Mononuclear Copper(I) complexes based on phenanthroline derivatives P^N^N^P tetradentate ligands: Syntheses, crystal structure, photochemical properties

Article abstract of DOI:10.1016/j.dyepig.2019.108000

Two novel heteroleptic Cu(I) complexes with the single tetradentate ligands have been designed and synthesized from phenanthroline. The complexes having one copper structure were fully characterized by NMR, ESI-MS and the single-crystal X-ray structures. Their photoelectric chemical properties were investigated by using cyclic voltammetry, UV/vis and fluorescence spectroscopy. Compared with the classic Cu(P^P)(N^N) complexes, this distorted tetrahedral coordination structure of Cu(P^N^N^P) complexes showed a wider excitation wavelength and a red-shifted about 100 nm emission peak, due to the link function between phenanthroline and phosphorus ligands. Moreover, the copper complex B having the naphthyl link groups displayed high red-emissive photoluminescence quantum efficiency (PLQY), which was up to 3.8%.

Full text of DOI:10.1016/j.dyepig.2019.108000

Journal Pre-proof
Mononuclear Copper(I) complexes based on phenanthroline derivatives P^N^N^P
tetradentate ligands: Syntheses, crystal structure, photochemical properties
Hao Chen, Liang-Xuan Xu, Li-Juan Yan, Xue-Fen Liu, Dan-Dan Xu, Xiao-Cong Yu,
Jin-Xuan Fan, Qing-An Wu, Shu-Ping Luo
PII:
S0143-7208(19)31998-9
DOI:
https://doi.org/10.1016/j.dyepig.2019.108000
DYPI 108000
Reference:
To appear in: Dyes and Pigments
Received Date: 24 August 2019
Revised Date: 18 October 2019
Accepted Date: 26 October 2019
Please cite this article as: Chen H, Xu L-X, Yan L-J, Liu X-F, Xu D-D, Yu X-C, Fan J-X, Wu Q-A, Luo
S-P, Mononuclear Copper(I) complexes based on phenanthroline derivatives P^N^N^P tetradentate
ligands: Syntheses, crystal structure, photochemical properties, Dyes and Pigments (2019), doi: https://
doi.org/10.1016/j.dyepig.2019.108000.
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2019 Published by Elsevier Ltd.

Mononuclear Copper(I) Complexes Based on Phenanthroline derivatives
P^N^N^P Tetradentate Ligands: Syntheses, Crystal Structure, Photochemical
Properties
a
a
b
c
a
a
Hao Chen , Liang-Xuan Xu , Li-Juan Yan , Xue-Fen Liu , Dan-Dan Xu Xiao-Cong Yu ,
a
a
a
Jin-Xuan Fan , Qing-An Wu , Shu-Ping Luo ,*
a
State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of
Technology.310014, Hangzhou (China)
b
College of Electronics & Information Engineering, Guangdong Ocean University, 524088, Zhanjiang (China)
c
Qiangjiang College, Hangzhou Normal University, 310012 Hangzhou (China)
The novel heteroleptic Cu(I) complexes with the tetradentate phenanthroline-based P^N^N^P-type
ligands have been prepared and studied.

