Synthesis, characterization and luminescent properties of copper(I) halide complexes containing biphenyl bidentate phosphine ligand

Article abstract of DOI:10.1080/00958972.2017.1415432

Copper(I) halide complexes having thermally activated delayed fluorescence (TADF) and phosphorescence have attracted much attention. Here, a series of four-coordinate dinuclear copper(I) halide complexes, [CuX(bpbp)]₂ (bpbp?=?2,2′-bis(diphenylphosphino)biphenyl, X?=?I (1), Br (2) and Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. The structural analysis reveals that two copper(I) centers are bridged by two halogen ligands to form a dinuclear structure with a four-membered Cu₂X₂ ring. These complexes exhibit yellow to blue emission in the solid state at room temperature and have peak emission wavelengths at 575–487?nm with microsecond lifetimes (τ?=?6.2–19.8?μs) and low emission quantum yields (<0.01%). The emissions of 1–3 originate from MLCT, XLCT, and IL (intraligand) transitions. Three complexes displayed good thermal stability.

Full text of DOI:10.1080/00958972.2017.1415432

Journal of Coordination Chemistry
ISSN: 0095-8972 (Print) 1029-0389 (Online) Journal homepage: http://www.tandfonline.com/loi/gcoo20
Synthesis, characterization and luminescent
properties of copper(I) halide complexes
containing biphenyl bidentate phosphine ligand
Bu-Lin Chen, Li Liu, Xin-Xin Zhong, Abdullah M. Asiri, Khalid A. Alamry,
Guang-Hua Li, Fa-bao Li, Nian-Yong Zhu, Wai-Yeung Wong & Hai-Mei Qin
To cite this article: Bu-Lin Chen, Li Liu, Xin-Xin Zhong, Abdullah M. Asiri, Khalid A.
Alamry, Guang-Hua Li, Fa-bao Li, Nian-Yong Zhu, Wai-Yeung Wong & Hai-Mei Qin (2017):
Synthesis, characterization and luminescent properties of copper(I) halide complexes
containing biphenyl bidentate phosphine ligand, Journal of Coordination Chemistry, DOI:
10.1080/00958972.2017.1415432
To link to this article: https://doi.org/10.1080/00958972.2017.1415432
Accepted author version posted online: 10
Dec 2017.
Submit your article to this journal
Article views: 3
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=gcoo20
Download by: [University of New England]
Date: 13 December 2017, At: 05:13

Publisher: Taylor & Francis
Journal: Journal of Coordination Chemistry
DOI: http://doi.org/10.1080/00958972.2017.1415432
Synthesis, characterization and luminescent properties of copper(I) halide
complexes containing biphenyl bidentate phosphine ligand
BU-LIN CHENa, LI LIU*a, XIN-XIN ZHONG*a,b, ABDULLAH M. ASIRIc, KHALID A. ALAMRYc, GUANG-
HUA LI*d, FA-BAO LI*a, NIAN-YONG ZHUe, WAI-YEUNG WONG*e,f and HAI-MEI QINb
aHubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry of Education Key
Laboratory for the Synthesis and Application of Organic Functional Molecules, School of Chemistry and
Chemical Engineering, Hubei University, Wuhan 430062, P. R. China
bState Key Laboratory of Physical Chemistry of Solid Surfaces, and Fujian Provincial Key Lab of Theoretical and
Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University,
Xiamen 361005, P. R. China
cChemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
dState Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University,
Changchun 130012, P. R. China
eInstitute of Molecular Functional Materials and Department of Chemistry, Hong Kong Baptist University,
Waterloo Road, Hong Kong, P. R. China
fDepartment of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University,
Hung Hom, Hong Kong, P. R. China
Copper(I) halide complexes having thermally activated delayed fluorescence (TADF) and
phosphorescence have attracted much attention. Here, a series of four-coordinate dinuclear
copper(I) halide complexes, [CuX(bpbp)]2 (bpbp = 2,2’-bis(diphenylphosphino)biphenyl, X =
I (1), Br (2) and Cl (3)), were synthesized, and their molecular structures and photophysical
*Corresponding authors. Email: liulihubei@hubu.edu.cn; xxzhong@hubu.edu.cn; leegh@jlu.edu.cn;
lfb0615@hubu.edu.cn; wai-yeung.wong@polyu.edu.hk
1

properties were investigated. The structural analysis reveals that two copper(I) centers are
bridged by two halogen ligands to form a dinuclear structure with a four-membered Cu2X2 ring.
These complexes exhibit yellow to blue emission in the solid state at room temperature and have
peak emission wavelengths at 575-487 nm with microsecond lifetimes (τ = 6.2-19.8 μs) and low
emission quantum yields (<0.01%). The emissions of 1-3 originate from MLCT, XLCT and IL
(intraligand) transitions. Three complexes displayed good thermal stability.
Keywords: Neutral; Cu(I) Complexes; Photoluminescence; Synthesis; 2,2'-
Bis(diphenylphosphino)biphenyl
1. Introduction
Since Tang and VanSlyke reported the first OLED, various Ir [1], Pt [2], and Os [3] based
emitters have been investigated with respect to both increasing the quantum efficiency and
allowing for color tuning. As an attractive alternative to expensive, less abundant, and more toxic
heavy metals, electroluminescent materials containing Cu(I)-organic compounds have become
popular over the past decade [4-16]. Cu(I) is the most widely investigated typical d10 metal used
to construct metal-organic complexes with low-lying metal-to-ligand charger transfer (MLCT)
excited states and small singlet-triplet energy gap (ΔE(S1-T1)), thus efficiently harvesting triplet
excitons for thermally activated delayed fluorescence (TADF) emission [17-19].
Cationic Cu(I) complexes based on α,α´-diimine and triphenylphosphine mixed ligands
showing TADF and phosphorescence have become potential candidates for preparing highly
efficient OLEDs [20, 21]. However, unexpected effects on the efficiency of OLED devices may
result from the existence of counter ions in the cationic Cu(I) complexes, especially under high
electrical fields [22, 23].
Photophysical studies of neutral Cu(I) complexes showing TADF have received much
attention [24-28]. Recently, a highly efficient green, three-coordinate Cu(I) halide complex
containing bidentate 1,2-bis(o-ditolylphosphino)benzene with an external quantum efficiency
2

