Article pubs.acs.org/IC
Photophysical and Electroluminescent Properties of PtAg2 Acetylide Complexes Supported with meso- and rac-Tetraphosphine Hui-Xing Shu,† Jin-Yun Wang,*,† Qian-Chong Zhang,† and Zhong-Ning Chen*,†,‡ †
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155 Yangqiao Road West, Fuzhou 350002, China ‡ State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China S Supporting Information *
ABSTRACT: 1,2-Bis[[(diphenylphosphino)methyl](phenyl)phosphino]ethane (dpmppe) was prepared as a new tetraphosphine, and the corresponding rac and meso stereoisomers were successfully separated in view of their solubility difference in acetone. The substitution of PPh3 into Pt(PPh3)2(CCR)2 (R = aryl) with rac- or meso-dpmppe gives Pt(rac-dpmppe)(CCR)2 or Pt(meso-dpmppe)(CCR)2, respectively. Using Pt(rac-dpmppe)(CCR)2 or Pt(mesodpmppe)(CCR)2 as a precursor, PtAg2 heterotrinuclear cluster complexes were synthesized and characterized by X-ray crystallography. Depending on the conformations of tetraphosphine, the structures of PtAg2 complexes supported with rac- and meso-dpmppe are quite different. The higher molecular rigidity of rac-dpmppesupported PtAg2 complexes results in stronger phosphorescent emission than that of PtAg2 species with meso-dpmppe. The high phosphorescent quantum yields (as high as 90.5%) in doping films warrant these PtAg2 complexes as excellent phosphorescent dopants in organic light-emitting diodes (OLEDs). The peak current and external quantum efficiencies in solution-processed OLEDs are 61.0 cd A−1 and 18.1%, respectively. Electroluminescence was elaborately modulated by modifying the substituent in aromatic acetylide and the conformations in tetraphosphine so as to achieve cyan, green, green-yellow, yellow, and orange-red emission.
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of hydrogen bonding.11−23 For example, platinum(II) tetraacetylide complexes [Pt(CCR)4]2− (R = alkyl or aryl) are mostly nonemissive, but upon further binding to copper(I)/ silver(I) ions via copper/silver acetylide coordination, the produced Pt2M4 cluster species with a noticeable Pt−M contact become moderately phosphorescent at room temperature because of the lower energy in the emitting states as well as the increased molecular rigidity so that nonradiative decay through thermally activated d−d transition is highly suppressed.17−23 In this paper, we report a series of highly phosphorescent PtAg2 acetylide complexes supported by a new tetraphosphine, 1,2-bis[[(diphenylphosphino)methyl](phenyl)phosphino]ethane (dpmppe). Although mononuclear platinum(II) acetylide complexes with rac- or meso-dpmppe are nonluminescent at ambient temperature, the corresponding PtAg2 cluster complexes with substantial Pt−Ag contact exhibit moderateto-intense phosphorescence in fluid solutions and solid states. It is obvious that the formation of PtAg2 aggregates through silver acetylide π coordination as well as Pt−Ag intermetallic interaction results in dramatic phosphorescent enhancement
INTRODUCTION Phosphorescent emission in platinum(II) complexes is normally relevant to strong spin−orbit coupling of the heavyatom effect that promotes rapid intersystem crossing from singlet to triplet states (∼10−12 s−1), which is much faster than the typical radiative rate of singlet excited states (∼10−8 s−1).1−4 To inhibit competitive nonradiative decay through a thermally activated d−d transition in platinum(II) complexes, raising the energy level of a d−d transition to make it thermally inaccessible is one of the viable approaches by introducing strong-field ligands with carbon, phosphorus, or sulfur donors. Of the various strong-field ligands, anionic acetylides and neutral phosphines are mostly utilized as coligands to design phosphorescent platinum(II) complexes because of their analogous bonding character to platinum(II) ions. A number of mononuclear and oligonuclear platinum(II) complexes with various acetylides or phosphines as well as mixed acetylide and phosphine ligands have been prepared,5−10 but they are weakly phosphorescent at ambient temperature in most cases. To enhance phosphorescent emission in platinum(II) acetylide complexes, a feasible strategy is to introduce d10 metal ions such as copper(I), silver(I), or gold(I) to form aggregate structures through d10 metal acetylide π bonding as well as additional d8− d10 metallophilic interaction with the energy comparable to that © XXXX American Chemical Society
Received: February 22, 2017
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DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry Scheme 1. Synthetic Route to dpmppe
Scheme 2. Synthetic Route to PtAg2 Complexes with rac-Tetraphosphine
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RESULTS AND DISCUSSION Synthesis and Characterization. As shown in Scheme 1, dpmppe was prepared by two-step reactions. 1,2-Bis(diphenylphosphino)ethane [Ph2P(CH2)2PPh2] was treated with lithium in anhydrous THF to produce deep-purple dilithium ethane-1,2-diylbis(phenylphosphanide) [LiPhP(CH 2 ) 2 PPhLi]. The reaction of dilithium salt with (chloromethyl)trimethylsilane (Me 3 SiCH 2 Cl) gave bis[[(trimethylsilyl)methyl](phenyl)phosphino]ethane [Me3SiCH2PhP(CH2)2PPhCH2SiMe3, tmsmppe] as a clear oil in 90% yield. The further reaction of Me3SiCH2PhP(CH2)2PPhCH2SiMe3 with Ph2PCl under solvent-free conditions at 95 °C for 1 h produced dpmppe as a mixture of meso and rac isomers in a 1.1:1.0 ratio, as revealed by 31P{1H} NMR spectroscopy. It is fortunate that rac- and meso-dpmppe were
relative to mononuclear platinum(II) precursors. Depending on the conformations of tetraphosphine, the structures of racdpmppe-supported PtAg2 complexes are largely different from those with meso-dpmppe. The rac-dpmppe-supported PtAg2 complexes show more rigid structures and thus much higher phosphorescent quantum yields than the corresponding PtAg2 species with meso-dpmppe. Taking advantage of PtAg 2 complexes as phosphorescent dopants to fabricate solutionprocessed organic light-emitting diodes (OLEDs), highefficiency electroluminescence (EL) is successfully achieved with the peak current efficiency (CE) of 61.0 cd A−1 and external quantum efficiency (EQE) of 18.1%. Both photoluminescence (PL) and EL are systematically modulated to attain cyan, green, green-yellow, yellow, and orange-red phosphorescent emission. B
DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry Scheme 3. Synthetic Route to PtAg2 Complexes with meso-Tetraphosphine
rac-1−rac-6 in 70−73% yield (Scheme 2). When Pt(mesodpmppe)(CCR)2 reacted with Ag(tht)ClO4 and monophosphine in the presence of nBu4NX (X = Cl, I), PtAg2 heterometallic complexes meso-7−meso-11 were isolated in 70−75% yield, as depicted in Scheme 3. The PtAg2 complexes were characterized by high-resolution mass spectrometry (HRMS), IR, and 1H and 31P{1H} NMR spectroscopy. The ν(CC) bands in IR spectra of PtAg2 complexes show 10−40 cm−1 shifts to lower wavenumber relative to those in the corresponding mononuclear platinum(II) complexes because further coordination of the acetylides to silver atoms obviously weakens the CC bonds. The 31P{1H} NMR spectra display three sets of signals due to phosphorus donors of dpmppe bonded to platinum and silver atoms as well as monodentate phosphine. For rac-1−rac-6, the phosphorusdonor signals of dpmppe bound to platinum and silver centers occur at 46.0−47.0 and 0.6−3.4 ppm, respectively, whereas the signal of the monodentate phosphine is observed at 11.8−15.3 ppm. For meso-7−meso-11, the signals due to phosphorus donors of dpmppe are observed at 47.1−48.6 and −8.9 to −11.7 ppm, whereas the signal of the monodentate phosphine appears at 7.2−10.4 ppm. The JPt−P constants are in the range 2375−2448 Hz in the 31P{1H} NMR spectra of PtAg2 complexes. The average coupling constants (J Ag−P) of 107 Ag−31P and 109Ag−31P are in the range 506−601 Hz for dpmppe and 369−526 Hz for the monodentate phosphine. Compared with those in mononuclear platinum(II) precursors (38.7−39.6 ppm), the signals of phosphorus donors bound to platinum centers in the corresponding PtAg2
successfully separated in relatively high yield (30% for rac and 35% for meso) based on their solubility difference in acetone.24 In view of the lower solubility of meso-dpmppe in acetone, it first precipitated in 35% yield from an acetone solution at 2 °C. Pure rac-dpmppe was then accessible in 30% yield from the remaining acetone solution by the addition of ethanol. The 31 1 P{ H} NMR spectrum (Figure S1c) of dpmppe before separation coincides perfectly with the overlapped spectra of the rac (Figure S1a) and meso (Figure S1b) isomers. When meso-dpmppe in the solid state was heated at above 160 °C under an argon atmosphere, a distinct conversion to the rac counterpart was attained because of the better thermodynamic stability for the latter. Initially, rac-dpmppe-supported PtAg2 complexes (Scheme 2) were isolated from the reactions of trans-Pt(PPh3)2(C CR)2, Ag(tht)ClO4, and rac-dpmppe in relatively low yields (250 °C), and favorable solubility in organic solvents such as CH2Cl2, it is feasible to fabricate OLEDs through solution processing.
