cathode or anode and the emitter layer so that the emitter layer and the anode and / or cathode do not touch each other , but are electrically connected to each other via further intermediate layers.
• a voltage for example a voltage of 2-20 V, in particular 5-10 V
• negatively charged electrons emerge from the cathode, for example a conductive metal layer, particularly preferably from an aluminum cathode, and migrate in the direction of the positive anode. From this anode, in turn, positive charge carriers, so-called holes, travel in the direction of the cathode.
• organometallic complexes of the formulas (I) are present as emitter molecules.
• the migrating charge carriers ie a negatively charged electron and a positively charged hole, recombine, leading to neutral but energetically excited states of the emitter molecules.
• the excited states of the emitter molecules then give off the energy as light emission.
• the light-emitting devices according to the invention can be produced by vacuum deposition.
• a construction via wet-chemical application is possible, for example via spin coating processes, inkjet printing or screen printing processes.
• the structure of OLED devices is described in detail, for example, in US2005 / 0260449 A1 and in WO 2005/098988 A1.
• a hole Injection eg CuPc
• hole conduction layer or hole conduction layer eg ⁇ -NPD
• the emitter layer preferably consists of an organic matrix material having a sufficiently large singlet S 0 - triplet TV energy gap (UGH matrix material), eg of UGH, PVK (polyvinylcarbazole), CBP (4,4'-bis (9-carbazolyl) biphenyl) or other matrix materials.
• UGH matrix material eg of UGH, PVK (polyvinylcarbazole), CBP (4,4'-bis (9-carbazolyl) biphenyl) or other matrix materials.
• the emitter complex is doped, for example preferably with 1 to 10 weight percent.
• the values of the HOMO and LUMO energies of some selected biphenyl-Pt (II) complexes which are important for the selection of matrix materials in OLED devices are summarized in Table 2.
• the emitter layer can also be without a matrix be realized by the corresponding complex is applied as 100% material.
• a corresponding embodiment is described below.
• the light-emitting device according to the invention also has a CsF intermediate layer between the cathode and the emitter layer or an electron conductor layer.
• This layer has in particular a thickness of 0.5 nm to 2 nm, preferably of about 1 nm.
• This intermediate layer mainly causes a reduction of the electron work function.
• the light-emitting device is applied to a substrate, for example on a glass substrate.
• an OLED structure for a sublimable emitter also comprises, in addition to an anode, emitter layer and cathode, at least one, in particular a plurality and particularly preferably all of the layers mentioned below and shown in FIG. 1B.
• the entire structure is preferably located on a carrier material, in which case in particular glass or any other solid or flexible transparent material can be used.
• the anode is arranged on the carrier material, for example an indium tin oxide anode (ITO).
• ITO indium tin oxide anode
• HTL Hole Transport Layer
• the thickness of the hole transport layer is preferably 10 to 100 nm, in particular 30 to 50 nm.
• Further layers can be arranged between the anode and the hole transport layer, which improve the hole injection, for example a copper phthalocyanine (CuPc) layer. This layer is preferably 5 to 50, in particular 8 to 15 nm thick.
• CuPc copper phthalocyanine
• this electron-blocking layer On the hole transport layer and between hole transport and emitter layer is preferably an electron-blocking layer applied, which ensures that the electron transport to the anode is prevented, since such a current would only cause ohmic losses.
• the thickness of this electron-blocking layer is preferably 10 to 100 nm, in particular 20 to 40 nm. This additional layer can be dispensed with in particular if the HTL layer is intrinsically already a poor electron conductor.
• the next layer is the emitter layer which contains or consists of the emitter material according to the invention.
• the emitter materials are preferably applied by sublimation.
• the layer thickness is preferably between 10 nm and 200 nm, in particular between 50 nm and 150 nm.
• the emitter material according to the invention can also be coevaporated together with other materials, in particular with matrix materials.
• matrix materials for emitter materials according to the invention which emit in the green or red, common matrix materials such as PVK or CBP are suitable. But it is also possible to build a 100% emitter material layer.
• UHG matrix materials are preferably used for emitter materials emitting in the blue according to the invention (compare M. E. Thompson et al., Chem. Mater., 2004, 16, 4743).
• co-evaporation can likewise be used.
• matrix materials for OLEDs, but also largely inert polymers or small matrix molecules without particularly pronounced hole or electron mobilities, can be used as matrix materials.
• a hole-blocking layer is preferably applied, which reduces ohmic losses that could arise through hole currents to the cathode.