Mononuclear Copper(I) Complexes Based on Phenanthroline derivatives
P^N^N^P Tetradentate Ligands: Syntheses, Crystal Structure, Photochemical
Properties
a
a
b
c
a
a
Hao Chen , Liang-Xuan Xu , Li-Juan Yan , Xue-Fen Liu , Dan-Dan Xu Xiao-Cong Yu ,
a
a
a
Jin-Xuan Fan , Qing-An Wu and Shu-Ping Luo ,*
a
State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of
Technology.310014, Hangzhou (China)
b
College of Electronics & Information Engineering, Guangdong Ocean University, 524088, Zhanjiang (China)
c
Qiangjiang College, Hangzhou Normal University, 310012 Hangzhou (China)
Abstract: Two novel heteroleptic Cu(I) complexes with the single tetradentate ligands have been
designed and synthesized from phenanthroline. The complexes having one copper structure were
fully characterized by NMR, ESI-MS and the single-crystal X-ray structures. Their photoelectric
chemical properties were investigated by using cyclic voltammetry, UV/vis and fluorescence
spectroscopy. Compared with the classic Cu(P^P)(N^N) complexes, this distorted tetrahedral
coordination structure of Cu(P^N^N^P) complexes showed a wider excitation wavelength and a
red-shifted about 100 nm emission peak, due to the link function between phenanthroline and
phosphorus ligands. Moreover, the copper complex B having the naphthyl link groups displayed
high red-emissive photoluminescence quantum efficiency (PLQY), which was up to 3.8%.
Keywords: heteroleptic Cu(I) complexes, tetradentate ligand, phenanthroline.
Introduction
The metal complexes consisted of diverse ligands have various performance requirements,
1
2, 3
4
5, 6
such as Ru , Ir , Ni , Cu , which are considered as active components in organic light emitting
7
, 8
9, 10
11
diodes (OLEDs) , as photosensitizers
in solar-energy conversion system, as photocatalysts
1
2
and photoinitiators in the photocatalytic reactions, etc. The first row transition metal compounds
are noticeable because of the price and abundance in the world. In addition, they are less toxic and
more easily available than the currently used second and third row noble metal complexes which
are expensive, toxic and difficult to obtain. Above all, Cu(I) complexes exhibit an electron
1
0
13-16
arrangement with a d structure and a relatively large number of coordination mode.
Considering the characteristic combination of chemical stabilities, redox properties, luminescence
emission and excited state lifetime, most of the work on Cu(I) complexes with phenanthroline and
1
7-19
P-donor ligands have attracted considerable attention scaffold.
0-phenanthroline, its structural unit is rigid, and could offer two aromatic nitrogens whose
unshared electron pairs were perfectly placed to act cooperatively in chelating transition metal
As an important ligand, 1,
1
1
0
cations. Interestingly, phosphorus ligands could effectively stabilize Cu(I)-d metal centers owing
2
0
to the soft nature of the P-donor atoms. These heteroleptic Cu(I) complexes showed excellent
photophysical properties and high photocalalytic activities in solar-energy conversion system.
Recently, scientists have committed to design and synthesize complicated N^P mono- or
multi-nuclear Cu(I) complexes with a specific function. In 2018, Ishitani’s group reported a
2
1
dinuclear Cu(I) complexes based on phenanthroline ligands (Scheme 1) and Mn-catalysts in
photocatalytic systems for CO reduction. And just this year, Sauvage’s group also reported a
2
series of heteroleptic copper(I) complexes constructed from macrocyclic with different ring sizes
2
2
I
+
and bis-phosphines (Scheme 1). Compared to analogous [Cu (P^P)(N^N)] built from acyclic
NN ligands, a high stability and PLQY have been demonstrated for the systems incorporating
macrocyclic phenanthrolines through photophysical properties.

Our interest in designing new P^N^N^P-type ligands and studying the photo- and
electro-chemistry behavior of mononuclear Cu(I) complexes based on the single tetradentate
phenanthroline ligands has produced from the previous studies (Scheme 2). In this context, two
novel Cu(I) complexes A and B with the tetradentate phenanthroline ligands successfully prepared
by a six-step reaction. Their structures were determined by X-ray diffraction analysis. Next, the
photophysical and electrochemical properties as well as the density functional theory (DFT) study
of these Cu(I) complexes were also probed.
Scheme 1 The chemical structures of the Cu(I) complexes.
Scheme 2 The structural design of the Cu(I) complexes.
Results and discussion
Syntheses
The detailed syntheses routes of the complexes A and B were presented in Fig.1. As shown in Fig.
1
, the two new complexes A and B composed of a unique ligand structure unit were designed and
2
3
obtained under the six typical reactions:(1) palladium-catalyzed synthesis of phenylboronate ; (2)
2
4
25
26
NBS-bromination ; (3) P-nucleophilic substitution reaction ; (4) Suzuki-reaction ; (5) and (6)
2
7
reduction reaction and in situ reaction. In the third-step reaction, the original P-reagent we used
was diphenylphosphine. Later, we replaced it with diphenylphosphine oxide because of the
oxidation properties of the P atom in the air, which could make manipulations easier. In the end,
phosphine oxides had to be reduction and then coordinated with Cu(I) ion using in situ method.

