and Tridentate Carbazole Phosphine Oxides for ... - ACS Publications

Subscriber access provided by - Access paid by the | UCSB Libraries

C: Plasmonics, Optical Materials, and Hard Matter

Effective Europium Coordination Luminophores Linked with Bi-and Tridentate Carbazole Phosphine Oxides for Organic Electroluminescent Devices Yasuchika Hasegawa, Shiori Natori, Jun Fukudome, Takashi Nagase, Takayuki Nakanishi, Yuichi Kitagawa, Koji Fushimi, Hiroyoshi Naito, and Takashi Kobayashi J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.8b01375 • Publication Date (Web): 16 Apr 2018 Downloaded from http://pubs.acs.org on April 16, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

Effective Europium Coordination Luminophores Linked with Bi-and Tridentate Carbazole Phosphine Oxides for Organic Electroluminescent Devices Yasuchika Hasegawa,†* Shiori Natori,† Jun Fukudome,§ Takashi Nagase,§ Takashi Kobayashi,§ Takayuki Nakanishi,† Yuichi Kitagawa,† Koji Fushimi,† Hiroyoshi Naito§ †

Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, N13 W8, Kita-ku,

Sapporo, Hokkaido 060-8628, Japan. §

Department of Physics and Electronics Graduate School of Engineering, Osaka Prefecture University,

 1-1 Gakuen-cho, Naka-ku, Sakai, 1-2 Osaka 599-8531, Japan.

RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required according to the journal that you are submitting your paper to)

Corresponding author footnote: Tel/Fax: +81 11 706 7114 E-mail address: [email protected] (Y. Hasegawa)

ACS Paragon Plus Environment

1

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 26

ABSTRACT: Lanthanide coordination polymers with charge combination parts, hole and electron transport units, [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n (ntfa = 3-(2-naphthoyl)-1,1,1-trifluoroacetonate, dppcz = 3,6-bis(diphenylphosphoryl)-9-phenylcarbazole),

tpcz

=

3,6-bis(diphenylphosphoryl)-9-[4-

(diphenylphosphoryl)phenyl]carbazole) are reported as an emitting material for organic EL device. The intrinsic emission quantum yield Φ4f–4f of [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n in solid were calculated to be 32 % and 45%, respectively. The photosensitized energy transfer efficiencies ηsens from organic ntfa ligands to luminescent Eu(III) ions in [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n were found to be 84 and 39%, respectively. The energy transfer efficiency ηsens from ntfa to Eu(III) ion is dependent on the network structure in Eu(III) coordination polymers in solid. The ηsens values and characteristic structures of Eu(III) coordination polymers are directly linked to maximum luminances and current efficiencies in solid EL devices, respectively. The luminance of EL device containing [Eu(ntfa)3(dppcz)]n was estimated to be 188 cd/m2 at 15 V, which is larger than that of previous reported EL device with Eu(III) complexes.


2

Page 3 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


INTRODUCTION Lanthanides in the stable (III) oxidation state are simply characterized by an incompletely filled 4f shell. The lanthanide ions with characteristic 4f orbitals show attractive highly monochromatic clear luminescence with narrow FWHM (full width at half maximum < 10 nm).1 Inorganic phosphors and coordination compounds including lanthanide ions have been extensively studied.2-5 We focus on lanthanide complex with aromatic organic ligands as a future display material.6 The lanthanide complexes are coordinated with aromatic molecular antenna for high photon absorption efficiency (ε ~ 50,000 mol-1cm-1), resulting in brilliant and efficient luminescence compared with those of lanthanide ions (ε < 10 mol-1cm-1). At the present stage, various types of lanthanide complexes with characteristic aromatic antenna ligands have been reported.7-9 Among them, the monochromatic emission of Eu(III) and Tb(III) ions plays an important role of construction of red and green elements in the full-color display devices such as those that are organo-electroluminescent (EL) or electrochemically luminescent (ECL), light-emitting diode (LED) tip-devices. Xu reported on effective EL devices using carbazolepolymer linked with Eu(III) complex with aromatic tta (4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione) and bidentate phosphine oxide as a branch (149 cd/m2).10 Yang also described carbazole-polymer containing Eu(III) complex with tta and terpyridyl ligands for EL devices (68 cd/m2).11 Nakamura provides conceptual dual emission and quick responded ECL devices using Eu(III) complexes with tta ligands.12 Display devices using luminescent lanthanide complexes are expected to be useful in application such as flexible and wearable organic devices.13 According to the luminescent lanthanide complexes with aromatic organic ligands, lanthanide coordination polymers have been recently explored.14 The one-dimensional alternating sequence of lanthanide(III) ions and organic joint ligands exhibits remarkable characteristics as novel organic materials with various structural and unique photophysical properties. We have reported on the luminescent lanthanide coordination polymers linked with phosphine oxide joint ligands.15-19 Lowvibrational frequency phosphine oxides as the linking part in lanthanide coordination polymer are selected for suppression of non-radiative transition via vibrational relaxation, resulting in their high ACS Paragon Plus Environment

3


emission quantum yields (> 75%).15,

16

Page 4 of 26

Lanthanide coordination polymers also provide unique

photophysical properties such as effective luminescence under 400oC, 17 thermo-sensitive luminescent color changing phenomena,18 and triboluminescence properties.19 The characteristic structural and photophysical properties of lanthanide coordination polymers are promoted by steric moiety of the organic linker ligands, which provide formation of their polymeric and network structures. The linker organic ligand is a promising key-molecule for control of photophysical and structural properties of lanthanide coordination polymers. We here attempted to prepared organic EL device using lanthanide coordination polymer as an emitting layer. In this study, bidentate and tridentate phosphine oxides with carbazole units, dppcz (dppcz