• This hole-blocking layer is preferably 10 to 50 nm, in particular 15 to 25 nm thick.
• An ETL layer of electron transport layer (ETL) is preferably applied to the hole-blocking layer and between this layer and the cathode.
• this layer consists of aufdampfbarem Alq 3 with a thickness of 10 to 100 nm, in particular from 30 to 50 nm.
• an intermediate layer is preferably applied, for example, from CsF or LiF.
• This interlayer reduces the electron injection barrier and protects the ETL layer.
• This layer is usually applied by evaporation.
• the intermediate layer is preferably very thin, in particular 0.2 to 5 nm, more preferably 0.5 to 2 nm thick.
• a conductive cathode layer is evaporated, in particular with a thickness of 50 to 500 nm, more preferably 100 to 250 nm.
• the cathode layer is preferably made of Al, Mg / Ag (in particular in the ratio 10: 1) or other metals. Voltages between 3 and 15 V are preferably applied to the described OLED structure for a sublimable emitter according to the invention.
• the OLED device can also be made partially wet-chemically, for example according to the following structure: Glass substrate, transparent ITO layer (of indium tin oxide), e.g. PEDOT / PSS
• an OLED structure for a soluble emitter according to the invention has the structure described below and illustrated in FIG. 1C, but comprises at least one, more preferably at least two and most preferably all of the following layers.
• the device is preferably applied to a carrier material, in particular to glass or another solid or flexible transparent material.
• An anode is applied to the carrier material, for example an indium tin oxide anode.
• the layer thickness of the anode is preferably 10 nm to 100 nm, in particular 30 to 50 nm.
• An HTL layer of a hole conductor material is applied to the anode and between the anode and emitter layer, in particular of a hole conductor material which is water-soluble.
• a hole conductor material are, for example, PEDOT / PSS (polyethylenedioxythiophene / polystyrenesulfonic acid) or new HTL materials (DuPont) for extending the device lifetime.
• the layer thickness of the HTL layer is preferably 10 to 100 nm, in particular 40 to 60 nm.
• the emitter layer (EML) is applied, which contains a soluble emitter according to the invention.
• the material can be dissolved in a solvent, for example in acetone, dichloromethane or acetonitrile. As a result, a dissolution of the underlying PEDOT / PSS layer can be avoided.
• the emitter material according to the invention can be used in a low concentration, for example 2 to 10 wt .-%, but also in a higher concentration or as a 100% layer. It is also possible to apply the emitter material highly or moderately doped in a suitable polymer layer (eg PVK).
• the application can be carried out by a colloidal suspension in a polymer. Oligomer strands can be reduced prior to introduction into the polymer under ultrasonic processing and introduced into the polymer after filtration through nanofilter.
• the emitter layer preferably has a layer thickness of 10 to 80 nm, in particular from 20 to 60 nm.
• a layer of electron transport material is preferably applied to the emitter layer, in particular with a layer thickness of 10 to 80 nm, more preferably of 30 to 50 nm suitable material for the electron transport material layer is, for example, Alq 3 , which is aufdampfbar.
• a thin intermediate layer is preferably applied which reduces the electron injection barrier and protects the ETL layer.
• This layer preferably has a thickness of between 0.1 and 2 nm, in particular between 0.5 and 1.5 nm, and preferably consists of CsF or LiF. This layer is usually applied by evaporation.
• the ETL and / or the interlayer may optionally be omitted.
• the cathode layer preferably consists of a metal, in particular of Al or Mg / Ag (in particular in the ratio 10: 1).
• Voltages of 3 to 15 V are preferably applied to the device.
• the light-emitting device contains as emitter at least one complex of the formula (I).
• Free biphenyl shows fluorescence between 300-350 nm when excited in UV (see IB Berlman, Handbook of Fluorescence Spectra of Aromatic Molecules, Adcademic Press, 1971) and phosphorescence at 433 nm (in butyronitrile, 77 K but not in) Room temperature), (see M. Maestri et al., HeIv. Chim. Acta 1988, 71, 1053). Because of the steric interaction of the ortho-hydrogen atoms, the two phenyl groups are twisted against each other, which reduces the conjugation length. Coordination in the 2,2'-position to a single center planarizes the rings and makes the ⁇ system larger.
• complexes of the formula (I) (s-bph) ML are used as emitter molecules. These complexes are in particular luminescent compounds.
• the complexes have a central atom selected from Pt, Rh, Ir, Pd or Au.