Fig. 1 Illustration for the syntheses of the Cu(I) complexes A (solid) and B (dash). Reagents and conditions:
(
1) PdCl (dppf), KOAc, dioxane, reflux (2) NBS, AIBN, CH CN, reflux (3) diphenylphosphine oxide, NaH, THF,
2
3
rt (4) 2,9- dibromo - 4,7-diphenyl-1,10-phenanthroline, Pd(PPh ) , K CO , C H CH , CH CH OH, H O, reflux (5)
3
4
2
3
6
5
3
3
2
2
i
Ti(O Pr) , HSi(OC H ) , C H CH , reflux (6) Cu(CH CN) PF , DCM, rt.
4
2
5 3
6
5
3
3
4
6
Structural characterization
The mononuclear Cu(I) complexes A and B were elucidated in the solid state by the single-crystal
X-ray diffraction analysis (Fig. 2 and Table S1†). Their crystal structures revealed a big distorted
tetrahedral geometry around the copper center (plane angle: 74.3 for A and 75.3 for B), which was
I
+
28
consistent with previous research of complex C ([Cu (xantphos)(bcp)] (bcp = bathocuproine)) .
The distortion developed mainly from the considerable differences in the bite-angles of the P-Cu-P
(for complex A in Table 1: P(1)-Cu(1)-P(2) 130.23(7)°) compared to that of xantphos in complex
C (P(1)-Cu(1)-P(2) 119.48(4)°) and also from intramolecular ligand interactions. Owing to the
limitations of the single phenanthroline-based P^N^N^P ligand, the two compounds exhibited
similar Cu-N, Cu-P bond lengths, the values of the bite-angles of N-Cu-N and P-Cu-P. All results
implied a reactively small effect of phenyl or nathphyl substituents in complexes A and B onto
photophysical properties that were also in agreement with the electronic characteristics (see
below).
Table 1 Selected crystallographic bond lengths and angles of complexes A and B. For more detailed information
see the supporting information.
Complex A
Complex B
Bond lengths, Å
Cu(1)-N(1)
2.044(6)
2.062(6)
2.2225(17)
2.218(2)
2.052(5)
2.085(5)
2.248(2)
2.239(2)
Cu(1)-N(2)
Cu(1)-P(1)
Cu(1)-P(2)
Bond angles,°
N(1)-Cu(1)-N(2)
N(1)-Cu(1)-P(1)
N(1)-Cu(1)-P(2)
N(2)-Cu(1)-P(2)
N(2)-Cu(1)-P(1)
81.5(2)
80.1(2)
97.90(14)
120.35(16)
100.26(15)
116.94(15)
100.52(15)
111.70(16)
97.20(15)
124.78(16)

P(1)-Cu(1)-P(2)
plane angle
130.23(7)
130.95(8)
[
a]
[a]
74.3
75.3
[a] Calculated angle between the NN ligands and PP ligands.
Fig. 2 Solid-state molecular structures (ORTEP) of complexes A (left) and B (right) with thermal ellipsoids set at a
probability level of 50%. Hydrogen atoms, counter anions and solvent molecules have been omitted for clarity.
Photophysical and electrochemical properties
The photophysical investigation was measured in THF and the data were given in Table 2. As can
be seen from the Fig. 3, the absorption and fluorescence spectra of A and B were essentially
identical, which were determined by the structure of the complexes. The as-synthesized
tetradentate Cu(I) complexes presented very strong absorption at about 300 nm, which was clearly
ascribed to the ligand-centered π-π* intraligand charge transfer (ILCT) located on
2
9, 30
phenanthroline
(L-A-4 and L-B-4). In particular, the absorption peaks at around 350nm were
observed in the spectra of complex B and the L-B-4 because of the connections between the
naphthyl link groups and phenanthroline (ILCT). Furthermore, the slight broad shoulder
absorption at 425 nm of the complexes A and B were observed, corresponded to metal-to-ligand
3
1
charge-transfer (MLCT) transition which was feature absorption peak . The fluorescence spectra
of L-A-4 and L-B-4 were at 430nm, while the fluorescence spectra of A and B showed clearly red
shift because of MLCT in Fig 3. Furthermore, compared with the classic Cu(P^P)(N^N)
2
8
complexes (λ =520-570 nm) , they also showed a red-shifted about 100 nm emission peak. This
em
might be explained by a more distorted structure in A and B with π-π-interaction between one
phenyl or one nathphyl ring and phenanthroline ring of ligands. The excited state lifetime (τ) (Fig.
S1 and S2) and the quantum yield (PLQY) of the complexes were also calculated in Table 2. The
copper complex B having the naphthyl link groups displayed higher quantum efficiency than the
3
2
complex A having the phenyl link groups and complex C (3.1 %) because of a more strong
interactions in B. More importantly, the photostability tests of these complexes were also
measured. The results manifested that the photostability of the complexes A and B were better
than complex C in THF solution (Fig. S3). Later, upon cyclic voltammetry, the two complexes
presented a comparable electrochemical behavior with the two reversible reduction waves
+
+
+
(
Complex A at -2.04 V vs. Fc/Fc and -1.65 V vs. Fc/Fc ; Complex B at -2.01 V vs. Fc/Fc and
+
-
1.65 V vs. Fc/Fc ) and three irreversible oxidation processes in acetonitrile solution (Fig. 4),
3
3
which was resemble to this type of compounds . The reversible reduction waves of A and B were
at around -2.00 V and -1.65 V, ascribed to the one-electron reduction of the diimine ligand and the