dpmppe, as revealed by time-dependent density functional theory (TD-DFT) computational studies (vide infra). Upon excitation at λex > 300 nm, PtAg2 complexes display weak-to-moderate luminescence in degassed CH2Cl2 solutions, but the emission becomes much stronger in solid states. Quite large energy gaps between low-energy absorption maxima and emission peaks together with the microsecond range of emissive lifetimes are suggestive of a phosphorescent nature with triplet excited states. As summarized in Table 1, the distinctly higher phosphorescent quantum yields of PtAg2 complexes with rac-dpmppe than those with meso-dpmppe in both solutions and solid states result most likely from the better molecular rigidity for the former. For PtAg2 complexes with racdpmppe, the emission spectra (Figure 2a) in fluid CH2Cl2 display a progressive red shift following rac-1 (495 nm) → rac2 (550 nm) → rac-3 (554 nm) → rac-4 (571 nm) → rac-5 (590 nm) → rac-6 (670 nm). For rac-3 and rac-4 with the same acetylide ligand CC-3-Phcarb-9 but different monodentate phosphine ligands, the emission spectrum of rac-4 (571 nm) is distinctly red-shifted compared with that of rac-3 (554 nm) because P(Et-9-carb-3)3 in rac-4 shows a more extended π conjugation and a stronger π-electron-accepting capability than PPh3 in rac-3. For rac-5 and rac-6 with the same monodentate phosphine ligand P(Et-9-carb-3)3 but different acetylide ligands, the emission of rac-6 (670 nm) exhibits an obvious red shift relative to that of rac-5 (590 nm), ascribable to a stronger electron-donating character of phenothiazine than that of the carbazole group. For PtAg2 complexes with meso-dpmppe (Figure 2b), the emission spectra in fluid CH2Cl2 show a gradual red shift following meso-7 (461 nm) → meso-8 (489 nm) → meso-9 (521 nm) ≈ meso-10 (524 nm) → meso-11 (626 nm). The emission of meso-8 (489 nm) displays a distinct red shift relative to that of meso-7 (461 nm) because electron-donating But in the acetylide ligand results in a higher energy of HOMO and thus a smaller HOMO−LUMO gap in meso-8 than in meso-7 with electron-withdrawing CF3 in phenylacetylide. Nearly identical phosphorescent spectral peaks for meso-9 (521 nm) and meso-10 (524 nm) with the same monodentate phosphine and acetylide ligands but a different halide indicate that bridging halide exerts an insignificant influence on the emissive properties, which is verified by the negligible contribution of bridging halide to frontier orbitals responsible for the triplet-state transition from the TD-DFT studies. It is noticeable that the emission of meso-10 and meso-11 with bridging iodide is obviously stronger than that of meso-7 to meso-9 with bridging chloride, probably because of the larger heavy-atom effect of iodide and thus a more effective intersystem crossing from the singlet to triplet excited state. E
DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry
mixed host materials (Table S9), the devices brought about a better device performance than those with a single host material because of a better carrier balance for the former. Moreover, the use of hole-transporting 2,6-DCZPY and electron-transporting OXD-7 as mixed host materials gave higher EL efficiencies than those of mCP:OXD-7 and CBP:OXD-7. The devices were further optimized by using different ETLs such as TPBi, BmPyPb, or BCP. The use of BmPyPb as the ETL afforded a better device performance. Consequently, using a three-layer configuration, ITO/PEDOT:PSS (50 nm)/2,6-DCZPY (70.5%):OXD-7 (23.5%):6% PtAg2 complex (50 nm)/BmPyPb (50 nm)/LiF (1 nm)/Al (100 nm), the devices gave a peak current efficiency (CE), a power efficiency (PE), an external quantum efficiency (EQE), and a turn-on voltage of 27.7 cd A−1, 10.4 lm W−1, 10.6%, and 6.7 V for rac-1, 65.3 cd A−1, 25.6 lm W−1, 18.6%, and 6.2 V for rac-4, 58.2 cd A−1, 21.6 lm W−1, 16.8%, and 6.1 V for rac-5, and 19.3 cd A−1, 6.9 lm W−1, 9.7%, and 6.1 V for rac-6, respectively. In order to reduce the turn-on voltage and raise the power efficiency, cuprous thiocyanate (CuSCN) was spin-coated in diethyl thioether onto a PEDOT:PSS hole-injection layer to serve as a hole-transporting layer. As a result, using a four-layer device configuration, ITO/PEDOT:PSS (50 nm)/CuSCN (30 nm)/2,6-DCZPY (70.5%):OXD-7 (23.5%):6% PtAg2 complex (50 nm)/BmPyPb (50 nm)/LiF (1 nm)/Al (100 nm), the devices gave a superior EL performance, as shown in Table 2. The optimized devices gave CE, PE, EQE, and turn-on voltage of 27.2 cd A−1,13.3 lm W−1, 11.1%, and 4.8 V for rac-1, 61.0 cd A−1, 30.9 lm W−1, 18.1%, and 4.8 V for rac-4, 57.0 cd A−1, 28.7 lm W−1, 16.6%, and 4.7 V for rac-5, and 19.8 cd A−1, 9.9 lm W−1, 12.4%, and 4.6 V for rac-6, respectively. Obviously, the use of CuSCN as a hole-transport layer in four-layer devices largely reduces the turn-on voltage with much increased PE, ascribed to more efficient hole-transporting and electronblocking properties as well as the better charge-carrier balance than those in three-layer devices. This is because the energy barrier from the hole-transporting layer (CuSCN) to the emitting layer in four-layer devices is smaller because of the deep valence band (−5.5 eV) of CuSCN.30 Figure 5 depicts the current density−voltage−luminance (J− V−L) characteristics and CE/EQE versus L for the devices based on complex rac-4. At the brightness of 100, 500, and 1000 cd m−2, the CE values are 55.5, 48.6, and 43.0 cd A−1 and the EQE values are 16.5%, 14.5%, and 12.8%, corresponding to efficiency roll-off values of 8%, 20%, and 29%, respectively. The EL spectra (Figure 6) coincide perfectly with the corresponding PL emission spectra in doping light-emitting layers, demonstrating that EL originates indeed from the phosphorescent emission of PtAg2 complexes. The EL peaks of rac-1, rac-4, rac5, and rac-6 are observed at 486, 527, 537, and 616 nm to afford cyan, green, green-yellow, and orange-red emission, respectively. For meso-11, the use of 2,6-DCZPY as a single host material results in a better device performance than that using 2,6DCZPY and OXD-7 as mixed host materials (Table S9). On the basis of the optimized device structure ITO/PEDOT:PSS (50 nm)/CuSCN (30 nm)/90% 2,6-DCZPY:10% PtAg2 complex (50 nm)/BmPyPb (50 nm)/LiF (1 nm)/Al (100 nm), the turn-on voltage, peak luminance, CE and EQE are 3.9 V, 2336 cd m−2, 30.7 cd A−1, and 10.4%, respectively. The yellow EL spectrum centered at 572 nm accords well with the PL emission peak at 570 nm in a light-emitting layer. Consequently, the EL (Figure 6) is well modulated to afford
Figure 3. HOMO and LUMO plots of rac-2, rac-6, meso-8, and meso11 from TD-DFT studies in the triplet states.
