Article pubs.acs.org/Organometallics
Synthesis, Structures, and Photophysical Properties of Ruthenium(II) Quinolinolato Complexes Jing Xiang,†,‡ Larry Tso-Lun Lo,† Chi-Fai Leung,† Shek-Man Yiu,† Chi-Chiu Ko,*,† and Tai-Chu Lau*,† †
Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China ‡ College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434020, HuBei, People's Republic of China S Supporting Information *
ABSTRACT: Reaction of [RuII(PR3)3Cl2] with 2-methyl-8quinolinolate (MeQ) in the presence of Et3N in MeOH produced the neutral carbonyl hydrido complexes [RuII(MeQ)(PR3)2(CO)(H)] (R = Ph (1), MeC6H4 (2), MeOC6H4 (3)). An analogous reaction occurs between [RuII(PPh3)3Cl2] and MeQH in ethanol to give [RuII(MeQ)(PPh3)2(CO)(CH3)] (4). The carbonyl, hydride, and methyl ligands of these complexes are most likely derived from the decarbonylation of ROH. Reaction of [RuII(PPh3)3(CO)(H)2] with 5-substituted quinolinolato ligands (XQ, X = H, Cl, Ph) produced the neutral complexes [RuII(XQ)(PPh3)2(CO)(H)] (XQ = Q (5), ClQ (6), PhQ (7)). Treatment of 1 and 5−7 with excess KCN in MeOH following by metathesis with PPh4Cl afforded PPh4+ salts of the anionic carbonyl dicyano complexes [RuII(XQ)(CO)(CN)2(PPh3)]− (XQ = MeQ (8), Q (9) ClQ (10), PhQ (11)). Under similar conditions, reaction of 1 with excess CyNC in the presence of NH4PF6 afforded [RuII(MeQ)(CyNC)2(CO)(PPh3)]+ (12). All complexes have been characterized by IR, ESI/MS, 1H NMR and elemental analysis. The crystal structures of complexes 3, 4, 8, and 12 have been determined by X-ray crystallography. The UV and emission spectra of these complexes have also been investigated. All complexes exhibit short-lived quinolinolate-based LC fluorescence in solution at room temperature and dual emissions derived from LC fluorescence and phosphorescence at 77 K glassy medium. These emissions are relatively insensitive to the nature of the ancillary ligands but are readily tunable by varying the substituents on the quinolinolato ligand.
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INTRODUCTION
Physical Measurements and Instrumentation. IR spectra were recorded as KBr pellets on a Nicolet Avatar 360 FT-IR spectrometer at 4 cm−1 resolution. UV−vis absorption spectra were recorded on either a Perkin-Elmer Lambda 19 or a Shimadzu UV3100 spectrophotometer. 1H NMR spectra were recorded on a Varian (300 MHz) NMR spectrometer or a Bruker (400 MHz) NMR spectrometer. The chemical shifts (δ, ppm) were reported with reference to tetramethylsilane (TMS). Electrospray ionization mass spectra (ESIMS) were obtained on a PE SCIEX API 365 mass spectrometer. Elemental analyses were done on an Elementar Vario EL III analyzer. Electronic absorption spectra were recorded on a Hewlett-Packard 8452A diode array spectrophotometer. Steady-state emission and excitation spectra at room temperature and at 77 