cationic copper, whereas the oxidation of both complexes occurred about 1.17-1.64 V.
Table 2 Photophysical and electrochemical properties of Cu(I) complexes.
[a]
[a]
Absorption
Complex λmax
nm)
425
Emission
[
b]
[b]
[c]
Entry
1
ɛ
λmax
Eox
(V)
Ered
(V)
PLQY
(%)
τ
-1
-1
(
(M cm ) (nm)
(ns)
88.6
A
2857
637
+1.17 -2.04 2.9
+
+
1.39
1.64
2
B
428
3142
627
+1.19 -2.01 3.8
86.9
+
+
1.40
1.57
[
a] Absorption and emission spectra were measured in THF solution at room temperature. [b] Eletrochemical
+
measurement was performed at oxygen free condition in acetonitrile vs. Fc/Fc and the redox events
were not reversible. [c] Measured with respect to quinine sulfate (1 N, H SO ) as standard (PLQY= 0.546).
2
4
Fig. 3 UV-visible absorption and photoluminescence spectra of L-A-4, L-B-4, A and B in THF at room
temperature.
Fig. 4 Cyclic voltammograms of A, B in CH CN solution, containing 0.1M Bu NPF as a supporting electrolyte
3
4
6
-
1
under a scam rate of 100 mV
·s .
Theoretical calculation
Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations of complexes A and B
simplified P-ligands to decrease complexity) were undertaken (Table S2 and S3). Through the
DFT/TD-DFT calculations, the above spectral viewpoints were supported. Molecular orbitals
(

involving the distribution of HOMO and LUMO in the MLCT transition were calculated. The
spatial plots of the highest occupied molecular orbital (HOMO) and the lowest unoccupied
molecular orbital (LUMO) for complexes A and B were represented in Fig. 6 and they were in
6
consonance with previous reports on bidentate NP Cu(I) complexes . The HOMO and LUMO
were apparently parted, suggesting intramolecular charge separation interactions between the
separated fragments in the complexes. For complexes A and B, the electron density of the HOMO
was found to be mainly distributed to the copper moiety (A-58%, B-62%) and the LUMO had
main contributions from the phenanthroline moiety (A-96%, B-92%). In terms of the MLCT
I
transition, it was reported that the tetrahedral spatial configuration of the Cu complex was
I
II
distorted upon transition because Cu was oxidized to Cu , which favored square planar geometry.
Normally, such molecular distortion going along with the electronic transition on levels triggered
32
the non-radiative deactivation pathway to lower the PLQY and curtail the PL lifetime . The
results verified the above tests that were unobtrusive values of the PLQY and PL lifetime.
Fig. 5 Molecular orbital contour diagrams of complexes A and B.
Conclusion
In this work, both heteroleptic Cu(I) complexes A and B containing a tetradentate
phenanthroline-based P^N^N^P-type ligands were firstly synthesized. The structures of the new
complexes were confirmed by the single-crystal X-ray diffraction. Also, their photophysical and
electrochemical properties were investigated. Compared with the typical Cu(P^P)(N^N)
complexes, the results showed that they had the broad metal-to-ligand charge-transfer (MLCT)
transition and a red-shifted about emission peak. Moreover, the copper complex B having the
naphthyl link groups displayed higher quantum efficiency than the complex A having the phenyl
link groups, which was up to 3.8%. These not only provided new ideas for the design of copper
complexes, but also contributed to discover potentially application in the electro-optic field.
Experimental section
Syntheses