=

3,6-bis(diphenylphosphoryl)-9-phenylcarbazole)

and

tpcz

(tpcz

=

3,6-

bis(diphenylphosphoryl)-9-[4-(diphenylphosphoryl)phenyl]carbazole) were prepared as joint linker ligands for formation of lanthanide coordination polymers. The carbazole unit in the joint linker ligand plays an important role of hole transfer in an emitting layer.11 Luminescent Eu(ntfa)3 parts (ntfa = 3-(2naphthoyl)-1,1,1-trifluoroacetonate) were also selected for smooth formation of excited state on the antenna ligands under electron and hole transfers from each transport materials in EL devices.20 Based on their elemental analyses, ratio of Eu(III) complexes and bidentate-dppcz was found to be 1:1 (onedimensional structure). Ratio to Eu(ntfa)3 and tridentate-tpcz was estimated to be 1.5 (two-dimensional structure). Obtained Eu(III) coordination polymers [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n promote formation of characteristic polymer structures in emitting layers of EL devices (Figure 1). Their photophysical properties in solid were evaluated using the emission spectra and the emission lifetimes, resulting in calculations of the intrinsic emission quantum yields Φ4f–4f, radiate kr and non-radiative knr rate constants. We also measured the emission quantum yields excited at π−π∗ transition bands of ntfa ligands Φπ–π* for estimation of energy transfer efficiency between ntfa ligand and Eu(III) ion ηsens. For fabrication of EL devices, electron and hole transport molecules mCP, OXD-7, PVK, and PEDOT:PSS (mCP: 1,3-Bis(N-carbazolyl)benzene, OXD-7: 2,2'-(1,3-Phenylene)bis[5-(4-tert-butylphenyl)-1,3,4-


4

Page 5 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


oxadiazole], PVK: polyvinylcarbazole, PEDOT:PSS: poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) are used for smooth charge combination of electron and hole in emitting layers. The device structure and the energy band diagram are shown in Figure 2. In this study, we report that the photo- and electro-luminescent performances are influenced by the characteristic structure of Eu(III) coordination polymers. The energy transfer efficiencies ηsens and steric structures of Eu(III) coordination polymers are directly linked to maximum luminances and current efficiencies in solid EL devices, respectively. The photophysical and electroluminescent performances of lanthanide coordination luminophores linked with bi- and tridentate carbazole phosphine oxides are demonstrated in terms of network structures.

EXPERIMENTAL SECTION Materials: Europium acetate monohydrate (99.9%) was purchased from Wako Pure Chemical Industries Ltd. 9-(4’-Bromophenyl)-3,6-dibromocarbazole and chlorodiphenylphosphine were obtained from Tokyo Kasei Organic Chemicals and Aldrich Chemical Company Inc. All other chemicals and solvents were reagent grade and were used without further purification. Apparatus: Infrared spectra were recorded on a JASCO FT/IR–420 spectrometer. 1H NMR (400 MHz) spectra were recorded on a JEOL ECS 400. Chemical shifts are reported in δ ppm, referenced to an internal tetramethylsilane standard for 1H NMR. Elemental analyses were performed using a an Exeter Analytical CE440. Preparation

of

tris(3-(2-naphthoyl)-1,1,1-trifluoroacetonate)europium

dihydrates

[Eu(ntfa)3(H2O)]: Europium chloride hexahydrate (0.54 g, 1.5 mmol) was dissolved in ethanol (10 mL) in a 100 mL flask. A solution of 3-(2-naphthoyl)- 1,1,1-trifluoroacetone (ntfa; 1.2 g, 4.5 mmol) in ethanol (40 mL) and triethylamine (0.6 mL, 4.5 mmol) was added dropwise to the flask. A white/yellow precipitate formed after stirring for 2 h at room temperature. The reaction mixture was filtered, and the resulting solid was recrystallized from methanol/water. 2.55 g, Yield: 42.6%. Anal. Calcd for [C42H26EuF9O7]: C, 52.24; H, 2.71. Found: C, 52.10; H, 3.48. ACS Paragon Plus Environment

5


Preparation

of

3,6-bis(diphenylphosphoryl)-9-phenylcarbazole

Page 6 of 26

(dppcz):

3,6-

Bis(diphenylphosphoryl)-9-phenylcarbazole was synthesized according to a published procedure.12 A solution of n-BuLi (1.6m in hexane, 8.8 mL, 14 mmol) was added dropwise to a solution of 3,6dibromo-9-phenylcarbazole (2.4 g, 6.0 mmol) in dry THF (30 mL) at -78oC. The addition was completed within approximately 10 min, during which time a white yellow precipitate formed. The mixture was stirred for 2 h at 10oC, after which time PPh2Cl (2.6 mL, 14 mmol) was added dropwise at 78oC. The mixture was gradually warmed to room temperature and stirred for 18 h to give a white precipitate. The precipitate was filtered, washed with methanol several times, and dried in vacuo. The obtained white powder and dichloromethane (40 mL) were placed in a flask. The solution was cooled to 0oC and then 30% aq H2O2 (8 mL) was added. The reaction mixture was stirred for 2 h. The product was extracted with dichloromethane, and the extracts were washed with brine three times and dried over anhydrous MgSO4. The solvent was evaporated to afford a white powder. Recrystallization from dichloromethane/hexane gave the title compound as colorless crystals (2.0 g, 53 %). 1H NMR (400 MHz, CDCl3, 25 oC) δ = 8.43– 8.47 (d, J = 12.0 Hz, 2 H), 7.63–7.76 (m, 11 H), 7.43–7.60 ppm (m, 18H); IR(KBr): v=1122cm-1 (s, P=O); MS(ESI): m/z: 644.2[M+H]+; elemental analysis calcd (%) for C42H31NO2P2: C 78.37, H 4.85, N 2.18; found: C 78.42, H 5.00, N 2.18. Preparation of 3,6-bis(diphenylphosphoryl)-9-[4-(diphenylphosphoryl)phenyl]carbazole (tpcz): A solution of n-BuLi (8.44 mL, 1.6 M hexane, 13.2 mmol), was added dropwise to a solution of 9-(4’bromophenyl)-3,6-dibromocarbazole (1.9 g, 4 mmol) in dry THF (100 mL) at -78 °C. The mixture was allowed to stir for 3h at -78°C, after which a chlorodiphenylphosphine (PPh2Cl: 2.44 mL, 13.2 mmol) was added dropwise at -78°C. The mixture was gradually brought to room temperature, and stirred for 14 h. The product was extracted with ethyl acetate, the extracts washed with brine for three times and dried over anhydrous MgSO4. The solvent was evaporated, and resulting residue was purified by column chromatography (silica, ethylacetate/methanol, 10:1). White powder. (0.5 g, yield: 9 %).