K were recorded on a SPEX FluoroLog 3-TCSPC spectrofluorometer. Solutions were rigorously degassed on a high-vacuum line in a two-compartment cell with no less than four successive freeze−pump−thaw cycles. Timeresolved emission measurements were carried out in the spectral mode of a Edinburgh Instruments LP920-KS using the third harmonic output (355 nm; 6−8 ns fwhm pulse width) of a Spectra-Physics Quanta-Ray Q-switched LAB-150 pulsed Nd:YAG laser (10 Hz) as the excitation source. Measurements of the EtOH/MeOH/CH2Cl2 (4/1/ 1, v/v/v) glass samples at 77 K were carried out with dilute EtOH/
The use of the aluminum 8-quinolinolato complex AlQ3 and its derivatives in electroluminescent devices has attracted enormous attention due to their excellent electron-transporting and emissive properties.1 The structure−function relationship of various AlQ3 complexes has been extensively studied,2 which has led to the development of AlQ3 derivatives with tunable HOMO−LUMO energy gaps and emission colors from blue to red. 2 A number of metal complexes bearing various quinolinolato ligands have also been investigated.3 In contrast to AlQ3 derivatives, which only exhibit singlet emission, luminescence derived from both the singlet and triplet emissive excited states have also been reported in some heavy-transitionmetal quinolinolato complexes.3a−g We have been interested in the development of ruthenium(II) quinolinolato complexes with potential applications in luminescent devices.3f A ruthenium(II) quinolinolato complex bearing a bipyridyl ligand has recently been shown to be potentially useful in dye-sensitized solar cell devices.4 We report herein the synthesis, characterization, and photophysical properties of a new class of ruthenium(II) quinolinolato complexes bearing various ancilliary ligands. © 2012 American Chemical Society
EXPERIMENTAL SECTION
Received: July 5, 2012 Published: October 10, 2012 7101
dx.doi.org/10.1021/om300621x | Organometallics 2012, 31, 7101−7108
Organometallics
Article
Table 1. Crystal Data and Structure Refinement Details for Complexes 3, 4, 8, and 12 formula Mr T/K cryst syst space group a/Å b/Å c/Å α/deg β/deg γ/deg V/Å3 Z ρcalcd/g cm−3 F(000) no. of collected rflns no. of unique rflns R(int) final R indices, I > 2σ(I) GOF no. of params
3·2CH2Cl2
4
8·0.25CH2Cl2·H2O
12
C53H51NO8P2Ru·2CH2Cl2 1162.81 133 (2) monoclinic P21/n 12.4343(3) 28.1257(5) 15.6486(3) 90 101.690(2) 90 5359.18(18) 4 1.441 2392 23 013 10 291 0.025 R1(obsd) = 0.048 wR2(all) = 0.139 1.11 733
C48H41NO2P2Ru 826.83 173 (2) triclinic P1̅ 9.2381(3) 12.5884(4) 17.4284(5) 82.761(2) 86.015(3) 74.412(3) 1935.36(10) 2 1.419 852 12 258 6737 0.027 R1(obsd) = 0.034 wR2(all) = 0.118 1.23 489
C55.25H45.50Cl0.50N3O3P2Ru 980.18 133 (2) triclinic P1̅ 12.5278(5) 13.1009(5) 16.4148(5) 101.879(3) 92.797(3) 111.000(3) 2439.04(15) 2 1.335 1009 16 693 8596 0.018 R1(obsd) = 0.036 wR2(all) = 0.108 1.08 589