The energy-level diagrams of transporting and emitting materials are depicted in Figure 4. A three-layer device structure, ITO/PEDOT:PSS/host:PtAg2 complex/ETL/LiF/ Al [ITO = indium tin oxide, PEDOT:PSS = poly(3,4ethylenedioxythiophene):poly(styrenesulfonate), and ETL = electron-transport layer], was initially adopted to optimize the EL performance. PEDOT:PSS was used as hole-injection layer through spin coating in an aqueous solution. When the PEDOT:PSS layer was treated with UV ozone, an obvious improvement of the device performance was observed because holes are more facile to inject and transport into a lightemitting layer through an increase of the work function (−5.4 vs −5.2 eV without UV-ozone treatment).25,26 The devices were first improved by changing the host materials and doping percentage. When a PtAg2 emitter was doped to a hole-transport host material such as CBP, mCP, or 2,6-DCZPY, the devices based on 2,6-DCZPY gave the best performance because of its dipolar character, with both holeand electron-transport capability favorable for carrier balance in the emitting layer as well as its higher triplet energy (2.93 eV) than that of CBP (2.56 eV) or mCP (2.90 eV)27−29 so that energy transfer is more effective from the host material (2,6DCZPY) to the PtAg2 emitter. For rac-dpmppe-supported PtAg2 complexes, doping 6% concentration to host materials induced the highest PL in the emitting layers as well as the best device performance among various doping concentrations. When hole- and electrontransporting compounds were simultaneously adopted as F
DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry
Figure 4. Organic materials used in the devices and HOMO−LUMO energy-level diagrams of the transport and emitting materials. The HOMO and LUMO energy levels were determined by cyclic voltammetry and UV−vis absorption spectroscopy.
difference in acetone. As determined by X-ray crystallography, rac-dpmppe-supported PtAg2 heteronuclear acetylide complexes display structures different from those supported with meso-dpmppe. Both rac- and meso-dpmppe-supported PtAg2 complexes exhibit room-temperature phosphorescence in solutions and solid states, originating normally from aromatic acetylide to dpmppe (LLCT) and PtAg2 cluster (LMCT) charge-transfer triplet excited states. The phosphorescence in rac-dpmppe-supported PtAg2 complexes is much stronger than that in meso-dpmppe counterparts because of the more rigid structures for the former. The phosphorescent quantum yields of PtAg2 complexes doped to the films of 2,6-DCZPY (70.5%):OXD-7 (23.5%) are as high as 90.5%. When 6% PtAg2 species with rac-dpmppe is doped to blend host materials of 2,6-DCZPY (70.5%):OXD-7 (23.5%) as emitting layers, the OLEDs produce high-efficiency EL with CE of 61.0 cd A−1 and EQE of 18.1%. The EL spectra and colors are systematically modulated by modifying both aromatic acetylides and conformations in tetraphosphine to afford cyan, green, greenyellow, yellow, and orange-red emission.
Table 2. Performance Data of OLEDs Based on Phosphorescent PtAg2 Complexes rac-1, rac-4, rac-5, rac-6, and meso-11 λEL (nm) Vona (V) Lb (cd m−2) CEc (cd A−1) PEd (lm W−1) EQEe (%) CIE
rac-1
rac-4
rac-5
rac-6
meso-11
486 4.8 1703 27.2 13.3 11.1 0.19, 0.24
527 4.8 7764 61.0 30.9 18.1 0.24, 0.48
537 4.7 6652 57.0 28.7 16.6 0.23, 0.51
616 4.6 1898 19.8 9.9 12.4 0.53, 0.46
572 3.9 2336 30.7 18.8 10.4 0.41, 0.54
a Turn-on voltage at 1 cd m−2. bMaximum luminance. cMaximum current efficiency. dMaximum power efficiency. eMaximum external quantum efficiency.
cyan, green, green-yellow, yellow, and orange-red emission through the modification of both substituents in aromatic acetylide and the conformations in tetraphosphine.
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CONCLUSIONS New tetraphosphine dpmppe was prepared and corresponding rac and meso isomers were separated in view of their solubility G
DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry
Figure 5. (a) J−V−L characteristics. (b) CE/EQE versus L for the device based on complex rac-4. Hz), 7.61−7.55 (m, 9H), 7.46−7.33 (m, 16H). 31P{1H} NMR (CDCl3): δ −4.0 (s, 1P). Bis[[(diphenylphosphino)methyl](phenyl)phosphino]ethane (meso- and rac-dpmppe). To a dry THF (250 mL) solution of dppe (5.0 g, 12.5 mmol) in a two-necked flask was added a lithium strip (0.87 g) with stirring at 0 °C for 1 day to give a deep-purple solution. The residual lithium was taken out, and tBuCl (1.3 mL, 24.8 mmol) was added immediately to eliminate the generated phenyllithium. Then Me3SiCH2Cl (3.1 g, 25.5 mmol) was added to the above solution at 0 °C. The solution was then stirred at 50 °C for 3 h, with the color changing to pale yellow. Upon removal of the solvent under vacuum, the residue was purified by a short silica column under an argon atmosphere using dichloromethane/petroleum ether (1:2, v/v) as the eluent to afford bis[[(trimethylsilyl)methyl](phenyl)phosphino]ethane (tmsmppe) as a clear oil in 90% yield, in which the ratio of meso and rac isomers was 1.1:1.0, as determined by 31 1 P{ H} NMR spectroscopy. In another dried two-necked flask, a solvent-free mixture of Ph2PCl (5.1 g, 23 mmol) and tmsmppe (4.7 g, 11.25 mmol) was heated at 95 °C for 1 h, giving a viscous liquid. Upon cooling, the produced chlorotrimethylsilane was removed from the crude product in vacuo to give a pale-yellow solid. The crude product was purified through a silica gel column using dichloromethane/petroleum ether (1:1, v/v) as the eluent to give a colorless solid with a 1.1:1.0 ratio of meso- and racdpmppe, as revealed from 31P{1H} NMR spectral studies. Yield: 75% (5.4 g). Anal. Calcd for C40H38P4: C, 74.76; H, 5.96; P, 19.28. Found: C, 74.70; H, 5.95; P, 19.36. ESI-MS: m/z 643.1999 (100%) ([M + H+]+). The pure meso-dpmppe was precipitated from a saturated acetone solution of a mixture of meso- and rac-dpmppe, upon being put aside at 2 °C. The pure rac-dpmppe was isolated from the remaining acetone solution by the addition of ethanol. meso-dpmppe. Yield: 35% (2.5 g). 1H NMR (CDCl3): δ 7.42− 7.35 (m, 12H), 7.34−7.27 (m, 18H), 2.34 (m, 4H), 1.72 (m, 4H). 31 1 P{ H} NMR (CDCl3): δ −22.6 (m, 2P), −25.4 (m, 2P). rac-dpmppe. Yield: 30% (2.2 g). 1H NMR (CDCl3): δ 7.42−7.33 (m, 12H), 7.32−7.27 (m, 18H), 2.34 (m, 4H), 1.76 (m, 4H). 31P{1H} NMR (CDCl3): δ −22.5 (m, 2P), −25.8 (m, 2P). Pt(rac-dpmppe)(CCC6H4But-4)2 (rac-Pt-1). To a CH2Cl2 (20 mL) solution of trans-Pt(PPh3)2(CCC6H4But-4)2 (80.6 mg, 0.078 mmol) was added rac-dpmppe (50 mg, 0.078 mmol) with stirring at ambient temperature for 1 h. The addition of 20 mL of n-hexane to the above solution resulted in isolation of the product as a pale-yellow solid. Yield: 90%. Anal. Calcd for C64H64P4Pt: C, 66.72; H, 5.60. Found: C, 66.60; H, 5.55. HRMS (ESI): m/z 1153.3626. Calcd: m/z 1153.3636 ([M + H]+). 1H NMR (CDCl3): δ 8.09−8.04 (dd, 4H, J1 = 12 Hz, J2 = 8 Hz), 7.43−7.36 (m, 6H), 7.32−7.25 (m, 8H), 7.18−7.04 (m, 20H), 3.42−3.35 (m, 2H), 3.19−3.13 (m, 2H), 2.34−2.14 (m, 2H), 1.28 (s, 18H), 1.12−1.10 (m, 2H). 31P{1H} NMR (CDCl3): δ 38.7 (m, 2P, JP−P = 65 Hz, JPt−P = 2280 Hz), −25.8 (m, 2P, JP−P = 65 Hz). IR (KBr, cm−1): 2118w (CC). Pt(rac-dpmppe){(CC-4)C6H4-carb-9}2 (rac-Pt-2). This compound was prepared by the same procedure as that of rac-Pt-1 except for the use of trans-Pt(PPh3)2{(CC-4)C6H4-carb-9}2 instead of trans-Pt(PPh3)2(CCC6H4But-4)2. Yield: 91%. Anal. Calcd for
Figure 6. (a) PL spectra (solid) in light-emitting layers and EL spectra (dash) of the devices based on PtAg2 complexes. (b) CIE chromacity of the devices based on rac-1, rac-4, rac-5, rac-6, and meso-11.