1

H

NMR (400 MHz, CDCl3, 25°C): δ 8.45 (d, 2H, J=12.4 Hz), 7.96 (d, 1H, J = 8.8 Hz), 7.90 (d, 1H, J = 9.6 Hz), 7.66-7.78 (m,16H) and 7.44-7.64 (m, 20H) ppm. 31P NMR (CDCl3): δ 28.0, 30.8 ppm. ACS Paragon Plus Environment

6

Page 7 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


General Procedure for the Preparation of Eu(III) coordination polymers: A solution of the phosphine oxide ligand (0.11 mmol) in methanol (2 mL) was added to a solution of [Eu(ntfa)3(H2O)] (0.33 mmol) in methanol (7.5 mL). The solution was stirred at room temperature for 4 h to give a white precipitate. The precipitate was filtered, washed with ethanol and hexane several times, and dried in vacuo. [Eu(ntfa)3(dppcz)]n: ESI-MS (m/z) = 1326.2 [Eu(ntfa)2(dppcz)]+,1969.38 [Eu(ntfa)2(dppcz)2]+,2917.40 [Eu2(ntfa)5(dppcz)2]+. Anal. Calcd for EuC84H55NO8F9P2: C, 63.40; H, 3.48; N, 0.88 %. Found: C, 63.54; H, 3.55; N, 0.99 %. Decomposition temperature = 280oC. [Eu3(ntfa)9(tpcz)2]n: ESI-MS (m/z) = 1526.20 [Eu(ntfa)2(tpcz)]+, 2370.35 [Eu(ntfa)2(tpcz)2]+, 3318.36 [Eu2(ntfa)5(tpcz)2]+. Anal. Calcd for Eu3C234H152N2O24F27P6: C, 62.04; H, 3.38; N, 0.62 %. Found: C, 61.43; H, 3.65; N, 0.62%. Decomposition temperature = 310oC. Optical Measurements: Excitation and emission spectra of the lanthanide complexes were measured with a Horiba Fluorolog spectrometer, which corrected for the response of the detector system. The emission quantum yields excited at 365 nm (Φπ–π*) were estimated using a JASCO F-6300-H spectrometer attached with JASCO ILF-533 integrating sphere unit (φ = 100 nm). The wavelength dependence of the detector response and the beam intensity of the Xe light source for each spectrum were calibrated using a standard light source. The emission spectra are normalized with respect to the magnetic dipole transition intensities at 592 nm (Eu: 5D0–7F1), which are known to be insensitive to the surrounding environment of the lanthanide ions. Emission lifetimes of lanthanide coordination polymers were measured using the third harmonics (355 nm) of a Q-switched Nd: YAG laser (Spectra Physics, INDI-50, fwhm = 5 ns, λ = 1064 nm) and a photomultiplier (Hamamatsu Photonics, R5108, response time ≤ 1.1 ns). The Nd:YAG laser response was monitored with a digital oscilloscope (Sony Tektronix, TDS3052, 500 MHz) synchronized to the single-pulse excitation. Emission lifetimes were determined from the slope of logarithmic plots of the decay profiles. Calculation of the emission quantum yields: The 4f–4f emission quantum yields (Φ4f–4f), and the radiative (kr) and nonradiative (knr) rate constants were estimated (Table 1) using following equations, ACS Paragon Plus Environment

7


=

1 (1)

=

1 (2) +

=

Page 8 of 26

= (3) +

= , (4)

=

1

−

1

(5),

where AMD,0 is the spontaneous emission probability for the 5D0–7F1 transition in vacuo (14.65 s−1), n is the refractive index of the medium (an average index of refraction equal to 1.5 was employed), and (Itot / IMD) is the ratio of the total area of the corrected Eu(III) emission spectrum to the area of the 5D0–7F1 band. Fabrication and measurement of EL devices: EL devices were fabricated on ITO coated glass substrates. The substrates were cleaned by ultrasonic cleaning in acetone and 2-propanol for 10 min each and then were treated by UV–ozone for 1 hour. A 45 nm-thick PEDOT:PSS layer was first spin coated on ITO and dried at 150 oC for 30 min. After the samples transferred to a nitrogen-filled glove box (dew point: -80 oC), a 15 nm-thick PVK layer was spin coated on PEDOT:PSS layer from chlorobenzene at a concentration of 0.5 wt% and dried at 150 oC for 10 min in vacuum. A 30-60 nmthick [Eu(ntfa)3(dppcz)]n or [Eu3(ntfa)9(tpcz)2]n:mCP:OXD-7 layer was spin coated on PVK layer and dried at 80

o

C for 20 min in vacuum. P-xylene and acetonitrile solvents were used for

[Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n respectively at a concentration of 1.0-2.0 wt%. The mixing ratio of mCP:OXD-7 was 5:5, 6:4, 7:3. The concentration of Eu(III) coordination polymers was 5-20 wt% to the mixture of mCP and OXD-7. A 20 nm-thick Ca and a 40 nm-thick Al were thermally evaporated as the cathode in a vacuum chamber at a base pressure of 10-4 Pa. Finally, the samples were ACS Paragon Plus Environment