C43H45N3O2PRuF6P 912.83 133 (2) monoclinic P21/n 12.4298(3) 24.7828(6) 13.3653(3) 90 94.183(2) 90 4106.15(17) 4 1.477 1872 29 571 7306 0.026 R1(obsd) = 0.040 wR2(all) = 0.099 1.03 578
H 4.84; N, 1.72. Found: C, 69.10; H, 4.72; N, 1.77. UV/vis (CH2Cl2): λmax (nm) (ε (mol−1 dm3 cm−1)): 265 sh (24 350), 354 (6930), 421 (3710). [RuII(MeQ)(H)(CO){P(C6H4Me)3}2] (2). The complex was synthesized according to a procedure similar to that for 1, except [Ru{P(C6H4Me)3}3Cl2] was used instead of [Ru(PPh3)3Cl2]. Yield: 268 mg, 59%. IR (KBr, cm−1): ν(CO) 1907, ν(Ru−H) 1944. ESI-MS: m/z 896 [M − H]+, 739 [M − MeQ]+. 1H NMR (400 MHz, CDCl3): δ 7.35−7.40 (dt, J = 8.0, 4.9 Hz, 12H, Ar H), 6.90 (d, J = 6.8 Hz, 12H, Ar H), 6.76 (t, J = 7.8 Hz, 1H, Ar H), 6.54 (d, J = 8.4 Hz, 1H, Ar H), 6.22 (d, J = 7.8 Hz, 1H, Ar H), 6.15 (d, J = 8.2 Hz, 1H, Ar H), 5.30 (s, 1H, Ar H), 2.23 (s, 18H, PC6H4−CH3), 2.04 (s, 3H, Ar−CH3), −10.69 (t, J = 20.2 Hz, 1H, Ru−H). 31P{1H} NMR (162 MHz, CDCl3): δ 41.9 (s, P(C6H4Me)3). Anal. Calcd for C53H51NO2P2Ru: C, 70.97; H, 5.73; N, 1.56. Found: C, 70.78; H, 5.82; N, 1.60. UV/vis (CH2Cl2): λmax (nm) (ε (mol−1 dm3 cm−1)): 271 sh (27 990), 352 (6440), 425 (3630). [RuII(MeQ)(H)(CO){P(C6H4OMe)3}2] (3). The complex was synthesized according to a procedure similar to that for 1, except [Ru{P(C6H4OMe)3}3Cl2] was used instead of [RuII(PPh3)3Cl2]. Yield: 275 mg, 55%. IR (KBr, cm−1): ν(CO) 1902, ν(Ru−H) 1964. ESI-MS: m/z 992 [M − H]+, 835 [M − MeQ]+. 1H NMR (400 MHz, CD2Cl2): δ 7.51 (d, J = 8.4 Hz, 1H, Ar H), 7.36−7.42 (m, 12H, Ar H), 6.80 (t, J = 7.8 Hz, 1H, Ar H), 6.65−6.71 (m, 13H, Ar H), 6.25 (d, J = 7.7 Hz, 1H, Ar H), 6.18 (d, J = 7.1 Hz, 1H, Ar H), 3.74 (s, 18H, CH3O−), 2.07 (s, 3H, −CH3), −10.75 (t, J = 20.4 Hz, 1H, Ru−H). 31 1 P{ H} NMR (162 MHz, CDCl3): δ 39.3 (s, P(C6H4OMe)3). Anal. Calcd for C53H51NO8P2Ru: C, 64.11; H, 5.18; N, 1.41. Found: C, 64.20; H, 5.22; N, 1.37. UV/vis (CH2Cl2): λmax (nm) (ε (mol−1 dm3 cm−1)): 272 sh (30 750), 341 (6370), 424 (3010). [RuII(MeQ)(Me)(CO)(PPh3)2] (4). The synthesis is similar to that for 1, except EtOH (150 mL) was used as solvent instead of MeOH. Yield: 279 mg, 67%. IR (KBr, cm−1): ν(CO) 1894. ESI-MS: m/z 812 [M − CH3]+, 669 [M − MeQ]+. 1H NMR (400 MHz, CD2Cl2): δ 7.53 (d, J = 8.6 Hz, 1H, Ar H), 7.28−7.30 (m, 19H, Ar H), 7.15−7.20 (m, 12H, Ar H), 6.92 (t, J = 7.8 Hz, 1H, Ar H), 6.68 (d, J = 8.4 Hz, 1H, Ar H), 6.48 (d, J = 7.1 Hz, 1H, Ar H), 6.35 (d, J = 8.4 Hz, 1H, Ar H), 1.80 (s, 3H, Ar−CH3), 0.52 (t, J = 6.5 Hz, 3H, Ru-CH3). 31P{1H} NMR (162 MHz, CDCl3): δ 34.0 (s, PPh3). Anal. Calcd for C48H41NO2P2Ru: C, 69.72; H, 5.00; N, 1.69. Found: C, 69.66; H,
MeOH/CH2Cl2 sample solutions contained in a quartz tube inside a liquid nitrogen filled quartz optical Dewar flask. The emission lifetimes were measured in the TCSPC mode with NanoLED-375LH (λex 375 nm; pulse width