(EQE) over 20% has been reported [27]. Compared to a large number of cationic Cu(I)
compounds, neutral Cu(I) complexes still remain relatively rare. There are only a few reports of
devices fabricated by vacuum deposition containing neutral Cu(I) complexes [11, 27, 29-32].
Neutral Cu(I) halide complexes with bidentate phosphine ligands were rarely reported.
The preparation of neutral Cu(I) complexes using different halides and phosphine ligands
is still a challenge. TADF in copper complexes is still difficult to predict, as it is an excited state
property. As a continuation of our previous work on a series of neutral Cu(I) halide complexes
[33], we report here a series of neutral luminescent four-coordinate dinuclear Cu(I) halide
complexes containing the bidentate ligand 2,2’-bis(diphenylphosphino)biphenyl, and their
molecular structures and photophysical properties were investigated.
2. Experimental
2.1. General methods
All reagents and solvents are of commercial reagent grade and used without purification except
where noted. Copper(I) halides and 1,2-dibromobenzene were purchased from Aladdin Company
and used without purification. Tetrahydrofuran (THF) was distilled under nitrogen in the
presence of sodium chips using benzophenone ketyl as an indicator. Infrared spectra were
recorded on KBr pellets on a Nicolet iS10 FTIR spectrometer. 1H NMR spectra were recorded on
a Varian 600 MHz NMR spectrometer using deuterated solvents as the lock and reference.
Chemical shifts were reported in ppm relative to SiMe4 for the 1H and 85% H3PO4 for the 31P
nucleus. High-resolution mass spectra reported as m/z were obtained on a Bruker Autoflex
MALDI-TOF mass spectrometer. C and H analyses were determined using a Vario Micro Cube
elemental analyzer. The single crystal structures of 1-3 were measured at room temperature using
a Bruker APEX DUO or Bruker D8 Venture diffractometer. UV–vis spectra were recorded on a
Unicam Heλios α spectrometer. Photoluminescence spectra were recorded on a FLS920 steady
state and time-resolved fluorescence spectrometer. Solid-state ΦPL values were determined using
a Hamamatsu system for absolute PL quantum yield measurements equipped with an integrating
3

sphere with Spectralon inner surface coating. The samples were carefully degassed by at least
five freeze-pump-thaw cycles. Thermogravimetric analysis (TGA) was performed on a Perkin-
Elmer Diamond TG/DTA thermal analyzer.
2.2. Syntheses
2.2.1. Synthesis of (2-bromophenyl)diphenylphosphine. This compound was synthesized from
a modification of the literature protocol [34]. A solution of n-BuLi (1.6 M in hexanes, 6.22 mL,
9.95 mmol) was added dropwise over 45 min to a solution of 1,2-dibromobenzene (2.35 g,
9.95 mmol) in Et2O/THF (1/1 v/v, 50 mL) at -110 °C. After 30 min of stirring at the same
temperature, a white precipitate appeared and chlorodiphenylphosphine (2.20 g, 9.95 mmol) was
added dropwise. The mixture was then allowed to warm to room temperature overnight and the
volatile components were removed under vacuum. The residue was taken up into CH2Cl2/Et2O
(1/2 v/v, 15 mL) and filtered through silica which was then washed with CH2Cl2/Et2O (1/2 v/v,
9 mL). The filtrate was evaporated under reduced pressure to give the pure product as a white
solid (2.44 g, 72%). The characterization data were identical to those previously reported in the
literature [35].
2.2.2. Synthesis of 2,2’-bis(diphenylphosphino)biphenyl (bpbp). This compound was
synthesized from a modified protocol of the literature [36]. To a solution of (2-
bromophenyl)diphenylphosphine (0.41 g, 1.20 mmol) in THF (5 mL) was added at -78 °C under
nitrogen n-BuLi (1.6 M in hexane) (0.75 mL, 1.20 mmol) and the resulting solution was stirred at
this temperature during one hour. A solution of Fe(acac)3 (0.51 g, 1.44 mmol) in THF (7 mL)
was then added and the stirring was maintained for one hour at -78 °C. The solution was
quenched with water (2 mL) and extracted with dichloromethane (3×10 mL). The organic phases
were dried over MgSO4 and the solvent evaporated under vacuum to give a residue which was
purified by chromatographic column on silica gel using petroleum ether/dichloromethane (2/1)
4