All reactions and operations involving air or moisture sensitive compounds were carried out under
dry nitrogen. All commercially available chemicals were purchased and used without further
purification from Energy Chem. Anhydrous THF, toluene were freshly distilled through Na and
benzophenone. Anhydrous DMF was freshly distilled over calcium hydride. Reactions were
monitored by thin layer chromatography (TLC) and column chromatography
purifications were carried out using silica gel (200-300 mesh).
4
,4,5,5-tetramethyl-2-(o-tolyl)-1,3,2-dioxaborolane (A-1)
1
-bromo-2-methylbenzene (1.71 g, 10 mmol), bis(pinacolato)diboron (5.08 g, 20 mmol), KOAc
(
5.89 g, 60 mmol) and PdCl (dppf) (366 mg, 0.5 mmol) were dissolved in DMF (100 mL) under
2
argon atmosphere. The reaction mixture was stirred at 85℃ for 48 hours and cooled to room
temperature. Then, water (500 mL) was added and extracted with ethyl acetate (3 × 100 mL). The
organic layer was washed with brine, dried with anhydrous sodium sulfate and evaporated under
reduced pressure to yield a crude reaction product which was purified through column
1
chromatography (petroleum ether) to provide A-1 (1.2 g, 55%). H NMR (500 MHz, CDCl ) δ 7.77
3
(
dd, J = 7.7, 1.6 Hz, 1H), 7.29 (m, 1H), 7.14 (m, 2H), 2.54 (s, 3H), 1.32 (s, 12H). The NMR spectra
3
4
were consistent with literature values.
2
-(2-(Bromomethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (A-2)
The A-1 (2.18 g, 10 mmol),N-bromosuccinimide (1.96 g, 11 mmol), azobisisobutylonitrile (16 mg,
mol %), and acetonitrile (50 mL) were refluxed at 90°C for 2 h under nitrogen and then allowed
1
to cool to room temperature. The mixture was condensed under reduced pressure until a solid
began to form. The solid was filtered, and the filtrate was condensed further. The crude product
was then purified using flash chromatography on silica gel (with petroleum ether as eluent) to
1
yield compound A-2 as a white solid ( 2.73 g, 92 %). H NMR (500 MHz, CDCl ) δ 7.84 – 7.79
3
1
3
(
m, 1H), 7.43 – 7.36 (m, 2H), 7.28 (m, 1H), 4.92 (s, 2H), 1.37 (s, 12H). C NMR (125 MHz,
CDCl ) δ 144.24, 136.39, 131.29, 130.05, 127.59, 83.85, 33.92, 24.86. The NMR spectra were
3
3
5
consistent with literature values.
Diphenyl(2-(4,4,5,5,-tetramethyl-1,3,2-dioxaboralan-2-yl)benzyl)phosphine oxide (A-3).
Sodium hydride (60%) (0.16 g, 4 mmol) was dissolved in DMF (10 mL) and cooled to 0 °C before
diphenylphosphine oxide (0.41 g, 2 mmol) was added. The mixture was stirred at this temperature
for 2 h and then A-2 (0.59 g, 2 mmol) in soln in anhyd DMF (3 mL) was added dropwise to the
white mixture at room temperature. After completion of the reaction (TLC), adding a few drops
saturated ammonium chloride aqueous solution slowly at 0 °C, the reaction was considered to be
complete when the generation of more gas was no longer observed. The mixture was washed by
water, and the crude product was extracted with dichloromethane (3 x 30 mL). The combined
organic fractions were dried with anhydrous magnesium sulfate, followed by filtration and
removal of the solvent in vacuo. Then the concentrated mixture was directly purified by silica-gel
column chromatography using ethyl acetate/hexane as eluent in increasing polarity to yield a
1
colorless solid (0.66, 79 % yield). H NMR (500 MHz, CDCl ) δ 7.77 – 7.72 (m, 1H), 7.67 (m,
3
4
1
1
1
2
H), 7.50 – 7.44 (m, 2H), 7.42 – 7.28 (m, 6H), 7.19 (tt, J = 7.4, 1.5 Hz, 1H), 4.21 (s, 1H), 4.18 (s,
1
3
H), 1.27 (s, 12H). C NMR (125 MHz, CDCl ) δ 138.07 (d, J =8.7 Hz), 136.38 (d, J =2.5 Hz),
3
P
P
32.62 (d, J =97.5 Hz), 131.47(d, J =2.5 Hz), 131.39 (d, J =8.7 Hz), 130.95 (d, J =2.5 Hz),
P
P
P
P
30.57 (d, J =5 Hz), 128.17(d, J =11.2 Hz), 125.97 (d, J =2.5 Hz), 83.61, 37.06 (d, J =65 Hz),
P
P
P
P
31
+
4.94. P NMR (500 MHz, CDCl ) δ 30.68. ESI-MS: [M+H] =419.20.
3
(((4,7-diphenyl-1,10-phenanthroline-2,9-diyl)bis(2,1 phenylene) bis (methylene) bis