8

Page 9 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


encapsulated with epoxy. The device structure was ITO/PEDOT:PSS(45 nm)/PVK(15 nm)/ [Eu(ntfa)3(dppcz)]n or [Eu3(ntfa)9(tpcz)2]n:mCP:OXD-7(30-60 nm)/Ca(20 nm)/Al(40 nm). The film thickness was measured by using a probe type step profiler (Tencor Alpha-Step 500). The current density-voltage-luminance (J-L-V) characteristics were recorded with a source measure unit (Keithley 2411) and a luminance meter (Konica Minolta CS-200). The electroluminescence (EL) spectra were measured with a photonic multichannel analyzer (Hamamatsu Photonics PMA11). All measurements were performed in ambient air

RESULTS AND DISCUSSION Photoluminescence properties of Eu(III) coordination polymers in solid: The Eu(III) coordination polymers, [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n, were prepared by the complexation of Eu(ntfa)3(H2O)2 with the corresponding phosphine oxide ligands. The polymeric structures of [Eu(ntfa)3(tpcz)]n and [Eu3(ntfa)9(dppcz)2]n were characterized using ESI-MS and elemental analyses. The observed signals with mass numbers (m/z) of 1326.20, 1969.38, and 2917.40, were assigned to fragments [Eu(ntfa)2(dppcz)]+, [Eu(ntfa)2(dppcz)2]+, and [Eu2(ntfa)5(dppcz)2]+, respectively. The assignment was made by comparing the observed isotope distribution of [Eu(ntfa)2(dppcz)]+ (m/z at around 1326.20) with the calculated data. We also found that signals with mass numbers (m/z) of 1526.20, 2370.35, and 3318.36 were attributed to fragments [Eu(ntfa)2(tpcz)]+, [Eu(ntfa)2(tpcz)2]+ and [Eu2(ntfa)5(tpcz)2]+, respectively. Ratio of Eu(ntfa)3 and tridentate-tpcz for elemental analysis agrees with that of previous Eu(III) coordination polymers with rigid triangular linker ligands [Eu3(ntfa)9(tppb)2]n (tppb: tris(4-diphenylphosphorylphenyl)benzene).21 The decomposition temperatures (dp) of [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n were found to be 280 and 310oC, respectively (see supporting information Figure S1). Their decomposition temperatures are similar to those of previous one-dimensional [Eu(hfa)3(dppcz)]n (dp = 300 oC). Previously, we reported that [Eu(hfa)3(dppcz)]n exhibits tightly packed π/π, CH/π, CH/F interactions in polymer chains.15 The characteristic molecular


9


Page 10 of 26

chains in [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n should be also packed with π/π, CH/π, CH/F interactions in solid. The steady-state emission spectra of [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n in the solid state are shown in Figure 3a. The wavelength dependences of the detector response and the beam intensity of the Xe light source for each emission spectrum are calibrated using a standard light source. Emission bands for the Eu(III) coordination polymers are observed at around 578, 592, 613, 650, and 698 nm, and are attributed to the 4f–4f transitions of 5D0–7FJ with J = 0, 1, 2, 3 and 4, respectively. The spectra are normalized with respect to the magnetic dipole transition intensities at 592 nm (Eu: 5D0–7F1), which is known to be insensitive to the surrounding environment of the lanthanide ions.22 The electric dipole transition intensity (5D0–7F2: 613 nm) of [Eu3(ntfa)9(tpcz)2]n is larger than that of [Eu3(ntfa)9(dppcz)2]n. The transition intensity is directly linked to the transition probability related with a radiative rate constant, kr. Generally, asymmetric coordination structure of lanthanide complex promotes large kr. The coordination structure of [Eu3(ntfa)9(tpcz)2]n should provide large kr based on the asymmetric tight packings. Their excitation spectra are also shown in Figure 3a. The transition bands at 465 and 532 nm are assigned to 4f–4f transitions (7F0–5D2 and 7F0–5D1, respectively) of Eu(III) ion. The broad excitation bands of [Eu3(ntfa)9(dppcz)2]n at around 400 nm are due to the π−π* transition of ntfa ligands. In previous papers, specific transition band at around 400 nm in tight-packed Eu(III) coordination polymers, ILCT (Inter or Intra ligand charge transfer band of the ligand), has been observed.23-25 Redsifted excitation band of [Eu3(ntfa)9(tpcz)2]n might be due to formation of specific ILCT interaction between ntfa and two-dimensional tight-stacked tpcz joint ligands. The time-resolved emission profiles of [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n revealed singleexponential decays with lifetimes in the millisecond time scale (Figure 3b). The emission lifetimes were determined from the slopes of logarithmic plots of the decay profiles. The observed emission lifetimes (τobs) of [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n were found to be 0.36 and 0.37 ms, respectively. The calculated emission quantum yields (Φ4f–4f) and radiative (kr) and nonradiative (knr) rate constants for the Eu(III) coordination polymers are shown in Table 1. The Φ4f–4f of [Eu3(ntfa)9(tpcz)2]n was found ACS Paragon Plus Environment