as eluent. The titled compound was obtained as white solid (0.15 g, 48%). 1H NMR (600 MHz,
CDCl3): δ 7.32-7.13 (m, 24H), 7.07 (d, J = 6 Hz, 2H), 6.90 (d, J = 6 Hz, 2H).
2.2.3. Synthesis of di(μ-iodo)bis[2,2’-bis(diphenylphosphino)biphenyl copper(I)] (1). A
suspension of copper(I) iodide (0.057 g, 0.30 mmol) and bpbp (0.157 g, 0.30 mmol) in 30 mL of
CH2Cl2 was stirred for 5 h at room temperature to form a white precipitate. The precipitate was
filtered off and purified by recrystallization from CH2Cl2/CH3CN to give colorless crystals
(Yield: 0.165 g, 77%). 1H NMR (600 MHz, CDCl3) δ: 8.00-7.99 (m, 8H), 7.46-7.43 (m, 8H),
7.39-7.38 (m, 12H), 7.17 (t, J = 6 Hz, 4H), 7.08 (t, J = 6 Hz, 8H), 6.91 (t, J = 6 Hz, 4H), 6.83
(t, J = 9 Hz, 8H), 6.59 (d, J = 6 Hz, 4H). 31P NMR (240 M, CDCl3) δ: -8.73 (s). Anal. Calcd for
C72H56I2Cu2P4: C, 60.64; H, 3.96. Found: C, 60.71; H, 3.93. MS (MALDI-TOF): m/z calcd for
[C36H28CuP2]+, 586.0996, found: 586.0936.
2.2.4. Synthesis of di(μ-bromo)bis[2,2’-bis(diphenylphosphino)biphenyl copper(I)] (2).
Complex 2 was obtained by a similar method as described for 1 using copper(I) bromide
(0.043 g, 0.30 mmol) in place of copper(I) iodide. Colorless crystals of 2 were obtained (Yield:
0.158 g, 79%). 1H NMR (600 MHz, CDCl3) δ: 7.98-7.91 (m, 8H), 7.54-7.53 (m, 8H), 7.21-7.15
(m, 16H), 7.10 (t, J = 9 Hz, 8H), 6.91 (t, J = 6 Hz, 4H), 6.87-6.84 (m, 4H), 6.81 (t, J = 6 Hz, 4H),
6.53 (d, J = 6 Hz, 4H). 31P NMR (240 M, CDCl3) δ: -11.23 (s). Anal. Calcd for C72H56Br2Cu2P4:
C, 64.92; H, 4.24. Found: C, 64.98; H, 4.20. MS (MALDI-TOF): m/z calcd for [C36H28CuP2]+,
586.0996, found: 586.0949.
2.2.5. Synthesis of di(μ-chloro)bis[2,2’-bis(diphenylphosphino)biphenyl copper(I)] (3).
Complex 3 was obtained by a similar method as described for 1 using copper(I) chloride (0.030
g, 0.30 mmol) in place of copper(I) iodide. Colorless crystals of 3 were obtained (Yield: 0.150 g,
80%). 1H NMR (600 MHz, CDCl3) δ: 7.99 (m, 8H), 7.53 (m, 8H), 7.22-7.10 (m, 24H), 6.89-6.79
(m, 12H), 6.57-6.56 (d, J =6 Hz, 4H). 31P NMR (240 M, CDCl3) δ: -10.20 (s). Anal. Calcd for
5

C72H56Cl2Cu2P4: C, 69.57; H, 4.54. Found: C, 69.63; H, 4.51. MS (MALDI-TOF): m/z calcd for
[C36H28CuP2]+, 586.0996, found: 586.0925.
2.3. X-ray crystallography
Colorless crystals of 1-3 suitable for X-ray diffraction studies were grown by slow evaporation
of their respective solutions in dichloromethane and acetonitrile at room temperature. Geometric
and intensity data were collected using graphite-monochromated Mo Kα radiation (λ =
0.71073 Å) on a Bruker AXS APEX II CCD area detector. The collected frames were processed
with the software SAINT [37], and an absorption correction was applied (SADABS) [38] to the
collected reflections. The structures were solved by direct methods (SHELXTL) [39] in
conjunction with standard difference Fourier techniques and subsequently refined by full-matrix
least-squares analyses on F2. All non-hydrogen atoms were assigned with anisotropic
displacement parameters.
2.4. Theoretical calculations
The structural parameters for 1-3 were obtained from the crystal data which are listed in tables 1
and 2. The density functional theory (DFT) and time-dependent density functional theory
(TDDFT) calculations were then performed to compute the HOMO-LUMO energy gap, the
natural bond orbital (NBO) analysis as well as the properties of the excited states. All the
calculations were manipulated by the Gaussian 09 suite [40] at the B3LYP/DGDZVP level.
3. Results and discussion
3.1. Description of syntheses and structures
The synthetic routes for the Cu(I) complexes are outlined in scheme 1. First, the synthesis of 2-
bromophenyllithium was carried out in a mixture with the mole ratio of 1:1 for 1,2-
dibromobenzene and n-butyllithium. By the addition of chlorodiphenylphosphine to 2-
bromophenyllithium in THF at -110 °C under nitrogen, (2-bromophenyl)diphenylphosphine was
6

