Construction, Characterization and Photoluminescence of
Conjugated Micro Porous Polymer Containing Europium
(III) Complexes Hybrid Materials
H Hu, Y Li
*
, N Dong and W F Jiang
School of Material Science and Engineering, University of Shanghai for Science and
Technology, Shanghai 200093, P. R. China
Abstract. We have synthesized a serious of bipyridine-functionalized conjugated micro
porous polymers (CMP-Bpy
x
) and prepared the first example of a micro porous polymer
comprising a luminescent europium complex in the network. This is a new type of red
luminescent hybrid materials, named CMP-Bpy
x
@Eu(TTA)
3
, which were formed by doping
[Eu(TTA)
3
] into CMP-Bpy
x
. The resulting products are amorphous and thermally robust.
Further investigation on the luminescence properties of CMP-Bpy
x
@Eu(TTA)
3
show that the
characteristic luminescence of the corresponding Eu
3+
through the intramolecular energy
transfers from the 2-Thenoyltrifluoroacetone (TTA) to the central Eu
3+
ions. The property of
thermal stability and photoluminescence properties have been enhanced by introducing of
conjugated micro porous polymer.
1. Introduction
Bipyridine is a common energy transfer ligand for rare earth complexes[1,2], which satisfies the
coordination environment of central rare earth ions[3], and enables the first ligand like β-diketone to
transmit energy more effectively[4,5]. However, the simple complex has low light and thermal
stability, which severely restricts its practical application. Conjugated microporous polymer(CMP) is
a kind of microporous organic polymer consists of a fully conjugated molecular chain with a
three-dimensional network structure[6,7]. The material has the optoelectronic properties of some
conjugated polymers and provides stable internal porosity, which shows a unique and excellent
designable feature[8-13]. Here we selected CMP containing the bipyridine structure to load the rare
earth ions. Through the coordination bond, rare earth β-diketone complexes with good fluorescent
grafted into microporous channels. A new type of rare-earth/CMP based hybrid material has been
constructed. The study of the fluorescence and thermal stability of the materials laid the foundation
for the application in electroluminescence.
2. Experimental Section
Synthesis of bipyridine functionalized polymer networks CMP-Bpy
x
and CMP-Bpy
x
@Eu(TTA)
3.
CMP-Bpy was prepared according to the literature[14]. The general procedure is as follow:
1,3,5-Triethynylbenzene (375mg,2.5mmol),1,4-dibromobenzene (472mg, 2.0 mmol),
Hu, H., Li, Y., Dong, N. and Jiang, W.
Construction, Characterization, and Photoluminescence of Conjugated Micro Porous Polymer Containing Europium (III) Complexes Hybrid Materials.
In Proceedings of the International Workshop on Environmental Management, Science and Engineering (IWEMSE 2018), pages 453-458
ISBN: 978-989-758-344-5
Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
453

5,5-dibromo-2,2’-bipyridine (157 mg, 0.5 mmol), tetrakis-(triphenylphosphine)palladium(0) (30 mg),
and copper(I) iodide (10 mg) were dissolved in a mixture of DMF (4 mL) and Et
3
N (4 mL). The
reaction mixture was heated to 90 °C and stirred for 72 hours under nitrogen atmosphere. The
mixture was cooled to room temperature and the insoluble precipitated network polymer was filtered
and washed four times with chloroform, water, methanol, and acetone to remove any unreacted
monomers or catalyst residues. Further purification of the polymer was carried out by Soxhlet
extraction with methanol for 24 hours. The product was dried in vacuum for 24 hours at 70 °C and
isolated as fine light yellow powder. Then, CMP-Bpy
x
(100mg) was added into a solution of TTA (3
mmol) in 25 mL ethanol, and then the europium chloride (1 mmol in 10 ml of ethanol solvent) was
added dropwise to the solution. After stirred for 24 hours, the mixture was cooled to room
temperature and the insoluble precipitated network polymer was filtered and washed four times with
chloroform, water, methanol, and acetone to remove any unreacted europium complex. The product
was then dried under vacuum for 24 hours at 70 °C to give a brown powder.
3. Results and discussion
Figure 1. The FT-IR spectra of CMP-Bpy
10/20/50
and CMP-Bpy
10/20/50
@Eu(TTA)
3.
It can be seen from the Figure 1 that all CMP-Bpy
x
and hybrid materials have peaks at 1576 cm
-1
and
1454 cm
-1
, corresponding to the vibration of aromatic ring skeleton and C-H bond, which means the
polymerized polymer networks[7]. As expected, CMP-Bpy
50
@Eu(TTA)
3
has an obvious wide peak
at 1000-1250 cm
-1
compared to CMP-Bpy
50
. Especially the two additional vibration peaks located at
1307 cm
-1
and 1091 cm
-1
can be ascribed to the characteristic features of C=O and C-F of TTA
groups in the europium complexes moiety. This is due to the bipyridine structure is the coordination
site of Eu complex. The higher the bipyridine content, the more the TTA will combined with. This
means that the rare earth complexes are successfully assembled into the channels through
IWEMSE 2018 - International Workshop on Environmental Management, Science and Engineering
454

