Luminescent properties of Ag(i)/Cu(i) coordination polymers: Crystal structures and high intensity luminescence of a PMMA-doped hybrid material based on a quinoline-2,3-dicarboxylic acid ligand

Article abstract of DOI:10.1039/c4ra16863a

Three one-dimensional (1D) Ag(i)/Cu(i) coordination polymers, formulated as [Ag(2,3-Hqldc)]_n (Ag1), [Ag(3-qlc)]_2n (Ag2) and [CuI(3-Hqlc)]_n (Cu1) based on the ligand quinoline-2,3-dicarboxylic acid (H₂qldc), were synthesized through hydrothermal (solvothermal) method and structurally characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analysis. Molecular structural analysis reveals that Ag1 was a 1D + 1D → 1D infinite chain synthesized at a relatively low temperature 80 °C, which further forms a three-dimensional (3D) structure by π-π stacking interactions. Ag2 forms a 1D dimer chain structure and via π...π packing interactions shows a two-dimensional (2D) supramolecular network. Both Ag1 and Ag2 display stable blue luminescent in the solid state and in organic solvents (DMSO, CH₃CN and CH₃OH) at 298 K and 77 K. However, Cu1 possess a 1D ladder chain structure, which further forms a 2D structure by hydrogen bonding interactions. Cu1 shows tunable luminescence at 298 K and 77 K in the solid state with a large red-shift of 70 nm and the CIE color shifts from bright yellow (0.51, 0.48) to red (0.67, 0.30), indicating thermochromic luminescence for Cu1. After doping with poly(methylmethacrylate) (PMMA), not only are the luminescence intensity and lifetimes enhanced, but the thermal stability is also increased in comparison with Cu1. After Cu1 was doped with PMMA (Cu1@PMMA), the lifetime of the polymer film material Cu1@PMMA increases and reaches a maximum at 1.0% (τ = 95.57 μs), which is more than eight times longer than that of Cu1 (τ = 13.78 μs). Cu1@PMMA is confirmed as a bright yellow luminescent polymer film material. This journal is

Full text of DOI:10.1039/c4ra16863a

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Luminescent properties of Ag(I)/Cu(I) coordination
polymers: crystal structures and high intensity
luminescence of a PMMA-doped hybrid material
based on a quinoline-2,3-dicarboxylic acid ligand†
Cite this: RSC Adv., 2015, 5, 17343
a
a
Yang Song, Rui-Qing Fan, Hui-Jie Zhang,a Zhi-Wei Liu,a Xue-Tao Wang,a
*
a
a
Cai-Tu Tan, Yu-Lin Yang and Yu-Lei Wangb
*
Three one-dimensional (1D) Ag(I)/Cu(I) coordination polymers, formulated as [Ag(2,3-Hqldc)]n (Ag1), [Ag(3-
qlc)]2n (Ag2) and [CuI(3-Hqlc)]n (Cu1) based on the ligand quinoline-2,3-dicarboxylic acid (H2qldc), were
synthesized through hydrothermal (solvothermal) method and structurally characterized by single-crystal
X-ray diffraction, IR spectroscopy and elemental analysis. Molecular structural analysis reveals that Ag1
was a 1D + 1D / 1D infinite chain synthesized at a relatively low temperature 80 ꢀC, which further
forms a three-dimensional (3D) structure by p–p stacking interactions. Ag2 forms a 1D dimer chain
structure and via p/p packing interactions shows a two-dimensional (2D) supramolecular network.
Both Ag1 and Ag2 display stable blue luminescent in the solid state and in organic solvents (DMSO,
CH3CN and CH3OH) at 298 K and 77 K. However, Cu1 possess a 1D ladder chain structure, which further
forms a 2D structure by hydrogen bonding interactions. Cu1 shows tunable luminescence at 298 K and
77 K in the solid state with a large red-shift of 70 nm and the CIE color shifts from bright yellow (0.51,
0.48) to red (0.67, 0.30), indicating thermochromic luminescence for Cu1. After doping with
poly(methylmethacrylate) (PMMA), not only are the luminescence intensity and lifetimes enhanced, but
the thermal stability is also increased in comparison with Cu1. After Cu1 was doped with PMMA
(Cu1@PMMA), the lifetime of the polymer film material Cu1@PMMA increases and reaches a maximum at
1.0% (s ¼ 95.57 ms), which is more than eight times longer than that of Cu1 (s ¼ 13.78 ms). Cu1@PMMA is
confirmed as a bright yellow luminescent polymer film material.