synthesized in 72% yield. Then, 2-(diphenylphosphino)phenyllithium was synthesized in a
similar way in a mixture of n-butyllithium and (2-bromophenyl)diphenylphosphine. Under the
catalysis of Fe(III) acetylacetonato, 2,2’-bis(diphenylphosphino)biphenyl (bpbp) was obtained in
46% yield by the homocoupling of (2-bromophenyl)diphenylphosphine. Complexes 1-3 were
prepared in 76-80% yield by mixing a suspension of CuX (X = I for 1, Br for 2, Cl for 3) in
dichloromethane with 1 equiv of bpbp. All the new Cu(I) complexes were obtained as air stable
solids in high purity and found to be generally soluble in CH2Cl2. They all gave satisfactory
analytical data and were characterized by NMR spectroscopy, MALDI-TOF spectrometry and
single crystal X-ray diffraction.
PPh2
Li
PPh2
Br
Br
Br
Li
n-BuLi
Ph2PCl
THF
n-BuLi
THF
THF
Br
Fe(acac)3
THF
Ph
Ph
Ph
Ph
PPh2
PPh2
CuX
CH2Cl2
P
P
P
P
X
X
Cu
Cu
Ph Ph
Ph
Ph
bpbp
1 X=I
2 X=Br
3 X=Cl
Scheme 1. Synthetic pathways to ligand bpbp and their dinuclear copper(I) complexes.
3.2. X-ray crystallographic study
Perspective views of 1-3 are shown in figure 1. There is one solvent CH3CN molecule in the
structure of 1 and one CH2Cl2 molecule in 2. Crystallographic data and selected bond lengths and
angles are given in tables 1 and 2, respectively. The copper(I) in 1-3 exhibits distorted tetrahedral
coordination, with the XCuX angles ranging from 95.01 to 97.60°. Two copper(I) centers are
bridged by two halogen ligands to form a dinuclear structure with a four-membered Cu2X2 ring.
7

Compared with halogen-bridged copper complexes typically having a planar Cu2X2 geometry
[33d, 41-43], 1-3 have approximately planar Cu2X2 geometries. The dihedral angles between two
CuX2 triangles in Cu2X2 are 173.17, 176.36 and 174.83° for 1, 2 and 3, respectively. As listed in
table 2, the Cu–X distances of 1, 2 and 3 elongate with an increase in the van der Waals radius
of X. The Cu···Cu distances are 3.625, 3.404 and 3.149 Å for 1, 2 and 3, respectively, indicating
a weak interaction between two copper atoms, as compared with the sum of van der Waals radius
of copper (2.8 Å). In 1-3, the distances of the halogen to the closest H, H···I, H···Br and H···Cl
are 2.946, 2.851 and 2.591 Å, respectively, displaying potential hydrogen bonds. In solid state, 1-
3 show intermolecular C–H···π interactions between phenyl rings attached to phosphorus with
the closest C-to-H distances of 2.822 Å for 1, 2.843 Å for 2 and 2.634 Å for 3, respectively. The
smallest dihedral angles between XCuX plane and phenyl ring plane of biphenyl is 33.40°
for 1, 35.50° for 2 and 42.20° for 3, respectively.
3.3. Photophysical properties
The absorption spectra of 1-3 and bpbp in CH2Cl2 at room temperature are shown in figure 2.
The absorption spectrum of bpbp exhibits a broad, intense band at 272 nm (ε = 6.69×104 M-1 cm-
1), which is characteristic of an arylphosphine compound. This band is assigned to a mixed
transition of n-π* and π-π*; the former one involves the transition of an electron from the lone
pair orbital on phosphorus to an empty antibonding π* orbital on a phenyl ring or a biphenyl ring
and the latter is the internal transition from a phenyl or a biphenyl ring or the electron transition
from a biphenyl ring to a phenyl ring. Complexes 1-3 have an intense absorption band with a
maximum at 268-275 nm [ε = (2.51-3.01) × 104 M-1 cm-1] and a broad shoulder at 297 nm and a
weaker band tail at 340-400 nm. The weaker band tail may be attributed to the electronic
transition affected by the copper ions, the halide ligands, or both or ligand-to-ligand charge
transfer character.
As shown in figure 3, DFT calculations carried out for 1-3 reveal that the electrons in the
highest occupied molecular orbital (HOMO) are mainly distributed over the copper, halogen
8