• the central atom is preferably present as Pt (II), Rh (I), Ir (I), Pd (II) or Au (III), ie as a single or double or triple positively charged ion.
• the central atom is Pt (II).
• the central atom is fourfold coordinated, in particular quadratic-planar complexes is. Particularly favorable are four-coordinate 16-valence electron complexes, in particular with Pt (II).
• the complex used according to the invention comprises a group L, which is a bidentate ligand, or the group X 2 , wherein each X independently represents a monodentate ligand.
• L is a sterically demanding ligand L. If the complex center M is sufficiently shielded by sterically demanding ligands or a complex arrangement with short MM distances is prevented; can not form MM interactions in the solid state or in concentrated solutions. By steric shielding by the ligand L can also be achieved a reduction of quenching processes and consequently an increase in the photoluminescence quantum yield.
• Suitable sterically demanding ligands L are, for example, bidentate phosphines, amines, arsines or dienes.
• phosphines for example, bidentate phosphines, amines, arsines or dienes.
• high ligand field strength and stability of the resulting complexes and energetically high triplet levels are considered.
• ligands L which are each neutral and bidentate binding (chelates) are:
• each phosphorus atom may be independently replaced by nitrogen or arsenic and wherein each R is hydrogen, an alkyl, aryl, alkoxy, aryloxy, alkylamine or arylamine group which may be optionally substituted or / and one or more heteroatoms can.
• the heteroatoms are in particular selected from O, S, N, P, Si and / or Se.
• Suitable substituents are, for example, halogen, in particular F, Cl, Br or I, alkyl, in particular C 1 to C 20 , even more preferably C 1 to C 6 -alkyl, aryl, OR, SR or PR 2 .
• L contains at least one fluorine atom as a substituent to increase the volatility of the complex.
• alkyl or alk each independently denotes a C 1 -C 20 , especially a C 1 -C 6, hydrocarbon group.
• aryl denotes an aromatic system having 5 to, for example, 20 C atoms, in particular having 6 to 10 C atoms, it being possible where appropriate for one or more C atoms to be replaced by heteroatoms (for example N, S, O).
• heteroatoms for example N, S, O.
• the complex of the formula (I) (s-bph) ML present in the emitter layer according to the invention is derived from a complex of the formula (III)
• L 1 represents a ligand having a polymerizable group.
• the (s-bph) ML complex can be fixed by a functionalization of the ligand L with a polymerizable group to a polymer. As a result, the complex is demobilized, so that unwanted crystallization of the emitter in the emitter layer, which is often a reason for a limited device lifetime of OLEDs is prevented.
• the complex of formula (I) in the emitter layer is bonded to a polymer via the polymerizable ligand. By bonding to a polymer, a homogeneous distribution of the emitter in the emitter layer and also a reliable control of the complex content can be achieved.
• a polymer which contains (s-bph) ML 'groupings bound as building blocks can first be prepared and then applied, for example as a solution by means of spin coating or inkjet printing. But it is also possible to apply the monomer and to polymerize on site.
• the phosphine CH 2 C (PR 2 J 2) is commercially available, and when complexed to a metal, the ⁇ -function receives a positive charge and is therefore activated for nucleophilic attack, thus this group can be attached to a polymer or used as a monomeric building block
• the monomers to be reacted with the phosphine are, in particular, nucleophiles, such as, for example, alcohols, thiols, primary amines or phosphanes, silanes or boranes, which are functionalized with a vinyl group
• the other indicated phosphane can be prepared from bis (diphenylphosphino) methane by reaction with n-butyllithium and p-vinylbenzyl chloride and can be polymerized free-radically, anionically, cationically or catalytically.
• the invention further relates to a complex of the formula (III)
• M represents Pt (II), Rh (I), Ir (I), Pd (II) or Au (III), and L 1 represents a bidentate ligand or
• L 1 X ' 2 , wherein each X 1 independently represents a monodentate ligand, wherein L 1 or at least one X 1 comprises a polymerizable group, and sbph represents a ligand having an Ar-Ar moiety, Ar being an aromatic ring system , Emitter with small Liqanden / Oliqomer-E ⁇ nitter
• the ligand L * is a sterically less demanding ligand.
• the emitter layer comprises complexes of the formula (I) in a concentration of, for example,> 10% by weight, based on the total weight of the emitter layer, in particular> 20% by weight, more preferably> 50% by weight, in particular> 80% by weight, and most preferably> 90% by weight.