Received 22nd December 2014
Accepted 3rd February 2015
DOI: 10.1039/c4ra16863a
www.rsc.org/advances
had been around for a long time but without blue light, white
lamps could not be created. Despite considerable efforts, both
Introduction
in the scientic community and in industry, the blue LED had
remained a challenge for three decades.5 As luminescent
materials, silver(I) coordination polymers can be used as stable
blue luminescent complexes6 in optical devices. However, until
now, only a few cases have been reported about blue emitting
silver(I) coordination polymers, and the realization of high
luminescence efficiency remains a big challenge.7
In addition, monovalent copper complexes show a variety of
structure and rich photophysical properties. Nevertheless, Cu(I)
is easy to oxidize into Cu(II) in the process of synthesis, thus
create monovalence copper complexes as luminescent material
is difficult but very meaningful. A popular polymer matrix used
as a host for luminescent transition coordination polymers is
poly(methyl methacrylate) (PMMA), which is a low-cost, simply
prepared polymer with excellent optical quality.8 Until now
most of the reports are rare earth doped with PMMA.9 There is
no doubt that rare earth element shows excellent luminescent
properties, but luminous color of rare earth element has defects
which is not easy to control. Compared with noble metal Pt, Au,
Silver(I) and copper(I) coordination polymers have interesting
luminescent properties1 that have been utilized in areas such as
light emitting diodes, luminescence probes2 and emitting layers
in polymer light-emitting diodes.3 Although the coordination
polymers have better luminescence and higher thermal
stability, polymer-doped systems have clear technical advan-
tages over glass ones, such as exibility and prominent pro-
cessing ability, which are important for optical bers and ber
ampliers.4 When Isamu Akasaki, Hiroshi Amano and Shuji
Nakamura produced bright blue light beams from their semi-
conductors in the early 1990s, they triggered a fundamental
transformation in lighting technology. Red and green diodes
aDepartment of Chemistry, Harbin Institute of Technology, Harbin 150001, P. R.
China. E-mail: fanruiqing@hit.edu.cn; ylyang@hit.edu.cn; Fax: +86-0451-86413710
bNational Key Laboratory of Science and Technology on Tunable Laser, Harbin
Institute of Technology, Harbin 150080, P. R. China
† Electronic supplementary information (ESI) available. CCDC 1036463 and
1036466. For ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/c4ra16863a
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Ag even rare earth, Cu(I) with the advantage of cheap and non- ACF 400 MHz at room temperature. X-ray powder diffraction
poison, which also can modify ligands and control the emitting. (XRPD) patterns were analyzed with monochromated Cu Ka
Hence, copper-based systems with favorable luminescence are radiation of 40 mA, 40 kV. UV-vis spectra were recorded on a
beginning to receive more attention.10 When copper(I) coordi- Perkin-Elmer Lambda 20 spectrometer. The solid-state and
nation polymers incorporate with PMMA forming a new solution photoluminescence analyses were carried out on an
complex-containing polymer/lm,11 it will lead to signicant Edinburgh FLS920 uorescence spectrometer in the range of
exibility, versatility, thermal and photostability.12
200–800 nm at 298 K and 77 K.
In this work, we choose quinoline-2,3-dicarboxylic acid
(H2qldc) as the ligand. H2qldc as a derivative of 2,3-H2pydc Synthesis of [Ag(2,3-Hqldc)]n (Ag1)
which has a relatively large p-conjugated system in the quino-
A mixture of AgNO3 (0.034 g, 0.20 mmol), 2,3-H2qldc (0.021 g,
line ring, which might not only contribute to the desirable
uorescence properties resulting from the interaction between
2,3-qldc2ꢁ anions and metal ions, but also easily assemble into
high dimensionality, supramolecular networks via p/p
packing interactions between two adjacent aromatic rings as
well as hydrogen bonding interactions. To the best of knowl-
edge, cases of metal–organic complexes linked by H2qldc have
been presented. Y. P. Cai,13 J. H. Lin,14 G. B. Che15 and their co-
workers use 2,3-H2qldc ligand to prepare a series of coordina-
tion polymers from zero- to two-dimension with Co(II), Zn(II),
Cd(II), Mn(II) and Ln(III) ions, which are summarized in Table
S1.†
0.10 mmol) with a mole ratio of 2 : 1 was dissolved in 8 mL H2O
and stirred for 20 min. The nal mixture was placed in a Teon-
lined stainless steel vessel (20 mL) under autogenous pressure
and heated at 80 ꢀC for 5 days. Aer slowly cooling to the room
temperature, the mixture was washed with distilled water and
colorless block-shaped crystals were ltered off and dried at
room temperature (yield ca. 65%, based on silver metal).