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EXPERIMENTAL SECTION
General Procedures and Materials. All manipulations were conducted under a dry argon atmosphere using Schlenk techniques and vacuum-line systems unless otherwise specified. The solvents were dried, distilled, and degassed prior to use except that those for spectroscopic measurements were of spectroscopic grade. 3-Ethynyl-9ethylcarbazole (HCC-3-Etcarb-9), 3-ethynyl-9-phenylcarbazole (HCC-3-Phcarb-9), 9-(4-ethynylphenyl)-9H-carbazole [(HCC4)C6H4-carb-9], and 10-ethyl-3-ethynyl-10H-phenothiazine (HCCPTZ-Et) were prepared by the reaction of 3-bromo-9-ethylcarbazole, 3-bromo-9-phenylcarbazole, 9-(4-bromophenyl)-9H-carbazole, and 3bromo-10-ethyl-10H-phenothiazine with ethynyltrimethylsilane in the presence of Pd(PPh3)2Cl2 and CuI, respectively. Other reagents were purchased from commercial sources and used as received unless stated otherwise. Tris(9-ethyl-9H-carbazol-3-yl)phosphine [P(Et-9-carb-3)3]. An anhydrous THF (200 mL) solution of 3-bromo-9-ethyl-9Hcarbazole (10 g, 51 mmol) was cooled to −78 °C under nitrogen. nButyllithium (22.4 mL, 56 mmol, 2.5 M in hexane) was then added dropwise to give a bright-yellow solution, which was thickened to form a slurry upon stirring for 1 h. Phosphorus trichloride (1.3 mL, 15.5 mmol) was added and the mixture stirred at the temperature for another 1 h. Then the temperature was raised gradually to room temperature. The reaction was quenched with ethanol (10 mL) under 0 °C. After the mixed solution was concentrated under vacuum, ethanol (50 mL) was added to precipitate a white solid, which was filtered and washed with ethanol (3 × 10 mL) and water (3 × 10 mL). Yield: 87% (8.3 g). 1H NMR (CDCl3): δ 8.25−8.23 (d, 3H, J = 8 Hz), 7.99−7.97 (d, 3H, J = 8 Hz), 7.59−7.55 (t, 3H, J = 8 Hz), 7.47−7.40 (m, 9H), 7.19−7.15 (t, 3H, J = 8 Hz), 4.40−4.35 (q, 6H, J = 7 Hz), 1.47−1.43 (t, 9H, J = 7 Hz). 31P{1H} NMR (CDCl3): δ −2.94 (s, 1P). Bis(9-phenyl-9H-carbazol-3-yl)phenylphosphine [PhP(Ph-9carb-3)2]. This compound was prepared by the same procedure as that of P(Et-9-carb-3)3 using 3-bromo-9-phenyl-9H-carbazole (10 g, 31 mmol), n-butyllithium (13.6 mL, 34 mmol, 2.5 M in hexane), and dichlorophenylphosphine (1.9 mL, 14 mmol). Yield: 78% (5.4 g). 1H NMR (CDCl3): δ8.24−8.22 (d, 2H, J = 8 Hz), 8.05−8.03 (d, 2H, J = 8 H
DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
2268 Hz), −27.8 (m, 2P, JP−P = 45 Hz). IR (KBr, cm−1): 2115w (C C). Pt(meso-dpmppe)(CC-PTZ-Et)2 (meso-Pt-3). This compound was prepared by the same procedure as that of meso-Pt-1 except for the use of trans-Pt(PPh3)2(CC-PTZ-Et)2 instead of trans-Pt(PPh 3 ) 2 (CCC 6 H 4 CF 3 -4) 2 . Yield: 90%. Anal. Calcd for C72H62N2P4PtS2: C, 64.61; H, 4.67; N, 2.09. Found: C, 64.32; H, 4.45; N, 1.91. HRMS (ESI): m/z 1361.2853. Calcd: m/z 1361.2802 ([M + Na]+). 1H NMR (CDCl3): δ 7.98−7.93 (dd, 4H, J1 = 12 Hz,J2 = 8 Hz), 7.49−7.45 (m, 4H), 7.29 (m, 8H), 7.25−7.17 (m, 14H), 7.13−7.08 (m, 8H), 6.88−6.81 (m, 4H), 6.70−6.68 (d, 2H, J = 8 Hz), 3.91−3.86 (q, 4H, J = 7 Hz), 3.49−3.35 (m, 2H), 3.09−3.03 (m, 2H), 2.09−1.90 (m, 4H), 1.41−1.37 (t, 6H, J = 7 Hz). 31P{1H} NMR (CDCl3): δ 38.7 (m, 2P, JP−P = 49 Hz, JPt−P = 2268 Hz), −27.9 (m, 2P, JP−P = 49 Hz). IR (KBr, cm−1): 2116w (CC). [PtAg2(rac-dpmppe)(CCC6H4But-4)2{PhP(Ph-9-carb-3)2}2](ClO4)2 (rac-1). To a CH2Cl2 (20 mL) solution of rac-Pt-1 (80.8 mg, 0.07 mmol) were added Ag(tht)ClO4 (41.4 mg, 0.14 mmol) and PhP(Ph-9-carb-3)2 (82.9 mg, 0.14 mmol) with stirring at ambient temperature for 3 h. The solution was chromatographed on a silica gel column using CH2Cl2/CH3CN (8:1, v/v) as the eluent to give a palegreen product. Yield: 70%. Anal. Calcd for C148H122Ag2Cl2N4O8P6Pt: C, 64.59; H, 4.47; N, 2.04. Found: C, 64.40; H, 4.55; N, 1.96. HRMS (ESI): m/z 1276.2909. Calcd: m/z 1276.2898 ([M − 2ClO4]2+). 1H NMR (CDCl3): δ 8.20−8.14 (dd, 4H, J1 = 16 Hz, J2 = 12 Hz), 8.08− 8.04 (dd, 4H, J1 = 12 Hz, J2 = 8 Hz), 7.73−7.59 (m, 12H), 7.53−7.35 (m, 36H), 7.27−7.11 (m, 20H), 6.95−6.88 (m, 12H), 6.69−6.67 (d, 4H, J = 8 Hz), 6.59−6.57 (d, 4H, J = 8 Hz), 4.29 (m, 2H), 3.02−2.93 (m, 2H), 2.63−2.46 (m, 2H), 0.97 (s, 18H), 0.54 (m, 2H). 31P{1H} NMR (CDCl3): δ 46.0 (d, 2P, JP−P = 78 Hz, JPt−P = 2448 Hz), 13.8 (m, 2P, JP−Ag = 526 Hz, JP−P′ = 38 Hz), 1.8 (m, 2P, JP−Ag = 526 Hz, JP−P = 77 Hz, JP−P′ = 38 Hz). IR (KBr, cm−1): 2081w (CC), 1099s (ClO4−). [PtAg2(rac-dpmppe){(CC-4)C6H4-carb-9} 2(PPh3) 2](ClO4) 2 (rac-2). This compound was synthesized by the same procedure as that of rac-1 except for the use of rac-Pt-2 and PPh3 instead of rac-Pt1 and PhP(Ph-9-carb-3)2, respectively. Yield: 71%. Anal. Calcd for C116H92Ag2Cl2N2O8P6Pt: C, 60.33; H, 4.02; N, 1.21. Found: C, 60.12; H, 4.02; N, 1.15. HRMS (ESI): m/z 1055.1713. Calcd: m/z 1055.1694 ([M − 2ClO4]2+). 