10

Page 11 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


to be 45%. The Φ4f–4f of [Eu(ntfa)3(dppcz)]n was also calculated to be 32 % in solid state, which are smaller than that of previously reported [Eu(hfa)3(dppcz)]n (hfa: hexafluoroacetylacetonate,Φ4f–4f = 84 %).15 The decrease of emission quantum yield is caused by large knr value of Eu(III) coordination polymers with nfta ligands. The non-radiative rate constant knr is related to number of C-H bond in the thermal relaxation from the excited state of Eu(III) complex.22 The ntfa ligand contains high-vibrational eight C-H bonds in molecular structure, in contrast, the hfa ligand have only one C-H bond in molecule structure. Large amount of C-H bond in ntfa ligands promotes an increase of knr constant, although the ntfa ligand promotes smooth formation of excited state on the antenna ligands under recombination between electron and hole in EL devices. The kr constant of [Eu3(ntfa)9(tpcz)2]n (1.2×103 s-1) is larger than those of [Eu(hfa)3(dppcz)]n (8.6×102 s-1) and [Eu(hfa)3(dppcz)]n (8.9×102 s-1). The large increase of the radiative rate constant indicates that electric transition probability of [Eu3(ntfa)9(tpcz)2]n is enhanced by formation of asymmetric coordination structure in solid. The photosensitized energy efficiencies ηsens are calculated using Φ4f–4f and Φπ–π* using an integrating sphere (φ = 100 mm). The ηsens of [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n were found to be 84 and 39%, respectively. The ηsens of [Eu(ntfa)3(dppcz)]n is larger than that of previous reported [Eu(hfa)3(dppcz)]n (ηsens = 64%).15 Expansion of π-conjugated system in diketonate ligands promotes tight packing structure with CH/π and π/π interactions. The tight packing structure in solid leads to formation characteristic ILCT band and enhancement of effective energy transfer between ligand and Eu(III) ion.19 We consider that the effective photosensitized energy transfer in solid should be affected by expanded π-conjugation system of naphtyl groups in [Eu(ntfa)3(dppcz)]n. The small ηsens of [Eu3(ntfa)9(tpcz)2]n might be influenced by overlap excitation of π-stacked tpcz ligands. In our previous study, the energy transfer from excited phosphine oxide ligand to Eu(III) is not effective because of the small energy overlap between Eu(III) ion and aromatic unit in phosphine oxide ligand.26 The energy transfer efficiency from ntfa to Eu(III) ion is dependent on the packing structures and electronic moieties in Eu(III) coordination polymers. ACS Paragon Plus Environment

11


Page 12 of 26

Electroluminescence properties of Eu(III) coordination polymers in EL devices: In order to evaluate the electroluminescent performance of one- and two-dimensional Eu(III) coordination polymers, EL devices using Eu(III) coordination polymers were fabricated. Hole transports (PEDOT:PSS and PVK layers) and emitting layer (electron and hole transport: mCP, electron transport: OXD-7, emitting: Eu(III) coordination polymers (Eu)) on ITO glass electrode were prepared using spin coating technique and drying process. Thermostable [Eu(ntfa)3(dppcz)]n (dp = 280oC) and [Eu3(ntfa)9(tpcz)2]n (dp = 310oC) are amorphous-formed with mCP and OXD-7 under heat treatments in vacuum under 150 oC. Counter electrode Ca/Al was layered on the emitting layer using vacuum deposition technique. We here optimized the mixing ratio and thickness of emitting layer in EL device using [Eu(ntfa)3(dppcz)]n. The optimum mixing ratio of host matrices mCP:OXD-7 based on fabrications of EL devices was decided to be 6:4, when concentration of [Eu(ntfa)3(dppcz)]n is 10 w% in emitting layer (see supporting information, Table S1). The morphology of the emission film, mCP:OXD-7: [Eu(ntfa)3(dppcz)]n, was observed using color 3D laser scanning microscope. The laser scanning microscope image shows that the micro-sized particles are located in host matrix, homogeneously. We consider that the micro-sized particles might be composed of [Eu(ntfa)3(dppcz)]n polymer (see surpporting information Fig. S3).

The electroluminescence spectra of EL devices containing

[Eu(ntfa)3(dppcz)]n based on the optimum mixing ratio of host matrices are shown in Figure 4a. Emission bands for the [Eu(ntfa)3(dppcz)]n in EL devices are observed at around 578, 592, 613, 650, and 698 nm, that are similar to those of photoluminescence spectral bands. The concentration ratio of [Eu(ntfa)3(dppcz)]n in emitting layer was optimized by diminishing of emission at around 450 nm by host matrices (Eu/mCP/OXD-7 = 20:48:32). The best thickness of the amorphous emitting layers was determined to be 50 nm (see supporting information, Table S2). The applied-voltage depended currrent density and luminance (J-L-V plot) of optimized EL devices with [Eu(ntfa)3(dppcz)]n are shown in Figure 4b. We observed electroluminescence from 11 V with smooth increase slope in J-L-V plot. The luminance at 15 V was 188 cd/m2, which is larger than that of previous ACS Paragon Plus Environment