Elemental analysis (%): calc. for C11H6AgNO4 (Mr: 324.04): C,
40.77; N, 4.32; H, 1.87%. Found: C, 40.72; N, 4.38; H, 1.89%. IR
(cmꢁ1): 3515 (br, s), 3404 (br, s), 3142 (w), 2235 (m), 1591 (vs),
1372 (vs), 1285 (s), 1132 (vs), 1001 (m), 750 (vs), 673 (s), 553 (w),
476 (w). 1H NMR (400 MHz, DMSO-d6): d ¼ 8.98 (s, 1H, H2qldc–
Three Ag(I)/Cu(I) coordination polymers constructed from
H2qldc, namely, [Ag(2,3-Hqldc)]n (Ag1), [Ag(3-qlc)]2n (Ag2) and
[CuI(3-Hqlc)]n (Cu1) have been synthesized under hydrothermal
conditions. During the solvothermal synthetic process, unex-
pected situ decarboxylation of H2qldc was observed. Through
0
H1), 8.24 (s, 1H, H2qldc–H5), 8.14 (d, 1H, H2qldc–H4 ), 7.95 (d,
1H, H2qldc–H2), 7.77 (d, 1H, H2qldc–H3) ppm. 1H NMR (400
MHz, CD3CN): d ¼ 9.13 (s, 1H, H2qldc–H1), 8.24 (s, 1H, H2qldc–
H5), 8.18 (d, 1H, H2qldc–H4), 8.06 (d, 1H, H2qldc–H2), 7.84 (d,
1
1H, H2qldc–H3) ppm. H NMR (400 MHz, CD3OD): d ¼ 8.94 (s,
ꢀ
ꢀ
controlling the temperature (from 80 C to 120 C) makes the
ligand 2,3-H2qldc decarboxylation and results in the formation
of 3-Hqlc ligand. Aer decarboxylation, the dihedral angle
between the planes of carboxyl and quinoline in one bridging
organic ligand is 3.70ꢀ in the Ag2, which is much smaller than
those of 61.98ꢀ and 30.49ꢀ in the Ag1. The nice coplanar feature
of the structure in Ag2 can enhance the luminescent efficiency.
The structure of Ag2 has been reported by C. B. Liu, et al.16 but
they directly use 3-Hqlc as ligand rather than decarboxylation of
H2qldc. In this work, we mainly talked about the decarboxyl-
ation process of H2qldc and compared with coordination poly-
mer Ag1. What's more, we also discussed the luminescent
properties of Ag1 and Ag2 in details. Both Ag1 and Ag2 display
stable blue luminescent in the solid state and in different
solvents (DMSO, CH3CN and CH3OH) at 298 K and 77 K.
However, Cu1 shows the interesting property of thermochromic
luminescence, which is rarely reported in literatures, and most
of cases only talked about the luminescent properties in the
solid state rather than the effect of solvent and temperature,
more comparisons are summarized in Table S2.†
1H, H2qldc–H1), 8.13 (d, 2H, H2qldc–H4,5), 7.95 (d, 1H, H2qldc–
H2), 7.76 (d, 1H, H2qldc–H3) ppm.
Synthesis of [Ag(3-qlc)]2n (Ag2)
A mixture of AgNO3 (0.034 g, 0.20 mmol), 2,3-H2qldc (0.021 g,
0.10 mmol), with a mole ratio of 2 : 1 was dissolved in 8 mL H2O
and stirred for 20 min. The nal mixture was placed in a Teon-
lined stainless steel vessel (20 mL) under autogenous pressure
and heated at 120 ꢀC for 5 days. Aer slowly cooling to the room
temperature, the mixture was washed with distilled water and
colorless block-shaped crystals were ltered off and dried at
room temperature (yield ca. 52%, based on silver metal).
Elemental analysis (%): calc. for C20H12Ag2N2O4 (Mr: 560.06): C,
42.89; N, 5.00; H, 2.16%. Found: C, 42.85; N, 5.03; H, 2.19%. IR
(cmꢁ1): 3437 (br, s), 3044 (w), 1597 (vs), 1558 (vs), 1394 (vs), 1317
(s), 793 (vs), 761 (m), 586 (m), 476 (w). 1H NMR (400 MHz,
DMSO-d6): d ¼ 9.32 (s, 1H, 3-qlc–H1), 9.01 (s, 1H, 3-qlc–H2), 8.20
(d, 1H, 3-qlc–H6), 8.12 (d, 1H, 3-qlc–H3), 7.89 (d, 1H, 3-qlc–H5),
7.67 (d, 1H, 3-qlc–H4) ppm. 1H NMR (400 MHz, CD3CN): d ¼ 9.39
(s, 1H, 3-qlc–H1), 9.84 (s, 1H, 3-qlc–H2), 8.13 (d, 2H, 3-qlc–H3,5),
7.89 (d, 1H, 3-qlc–H6), 7.71 (d, 1H, 3-qlc–H4) ppm. 1H NMR (400
MHz, CD3OD): d ¼ 9.39 (s, 1H, 3-qlc–H1), 9.05 (s, 1H, 3-qlc–H2),
8.28 (s, 1H, 3-qlc–H6), 8.13 (d, 1H, 3-qlc–H3), 7.93 (d, 1H, 3-qlc–
H5), 7.74 (d, 1H, 3-qlc–H4) ppm.
Experimental section
General characterization
All reagents were analytical grade (99.7%) from commercial
sources and were used directly without any further purication.