atoms and phosphorus atoms, while those in the lowest unoccupied molecular orbital (LUMO)
are localized on the phenyl and biphenyl rings of bpbp. We can thus conclude that the lowest
excited states of 1-3 consist of metal-to-ligand charge transfer (MLCT), a halogen-to-ligand
charge transfer (XLCT) state, and an intraligand transition, analogous to those in related
tetrahedral complexes [11, 44, 45].
The emission spectra of 1-3 in the solid state measured at 298 and 77 K are shown in
figure 4. Summarized in table 3 are the emission maxima, lifetimes and quantum yields of the
complexes at 298 and 77 K, and TDDFT calculation data based on the structures obtained by X-
ray structural analysis. These emission bands are broad and unstructured, suggesting that the
emissive excited states have charge-transfer character. At 293 K, 1-3 show yellow, blue and
green emission with λmax 575, 487 and 535 nm, respectively. The emission maxima and color can
be largely tuned by the halogen, quite different from previously reported neutral Cu(I) halide
phosphine complexes [11, 29, 30, 33]. From the observed long emission decay times between 6.2
and 19.8 μs at 293 K, which is 1 to 3 orders of magnitude shorter than those at 77 K, an
occurrence of a TADF (thermally activated delayed fluorescence) is indicated [46-51].
At 77 K, the emission maxima of 1-3 are located at 472, 528 and 512 nm, respectively.
For 2 and 3, the large Stokes shifts of these lower-lying emission peaks from the dipole-allowed
absorptions, plus the long emission lifetimes (1834-3163 μs), are indicative of their triplet
parentage, and they are thus assigned to the 3(ππ*) excited states (T1S0 emission). For 1, the
emission lifetime is not as long as 2 and 3 (65.6 μs). From the peak height ratio from triplet
emission to singlet emission at 77 K, which is a good parameter to evaluate the relative ISC
efficiency, we can conclude that low ISC efficiency for 1 results in not very long lifetime. Low
ISC efficiency can be attributed to low triplet state energy of 1 (table 3). The small dihedral
angles between X–Cu–X plane and phenyl ring plane of biphenyl may be the reason which
results in better conjugation in 1 that decreases the triplet energy.
Natural bond orbital (NBO) calculations and analysis indicate that the hole/electron pairs
can be used to describe these transitions. The hole is approximately in the HOMO and the
9

electron is approximately in the LUMO. The energy level of singlet and triplet states and
ΔE(S1−T1) of 1-3 are summarized in table 3. The energy gaps between the S1 and T1 levels of 1-
3 are small (0.1180-0.1619 eV), which provide further evidence to show that 1-3 exhibit TADF
[29].
According to the calculated frontier orbitals shown in figure 3, for 1-3, the contribution
from the Cu, halogen, and P to the hole distribution is 24, 31, 34; 39, 25, 17; 22, 26, 26%,
respectively. The electron distribution is mainly confined to the phenyl rings of diphenyl and
phenyl rings in bpbp. These indicate that the luminescence arises from the MLCT, XLCT and
intraligand transitions.
3.4. Thermal properties
Since good thermal stabilities of the complexes are important for OLED applications, the onset
decomposition temperatures (Tdec) of 1-3 were determined by thermogravimetric analysis (TGA)
under a stream of nitrogen. From the onset of the TGA curves (figure 5), all complexes show
good thermal stabilities with their Tdec values ranging from 360 to 367 °C. A sharp one-step
weight loss for all the complexes of ca. 73-84% was observed between 482 and 548 °C, which
can be ascribed to the removal of bpbp. These data render the materials suitable for the
fabrication of OLEDs by using the vacuum thermal deposition method.
4. Conclusion
The first examples of neutral luminescent dinuclear copper(I) halide complexes containing
biphenyl diphosphine bidentate ligand were synthesized and photophysically characterized. The
halogen largely tunes the emission color from yellow to blue in the solid state at room
temperature. Small S1–T1 energy gaps of 1-3 in the solid state indicate that the emission occurred
from a thermally activated excited singlet state at ambient temperature. The low emission
quantum yields (<0.01%) are attributed to the poor, rigid environment around the copper center,
which results in radiationless deactivations. More rigid bidentate diphosphines such as a 1,2-
10

diphosphinoaryl ligand and halogen ligands can be introduced to obtain high efficiency and
color-tunable Cu(I) complex-based luminescent materials in the future.
Acknowledgements
This work was supported by the National Natural Science Foundation of China [grant number
21671061], Natural Science Foundation of Hubei Province of China [grant number
2013CFA087] and Hubei Province High-End Talent Training Program. W.-Y.W. acknowledges
the financial support from the Areas of Excellence Scheme, University Grants Committee of
HKSAR, China (AoE/P-03/08) and the Hong Kong Polytechnic University (1-ZE1C).
References
[1]
(a) L. He, J. Qiao, L. Duan, G. Dong, D. Zhang, L. Wang, Y. Qiu. Adv. Funct. Mater.,
19, 2950 (2009). (b) T. Tsuzuki, S. Tokito. Adv. Mater., 19, 276 (2007). (c) C.H. Yang,
Y.M. Cheng, Y. Chi, C.J. Hsu, F.C. Fang, K.T. Wong, P.T. Chou, C.H. Chang, M.H.
Tsai, C.C. Wu. Angew. Chem. Int. Ed., 46, 2418 (2007). (d) M.S. Lowry, S. Bernhard.
Chem. Eur. J., 12, 7970 (2006). (e) C. Ulbricht, B. Beyer, C. Friebe, A. Winter, U.S.
Schubert. Adv. Mater., 21, 4418 (2009). (f) S. Lamansky, P. Djurovich, D. Murphy, F.
Abdel-Razzaq, R. Kwong, I. Tsyba, M. Bortz, B. Mui, R. Bau, M.E. Thompson. Inorg.
Chem., 40, 1704 (2001). (g) L. Flamigni, A. Barbieri, C. Sabatini, B. Ventura, F.
Barigelletti. Top. Curr. Chem., 281, 143 (2007). (h) H. Yersin, A.F. Rausch, R.
Czerwieniec, in Physics of Organic Semiconductors, W. Bruetting, C. Adachi, R.J.
Holmes (Eds.), Wiley-VCH Weinheim, p. 371 (2012). (i) T. Hofbeck, H. Yersin. Inorg.
Chem., 49, 9290 (2010). (j) K.H. Kim, C. . Moon, J.H. Lee, S.Y. Kim, J.J. Kim. Adv.
Mater., 26, 3844 (2014).
[2]
(a) G.J. Zhou, X.Z. Wang, W.Y. Wong, X.M. Yu, H.S. Kwok, Z. Lin. J. Organomet.
Chem., 692, 3461 (2007). (b) W.Y. Wong, Z. He, S.K. So, K.L. Tong, Z. Lin.
Organometallics, 24, 4079 (2005). (c) C.M. Che, C.C. Kwok, S.W. Lai, A.F. Rausch,
11