12

Page 13 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


reported EL device with Eu(III) complex.10

The large luminance is caused by caharacteristic

coordination polymer structure and large energy transfer efficiency from ntfa ligands to Eu(III) ion in [Eu(ntfa)3(dppcz)]n. The rigid coordination polymer chain of [Eu(ntfa)3(dppcz)]n in emitting layer plays a role in highway for electron and hole transports, resulting in smooth formation of excited ntfa ligands. The large energy transfer efficiency from excited ntfa ligands to Eu(III) ions in [Eu(ntfa)3(dppcz)]n (ηsens = 84%) exhibits high luminance performance. The liner structure of Eu(III) coordination polymer provides effective electroluminescence in optimaized EL device. We also measured photoluminescence spectrum and lifetime of Eu(III) thin film, Glass/mCP:OXD-7: [Eu(ntfa)3(dppcz)]n, excited at UV absorption band of Eu(III) complex (see surpporting information Fig. S4). The spectral shape of Eu(III) thin film is much similar to that of [Eu(ntfa)3(dppcz)]n powder. On the other hand, we observed double exponential decay of time-resolved emission profile (τ1=0.37 ms and τ2=0.65 ms). The longer lifetime component might be due to specific Eu(III) species on [Eu(ntfa)3(dppcz)]n polymer particle surface in matrix (mCP:OXD-7). The J-L-V plot of optimized EL devices with [Eu3(ntfa)9(tpcz)2]n are also shown in supporting informatoion Figure S2. The luminance at 17 V was 60 cd/m2. The small luminance might be due to small energy transfer efficiency in [Eu3(ntfa)9(tpcz)2]n (ηsens = 39%). We consider that the luminance in EL device is closely related to photosensitized energy transfer efficiency of Eu(III) coordination polymer. The current density-depended efficiencies of optimaized EL devices with [Eu(ntfa)3(dppcz)]n and [Eu3(ntfa)9(tpcz)2]n are shown in Figure 5. Large and stable current efficiency (aprroximately 0.40 cd/A) under applied voltage was observed in EL device including [Eu3(ntfa)9(tpcz)2]n. The large and stable current efficiency is due to smooth hole transport on carbazol units in EL device. The comparison of EL current efficiencies of [Eu3(ntfa)9(tpcz)2]n with previous EL devices are shown in surpporting information Fig. S4. We found that efficient EL perfomance of [Eu3(ntfa)9(tpcz)2]n is observed under lower applied voltage (< 10V), although previous devices are performed under higher applied voltages (> 13V). Note that [Eu3(ntfa)9(tpcz)2]n shows characteristic ILCT interaction in excitation spectrum. In emitting layer, the two-dimensional network joint ligands with carbazol unit, tpcz, might also construct ACS Paragon Plus Environment

13


Page 14 of 26

tight π−π stacking interaction with mCP (hole transporter with two carbazol unit in emitting layer) and PVK (conducting polymer with carbazol units in hole transport layer). The tight π−π stacking interaction promotes smooth injection and transport of hole from mCP and PVK to tpcz joint ligands in [Eu3(ntfa)9(tpcz)2]n.

CONCLUSIONS Photo- and electroluminescent properties of Eu(III) coordination polymer are dependent on their steric structures based on the photo- and applied physical chemistry in solid. We successfuly fabricated monochromatic red luminescent EL devices using Eu(III) coordination polymers linked with bi- and tridentate carbazole phosphine oxides for the first time. Their luminescent performances and novel aspects provide us to consider the importance of photophysical chemistry in soild for construction of effective opto-electrionic devices. We also reported monochromatic green luminecent Tb(III) complexes with highly emission quantum yield (Φ4f–4f = 88%).27 Effective green luminecent Tb(III) coordination polymer would be also required for construction of high-resolution full color display devices. Monochromatic luminescent EL device using Eu(III) coordination polymers are expected to open up frontier field of solid-state physical chemitry and material science.

ASSOCIATED CONTENT Supporting information Available TGA-curves of with [Eu3(ntfa)9(tpcz)2]n and [Eu(ntfa)3(dppcz)]n (Figure S1), EL spectra and J-L-V characteristics of EL devices with [Eu3(ntfa)9(tpcz)2]n (Figure S2), optimized data for mixing ratio and thickness of emitting layer in EL devices (Table S1 and S2). These information are available free of charge via the Internet at http://pubs.acs.org.

ACKNOWLEDGMENT


14

Page 15 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


This work was partly supported by Grants-in-Aid for Scientific Research on Innovative Areas of “New Polymeric Materials Based on Element-Blocks (No. 2401)” (24102012) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.

REFERENCES 1) Review on luminescence behaviors: Blasse, G.; Grabmaier, B. C. Luminescent Materials. SpringerVerlag, New York, 1994. 2) Bünzli, J.-C. G. On the Design of Highly Luminescent Lanthanide Complexes. Coord. Chem. Rev., 2015, 293, 19-47. 3) Binnemans, K. Interpretation of Europium(III) Spectra. Coord. Chem. Rev. 2015, 295, 1-45. 4) Wang, J.; Deng, R.; MacDonald, M. A.; Chen, B.; Yuan, J. Wang, F.; Chi, D.; Hor, T. S. A.; Zhang, P.; Liu, G. et al. Enhancing Multiphoton Upconversion Through Energy Clustering at Sublattice Level. Nat. Mater. 2014, 13, 157–162. 5) Vergeer, P.; Vlugt, T. J. H.; Kox, M. H. F.; den Hertog, M. I.; van der Herden, J. P. J. M.; Meijerink, A. Quantum Cutting by Cooperative Energy Transfer in YbxY1−xPO4:Tb3+. Phys. Rev. B 2005, 71, 014119. 6) Review on EL devices: de Bettencourt-Dias, A. Lanthanide-Based Emitting Materials in LightEmitting Diodes. Dalton Trans. 2007, 2229–2241. 7) Eliseeva, S. V. & Bünzli, J.-C. G. Lanthanide Luminescence for Functional Materials and BioSciences. Chem. Soc. Rev. 2010, 39, 189–227. 8) Bünzli, J.-C. G. & Eliseeva, S. V. Intriguing Aspects of Lanthanide Luminescence. Chem. Sci. 2013, 4, 1939–1949. 9) Parker, D.; Dickins, R. S.; Puschmann, H.; Crossland, C.; Howard, J. A. K. Being Excited by Lanthanide Coordination Complexes: Aqua Species, Chirality, Excited-State Chemistry, and Exchange Dynamics. Chem. Rev. 2002, 102, 1977–2010.