1H NMR (CDCl3): δ 8.21−8.13 (m, 8H), 7.59− 7.54 (m, 14H), 7.48−7.14 (m, 18H), 7.34−7.24 (m, 22H), 7.20−7.12 (m, 14H), 7.02−6.98 (m, 4H), 6.86−6.85 (d, 4H, J = 7 Hz), 4.59 (m, 2H), 3.15−3.06 (m, 2H), 2.73−2.59 (m, 2H), 0.61 (m, 2H). 31P{1H} NMR (CDCl3): δ 47.0 (d, 2P, JP−P = 76 Hz, JPt−P = 2375 Hz), 11.8 (m, 2P, JP−Ag = 506 Hz, JP−P′ = 35 Hz), 3.4 (m, 2P, JP−Ag = 410 Hz, JP−P = 76 Hz, JP−P′ = 35 Hz). IR (KBr, cm−1): 2091w (CC), 1099s (ClO4−). [PtAg2(rac-dpmppe)(CC-3-Phcarb-9)2(PPh3)2](ClO4)2 (rac3). This compound was synthesized by the same procedure as that of rac-1 except for the use of rac-Pt-3 and PPh3 instead of rac-Pt-1 a nd P hP(Ph-9-c arb- 3) 2 . Yie ld: 71%. A nal. Calcd for C116H92Ag2Cl2N2O8P6Pt: C, 60.33; H, 4.02; N, 1.21. Found: C, 60.20; H, 4.05; N, 1.16. HRMS (ESI): m/z 1055.1717. Calcd: m/z 1055.1694 ([M − 2ClO4]2+). 1H NMR (CDCl3): δ 8.17−8.12 (dd, 4H, J1 = 12 Hz, J2 = 8 Hz), 7.67−7.63 (t, 4H, J = 8 Hz), 7.54−7.46 (m, 22H), 7.43−7.40 (m, 8H), 7.37−7.31 (m, 10H), 7.29−7.18 (m, 10H), 7.13−7.03 (m, 20H), 6.95−6.92 (m, 4H), 6.83−6.81 (d, 2H), 4.45 (m, 2H), 3.18−3.09 (m, 2H), 2.69−2.50 (m, 2H), 0.59 (m, 2H). 31P{1H} NMR (CDCl3): δ 46.3 (d, 2P, JP−P = 75 Hz, JPt−P = 2384 Hz), 11.9 (m, 2P, JP−Ag = 510 Hz, JP−P′ = 37 Hz), 2.4 (m, 2P, JP−Ag = 398 Hz, JP−P = 75 Hz, JP−P′ = 37 Hz). IR (KBr, cm−1): 2075w (CC), 1093s (ClO4−). [PtAg2(rac-dpmppe)(CC-3-Phcarb-9)2{P(Et-9-carb-3)3}2](ClO4)2 (rac-4). This compound was synthesized by the same procedure as that of rac-1 except for the use of rac-Pt-3 and P(Et9-carb-3)3 instead of rac-Pt-1 and PhP(Ph-9-carb-3)2. Yield: 71%. Anal. Calcd for C164H134Ag2Cl2N8O8P6Pt: C, 65.39; H, 4.48; N, 3.72. Found: C, 65.14; H, 4.53; N, 3.53. HRMS (ESI): m/z 1406.8446. Calcd: m/z 1406.8429 ([M − 2ClO4]2+). 1H NMR (CDCl3): δ 8.27− 8.22 (dd, 4H, J1 = 12 Hz, J2 = 8 Hz), 8.20−8.17 (d, 6H, J = 12 Hz),
C80H62N2P4Pt: C, 70.12; H, 4.56; N, 2.04. Found: C, 70.40; H, 4.55; N, 1.96. HRMS (ESI): m/z 1371.3600. Calcd: m/z 1371.3541 ([M + H]+). 1H NMR (CDCl3): δ 8.17−8.12 (m, 8H), 7.60−7.58 (m, 4H), 7.52−7.46 (m, 6H), 7.42−7.35 (m, 16H), 7.30−7.24 (m, 6H), 7.22− 7.18 (m, 10H), 7.14−7.10 (m, 4H), 3.49−3.41 (m, 2H), 3.32−3.26 (m, 2H), 2.38−2.17 (m, 2H), 1.31−1.25 (m, 2H). 31P{1H} NMR (CDCl3): δ 39.5 (m, 2P, JP−P = 71 Hz, JPt−P = 2292 Hz), −25.8 (m, 2P, JP−P = 71 Hz). IR (KBr, cm−1): 2119w (CC). Pt(rac-dpmppe)(CC-3-Phcarb-9)2 (rac-Pt-3). This compound was prepared by the same procedure as that of rac-Pt-1 except for the use of trans-Pt(PPh3)2(CC-3-Phcarb-9)2 instead of trans-Pt(PPh 3 ) 2 (CCC 6 H 4 Bu t -4) 2 . Yield: 89%. Anal. Calcd for C80H62N2P4Pt: C, 70.12; H, 4.56; N, 2.04. Found: C, 70.41; H, 4.59; N, 1.95. HRMS (ESI): m/z 1371.3608. Calcd: m/z 1371.3541 ([M + H]+). 1H NMR (CDCl3): δ 8.19−8.14 (m, 4H), 7.98−7.94 (m, 4H), 7.59−7.52 (m, 10H), 7.44−7.33 (m, 14H), 7.25−7.07 (m, 22H), 3.53−3.47 (m, 2H), 3.34−3.27 (m, 2H), 2.37−2.17 (m, 2H), 1.15− 1.17 (m, 2H). 31P{1H} NMR (CDCl3): δ 39.1 (m, 2P, JP−P = 66 Hz, JPt−P = 2287 Hz), −25.7 (m, 2P, JP−P = 66 Hz). IR (KBr, cm−1): 2112w (CC). Pt(rac-dpmppe)(CC-3-Etcarb-9)2 (rac-Pt-4). This compound was prepared by the same procedure as that of rac-Pt-1 except for the use of trans-Pt(PPh3)2(CC-3-Etcarb-9)2 instead of trans-Pt(PPh 3 ) 2 (CCC 6 H 4 Bu t -4) 2 . Yield: 92%. Anal. Calcd for C72H62N2P4Pt: C, 67.86; H, 4.90; N, 2.20. Found: C, 67.40; H, 4.75; N, 2.16. HRMS (ESI): m/z 1275.3610. Calcd: m/z 1275.3541 ([M + H]+). 1H NMR (CDCl3): δ 8.18 (m, 6H), 7.93−7.92 (d, 2H, J = 8 Hz), 7.62−7.60 (d, 2H, J = 8 Hz), 7.45−7.36 (m, 14H), 7.24−7.08 (m, 20H), 4.34−4.28 (q, 4H, J = 7 Hz), 3.56−3.52 (m, 2H), 3.35− 3.29 (m, 2H), 2.34−2.22 (m, 2H), 1.43−1.39 (t, 6H, J = 7 Hz), 1.17− 1.14 (m, 2H). 31P{1H} NMR (CDCl3): δ 38.9 (m, 2P, JP−P = 66 Hz, JPt−P = 2282 Hz), −25.5 (m, 2P, JP−P = 67 Hz). IR (KBr, cm−1): 2113w (CC). Pt(rac-dpmppe)(CC-PTZ-Et)2 (rac-Pt-5). This compound was prepared by the same procedure as that of rac-Pt-1 except for the use of trans-Pt(PPh3)2(CC-PTZ-Et)2 instead of trans-Pt(PPh3)2(C CC6H4But-4)2. Yield: 90%. Anal. Calcd for C72H62N2P4PtS2: C, 64.61; H, 4.67; N, 2.09. Found: C, 64.45; H, 4.58; N, 1.99. HRMS (ESI): m/ z 1361.2843. Calcd: m/z 1361.2802 ([M + Na]+). 1H NMR (CDCl3): δ 8.07−8.02 (dd, 4H, J1 = 12 Hz,J2 = 8 Hz), 7.45−7.37 (m, 6H), 7.31− 7.26 (m, 4H), 7.22−7.18 (m, 6H), 7.16−7.07 (m, 18H), 6.88−6.81 (m, 4H), 6.69−6.66 (d, 2H, J = 8 Hz), 3.90−3.85 (q, 4H, J = 7 Hz), 3.45−3.29 (m, 2H), 3.19−3.13 (m, 2H), 2.35−2.12 (m, 2H), 1.40− 1.37 (t, 6H, J = 7 Hz), 1.16−1.09 (m, 2H). 31P{1H} NMR (CDCl3): δ 38.9 (m, 2P, JP−P = 68 Hz, JPt−P = 2289 Hz), −25.9 (m, 2P, JP−P = 68 Hz). IR (KBr, cm−1): 2121w (CC). Pt(meso-dpmppe)(CCC6H4CF3-4)2 (meso-Pt-1). To a CH2Cl2 (20 mL) solution of trans-Pt(PPh3)2(CCC6H4CF3-4)2 (82.5 mg, 0.078 mmol) was added meso-dpmppe (50 mg, 0.078 mmol) with stirring at ambient temperature for 1 h. Upon the addition of n-hexane to the concentrated CH2Cl2 solution, the product was precipitated as a white solid. Yield: 90%. Anal. Calcd for C58H46F6P4Pt: C, 59.24; H, 3.94. Found: C, 59.40; H, 4.05. HRMS (ESI): m/z 1176.2222. Calcd: m/z 1176.2132 ([M + H]+). 