coordination bonds.
Table 1 lists the specific surface area (BET) and pore volume of CMP-Bpy
x
. The BET of
CMP-Bpy
10/20
is larger than 400 m
2
/g, while the BET of CMP-Bpy
50
is lower. The microporous BET
and pore volume decreased with the increase of the mole percentage of bipyridine moiety. This may
attribute to the negative effect of bipyridine to microporous structure[14]. However, the total pore
volume increased with the increase of bipyridine moiety. This is due to the addition of bipyridine
disturbed the original microporous structure and lead to the formation of mesoporous and
macroporous, which is beneficial to our subsequent load of rare earth complexes.
Table 1. Physical property for polymer networks CMP-Bpy
x.
S
BET
[m
2
g
-1
]
S
micro
[m
2
g
-1
](t-plot)
V
tot
[cm
3
g
-1
]
V
mico
[cm
3
g
-1
]
CMP-Bpy
10
408.8
206.5
0.24
0.11
CMP-Bpy
20
412.1
179.1
0.28
0.09
CMP-Bpy
50
345.7
121.9
0.37
0.06
From the N
2
adsorption–desorption curves of CMP-Bpy
x
(Figure 2A), it can be seen that all of
them are typical I type adsorption isotherm curve for microporous materials. It shows that the outer
surface area is much smaller than the inner surface area. For CMP-Bpy
10
, the adsorption of the probe
molecules does not increase as the pressure continues to rise. The curves of CMP-Bpy
20
rise slightly,
while CMP-Bpy
50
increased significantly when the pressure increased. Figure 2B is the pore size
distribution curve of CMP-Bpy
x
. With the increase of bipyridine content, the number of pores in the
micropores and macropores is more, which is consistent with the N
2
desorption curve.
Figure 2. Nitrogen sorption analysis for CMP-Bpy
x
(A) and Pore size distribution (B).
Compared the thermogravimetric curve of the hybrid materials CMP-Bpy
x
@Eu(TTA)
3
with pure
matrix CMP-Bpy
x
(Figure 3), it can be seen that the pure CMP materials are stable before 400 ,
while the CMP hybrid materials start decompositing at 200 . Corresponding to the decomposition
of organic ligands (TTA) in the micropores, the second stage weightlessness also begins at 400 ,
and is the self decomposition of the CMP skeleton. The residual amount of CMP-Bpy
x
is higher than
CMP-Bpy
x
@Eu (TTA)
3
because of the rare earth complex in the excess pore. The results show that
the thermal stability of the CMP skeleton has been successfully endow to the hybrid materials
CMP-Bpy
x
@Eu(TTA)
3
, The thermal stability of the rare earth complex has been obviously improved.
Construction, Characterization, and Photoluminescence of Conjugated Micro Porous Polymer Containing Europium (III) Complexes Hybrid
Materials
455

This further indicates that the introduction of the stable CMP matrix can improve the thermal
stability of the rare earth complexs.
Figure 3. The thermogravimetric curve of CMP-Bpy
x
@Eu(TTA)
3.
Figure 4. The fluorescent emission spectra of CMP-Bpy
x
@Eu(TTA)
3.
From the fluorescence emission spectra of CMP-Bpy
x
@Eu(TTA)
3
(Figure 4), we can observe that
CMP based hybrid materials emit the characteristic emission of Eu
3+
ions under the excitation of
355nm wavelength. The transition is
5
D
0
→
7
F
J
(J = 0, 1, 2, 3), corresponding to the wavelengths at
580, 592, 618 and 650 nm, respectively[5]. Among them, the emission of
5
D
0
→
7
F
2
transition, i.e.,
IWEMSE 2018 - International Workshop on Environmental Management, Science and Engineering
456