• emitter layers which contain almost complete complexes of the formula (I) and in particular> 95% by weight, more preferably> 99% by weight.
• the emitter layer is complete, ie 100% of complexes of the formula (I).
• stacks of the complexes form with relatively short metal-metal distances. Such stacks are formed particularly in planar complexes and particularly favorable in planar platinum complexes. In these stacks strong electronic interactions occur, which lead to a completely different emission behavior than with the monomers.
• the emission wavelength is determined by the MM distance and can be determined in a simple manner by substitution on the grouping (s-bph) or by the type of ligand L *.
• the use of highly concentrated emitter layers and in particular of crystalline or quasi-crystalline layers offers considerable advantages. In particular, no concentration fluctuations occur in the production or affect these in highly concentrated systems only slightly.
• the charge carrier mobilities ie the electron or hole mobilities
• the electronic interaction between the molecules in the oligomers results in an increase of the HOMO and thus an improved hole conductivity as well as a lowering of the LUMO and thus an improved electron ability.
• the emitter complexes used according to the invention have an extremely intense emission with high emission quantum yield due to metal-metal interactions between the central atoms of the individual complexes, in particular due to metal-metal interactions between planar metal complexes. The emission is thus caused by the interaction of the complexes present in high concentration. In contrast to prior art materials, this makes it possible to provide emitter layers with a high proportion of emitter molecules and crystalline or quasi-crystalline emitter layers composed of uniform building blocks.
• the emitter monomer materials have good solubility in many solvents.
• these crystalline or quasicrystalline emitter layers can also be produced by spin coating or inkjet print processes.
• the monomers are also suitable for chemical linkage with polymers.
• metal-metal interactions can again result with the desired excellent emission properties.
• the emission layer does not require any additional components to enhance carrier mobility, that is, partially limiting ones Requirements for the matrix with respect to a good charge carrier mobility can be dispensed with when using the oligomer emitter.
• a specifically made mixture of different materials eg (s-bph) Pt (CO) 2 with (s-bph) Pd (CO) 2 ), of which at least one substance is described by the formula (I), allows another one , independent variation of properties,
• L * may be a flat, neutral, or singly or doubly charged bidentate ligand or two monodentate ligands.
• B is a bridging group which is an alkylene or arylene group which may be substituted and / or heteroatoms (eg N, O , P and / or S).
• L * X * 2
• XH CRR 1 , " C ⁇ CR, alkyl, aryl, heteroaryl groups, -OR, -SR, -SeR, -NR 2 , -PR 2 , -SiR 3 , where R and R ' each independently preferably represents an alkyl or aryl radical, in particular from 1 to 10, more preferably from 1 to 6, carbon atoms.
• the emitter complexes according to the invention having a columnar structure are particularly preferably used.
• This structure is formed in particular at high concentrations of the emitter complexes in the emitter layer, since, as stated above, the complexes according to the invention themselves have a planar structure.
• the individual complexes themselves may be neutral, positively or negatively charged and thus preferably have the formula [(s-bph) ML] ⁇ + / m " , where n and m are each an integer from 0 to 5, more preferably from 0 3, and in particular from 1 to 2.
• the central atom M is preferably selected from the group consisting of Rh (I), Ir (I), Pd (II), Pt (II) or Au (III) and is in particular Pt ( II)
• Rh (I), Ir (I), Pd (II), Pt (II) or Au (III) is in particular Pt ( II)
• a further variation can be achieved by forming columnar structures from different complexes of formula (I), where all ligands and the central atom can be varied independently of one another, the complexes in particular also having different charges.
• columnar salts are provided, for example of the type [(s-bph) ML *] n + [(s'-bph) M 1 L * '] m -, where s'-bph, M' and L * 1 may each have the meanings given under s-bph, M and L *, but wherein at least one of these groups is varied compared to the positively charged complex.
• X represents preferably each independently represent a ligand selected from the group consisting of F ", Cl”, Br ", I",
• Aryl group which may be substituted and / or heteroatoms
• R in particular Me, Et, n-Pr, i-Pr, n-Bu, t-Bu, i-Bu, Bz, Ph, m-Tol, p -Tol, o-Tol, m-PhCl, p-PhCl, o-PhCl, m-PhF 1 p-PhF, o-PhF or C 6 H 5 .
• the complexes according to the invention also contain a ligand s-bph which has a group Ar-Ar, Ar being in each case an independently aromatic ring system.
• Ar may anneliiert to other aromatic rings or comprise one or more heteroatoms and optionally substituted.