1H NMR (CDCl3): δ 7.97−7.92 (dd, 4H, J1 = 12 Hz,J2 = 8 Hz), 7.49−7.40 (m, 12H), 7.32−7.25 (m, 18H), 7.19−7.15 (m, 4H), 3.47−3.33 (m, 2H), 3.13−3.07 (m, 2H), 2.19− 1.93 (m, 4H). 31P{1H} NMR (CDCl3): δ 39.6 (m, 2P, JP−P = 55 Hz, JPt−P = 2278 Hz), −27.9 (m, 2P, JP−P = 55 Hz). IR (KBr, cm−1): 2118w (CC). Pt(meso-dpmppe)(CCC6H4But-4)2 (meso-Pt-2). This compound was prepared by the same procedure as that of meso-Pt-1 except for the use of trans-Pt(PPh3)2(CCC6H4But-4)2 instead of trans-Pt(PPh3)2(CCC6H4CF3-4)2. Yield: 92%. Anal. Calcd for C64H64P4Pt: C, 66.72; H, 5.60. Found: C, 66.39; H, 5.54. HRMS (ESI): m/z 1152.3696. Calcd: m/z 1153.3636 ([M + H]+). 1H NMR (CDCl3): δ 8.0−7.96 (dd, 4H, J1 = 12 Hz,J2 = 8 Hz), 7.50−7.46 (m, 4H), 7.33−7.27 (m, 10H), 7.24−7.19 (m, 14H), 7.14−7.10 (m, 6H), 3.51−3.37 (m, 2H), 3.08−3.03 (m, 2H), 2.11−1.90 (m, 4H), 1.29 (s, 18H). 31P{1H} NMR (CDCl3): δ 38.7 (m, 2P, JP−P = 45 Hz, JPt−P = I
DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
[PtAg2(meso-dpmppe)(CCC6H4But-4)2{P(Et-9-carb-3)3}(μCl)](ClO4) (meso-9). This compound was synthesized as the same procedure as that of meso-7 except for using meso-Pt-2 and P(Et-9carb-3)3 in place of meso-Pt-1 and PPh3. Yield: 74%. Anal. Calcd for C106H100Ag2Cl2N3O4P5Pt: C, 60.15; H, 4.76; N, 1.99. Found: C, 60.32; H, 4.73; N, 1.88. HRMS (ESI): m/z 2016.4011. Calcd: m/z 2016.3995 ([M − ClO4]+). 1H NMR (CDCl3): δ 8.48−8.45 (d, 2H, J = 12 Hz), 8.08−8.04 (dd, 4H, J1 = 12 Hz, J2 = 8 Hz), 7.94−7.92 (d, 2H, J = 8 Hz), 7.89 (m, 4H), 7.53−7.41 (m, 26H), 7.25−7.15 (m, 13H), 6.61−6.59 (m, 4H), 6.40−6.38 (m, 4H), 4.41−4.37 (q, 6H, J = 7 Hz), 3.76 (m, 2H), 3.49 (m, 2H), 2.24−2.05 (m, 4H), 1.49−1.47 (t, 9H, J = 7 Hz), 0.76 (s, 18H). 31P{1H} NMR (CDCl3): δ 47.5 (m, 2P, JP−P = 57 Hz, JPt−P = 2394 Hz), 10.4 (m, 1P, JP−Ag = 601 Hz), −9.3 (m, 2P, JP−Ag = 417 Hz, JP−P = 56 Hz). IR (KBr, cm−1): 2108w (CC), 1093s (ClO4−). [PtAg2(meso-dpmppe)(CCC6H4But-4)2{P(Et-9-carb-3)3}(μI)](ClO4) (meso-10). This compound was synthesized by the same procedure as that of meso-7 except for using meso-Pt-2, P(Et-9-carb3)3, and nBuN4I in place of meso-Pt-1, PPh3, and nBuN4Cl. Yield: 72%. Anal. Calcd for C106H100Ag2ClIN3O4P5Pt: C, 57.66; H, 4.56; N, 1.90. Found: C, 57.57; H, 4.60; N, 1.83. HRMS (ESI): m/z 2108.3432. Calcd: m/z 2108.3351 ([M − ClO4]+). 1H NMR (CDCl3): δ 8.51− 8.48 (d, 2H, J = 12 Hz), 8.11−8.07 (dd, 4H, J1 = 12 Hz, J2 = 8 Hz), 7.98−7.96 (d, 2H, J = 8 Hz), 7.82 (m, 4H), 7.54−7.40 (m, 26H), 7.29−7.16 (m, 13H), 6.54−6.52 (m, 4H), 6.37−6.35 (m, 4H), 4.39− 4.35 (q, 6H, J = 7 Hz), 3.71 (m, 2H), 3.52 (m, 2H), 2.25−2.05 (m, 4H), 1.49−1.47 (t, 9H, J = 7 Hz), 0.72 (s, 18H). 31P{1H} NMR (CDCl3): δ 48.5 (m, 2P, JP−P = 60 Hz, JPt−P = 2391 Hz), 9.0 (m, 1P, JP−Ag = 547 Hz), −11.7 (m, 2P, JP−Ag = 386 Hz, JP−P = 59 Hz). IR (KBr, cm−1): 2104w (CC), 1093s (ClO4−). [PtAg2(meso-dpmppe)(CC-PTZ-Et)2{P(Et-9-carb-3)3}(μ-I)](ClO4) (meso-11). This compound was synthesized by the same procedure as that of meso-7 except for using meso-Pt-3, P(Et-9-carb3)3, and nBuN4I in place of meso-Pt-1, PPh3, and nBuN4Cl. Yield: 70%. Anal. Calcd for C114H98Ag2ClIN5O4P5PtS2: C, 57.19; H, 4.13; N, 2.93. Found: C, 57.42; H, 4.33; N, 2.84. HRMS (ESI): m/z 2294.2671. Calcd: m/z 2294.2698 ([M − ClO4]+). 1H NMR (CDCl3): δ 8.54− 8.51 (d, 2H, J = 12 Hz), 8.09−8.04 (dd, 4H, J1 = 12 Hz, J2= 8 Hz), 7.95−7.93 (d, 2H, J = 8 Hz), 7.80 (m, 4H), 7.59−7.29 (m, 29H), 7.18−7.01 (m, 12H), 6.75 (m, 4H), 6.51−6.49 (d, 2H, J = 8 Hz), 6.41−6.39 (d, 2H, J = 8 Hz), 6.22 (s, 2H), 5.63−5.61 (d, 2H, J = 8 Hz), 4.45−4.27 (q, 6H, J = 7 Hz), 3.71 (m, 2H), 3.46 (m, 2H), 3.14− 3.08 (q, 4H, J = 6 Hz), 2.28−2.03 (m, 4H), 1.44−1.40 (t, 9H, J = 7 Hz), 0.86−0.81 (t, 6H, J = 6 Hz). 31P{1H} NMR (CDCl3): δ 48.6 (m, 2P, JP−P = 60 Hz, JPt−P = 2391 Hz), 9.1 (m, 1P, JP−Ag = 548 Hz), −11.4 (m, 2P, JP−Ag = 384 Hz, JP−P = 60 Hz). IR (KBr, cm−1): 2101w (C C), 1094s (ClO4−). Physical Measurements. UV−vis absorption spectra were measured on a PerkinElmer Lambda 35 UV−vis spectrophotometer. IR spectra were recorded on a Magna 750 FT-IR spectrophotometer with KBr pellets. Elemental analysis (carbon, hydrogen, and nitrogen) were carried out on a PerkinElmer model 240 C elemental analyzer. 1 H NMR (400 MHz) and 31P{1H} NMR (162 MHz) spectra were measured on a Bruker Advance 400 spectrometer with SiMe4 as the internal reference and H3PO4 as the external reference, respectively. HRMS was performed on an Impact II mass spectrometer using dichloromethane and methanol mixtures as mobile phases. The emission and excitation spectra together with the emissive lifetimes in solid states and degassed solutions were measured on an Edinburgh FLS920 fluorescence spectrometer. The absolute luminescent quantum yields in solutions, powders, and doped films were determined by the integrating sphere (142 mm in diameter) using an Edinburgh FLS920 fluorescence spectrometer. Crystal Structural Determination. Data collection was performed on a Mercury CCD diffractometer by the ω-scan technique at room temperature using graphite-monochromated Mo Kα (λ = 0.71073 Å) radiation. The CrystalClear software package was used for data reduction and empirical absorption correction. The structures were solved by direct methods. The heavy atoms were located from an E map, and the rest of the non-hydrogen atoms were found in