Elemental analyses (C, H, and N) were performed on a Perkin-
Synthesis of [CuI(3-Hqlc)]n (Cu1)
Elmer 240c elemental analyzer. IR spectra were recorded by A mixture of CuI (0.019 g, 0.10 mmol), 2,3-H2qldc (0.011 g, 0.05
Nicolet Impact 410 FTIR spectrometer (range in 4000–400 mmol) with a mole ratio of 2 : 1 was dissolved in 6 mL CH3CN
cmꢁ1). 13C NMR and 1H NMR spectra were recorded on a Bruker and stirred for 20 min. The nal mixture was placed in a
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Teon-lined stainless steel vessel (20 mL) under autogenous We found that the decarboxylation of free H2qldc was per-
ꢀ
ꢀ
pressure and heated at 120 C for 5 days. Aer cooling to the formed under solvothermal conditions at 120 C (without any
room temperature, the mixture was washed with distilled water other substance). The 13C NMR spectra of the reaction product
and yellow block-shaped crystals were ltered off and dried at as well as H2qldc are shown in Fig. S1 and S2 in the ESI,† in
room temperature (yield ca. 72%, based on copper metal). which the characteristic peaks of –COOH appeared at 167.99
Elemental analysis (%): calc. for C10H7CuINO2 (Mr: 363.61): C, and 166.22 ppm, but for the reaction product only one charac-
33.00; N, 3.85; H, 1.93%. Found: C, 33.59; N, 3.88; H, 1.96%. IR teristic peak of –COOH appeared at 166.30 ppm. As aforemen-
(cmꢁ1): 3437 (br, s), 3076 (br, m), 1700 (vs), 1613 (vs), 1427 (m), tioned reaction fact, coordination polymer Ag1 can be obtained
1285 (vs), 925 (w), 782 (vs), 465 (w). 1H NMR (400 MHz, DMSO- at 80 C. Based on these facts, we can deduce that, the coordi-
ꢀ
d6): d ¼ 9.40 (s, 1H, 3-qlc–H1), 9.16 (s, 1H, 3-qlc–H2), 8.32 (d, 2H, nation between the ligand and the metal center may be
3-qlc–H3,5), 7.93 (d, 1H, 3-qlc–H6), 7.78 (d, 1H, 3-qlc–H4) ppm. occurred before the decarboxylation of H2qldc in Ag1. Mean-
1H NMR (400 MHz, CD3CN): d ¼ 9.40 (s, 1H, 3-qlc–H1), 8.89 (s, while, when Ag1 assembling, the decarboxylation is too difficult
1H, 3-qlc–H2), 8.13 (d, 2H, 3-qlc–H3,5), 7.89 (s, 1H, 3-qlc–H6), to perform. As shown in TG curve, until 452.2 ꢀC, Ag1 begins to
7.67 (s, 1H, 3-qlc–H4) ppm. 1H NMR (400 MHz, CD3OD): d ¼ 9.93 lose the two carboxylates. Compared with Ag1, coordination
(s, 1H, 3-qlc–H1), 9.59 (s, 1H, 3-qlc–H2), 8.86 (d, 1H, 3-qlc–H6), polymer Ag2 was not obtained at 80 ꢀC (other conditions remain
8.70 (d, 1H, 3-qlc–H3), 8.51 (d, 1H, 3-qlc–H5), 8.28 (d, 1H, 3-qlc– unchanged except for the reaction temperature). The phenom-
H4) ppm.
enon can be explained as: in Ag2, the coordination reaction may
be occurred aer the decarboxylation process. The aryl group in
H2qldc ligand as electron attracting group is benecial to the
cleavage of C–C bond. The reaction mechanism of Ag1 and Ag2
are shown in Scheme 1.
Synthesis of Cu+ complex-doped PMMA polymer lms
The PMMA polymer was doped with the Cu(I) coordination
polymer Cu1 in the proportions 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 and
1.4% (w/w). The PMMA powder was dissolved in 6 mL N,N0-
dimethylformamide (DMF), followed by addition of the
required amount of coordination polymer Cu1 in DMF solution,
X-ray crystal structure determination
The X-ray diffraction data taken at room temperature for coor-
dination polymers Ag1 and Cu1 are collected on a Rigaku R-
AXIS RAPID IP diffractometer equipped with graphite-
ꢀ
and the resulting mixture was heated at 40 C for 60 min. The
polymer lm was obtained aer evaporation of excess solvent at
ꢀ
60 C.
˚
monochromated Mo Ka radiation (l ¼ 0.71073 A). The struc-
tures of Ag1 and Cu1 are solved by direct methods and rened
on F2 by the full-matrix least squares using the SHELXTL-97
crystallographic soware.18 Anisotropic thermal parameters
are rened to all of the non-hydrogen atoms. The hydrogen
atoms are held in calculated positions on carbon atoms and
nitrogen atoms and that are directly included in the molecular
formula on water molecules. ESI.† Crystal structure data and
details of the data collection and the structure renement are
listed as Table 1. Selected bond lengths and bond angles for
complexes are summarized in Table 2.