(diphenylphosphine oxide) (A-4).
To a round-bottom schlenk flask (10 ml) equipped with a condenser was added the degassed
solution (VC6H5CH3/VCH3CH2OH/VH2O=1/1/1, 9 ml) of Na CO (0.848 g, 8 mmol), Pd(PPh ) (58 mg,
2
3
3 4
0
.05 mmol), A-3 (1.82 g, 2 mmol) and 2,9-dibromo-4,7-diphenyl-1,10-phenanthroline (0.48 g, 1
mmol). After 12 h under reflux, the reaction mixture was cooled to room temperature, during
which process, a precipitate appeared. The crude mixture was purified by silica-gel column
chromatography (petroleum ether/ ethyl acetate 1:1) to yield a yellow solid A-4 (0.69 g, 76 %
1
yield). H NMR (500 MHz, CDCl ) δ 7.84 (s, 1H), 7.74 (m, 2H), 7.62 – 7.56 (m, 2H), 7.57 – 7.50
3
1
3
(
m, 5H), 7.37 (s, 4H), 7.27 (s, 1H), 7.03 (t, J = 7.6 Hz, 2H), 6.61 (m, 4H). C NMR (125 MHz,
CDCl ) δ 158.46, 148.93, 145.29, 138.14 (d, J =5), 137.90, 134.91(d, J =5), 132.60 (d, J =97.5
3
P
P
P
Hz), 131.20 (d, J =8.7 Hz), 131.12(d, J =2.5 Hz), 130.85, 130.78, 129.64, 129.46 (d, J =2.5 Hz),
P
P
P
1
28.71, 128.62, 127.55 (d, J =11.2 Hz), 127.43 (d, J =2.5 Hz), 125.07, 123.57 (d, J =15 Hz),
P P P
3
1
1
23.63, 123.51, 34.13 (d, J =62.5 Hz). P NMR (500 MHz, CDCl ) δ 28.46. ESI-MS:
P
3
+
[M+H] =913.30.
The complex A.
To a mixture of A-4 (182 mg, 0.20 mmol), titanium isopropoxide (34 mg, 0.12 mmol) and
triethoxy silane (77 mg, 1.2 mmol) were added 5 mL of anhydrous benzene under nitrogen. The
pale brown slurry was heated to reflux, and the solid dissolved and the solution turned gray–green
0
.5 h later. The reaction was stopped, cooled to rt and the solvent was removed by cold hydrazine
to give a brown solid. Then the degassed dichloromethane (10 mL) and Cu(CH CN) PF (74 mg,
3
4
6
0
.20 mmol) were added. The mixture was stirred for 12 h at room temperature. Subsequently, the
reaction mixture was evaporated to dryness and the crude material was purified by column
1
chromatography using dichloromethane as eluent to afford a yellow solid (82 mg, 38 % yield). H
NMR (500 MHz, CDCl ) δ 8.21 (s, 1H), 7.94 (s, 1H), 7.69 – 7.57 (m, 5H), 7.36 – 7.27 (m, 4H),
3
7
6
.23 (t, J = 7.4 Hz, 1H), 7.09 (t, J = 7.5 Hz, 2H), 7.02 (t, J = 7.5 Hz, 2H), 6.95 (d, J = 7.6 Hz, 1H),
1
3
.90 (q, J = 6.2 Hz, 2H), 6.80 – 6.75 (m, 2H), 3.76 (m, 1H), 3.05 (d, J = 13.2 Hz, 1H). C NMR
(
125 MHz, CDCl ) δ 159.47, 151.55, 143.09, 139.57, 136.00, 134.30, 133.77 (t, J =7.5, 8.7 Hz),
3
P
1
1
1
33.30, 133.18, 131.50, 131.01 (t, J =7.5, 7.5 Hz), 130.67 (d, J =7.5, 8.7 Hz), 130.06, 129.78,
P P
29.42, 129.21, 128.64 (t, J =5.0, 5.0 Hz), 128.32 (t, J =3.7, 5.0 Hz), 127.05 (d, J =95 Hz),
P
P
P
3
1
26.51, 125.18, 77.28, 32.07 (t, J =7.5, 7.5 Hz), 30.93. P NMR (500 MHz, CDCl ) δ 9.72.
P
3
+
+
ESI-MS: [M+H] =943.30. HRMS m/z (ESI+): Calculated for C62H46CuN2P2 (M ): 943.2427,
Found 943.2445.
4
,4,5,5-Tetramethyl-2-(2-methylnaphthalen-1-yl)-1,3,2-dioxaborolane (B-1).
The synthetic process of the compound B-1 was similar to the compound A-1.
1
H NMR (500 MHz, CDCl ) δ 8.10 (dd, J = 8.3, 1.1 Hz, 1H), 7.77 – 7.72 (m, 2H), 7.44 (ddd, J =
3
8
.4, 6.8, 1.4 Hz, 1H), 7.37 (ddd, J = 8.0, 6.8, 1.2 Hz, 1H), 7.27 (d, J = 8.4 Hz, 1H), 2.62 (s, 3H),
1
3
1
.48 (s, 12H). C NMR (125 MHz, CDCl ) δ 141.36, 136.64, 131.39, 129.57, 128.48, 128.12,
3
1
27.50, 125.99, 124.54, 83.98, 25.10, 22.62.The NMR spectra were consistent with literature
36
values.
2
-(2-(Bromomethyl)naphthalen-1-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (B-2).
The synthetic process of the compound B-2 was similar to the compound A-1.
1
H NMR (500 MHz, CDCl ) δ 8.30 (m, 1H), 7.86 – 7.75 (m, 2H), 7.51 – 7.41 (m, 3H), 4.96 (s,
3
1
3
2
H), 1.50 (s, 12H). C NMR (125 MHz, CDCl ) δ 141.68, 136.62, 132.65, 130.76, 128.47, 128.23,
3
1
27.62, 126.56, 126.11, 84.38, 34.39, 25.12.The NMR spectra were consistent with literature