W.J. Finkenzeller, N. Zhu, H. Yersin. Chem. Eur. J., 16, 233 (2010). (d) A.F. Rausch, L.
Murphy, J.A.G. Williams, H. Yersin. Inorg. Chem., 51, 312 (2012). (e) J.A.G. Williams.
Top. Curr. Chem., 281, 205 (2007). (f) J.A.G. Williams, S. Develay, D.L. Rochester, L.
Murphy. Coord. Chem. Rev., 252, 2596 (2008). (g) J. Kalinowski, V. Fattori, M. Cocchi,
J.A.G. Williams. Coord. Chem. Rev., 255, 2401 (2011).
[3]
[4]
(a) J.H. Kim, M.S. Liu, A.K.Y. Jen, B. Carlson, L.R. Dalton, C.F. Shu, R. Dodda. Appl.
Phys. Lett., 83, 776 (2003). (b) J. Lu, Y. Tao, Y. Chi, Y. Tung. Synth. Met., 155, 56
(2005). (c) P.T. Chou, Y. Chi. Eur. J. Inorg. Chem., 17, 3319 (2006). (d) J. Breu, C.
Kratzer, H. Yersin. J. Am. Chem. Soc., 122, 2548 (2000).
Y.M. Wang, F. Teng, Y.B. Hou, Z. Xu, Y.S. Wang, W.-F. Fu. Appl. Phys. Lett., 87,
233512 (2005).
[5]
[6]
V. Pawlowski, G. Knör, C. Lennartz, A. Vogler. Eur. J. Inorg. Chem., 15, 3167 (2005).
X. Gong, J.C. Ostrowski, G.C. Bazan, D. Moses, A.J. Heeger. Appl. Phys. Lett., 81, 3711
(2002).
[7]
[8]
L. Maini, D. Braga, P.P. Mazzeo, B. Ventura. Dalton Trans., 41, 531 (2012).
X. Gong, M.R. Robinson, J.C. Ostrowski, D. Moses, G.C. Bazan, A.J. Heeger. Adv.
Mater., 14, 581 (2002).
[9]
S. Welter, K. Brunner, J.W. Hofstraat, L. De Cola. Nature, 421, 54 (2003).
[10] Y.L. Tung, S.W. Lee, Y. Chi, L.S. Chen, C.F. Shu, F.I. Wu, A.J. Carty, P.T. Chou, S.M.
Peng, G.H. Lee. Adv. Mater., 17, 1059 (2005).
[11] A. Tsuboyama, K. Kuge, M. Furugori, S. Okada, M. Hoshino, K. Ueno. Inorg. Chem.,
46, 1992 (2007).
[12] T. McCormick, W.L. Jia, S. Wang. Inorg. Chem., 45, 147 (2006).
[13] W.L. Jia, T. McCormick, Y. Tao, J.P. Lu, S.N. Wang. Inorg. Chem., 44, 5706 (2005).
[14] G. Che, Z. Su, W. Li, B. Chu, M. Li, Z. Hu, Z. Zhang. Appl. Phys. Lett., 89, 103511
(2006).
12

[15] D.G. Cuttell, S.M. Kuang, P.E. Fanwick, D.R. McMillin, R.A. Walton. J. Am. Chem.
Soc., 124, 6 (2002).
[16] S.M. Kuang, D.G. Cuttell, D.R. McMillin, P.E. Fanwick, R.A. Walton. Inorg. Chem., 41,
3313 (2002).
[17] Q. Zhang, Q. Zhou, Y. Cheng, L. Wang, D. Ma, X. Jing, F. Wang. Adv. Mater., 16, 432
(2004).
[18] H. Uoyama, K. Goushi, K. Shizu, H. Nomura, C. Adachi. Nature, 492, 234 (2012).
[19] C. Adachi. Jpn. J. Appl. Phys., 53, 060101 (2014).
[20] N. Armaroli, G. Accorsi, F. Cardinali, A. Listorti. Top. Curr. Chem., 280, 69 (2007).
[21] A. Barbieri, G. Accorsi, N. Armaroli. Chem. Commun., 19, 2185 (2008).
[22] J. Min, Q. Zhang, W. Sun, Y. Cheng, L. Wang. Dalton Trans., 40, 686 (2011).
[23] Y. Tao, K. Yuan, T. Chen, P. Xu, H. Li, R. Chen, C. Zheng, L. Zhang, W. Huang. Adv.
Mater., 26, 7931 (2014).
[24] H.V.R. Dias, H.V.K. Diyabalanage, M.A. Rawashdeh-Omary, M.A. Franzman, M.A.
Omary. J. Am. Chem. Soc., 125, 12072 (2003).
[25] H.V.R. Dias, H.V.K. Diyabalanage, M.G. Eldabaja, O. Elbjeirami, M.A. Rawashdeh-
Omary, M.A. Omary. J. Am. Chem. Soc., 127, 7489 (2005).
[26] S.B. Harkins, J.C. Peters, J. Am. Chem. Soc., 127, 2030 (2005).
[27] J.C. Deaton, S.C. Switalski, D.Y. Kondakov, R.H. Young, T.D. Pawlik, D.J. Giesen, S.B.
Harkins, A.J.M. Miller, S.F. Mickenberg, J.C. Peters. J. Am. Chem. Soc., 132, 9499
(2010).
[28] A.J.M. Miller, J.L. Dempsey, J.C. Peters. Inorg. Chem., 46, 7244 (2007).
[29] M. Hashimoto, S. Igawa, M. Yashima, I. Kawata, M. Hoshino, M. Osawa. J. Am. Chem.
Soc., 133, 10348 (2011).
[30] M. Osawa, M. Hoshino, M. Hashimoto, I. Kawata, S. Igawa, M. Yashima. Dalton Trans.,
44, 8369 (2015).
13