Syntheses
Hydrothermal methods are widely used in the syntheses of
inorganic–organic polymers, especially when organic carbox-
ylate ligands are applied. Because under such reaction condi-
tions, the problems of ligand solubility can be minimized.17 The
structures of Ag1 and Ag2 were accomplished by introducing
the N and O containing ligands into the reaction system, which
may act as deprotonation and decarboxylation reagents. Coor-
dination polymers Ag1 and Ag2 reported here were synthesized
under hydrothermal reaction conditions, while reaction
temperature showed a remarkable inuence on the nal
structure. Ag1 was synthesized at a relatively low temperature
80 ꢀC to get the 1D + 1D / 1D innite chain, which is forms by
Results and discussion
IR spectroscopy
the H2qldc with m2–h1:h1:h0:h0 bridging mode and Ag1 further The IR spectra of coordination polymers Ag1, Ag2, Cu1 and the
forms three-dimensional (3D) structure by p–p stacking inter- free ligand 2,3-H2qldc are shown in Fig. S3.† The asymmetric
action. Ag2 was synthesized at a higher temperature 120 ꢀC, stretching vibrations of the carboxyl group in Ag1 and Ag2 are
forming 1D dimer chain structure and via p/p packing inter- observed at ca. 1590 cmꢁ1 and the band of symmetric stretching
actions show two-dimensional (2D) supramolecular network. vibrations are observed at ca. 1394 cmꢁ1. The frequent separa-
Meanwhile, aer replacing AgNO3 with CuI, and changing water tion between the asymmetric and symmetric stretching of
to organic solvent CH3CN, Cu1 was synthesized at a higher carboxyl group can be mode to distinction between these
temperature 120 ꢀC, which formed a 1D ladder chain.
binding states. The deviation D(vas(COOꢁ) ꢁ vs(COOꢁ)) was
Interestingly, the decarboxylation of H2qldc was observed in approximately 200 cmꢁ1, in the range of 100 cmꢁ1 to 200 cmꢁ1
,
the solvothermal synthetic process of Ag2 and Cu1. In order to which indicates that the coordination interaction exists
study the decarboxylation process of H2qldc, a series of control between the metal ion and the oxygen atoms of carboxyl group.
experiments were conducted. We did the experiment under the Therefore, the stretching vibrations of the carboxyl group shi
condition of without adding metal salts, only ligand H2qldc in 8 toward lower frequencies and the intensity is greatly reduced
mL H2O was placed in a Teon-lined stainless steel vessel (20 compared to that of free ligand (1700 cmꢁ1). The absence of
mL) under autogenous pressure and heated at 120 ꢀC for 5 days. strong bands ranging from 1579 to 1590 cmꢁ1 for coordination
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Scheme 1 The reaction mechanism of coordination polymers Ag1 and Ag2.
polymers Ag1 and Ag2 indicate that the ligand in these coor- similar. The asymmetric stretching vibration of the carboxyl
dination polymers are deprotonated, compared with those of group is observed at ca. 1700 cmꢁ1, and the band of symmetric
free ligands in these complexes. Coordination polymer Cu1 stretching vibration is observed at ca. 1285 cmꢁ1, as the same as
possesses identical ligand 2,3-H2qldc and their IR spectra are ligand 2,3-H2qldc, which indicates that the oxygen atoms of
carboxyl group does not coordinate to the metal ion. Weak
bands in the region of 476–597 cmꢁ1 are observed in the spectra
of coordination polymers, which are assigned to n(M–N) and
Table 1 Crystal data and structure refinement parameters of coordi-
n(M–O) stretching vibrations.19 These are in agreement with the
nation polymers Ag1 and Cu1
results of single-crystal X-ray diffraction analysis.
Identication code
Ag1
Cu1
Description of crystal structure
Empirical formula
Formula mass
Crystal system
Space group
C
11H6AgNO4
C10H7CuINO2
363.61
Monoclinic
P2(1)/n
4.2490(8)
15.962(3)
15.297(3)
90.00
90.03(3)
90.00
1037.5(4)
4
2.328
5.056
688
0.14 ꢂ 0.14 ꢂ
0.12 mm
3.69–27.46
ꢁ5 # h # 5
ꢁ20 # k # 20
ꢁ19 # l # 19
2368/0/136
1.267
Crystal structure of [Ag(2,3-Hqldc)]n (Ag1). The 1D mono-
nuclear coordination polymer Ag1 crystallizes in the triclinic
space group P1ꢀ. The asymmetric unit of Ag1 and Ag2 are shown
in Fig. 1. The asymmetric unit of Ag1 contains one Ag(I) cation,
one 2,3-Hqldcꢁ anion. Ag(I) center is three-coordinated by one
nitrogen atom (N1) from one 2,3-Hqldcꢁ anion and two oxygen
atoms (O1A and O4A) from two other 2,3-Hqldcꢁ anions,
324.04
Triclinic
ꢀ
p1
6.6702(13)
8.7729(18)
9.1647(18)
78.49(3)
72.67(3)
68.92(3)
475.13(2)
2
2.265
2.121
316
0.20 ꢂ 0.18 ꢂ
0.15 mm
3.24–27.48
ꢁ8 # h # 8
ꢁ11 # k # 11
ꢁ11 # l # 11
2168/0/155
0.983
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢀ)
b (ꢀ)
g (ꢀ)
˚
forming a plane triangle. Ag–N bond length is 2.261(3) A, Ag–O
bond lengths are 2.295(3) and 2.390(2) A respectively. All Ag–N
3
˚
V (A )
˚
Z
Dc/(g cmꢁ3
)
and Ag–O bond lengths as well as the bond angles around Ag(I)
ion are in the range expected for such coordination polymers.1b
Two adjacent silver ions are connected through N1 and O4
atoms deriving from one 2,3-Hqldcꢁ anion, giving rise to an
innite 1D zigzag chain. What's more, two adjacent 1D zigzag
chains are linked by bridging O atom, forming a new 1D + 1D /
m (Mo Ka)/mmꢁ1
F(000)
Crystal size
2q range (ꢀ)
Limiting indices
˚
1D chain with a Ag/Ag separation of 4.168 A (Fig. 2). It is
noteworthy that, in the Ag1 crystal structure, it exits weak
intermolecular forces including aromatic rings. Further anal-
ysis of the crystal packing reveals that adjacent 1D chains are
further connected by face-to-face p/p interactions between
Data/restraints/parameters
GOF on F2
Final R indices [I > 2s(I)]
a
˚
quinoline ring with a centroid to centroid distance of 3.697 A
R1
0.0324
0.0937
0.0814
0.2183
b
˚
wR2
(Fig. 3a) and 3.785 A (Fig. 3b). They play an important role in
stabilizing the network structure, and further resulting in a 3D
supramolecular architecture.