36
values.
Diphenyl((1-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)naphthalene-2 yl)methyl)phosphine
oxide (B-3).
The synthetic process of the compound B-3 was similar to the compound A-2.
1
H NMR (500 MHz, CDCl ) δ 8.44 (d, J = 8.4 Hz, 1H), 7.74 – 7.65 (m, 6H), 7.47 – 7.36 (m, 9H),
3
1
3
4
1
1
.28 (s, 1H), 4.25 (s, 1H), 1.40 (s, 12H). C NMR (125 MHz, CDCl ) δ 137.08 (d, J =1.2 Hz),
3 P
36.41(d, J =7.5 Hz), 132.64 (d, J =97.5 Hz), 131.92(d, J =1.2 Hz), 131.59 (d, J =2.5 Hz),
P
P
P
P
31.31 (d, J =8.7 Hz), 130.18 (d, J =1.2 Hz), 128.30 (d, J =11.2 Hz), 128.31, 128.17(d, J =7.5
P
P
P
P
3
1
Hz), 126.13, 125.17, 83.91, 38.27 (d, J =65 Hz), 25.14. P NMR (500 MHz, CDCl ) δ 30.10.
P
3
+
ESI-MS: [M+H] =469.20.
(((4,7-diphenyl-1,10-phenanthroline2,9-diyl)bis(naphthalene-1,2 diyl)) bis(methylene)) bis
(diphenylphosphine oxide) (B-4).
The synthetic process of the compound B-4 was similar to the compound B-3.
1
H NMR (500 MHz, CDCl ) δ 8.10 (d, J = 15.0 Hz, 1H), 7.76 (dd, J = 8.6, 3.5 Hz, 3H), 7.72 (m,
3
1
H), 7.59 (d, J = 9.2 Hz, 3H), 7.54 (dd, J = 15.0, 6.4 Hz, 2H), 7.45 (d, J = 9.3 Hz, 2H), 7.30 (dd, J
24.7, 10.5 Hz, 4H), 7.24 – 7.03 (m, 2H), 6.99 (d, J = 7.4 Hz, 2H), 6.91 (d, J = 8.1 Hz, 3H), 4.39
=
1
3
(t, J = 14.7 Hz, 1H), 3.72 (t, J = 14.9 Hz, 1H). C NMR (125 MHz, CDCl ) δ 157.75, 148.08,
3
1
46.97, 146.41, 143.91, 137.99, 137.65, 137.50, 132.16 (d, J =106.2 Hz), 131.47 (d, J =10.0 Hz),
P P
1
31.26 (d, J =8.7 Hz), 131.17, 130.94, 130.60 (d, J =10 Hz), 129.99, 128.68, 128.35 (d, J =11.2
P
P
P
Hz), 128.5 (d, J =11.2 Hz), 126.95, 126.76, 126.00, 125.84, 125.36, 124.23, 35.26 (d, J =63.7
P
P
3
1
+
Hz). P NMR (500 MHz, CDCl ) δ 29.93. ESI-MS: [M+H] =1013.30.
3
The complex B.
The synthetic process of the compound B was similar to the compound A.
1
H NMR (500 MHz, Chloroform-d) δ 8.36 (s, 1H), 7.97 (s, 1H), 7.84 (d, J = 8.1 Hz, 1H), 7.74 –
7
.69 (m, 3H), 7.65 – 7.55 (m, 3H), 7.47 (t, J = 7.4 Hz, 1H), 7.35 – 7.30 (m, 1H), 7.18 (m, 3H),
.90 – 6.77 (m, 5H), 6.64 (q, J = 6.4, 5.9 Hz, 2H), 6.53 (q, J = 6.9, 6.0 Hz, 2H), 3.72 (m, 1H), 3.15
6
1
3
(d, J = 12.8 Hz, 1H). C NMR (125 MHz, CDCl ) δ 157.66, 150.26, 144.05, 135.89, 135.21,
3
1
1
=
33.71 (t, J =7.5, 7.5 Hz), 132.47(d, J =3.5 Hz), 131.88,130.77 (t, J =7.5, 7.5 Hz), 130.49,