[31] Z. Liu, M.F. Qayyum, C. Wu, M.T. Whited, P.I. Djurovich, K.O. Hodgson, B. Hedman,
E.I. Solomon, M.E. Thompson. J. Am. Chem. Soc., 133, 3700 (2011).
[32] M. Osawa, I. Kawata, R. Ishii, S. Igawa, M. Hashimoto, M. Hoshino. J. Mater. Chem. C,
1, 4375 (2013).
[33] (a) B.L. Chen, L. Liu, X.X. Zhong, A.M. Asiri, K.A. Alamry, F.B. Li, N.Y. Zhu, W.Y.
Wong, H.M. Qin. J. Coord. Chem., 70, 2916 (2017). (b) Q. Li, L. Liu, X.X. Zhong, F.B.
Li, A.M. Asiri, K.A. Alamry, N.Y. Zhu, W.Y. Wong, H.M. Qin. J. Inorg. Organomet.
Poly., 27, S101 (2017). (c) X. Hong, B. Wang, L. Liu, X.X. Zhong, F.B. Li, L. Wang,
W.Y. Wong, H.M. Qin, Y.H. Lo. J. Luminesc., 180, 64 (2016). (d) L. Qi, Q. Li, X. Hong,
L. Liu, X.X. Zhong, Q. Chen, F.B. Li, Q. Liu, H.M. Qin, W.Y. Wong. J. Coord. Chem.,
69, 3692 (2016).
[34] L.N. Duchesneau, N. Lugan, G. Lavigne, A. Labande, V. César. Organometallics, 33,
5085 (2014).
[35] J. Bayardon, H. Laureano, V. Diemer, M. Dutartre, U. Das, Y. Rousselin, J.C. Henry, F.
Colobert, F.R. Leroux, S. Jugé. J. Org. Chem., 77, 5759 (2012).
[36] S. Juge, J. Bayardon, E. Remond, H. Laureano, P-chirogenic organophosphorus
compounds. U.S. Patent No. 9,186,661. 17 Nov. 2015.
[37] SAINT Reference Manual. Siemens Energy and Automation, Madison, WI (1994).
[38] G.M. Sheldrick, SADABS, Empirical Absorption Correction Program, University of
Göttingen, Göttingen, Germany (1997).
[39] G. M. Sheldrick, SHELXTL Reference Manual, Version 5.1, Siemens Energy and
Automation, Madison, WI (1997).
[40] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, G.
Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato, X. Li,
H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M. Hada, M.
Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, T. Vreven, J.A. Montgomery Jr., J.E. Peralta, F. Ogliaro, M. Bearpark, J.J.
14

Heyd, E. Brothers, K.N. Kudin, V.N. Staroverov, R. Kobayashi, J. Normand, K.
Raghavachari, A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J.M.
Millam, M. Klene, J.E. Knox, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R.
Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W.
Ochterski, R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth, P. Salvador, J.J.
Dannenberg, S. Dapprich, A.D. Daniels, O. Farkas, J.B. Foresman, J.V. Ortiz, J.
Cioslowski, D.J. Fox, Gaussian 09, Revision A. 1, Gaussian Inc., Wallingford, CT
(2009).
[41] H. Araki, K. Tsuge, Y. Sasaki, S. Ishizaka, N. Kitamura. Inorg. Chem., 44, 9667 (2005).
[42] P. Aslanidis, P.J. Cox, S. Divanidis, A.C. Tsipis. Inorg. Chem., 41, 6875 (2002).
[43] M. Henary, J.L. Wootton, S.I. Khan, J.I. Zink. Inorg. Chem., 36, 796 (1997).
[44] C. Kutal. Coord. Chem. Rev., 99, 213 (1990).
[45] H. Kunkely, V. Pawlowski, A. Vogler. Inorg. Chem. Commun., 11, 1003 (2008).
[46] M.J. Leitl, F.R. Küchle, H.A. Mayer, L. Wesemann, H. Yersin. J. Phys. Chem. A, 117,
11823 (2013).
[47] C.A. Parker, in: Advances in Photochemistry, Vol. 2, W.A. Noyes Jr., G.S. Hammond,
J.N. Pitts Jr. (Eds.), John Wiley & Sons Inc., New York, p. 305 (1964).
[48] G. Blasse, D.R. McMillin. Chem. Phys. Lett., 70, 1 (1980).
[49] D. Felder, J.F. Nierengarten, F. Barigelletti, B. Ventura, N. Armaroli. J. Am. Chem. Soc.,
123, 6291 (2001).
[50] H. Kunkely, V. Pawlowski, A. Vogler. Inorg. Chem. Commu., 11, 1003 (2008).
[51] H. Yersin, A.F. Rausch, R. Czerwieniec, In Physics of Organic Semiconductors, W.
Bruetting, C. Adachi, R.J. Holmes (Eds.), p. 371, Wiley-VCH Weinheim (2012).
15