R indices (all data)
R1
wR2
CCDC
0.0404
0.0995
1036463
0.0842
0.2192
1036466
P
Notably, though the chemical environments of the central Ag
cations are the same in Ag1 and Ag2, the major difference is the
dihedral angle between the carboxyl and quinoline in one
bridging organic ligand. The dihedral angle between the two
planes in one bridging ligand is 3.70ꢀ in the Ag2, which is much
P
P
P
R1 ¼ ||Fo| ꢁ |Fc||/ |Fo. wR2 ¼ [ [w(Fo ꢁ Fc2)2]/ [w(Fo2)2]]1/2
.
a
b
2
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Table 2 Selected bond lengths (A˚) and bond angles (ꢀ) for coordina-
tion polymers Ag1 and Cu1a
Ag1
Ag(1)–N(1)
Ag(1)–O(4)#3
Ag(1)–O(1)#2
2.261(3)
2.390(2)
2.295(3)
N(1)–Ag(1)–O(1)#2
O(1)#2–Ag(1)–O(4)#3
N(1)–Ag(1)–O(4)#3
128.8(1)
105.4(1)
120.8(0)
Cu1
I(1)–Cu(1)
2.645(2)
2.688(2)
2.694(3)
2.051(1)
2.688(2)
2.694(3)
2.723(4)
Cu(1)–I(1)–Cu(1)#1
Cu(1)–I(1)–Cu(1)#2
Cu(1)#1–I(1)–Cu(1)#2
N(1)–Cu(1)–I(1)
N(1)–Cu(1)–I(1)#1
I(1)–Cu(1)–I(1)#1
80.4(1)
61.3(3)
I(1)–Cu(1)#1
I(1)–Cu(1)#2
Cu(1)–N(1)
Cu(1)–I(1)#1
Cu(1)–I(1)#2
Cu(1)–Cu(1)#2
104.3(1)
122.3(4)
109.8(4)
99.6(1)
100.9(4)
118.7(2)
104.3(1)
134.9(4)
60.2(3)
Fig. 3 (a) Stick representation of the 2D layer through p/p packing in
Ag1; (b) stick representation of the 3D framework structure through
p/p packing in Ag1 and all the hydrogen atoms are omitted for clarity.
N(1)–Cu(1)–I(1)#2
I(1)–Cu(1)–I(1)#2
I(1)#1–Cu(1)–I(1)#2
N(1)–Cu(1)–Cu(1)#2
I(1)–Cu(1)–Cu(1)#2
I(1)#1–Cu(1)–Cu(1)#2
I(1)#2–Cu(1)–Cu(1)#2
114.0(4)
58.5(5)
a
Symmetry transformations used to generate equivalent atoms: #1: ꢁx,
ꢁy + 2, ꢁz; #2: ꢁx, ꢁy + 1, ꢁz + 1.
Fig. 4 (a) The structural unit of Cu1 with labeling scheme and 50%
thermal ellipsoids (hydrogen atoms are omitted for clarity). (b) Poly-
hedral representation of the coordination sphere of the Cu+ centre,
with display distorted tetrahedron arrangement in the coordination
polymer Cu1.
by three I ions and one N atom from 3-Hqlc with Cu–N distances
Fig. 1 The structural unit of Ag1 (a) and Ag2 (b) with labeling scheme
and 50% thermal ellipsoids (hydrogen atoms are omitted for clarity).
˚
of 2.051(1) A. The bridging iodine anions are coordinated
simultaneously to three Cu(I) metal centers (m3-bridges) with
slightly different coordination bond lengths span a range from
20
˚
2.645(2) to 2.694(3) A, which shows a rare ladder-like chain
smaller than those of 61.98ꢀ and 30.49ꢀ in Ag1. Hence, Ag2
overcomes the shortcoming of the coplanarity, which is con-
structed by carboxyl and quinoline ring and shows fantastic
coplanar structure.