em = 618 nm, is the strongest emission. accounting for 81% of the total emission intensity, which
indicates that Eu
3+
departured from the center of the inversion symmetry. In order to further study the
luminescent properties of hybrid materials. At room temperature, 355 nm and 407 nm were selected
as excitation wavelengths to measure the fluorescence attenuation curves of CMP-Bpy
x
@Eu(TTA)
3
and complexes
Table 2. luminescent efficiencies and lifetimes of europium (III) materials.
I
01
I
02
I
02
/I
01
τ (ms)
A
r
A
nr
η (%)
CMP-Bpy
10
@Eu(TTA)
3
10.474
69.854
6.669
0.322
574.974
2603.32
16.24
CMP-Bpy
20
@Eu(TTA)
3
8.207
49.473
6.028
0.308
457.293
2793.707
14.07
CMP-Bpy
50
@Eu(TTA)
3
4.008
35.025
8.739
0.265
379.835
3398.165
10.05
[Eu(TTA)
3
]·2H
2
O
46.329
369.41
7.974
0.238
498.718
3706.982
11.86
A
r
and A
nr
are radiative and nonradiative transition rates
[Eu(TTA)
3
]2H
2
O at
5
D
0
excited state.The curve shows a single exponential decline, and the fitting
curve gets the fluorescence lifetime. The fluorescence lifetime of CMP-Bpy
10
@Eu(TTA)
3
is larger
than lanthanide complexes [Eu(TTA)
3
]2H
2
O. The quantum efficiency of luminescence is further
calculated according to the lifetime, as shown in table 2.
4. Conclusions
The complexation of CMP-Bpy
x
@Eu(TTA)
3
with Eu
3+
ions results in a sharp red-emitting molecular
organic-inorganic hybrid material under ultraviolet illumination. Which compared with the pure
[Eu(TTA)
3
]·2H
2
O rare earth complex material, the property of thermal stability and
photoluminescence properties have been enhanced by the introducing of CMP. Ultimately, it is very
important to enrich the types of lanthanide luminescent hybrid materials, we believe that these new
multifunctional CMP materials will expand the field of lanthanide-based luminescent
organic-inorganic hybrid materials.
Acknowledgement
This work was supported by the National Natural Science Foundation of China (21101107,
51173107), the innovation Project of the Shanghai Municipal Education Commission (No.15ZZ076)
References
[1] Martinramos P, Lavin V, Ramossilva M, Martin I R, Lahoz F, Chamorro-Posada P, Paixão J A
and Martín-Gil J 2013 J. Mater. Chem. C 1 5701
[2] Nasso I, Geum N, Bechara G, Mestre-Voegtléab B, Galaupab C and Picard C 2014 J.
Photochem. Photobiol. A 274 124
[3] Gao B, Zhang D and Li Y 2018 Opt. Mater. 77 77
[4] Ren X, Wei C and Cheng G 2011 J. Optoelectron. Adv. M. 13 1167
[5] Gu Y J, Yan B and Qiao X F 2013 J. Solid State Chem. 199 116
[6] Jiang J, Su F, Trewin A, Wood C D, Campbell N L, Niu H, Dickinson C, Ganin A Y,
Rosseinsky M J, Khimyak Y Z and Cooper A I 2007 Angew. Chem. Int. Ed. 46 8574
[7] Jiang J, Su F, Trewin A, Wood C D, Niu H, Jones J T A and Khimyak Y Z 2008 J. Am. Chem.
Soc. 130 7710
[8] Gu C, Huang N, Gao J, Xu F, Xu Y H and Jiang D L 2014 Angew. Chem. Int. Ed 53 4850
[9] Yuan K, Guo-Wang P Y, Hu T, Shi L, Zeng R, Forster M, Pichler T, Chen Y W and Scherf U
2015 Chem. Mater. 27 7403
[10] Sigen A, Zhang Y W , Li Z P , Xia H , Xue M , Liu X M and Mu Y 2014 Chem. Commun.
Construction, Characterization, and Photoluminescence of Conjugated Micro Porous Polymer Containing Europium (III) Complexes Hybrid
Materials
457

50 8495
[11] Chen Y F, Sun H X, Yang R X, Wang T T, Pei C J, Xiang Z T, Zhu Z Q, Liang W D, Li A
and Deng W Q 2015 J. Mater. Chem. A 3 87
[12] Xiang L, Zhu Y L, Gu S, Chen D Y, Fu X, Zhang Y D, Yu G P, Pan C Y and Hu Y H 2015
Macromol. Rapid Comm. 36 1566
[13] Broicher C, Foit S, Rose M, Hausoul P J C and Palkovits R 2017 ACS Catal. 7 8413
[14] Jiang J, Wang C, Laybourn A, Hasell T, Clowes R, Khimyak Y, Xiao J, Higgins S, Adams D
and Cooper A I 2011 Angew. Chem. Int. Ed. 50 1072
IWEMSE 2018 - International Workshop on Environmental Management, Science and Engineering
458