• Suitable heteroatoms are, for example, O, N or S.
• Suitable substituents are, for example, halogen, in particular F, Cl 1 Br or Ci- C 6 -Alkylreste, in particular methyl or t-butyl.
• Ar is preferably phenyl, thienyl, furyl or pyrrole systems.
• the group Ar-Ar has one of the following formulas:
• R is H, alkyl, aryl, heteroaryl, alkenyl or alkynyl.
• the ligand s-bph preferably has the formula (II)
• R 1 to R 8 are each independently H, alkyl, aryl, heteroaryl, alkenyl, alkynyl, halo, -NR 2 , -PR 2 , -OR or -SR where R is H, alkyl, aryl, heteroaryl, alkenyl or alkynyl.
• the substituents R 1 to R 8 may be linked together and thus form additional aliphatic, aromatic or heteroaromatic rings.
• ligand s-bph are unsubstituted biphenyl as well
• the complexes used according to the invention as emitters can be tuned in a simple manner (by choice of suitable matrix materials) and in particular by the selection of electron-withdrawing or -shifting substituents in the wavelength range.
• Compounds are preferably used, at a temperature of> -50 0 C, preferably> 0 0 C, in particular> 10 0 C, and even more preferably> 20 ° C and at temperatures of preferably ⁇ 100 0 C, in particular ⁇ 70 0 C, more preferably ⁇ 50 0 C, even more preferably ⁇ 40 ° C, show an emission.
• atoms A 1 -A 8 are each independently selected from C 1 N, O and
• ring systems of the biphenyl ligand or of the heteroaromatic analogs can also be unsymmetrically substituted, as illustrated by the following examples.
• the atoms A 1 -A 8 are each independently selected from C, N, O, S 1
• the ligands R 1 - R 8 are each independently H 1 CH 3 , C 2 H 5 , CH (CH 3 ) 2 , C (CH 3 ) 3 , CF 3 , C n H 2n + I, F, CN, OCH 3 , OC n H 2n + 1 , SCH 3 , SC n H 2n + I, N (CH 3 ) 2 , N (C n H 2n + 1 )
• L 1 n L 2 is diphosphine, diamine, diarsan or diene, in particular a linear or cyclic diene having 6 to 10 carbon atoms or a diphosphane selected from
• R represents alkyl, aryl, alkoxy, phenoxy, alkylamine or arylamine.
• L 1 n L 2 Ph 2 represents P-CH 2 -CH 2 -PPh 2 or cyclooctadiene.
• Particularly preferred according to the invention are the compounds (biphenyl) -platinum-cyclooctadiene, (bph) Pt (COD) or (biphenyl) -platinum- (bis-) (diphenylphosphino) ethane), (bph) Pt (dppe)
• the invention further relates to the use of a compound of the formula (I) as defined herein as an emitter of a light-emitting device, in particular in an organic light-emitting device.
• FIG. 1A shows an example of an OLED device manufactured by vacuum sublimation.
• FIG. 1C shows an example of an OLED device with emitters according to the invention which are applied wet-chemically.
• Figure 2 shows the emission characteristics and electrochemical data of biphenyl-Pt (II) complexes.
• FIGS. 3 and 4 depict the emission spectra of two examples [(bph) Pt (COD) and (bph) Pt (dppe)].
• COD bulky ligands
• bph yellow-green emission
• a phosphorescence which results approximately from an intraligand transition.
• FIG. 5 shows the emission of a vacuum sublimated layer of (bph) Pt (CO) 2 at 300 K.
• oligomer emission (stack emission) takes place because of the small ligands.
• Figures 6 and 7 show the emission spectra of (d ⁇ Bubph) Pt (CO) 2 and of (tmbph) Pt (CO) 2 .
• Biphenyl-Pt (II) complexes are prepared from 2,2'-dilithio-biphenyl (from 2,2'-dibromobiphenyl and nBuLi) and CZs-KEt 2 S) 2 PtCl 2 ].
• the present in situ diethyl sulfide complex 1 is not isolated, since the purification leads experience according to large losses, but implemented by introducing carbon monoxide directly to the dicarbonyl compound 2, which precipitates as a green precipitate from the reaction solution.
• Complex 2 is a well-suited starting compound for the synthesis of further derivatives, since the carbon monoxide can be easily replaced by other ligands. For example, upon addition of disphosphanes or COD to a suspension of 2, a vigorous evolution of gas is observed and complexes 3 and 4 can be isolated in high yields and high purity.

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