P P P
29.89, 129.79, 129.39, 129.22, 128.94 (t, J =3.7, 5.0 Hz), 128.85, 128.64, 128.53, 128.08 (t, J
P
P
31
5.0, 5.0), 127.39 (d, J =101.2 Hz), 126.07, 125.55, 124.83, 33.50 (t, J =6.2, 12.5 Hz), 30.95. P
P
P
+
NMR (500 MHz, CDCl ) δ 10.80. ESI-MS: [M+H] =1043.30. HRMS m/z (ESI+): Calculated for
3
+
C70H50CuN2P2 (M ): 1043.2740, Found 1043.2738.
Characterization
1
13
31
H, C and P spectra were recorded on Bruker AVANCE III 500 MHz using CDCl as solvent
3
with TMS as internal standard. HRMS were recorded on Agilent 6210 TOF LC/MS mass
spectrometer. UV–vis absorption spectra were recorded using a Cary 500 UV–vis
spectrophotometer. Steady-state photoluminescence (PL) was recorded using a SENS-9000
spectrophotometer. Time-resolved PL was carried out using QM4 with time correlated
single-photon counting capability. Cyclic voltammetry (CV) measurements were performed using
a BASi Epsilon-EC workstation with anhydrous acetonitrile solvent, glass carbon as the working
electrode, platinum wire as the counter electrode, Ag/AgCl as the reference electrode, an
−
1
n-Bu NPF (0.1 M) electrolyte and a ferrocene standard at a scan rate of 100 mV·s . Application
4
6
software was Gaussian 16. A time-dependent-DFT approach (TDDFT) was used to interpret the
absorption and emission spectra in this system based on the optimized geometries at the

B3LYP/LANL2DZ and PCM levels of theory.
Acknowledgements
Financial support by the National Natural Science Foundation of China (No. 21376222), the
Natural Science Foundation of Zhejiang Province (No. LY18B060011) and the Professor Yang Li
(ZJU) is gratefully acknowledged.
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Mononuclear Copper(I) Complexes Based on Phenanthroline derivatives
P^N^N^P Tetradentate Ligands: Syntheses, Crystal Structure, Photochemical
Properties
Highlights
1
2
3
. The novel P^N^N^P-type ligands and the mononuclear tetradentate
phenanthroline Cu(I) complexes were designed and prepared.
. Compared with the typical Cu(P^P)(N^N) complexes, they showed a wider
excitation wavelength and a red-shifted about 100 nm emission peak.
. The copper complex B having the naphthyl link groups displayed high
red-emissive photoluminescence quantum efficiency, which was up to 3.8 %.