15


Page 16 of 26

10) Xu, H.; Zhu, R.; Zhao, P.; Huang, W. Monochromic Red-Emitting Nonconjugated Copolymers Containing Double-Carrier-Trapping Phosphine Oxide Eu3+ Segments: Toward Bright and Efficient Electroluminescence. J. Phys. Chem. C 2011, 115, 15627–15638. 11) Yang, C. Efficient Monochromatic Red-Light-Emitting PLEDs Based on a Series of Nonconjugated Eu-Polymers Containing a Neutral Terpyridyl Ligand. J. Mater. Chem. 2013, 1, 4885–4901. 12)

Nakamura, K.; Kobayashi, Y.; Kanazawa K.; Kobayashi, N. Thermoswitchable Emission and

Coloration of a Composite Material Containing a Europium(III) Complex and a Fluoran Dye. J. Mater. Chem. C 2013, 1, 617–620. 13) Choi, S.; Kwon, S.; Kim, H.; Kim, W.; Kwon, J.-H.; Lim, M.-S.; Lee, H.-S.; Choi, K.-C. Highly Flexible and Efficient Fabric-Based Organic Light-Emitting Devices for Clothing-Shaped Wearable Displays, Sci. Rep. 2017, 7: 6424. 14) Hasegawa, Y.; Nakanishi, T. Luminescent Lanthanide Coordination Polymers for Photonic Applications, RSC Adv. 2015, 5, 338–353. 15) Miyata, K.; Ohba, T.; Kobayashi, A.; Kato, M.; Nakanishi, T.; Fushimi, K.; Hasegawa, Y. Thermostable Organo-Phosphor: Low-Vibrational Coordination Polymers That Exhibit Different Intermolecular Interactions, ChemPlusChem 2012, 77, 277–280 16) Hirai, Y.; Nakanishi, T.; Kitagawa, Y.; Fushimi, K.; Seki, T.; Ito, H.; Hasegawa, Y. Luminescent

Europium(III) Coordination Zippers Linked with Thiophene-Based Bridges, Angew. Chem. Int. Ed. 2016, 55, 12059–12062. 17)

Nakajima, A.; Nakanishi, T.; Kitagawa, Y.; Seki, T.; Ito, H.; Fushimi K.; Hasegawa, Y. Hyper-

Stable Organo-EuIII Luminophore Under High Temperature for Photo-Industrial Application, Sci. Rep. 2016, 6: 24458. 18) Miyata, K.; Konno, Y.; Nakanishi, T.; Kobayashi, A.; Kato, M.; Fushimi, K. Hasegawa, Y. Chameleon Luminophore for Sensing Temperatures: Control of Metal-to-Metal and Energy Back Transfer in Lanthanide Coordination Polymers, Angew. Chem. Int. Ed. 2013, 52, 6413–6416.


16

Page 17 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


19) Hirai, Y.; Nakanishi, T.; Kitagawa, Y.; Fushimi, K.; Seki, T.; Ito, H.; Hasegawa, Y. Triboluminescence of Lanthanide Coordination Polymers with Face-to-Face Arranged Substituents, Angew. Chem. Int. Ed. 2017, 56, 7171–7175. 20) Hasegawa, Y.; Sugawara, T.; Nakanishi, T.; Kitagawa, Y.; Takada, M.; Niwa, A.; Naito, H.; Fushimi, K. Luminescent Thin Films Composed of Nanosized Europium Coordination Polymers on Glass Electrodes, ChemPlusChem 2016, 81, 187–193. 21) Hasegawa, Y.; Tateno, S.; Yamamoto, M.; Nakanishi, T.; Kitagawa, Seki, T.; Ito, Fushimi, K. Effective Photo- and Triboluminescent Europium(III) Coordination Polymers with Rigid Triangular Spacer Ligands. Chem. Eur. J. 2017, 23, 2666–2672. 22) Hasegawa, Y.; Yamamuro, M.; Wada, Y.; Kanehisa, N.; Kai, Y.; Yanagida, S. Luminescent Polymer Containing the Eu(III) Complex Having Fast Radiation Rate and High Emission Quantum Efficiency, J. Phys. Chem. A 2003, 107, 1697–1702. 23) DAleo, A.; Pointillart, F.; Ouahab, L.; Andraud, C.; Maury, O. Charge Transfer Excited States Sensitization of Lanthanide Emitting from the Visible to the Near-Infra-Red. Coord. Chem. Rev. 2012, 256, 1604–1620. 24) Eliseeva, S. V.; Kotova, O. V.; Gumy, F.; Semenov, S. N.; Kessler, V. G.; Lepnev, L. S.; Bünzli, J. C. G.; Kuzmina, N. P. Role of the Ancillary Ligand N,N-Dimethylaminoethanol in the Sensitization of EuIII and TbIII Luminescence in Dimeric β-Diketonates. J. Phys. Chem. A 2008, 112, 3614–3626. 25) Trivedi, E. R.; Eliseeva, S. V.; Jankolovits, J.; Olmstead, M. M.; Petoud, S.; Pecoraro, V. L. Highly Emitting Near-Infrared Lanthanide “Encapsulated Sandwich” Metallacrown Complexes with Excitation Shifted Toward Lower Energy. J. Am. Chem. Soc. 2014, 136, 1526–1534. 26) Kitagawa, Y.; Ohno, R.; Nakanishi, T.; Fushimi, K.; Hasegawa, Y. Visible Luminescent lanthanide Ions And a Large π-Conjugated Ligand System Shake Hands, Phys. Chem. Chem. Phys. 2016, 18, 31012–31016.