constructed by I and Cu atoms. The dihedral angle between two
Cu–I planes is 66.52ꢀ. On the other hand, the 3-Hqlc ligand uses
only one nitrogen atom of each quinoline ring to bridge two
metal centers belonging to adjacent [Cu2I2]n substructures, with
Crystal structure of [CuI(3-Hqlc)]n (Cu1). Coordination
polymer Cu1 crystallizes in a monoclinic space group P2(1)/n
and displays a 1D ladder chain structure, which further forms
2D structure by hydrogen bonding interaction. The asymmetric
unit of coordination polymer Cu1 contains one Cu(I) ion, one
iodine ion and one 3-Hqlc ligand (Fig. 4). Cu(1) is coordinated
˚
a Cu/Cu distance of 2.723(4) A, which is close to the sum of the
˚
van der Waals radii of Cu atoms (2.8 A), implying the existence
of weak Cu/Cu interactions.21 This conformation is stabilized
by intermolecular hydrogen bonding. In coordination polymer
Cu1, donor/acceptor distance in O–H/O can be found, which
˚
˚
is ranging from 1.682 to 2.562 A. The shortest distance 1.782 A
Fig. 2 Ball-and-stick representation of the 1D chain structure and the 1D + 1D / 1D chain structure in Ag1.
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Fig. 5 Drawings of the [Cu2I2]n infinite chain subunit, the sheet, and the crystal packing of coordination polymer Cu1.
refers to the intermolecular O2–H2/O1 (:OHO ¼ 172.99ꢀ) decreases. Accordingly, the luminescent emission peaks of Ag1,
hydrogen bond. A two-dimensional supramolecular network is Ag2 and Cu1 in solution display red shis signicantly from 298
formed by O–H/O hydrogen bonded interactions (Fig. 5).
K to 77 K.
The luminescence quantum yields of coordination polymers
Ag1, Ag2, Cu1 and H2qldc are determined in DMSO, CH3CN,
and CH3OH. The value of the quantum yields for H2qldc in
DMSO, CH3CN and CH3OH are 0.016, 0.012 and 0.008, respec-
tively, while those of Ag1 are 0.185, 0.143 and 0.092 (0.254, 0.212
and 0.126 for Ag2, 0.283, 0.224 and 0.151 for Cu1). The quantum
yields of Ag1, Ag2 and Cu1 are much higher than that of the free
ligand, which can be easily explained by aggregation of the pure
ligands in the solvents, which would also be in accordance with
their low quantum yield. Complexation with the silver or copper
might make aggregation and p-stacking more difficult than for
the pure ligands and when coordination polymers assemble,
the enhancement aer the connection of the ligand to metal
center increases the conformational rigidity of the ligands, and
the loss of energy via thermal vibration decay may be reduced.
Compared with coordination polymers Ag1, Ag2 and Cu1, the
luminescence quantum yields of Ag2 and Cu1 is signicantly
higher than Ag1, which is attributed to the decarboxylation
effect. Aer decarboxylation making the dihedral angle of
carboxyl and quinoline decreases and Ag1 has two dihedral
angles are 61.98ꢀ and 30.49ꢀ respectively. However, dihedral
angle of Ag2 is 3.70ꢀ and Cu1 is 5.47ꢀ. The nice coplanar feature
of the structure in Ag2 and Cu1 can enhance the mobility of p
electrons in organic aromatic rings, which is in favor of lumi-
nescent emission.
In the solid state, the maximum emission band for coordi-
nation polymer Ag1 is located at 455 nm (446 nm for Ag2), upon
excitation at 300 nm, exhibiting blue emissions at 298 K. The
solid-state uorescence spectra of Ag1 and Ag2 exhibit strong
red-shied photoluminescence emission in comparison with
that of free H2qldc ligand (lem ¼ 398 nm). It is noted that there
is no emission band for H2qldc ligand can be observed in the
region, the photoluminescence origin of the emission bands for
the coordination polymers Ag1 and Ag2 should be attributed to
MLCT22b,26 (Scheme 2). At 77 K, the emission band for coordi-
nation polymer Ag1 is located at 476 nm and Ag2 is located at
479 nm (lex ¼ 300 nm), exhibiting blue emissions in the solid
state (Fig. 7), which shows that Ag(I) coordination polymers can
be used as stable blue materials. The change of temperature
from 298 K to 77 K causes a bathochromic shi of emission
peaks in the solid state of Ag1 and Ag2. Obviously, the red shi
Photoluminescent properties and lifetimes of coordination
polymers
The emission spectra of Ag1, Ag2 and Cu1 are recorded in
different solvents and in the solid state at 298 K and 77 K. The