16

17

18

19

20

21

Table 1. Crystallographic data and refinement details for 1-3.
1 • CH3CN
2 • CH2Cl2
3
C72H56Cu2I2P4•CH3CN C72H56Cu2Br2P4•CH2Cl2
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
C72H56Cl2Cu2P4
1243.03
1508.11
299(2)
1416.87
298(2)
293(2)
0.71073
Orthorhombic
Pna2(1)
18.1760(12)
17.1223(11)
20.7707(13)
6464.2(7)
4
0.71073
0.71073
Orthorhombic
Pna2(1)
Orthorhombic
Pna2(1)
17.9538(9)
17.0019(9)
20.8190(9)
6354.9(7)
4
17.914(4)
15.702(3)
22.472(5)
6321.0(5)
4
b (Å)
c (Å)
V (Å3)
Z
ρ (g cm-3)
µ (mm-1)
1.507
1.481
1.306
1.755
2.155
0.900
F (0 0 0)
2936
2872
2560
θ range for data collection (°) 2.807 to 28.305
2.47 to 27.57
23 ≤ h ≤ 23
22 ≤ k ≤ 22
26 ≤ l ≤ 27
3.01 to 27.45
23 ≤ h ≤ 23
20 ≤ k ≤ 20
29 ≤ l ≤ 28
Index ranges
24 ≤ h ≤ 24
21 ≤ k ≤ 22
27 ≤ l ≤ 23
Independent reflections
15064 [R(int) = 0.0874] 14585 [R(int) = 0.0850]
14162 [R(int) =
0.0395]
Completeness to θ = 25.242°
Max. and min. transmission
Gof
99.8%
99.7 %
99.6 %
0.7457 and 0.6567
1.013
0.9188 and 0.6977
1.006
0.8014 and 0.7473
1.038
Final R indices [I > 2σ(I)]
R1 = 0.0531
wR2 = 0.0724
R1 = 0.1190
wR2 = 0.0891
0.919 and 1.091
R1 = 0.0519
wR2 = 0.0737
R1 = 0.1213
wR2 = 0.0883
0.357 and 0.447
R1 = 0.0433
wR2 = 0.1156
R1 = 0.0538
wR2 = 0.1218
0.988 and 0.509
R (all data)
Max/min (e Å3)
22

Table 2. Selected bond lengths (Å) and angles (°) for 1-3.
1 • CH3CN
2 • CH2Cl2
Complex
3
2.7197(12), 2.7229(11)
2.6846(10), 2.6658(11)
2.292(3), 2.289(2)
2.278(2), 2.272(2)
3.625(1)
2.5118(8), 2.5308(7)
2.5176(7), 2.5310(8)
2.2689(13), 2.2706(12)
2.2830(12), 2.2757(13)
3.4041(7)
2.3791(9), 2.4022(10)
2.3757(9), 2.3770(10)
2.2600(10), 2.2598(10)
2.2668(10), 2.2615(10)
3.1490(7)
CuX
CuP
Cu…Cu
PCuP
XCuX
CuXCu
PCuX
101.25(9), 101.26(9)
95.58(4), 95.22(3)
85.30(4), 83.53(3)
109.36(6), 115.72(7)
108.77(7), 126.11(7)
113.44(7), 114.18(7)
109.29(7), 123.61(7)
100.62(5), 101.01(5)
95.17(2), 95.01(2)
85.19(2), 85.19(2)
112.43(4), 115.09(4)
110.13(4), 123.86(4)
111.06(4), 115.21(4)
108.59(4), 125.94(4)
105.29(4), 105.15(4)
96.82(3), 97.60(3)
82.95(3), 82.43(3)
112.04(4), 115.58(4)
115.13(4), 112.30(4)
114.22(4), 111.48(4)
114.62(4), 114.02(4)
23

Table 3. Photophysical data of 1-3 in the solid state.
λmax (nm)a
τ (μs)b
Фc
S1 (eV)d T1 (eV)d ΔE(S1-T1)d (eV)
293 K
77 K
293 K 77 K 293 K
1
436*, 472*,
575
472, 487*,
577*
7.9
65.6
< 0.01%
3.2148 3.0968 0.1180
2
3
487
535
528
512
6.2
3163 < 0.01%
1834 < 0.01%
3.2563 3.1276 0.1287
3.3613 3.1994 0.1619
19.8
a Emission peak wavelength. Asterisks indicate emission peaks appear as shoulders or weak bands.
b Emission lifetime. Experimental errors are ± 5%.
c Absolute emission quantum in the solid state. Experimental errors are ± 5%.
d Calculated results (S1 and T1 energy levels, and energy gap between S1 and T1) obtained using structures determined
by the X-ray analysis.
24

25