8.04−7.99 (dd, 6H, J1 = 12 Hz, J2 = 8 Hz), 7.71 (s, 2H), 7.50−7.40 (m, 16H), 7.37−7.32 (m, 12H), 7.27−7.25 (m, 10H), 7.17−7.14 (m, 6H), 7.07−7.03 (t, 2H, J = 7 Hz), 7.0−6.90 (m, 12H), 6.88−6.77 (m, 16H), 6.73−6.66 (m, 4H), 4.4 (m, 2H), 3.88−3.83 (q, 12H, J = 7 Hz), 3.27−3.18 (m, 2H), 2.62−2.44 (m, 2H), 1.0−0.97 (d, 18H, J = 7 Hz), 0.72 (m, 2H). 31P{1H} NMR (CDCl3): δ 46.5 (d, 2P, JP−P = 78 Hz, JPt−P = 2380 Hz), 15.3 (m, 2P, JP−Ag = 534 Hz, JP−P′ = 37 Hz), 0.8 (m, 2P, JP−Ag = 378 Hz, JP−P = 79 Hz, JP−P′ = 37 Hz). IR (KBr, cm−1): 2081w (CC), 1093s (ClO4−). [PtAg 2(rac-dpmppe)(CC-3-Etcarb-9)2{P(Et-9-carb-3) 3}2](ClO4)2 (rac-5). This compound was synthesized by the same procedure as that of rac-1 except for the use of rac-Pt-4 and P(Et9-carb-3)3 instead of rac-Pt-1 and PhP(Ph-9-carb-3)2. Yield: 72%. Anal. Calcd for C156H134Ag2Cl2N8O8P6Pt: C, 64.25; H, 4.63; N, 3.84. Found: C, 64.02; H, 4.65; N, 3.58. HRMS (ESI): m/z 1358.3459. Calcd: m/z 1358.3429 ([M − 2ClO4]2+). 1H NMR (CDCl3): δ 8.25− 8.16 (m, 8H), 8.01 (m, 6H), 7.73−7.68 (m,10H), 7.44−7.27 (m, 26H), 7.18−7.02 (m, 10H), 6.94−6.82 (m, 22H), 6.70−6.64 (m, 4H), 4.33 (m, 2H), 4.05−3.99 (q, 4H, J = 7 Hz), 3.85−3.79 (q, 12H, J = 7 Hz), 3.26−3.22 (m, 2H), 2.64−2.51 (m, 2H), 1.29−1.15 (t, 6H, J = 7 Hz), 1.11−0.97 (t, 18H, J = 7 Hz), 0.71 (m, 2H). 31P{1H} NMR(CDCl3): δ 46.2 (d, 2P, JP−P = 78 Hz, JPt−P = 2376 Hz), 15.3 (m, 2P, JP−Ag = 524 Hz, JP−P′ = 38 Hz), 0.6 (m, 2P, JP−Ag = 369 Hz, JP−P = 77 Hz, JP−P′ = 38 Hz). IR (KBr, cm−1): 2073w (CC), 1093s (ClO4−). [PtAg2(rac-dpmppe)(CC-PTZ-Et)2{P(Et-9-carb-3)3}2](ClO4)2 (rac-6). This compound was synthesized by the same procedure as that of rac-1 except for the use of rac-Pt-5 and P(Et-9-carb-3)3 instead of rac-Pt-1 and PhP(Ph-9-carb-3)2. Yield: 73%. Anal. Calcd for C156H134Ag2Cl2N8O8P6PtS2: C, 62.86; H, 4.53; N, 3.76. Found: C, 62.62; H, 4.57; N, 3.59. HRMS (ESI): m/z 1390.8150. Calcd: m/z 1390.8150 ([M − 2ClO4]2+). 1H NMR (CDCl3): δ 8.16−8.13 (m, 8H), 8.01−7.96 (dd, 6H, J = 8 Hz), 7.58−7.55 (m, 6H), 7.42−7.38 (m, 12H), 7.34−7.30 (m, 8H), 7.15−6.99 (m, 22H), 6.90−6.86 (m, 14H), 6.69−6.67 (d, 2H, J = 8 Hz), 6.54−6.52 (d, 2H, J = 8 Hz), 6.35−6.32 (m, 4H), 5.92−5.90 (d, 2H, J = 8 Hz), 4.23 (m, 2H), 4.05− 3.99 (q, 12H, J = 7 Hz), 3.45−3.39 (q, 4H, J = 7 Hz), 3.06−2.97 (m, 2H), 2.64−2.45 (m, 2H), 1.18−1.14 (t, 18H, J = 7 Hz), 1.06−1.02 (t, 6H, J = 7 Hz), 0.59 (m, 2H). 31P{1H} NMR (CDCl3): δ 46.5 (d, 2P, JP−P = 78 Hz, JPt−P = 2376 Hz), 15.2 (m, 2P, JP−Ag = 536 Hz, JP−P′ = 39 Hz), 1.5 (m, 2P, JP−Ag = 381 Hz, JP−P = 77 Hz, JP−P′ = 39 Hz). IR (KBr, cm−1): 2081w (CC), 1093s (ClO4−). [PtAg2(meso-dpmppe)(CCC6H4CF3-4)2(PPh3)(μ-Cl)](ClO4) (meso-7). To a CH2Cl2 solution of meso-Pt-1 (82.4 mg, 0.07 mmol) were first added Ag(tht)ClO4 (41.4 mg, 0.14 mmol) and PPh3 (18.3 mg, 0.07 mmol) with stirring, followed by the addition of nBu4NCl (19.5 mg, 0.07 mmol). Upon stirring at ambient temperature for 3 h, the solution was chromatographed on a silica gel column using CH2Cl2/CH3CN (15:1, v/v) as the eluent to afford the product as a white powder. Yield: 75%. Anal. Calcd for C76H61Ag2Cl2F6O4P5Pt: C, 51.03; H, 3.44. Found: C, 51.21; H, 3.60. HRMS (ESI): m/z 1689.0808. Calcd: m/z 1689.0755 ([M − ClO4]+). 1H NMR (CDCl3): δ 8.03−7.96 (m, 8H), 7.59−7.36 (m, 22H), 7.33−7.29 (t, 4H, J = 7 Hz), 7.25−7.17 (m, 11H), 6.92−6.89 (m, 4H), 6.65−6.62 (m, 4H), 3.86 (m, 2H), 3.37 (m, 2H), 2.28−2.11 (m, 4H). 31P{1H} NMR (CDCl3): δ 47.6 (m, 2P, JP−P = 58 Hz, JPt−P = 2412 Hz), 7.6 (m, 1P, JP−Ag = 579 Hz), −8.9 (m, 2P, JP−Ag = 422 Hz, JP−P = 59 Hz). IR (KBr, cm−1): 2092w (CC), 1104s (ClO4−). [PtAg2(meso-dpmppe)(CCC6H4But-4)2(PPh3)(μ-Cl)](ClO4) (meso-8). This compound was synthesized as the same procedure as that of meso-7 except for using meso-Pt-2 in place of meso-Pt-1. Yield: 74%. Anal. Calcd for C82H79Ag2Cl2O4P5Pt: C, 55.80; H, 4.51. Found: C, 56.02; H, 4.74. HRMS (ESI): m/z 1665.2304. Calcd m/z 1665.2260 ([M − ClO4]+). 1H NMR (CDCl3): δ 8.03−7.97 (m, 8H), 7.53−7.50 (m, 7H), 7.41−7.31 (m, 18H), 7.24−7.16 (m, 12H), 6.71−6.59 (m, 8H), 3.81 (m, 2H), 3.46 (m, 2H), 2.18−2.01 (m, 4H), 1.45 (s, 18H). 31P{1H} NMR (CDCl3): δ 47.1 (m, 2P, JP−P = 58 Hz, JPt−P = 2409 Hz), 7.2 (m, 1P, JP−Ag = 565 Hz), −9.5 (m, 2P, JP−Ag = 417 Hz, JP−P = 58 Hz). IR (KBr, cm−1): 2092w (CC), 1093s (ClO4−). J
DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
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subsequent Fourier maps. All non-hydrogen atoms were refined anisotropically, while the hydrogen atoms were generated geometrically and refined with isotropic thermal parameters. The structures were refined on F2 by full-matrix least-squares methods using the SHELXTL-97 program package.31 For rac-2·4CH2Cl2, the unit cell contains 16 dichloromethane molecules, which were treated as a diffuse contribution to the overall scattering without specific atom positions by SQUEEZE/PLATON. Device Fabrication and Characterization. ITO substrates were cleaned by sonication in deionized water, acetone, and isopropyl alcohol followed by UV-ozone treatment for 15 min. PEDOT:PSS was filtered through a 0.22 μm filter, spin-coated (at 3000 rpm) on the precleaned substrates, dried at 140 °C for 20 min, and then treated with UV ozone for 8 min to give a film of 50 nm thickness. CuSCN dissolved in diethyl sulfide at a concentration of 10 mg/mL was spincoated (at 4400 rmp) onto a PEDOT:PSS hole-injecting layer and then annealed at 140 °C for 10 min to achieve a 30-nm-thick film. The emitting layer was then overlaid by spin coating (at 1500 rpm) using a filtered CH2Cl2 solution (5.5 mg/mL) with mixed host materials and a PtAg2 complex. Subsequently, 50 nm of BmPyPb, 1 nm of LiF, and 100 nm of aluminum were thermally deposited in an inert chamber at a base pressure of less than 4 × 10−4 Pa. The EL spectra were recorded on a Horiba Jobin-Yvon FluoroMax-4 spectrometer. The J−V−L curves of the devices were recorded on a Keithley 2400/2000 sourcemeter and a calibrated silicon photodiode. All measurements of the devices were carried out at room temperature under ambient conditions. Theoretical Methodology. To understand the electronic and spectroscopic properties, calculations were implemented by using the Gaussian 09 program package32 for compounds rac-2, rac-6, meso-8, and meso-11. The geometrical structures as isolated molecules in the ground state and the lowest triplet state were first optimized, respectively, by the restricted and unrestricted DFT method with the gradient-corrected correlation functional PBE1PBE.33 During the optimization process, the convergent values of maximum force, rootmean-square (rms) force, maximum displacement, and rms displacement were set by default. To analyze the spectroscopic properties, 80 singlet and 6 triplet excited states were calculated respectively based on the optimized structures in the ground state and lowest triplet state to determine the vertical excitation energies by TD-DFT34 with the same functional as that used in the optimization process. In the calculation of the excited states, the polarizable continuum model method35 using CH2Cl2 as the solvent was employed. The self-consistent-field convergence criteria of the rms and maximum density matrices were set at 10−8 and 10−6 atomic units, respectively, in excited-state calculations. The iterations of excited states continued until the changes on the energies of states were no more than 10−7 atomic units between the iterations, and then convergences were reached in all of the excited states. In these calculations, the Stuttgart−Dresden36 basis set and effective core potentials was used to describe the platinum, silver, and iodine atoms. Other nonmetal atoms of chlorine, sulfur, phosphorus, nitorgen, carbon, and hydrogen were described by the allelectron basis set of 6-31G*. Visualization of the frontier molecular orbitals were performed by GaussView. The Ros and Schuit method37 (C-squared population analysis method, SCPA) was supported to analyze the partition orbital composition by using the Multiwf n 3.3.8 program.38
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Article
AUTHOR INFORMATION
Corresponding Authors
*E-mail:
[email protected]. *E-mail:
[email protected]. ORCID
Zhong-Ning Chen: 0000-0003-3589-3745 Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We are grateful for financial support from the NSF of China (Grants U1405252, 21531008, 21601184, 21650110449, and 21473201), the 973 Project from MSTC (Grant 2014CB845603), the CAS/SAFEA International Partnership Program for Creative Research Teams, and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant XDB20000000).
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REFERENCES
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ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b00452. Tables and figures giving additional spectroscopic, computational, and EL data (PDF) X-ray crystallographic data in CIF format for rac-2 and meso-7 (CIF) K
DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
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DOI: 10.1021/acs.inorgchem.7b00452 Inorg. Chem. XXXX, XXX, XXX−XXX