17


Page 18 of 26

27) Yanagisawa, K.; Nakanishi, T.; Kitagawa, Y.; Seki, T.; Akama, T.; Kobayashi, M.; Taketsugu, T.; Ito, H.; Fushimi, K.; Hasegawa, Y. Seven-Coordinate Luminophores: Brilliant Luminescence of Lanthanide Complexes with C3v Geometrical Structures. Eur. J. Inorg. Chem. 2015, 2015, 4769–4774.


18

Page 19 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table 1 Photophysical properties of Eu(III) coordination polymers in solid. τobs a)

Φ4f–4f b)

Φπ–π∗ c)

ηsensd)

kr

knr

/ ms

/%

/%

/%

/ s-1

/ s-1

[Eu3(ntfa)9(tpcz)2]n

0.36

45

17

39

1.2×103

1.5×103

[Eu(ntfa)3(dppcz)]n

0.37

32

27

84

8.6×102

1.8×103

[Eu(hfa)3(dppcz)]ne)

1.1

83

53

64

8.9×102

1.8×102

a) Emission lifetime (τobs) of the Eu(III) coordination polymer were measured by excitation at 355 nm (Nd:YAG 3ω). b) Calculation methods are shown in the experimental section. c) Total emission quantum yield (excitation at 365 nm). d) Photosensitized energy-transfer efficiency ηsens =Φπ–π∗/Φ4f–4f. e) From reference 15.

Table 2 Electroluminescence properties of Eu(III) coordination polymers. Max. luminance /

Max. current

cd m-2

efficiency / cd A-1

60

60

0.42

50

188

0.22

coordination polymer

Film thickness / nm

[Eu3(ntfa)9(tpcz)2]n [Eu(ntfa)3(dppcz)]n

Device structure: ITO glass-electrode/ PEDOT:PSS/ PVK/ Eu(III)coordination polymer, mCP, OXD-7/ Ca/ Al.


19


Page 20 of 26

Figure captions

Figure 1. Chemical structures of a) [Eu3(ntfa)9(tpcz)2]n, b) [Eu(ntfa)3(dppcz)]n and c) [Eu(hfa)3(dppcz)]n. Figure 2. EL Device structure and energy band diagram. Figure 3. a) Emission and excitation spectra for [Eu(ntfa)3(dppcz)]n (red) [Eu3(ntfa)9(tpcz)2]n (black) in solid. Excitation wavelength for emission spectra are at 380 nm. Monitor wavelength for excitation spectra are at 615 nm. b) Emission lifetime profiles of [Eu(ntfa)3(dppcz)]n (red) and [Eu3(ntfa)9(tpcz)2]n (black) in solid. Excitation wavelength are at 355 nm (Nd:YAG: 3ω, fwhm = 5 nm, pulse energy = 0.1 mJ). Figure 4. a) EL spectra of device with [Eu(ntfa)3(dppcz)]n at room temperature. Device structure: ITO glass-electrode/ PEDOT:PSS/ PVK/ emitting layer (Eu(III)coordination polymer, mCP, OXD-7)/ Ca/ Al. Concentration ratios of [Eu(ntfa)3(dppcz)]n in emitting layer (host matrix, mCP: OXD-7= 6: 4): 5w% (blue: 10V), 10w% (red: 10V), and 20w% (black: 11V). The Emission of host matrix at around 450 nm in in emitting layer is also not observed at 20w%. b) J-L-V characteristics of EL device with [Eu(ntfa)3(dppcz)]n (concentration ratio of emitting layer: Eu:mCP:OXD-7 = 20:48:32). Red: Luminances. Blue: current densities. Figure 5. Current efficiencies of EL devices with [Eu(ntfa)3(dppcz)]n (red) and [Eu3(ntfa)9(tpcz)2]n (blue). Device structure: ITO glass-electrode/ PEDOT:PSS/ PVK/ Eu(III)coordination polymer, mCP, OXD-7/ Ca/ Al.


20

Page 21 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


TOC Graphic


21


Page 22 of 26

!"#$%&'(%)%#'*#%+,#-.(/0'#1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

%2

O P !"###

P O

N P O

F 3C

O C

O C

C H

n

3

32

O

O P

!"###

P N F 3C

O C

C H

O C

n

3

42 O

O P

!"###

P N

F 3C

O C

C H

O C

n

CF3

3


Page 23 of 26


N>#O"FIK"P"#IC#"9Q#REK+JI#%

O

O

89#$5&#'()

N N

N N

!"#$%&#'()

./012

*+ ,#(!- ,#./012 -:;#$%

*'IJKH#DJG(#L"M++(#9ILI9

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

%>? %>2

%>B

%>2 !"=89

-:;

(!-

6>B

6>@

5>2 73.

6>% -*0.3 ,-44

*+1 'CD" ./01 2 6>@ A>6

*(EFFEG'#9"HIJ ACS Paragon Plus Environment



Page 24 of 26

Page 25 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60





Page 26 of 26

and Tridentate Carbazole Phosphine Oxides for ... - ACS Publications

Recommend Documents