photoluminescent data for emission are gathered in Table 3. To
investigate the details of surrounding environment effects, the
emission spectra of Ag1, Ag2 and Cu1 in solutions (DMSO,
CH3CN and CH3OH) with the same concentration (1.0 ꢂ 10ꢁ5
mol Lꢁ1) were examined by luminescence spectrophotometry at
1
298 K and 77 K. The H NMR data indicates that Ag1, Ag2 and
Cu1 still keep polymeric structure in solutions and don't
decompose (Fig. S6–S8†). As shown in Fig. 6, there are high
energy (HE) emission and low energy (LE) emission in Ag1 and
Ag2. The corresponding maximum emissions are observed at
427 and 631 nm in DMSO (416 and 624 nm in CH3CN, 404 and
611 nm in CH3OH) for Ag1, and 446 and 609 nm in DMSO (431
and 618 nm in CH3CN, 412 and 628 nm in CH3OH) for Ag2. The
luminescence spectra of Ag1 and Ag2 show that the HE peaks
probably result from intraligand transitions in H2qldc, and the
Ag atoms may play some role in these transitions.22 What's
more, the LE emissions should be, without doubt, phospho-
rescence because of their long wavelengths and long lifetime in
microsecond scale.23 In addition, the maximum emission band
for coordination polymer Cu1 is located at 602 nm in DMSO
(590 nm in CH3CN, 578 nm in CH3OH), upon excitation at 360
nm at 298 K, the red-shied emission compared with ligand
H2qldc can be assigned to metal-to-ligand charge transfer
(MLCT), a combination of iodide-to-copper charge transfer
(XMCT) and d–s transitions in Cu1 (ref. 24) (Scheme 2). The
change of temperature from 298 K to 77 K (ref. 25) caused the
red shi of the emission peaks substantially in all the solutions
of Ag1, Ag2 and Cu1, the emission peaks show rich structural
features at 77 K. Such fascinating phenomenon may be attrib-
uted to the different state of solution at the low temperature. At
77 K, the viscosity of the solvent increases, and the interaction
between uorescent substance and solvent, the forces of
attraction and hydrogen bonds may be stronger in contrast with
those at 298 K. In this case, excited state is more stable, and the
energy level difference between ground state and excited state
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Table 3 Luminescence data for coordination polymers Ag1, Ag2, Cu1 and ligand H2qldc
Lifetimes (ms)
Coordination polymers/
ligands
Absorption (nm)
Excitation Emission CIE
Quantum yields
s1
s2
hsi
(3/dm3 cmꢁ1 molꢁ1) (l, nm)
(lmax, nm) (x, y)
(F)b
(ms) A1% (ms) A2% (ms)
Conditionsa
Ag1
Ag2
Cu1
267 (79 236)
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
360
360
360
360
360
360
360
360
300
300
300
300
427, 631 0.17,
0.12
416, 624 0.16,
0.05
404, 611 0.15,
0.06
0.185
0.143
0.092
—
1.72 46.39 13.71 53.61 12.54 DMSO,
298 K
1.77 45.68 13.49 54.32 12.33 CH3CN,
298 K
0.91 6.37 7.29 55.40 7.20 CH3OH,
298 K
227 (139 893)
222 (84 282)
—
455
0.23,
0.29
0.89 54.51 7.08 45.49 6.27 Solid, 298 K
—
453, 639 0.18,
0.22
434, 626 0.16,
0.16
425, 614 0.15,
0.15
—
1.37 51.73 18.03 48.27 16.78 DMSO, 77 K
—
—
2.04 43.31 15.55 56.69 14.32 CH3CN,
77 K
1.12 40.59 13.02 59.41 12.36 CH3OH,
77 K
—
—
—
476
0.23,
0.30
—
1.81 54.10 18.10 45.90 16.38 Solid, 77 K
276 (63 000)
446, 609 0.23,
0.14
431, 618 0.17,
0.06
412, 628 0.18,
0.17
0.254
0.212
0.126
—
1.16 49.43 11.29 50.57 10.37 DMSO,
298 K
1.44 64.73 10.99 35.27 9.14 CH3CN,
298 K
1.12 56.03 10.03 43.97 8.92 CH3OH,
298 K
222 (54 294)
215 (91 294)
—
446
0.23,
0.27
1.20 50.40 8.33 49.60 7.42 Solid, 298 K
—
471, 632 0.18,
0.26
452, 628 0.15,
0.21
445, 631 0.17,
0.21
—
1.29 48.60 13.03 51.40 12.03 DMSO, 77 K
—
—
1.09 57.14 12.37 42.86 11.18 CH3CN,
77 K
1.25 56.00 10.89 44.00 9.66 CH3OH,
77 K
—
—
—
479
602
590
578
576
627
612
606
646
434
419
406
398
0.24,
0.33
0.61,
0.39
0.58,
0.41
0.50,
0.49
0.51,
0.48
0.65,
0.34
0.57,
0.43
0.57,
0.43
0.67,
0.30
0.20,
0.20
0.16,
0.06
0.18,
0.12
0.20,
0.19
—
1.74 43.02 19.02 56.98 17.90 Solid, 77 K
297 (75 669)
0.283
0.224
0.151
—
1.40 50.24 16.07 49.76 14.88 DMSO,
298 K
1.71 47.03 13.17 52.97 11.99 CH3CN,
298 K
1.09 44.33 11.47 55.67 10.74 CH3OH,
298 K
276 (97 888)
274 (76 551)
—
1.98 40.38 14.85 59.62 13.78 Solid, 298 K
—
—
1.84 52.33 28.11 47.67 26.35 DMSO, 77 K
—
—
1.22 46.15 17.14 53.85 16.22 CH3CN,
77 K
1.12 51.29 13.00 48.71 12.01 CH3OH,
77 K
—
—
—
—
2.58 46.03 22.50 53.97 1.847 Solid, 77 K
H2qldc
274 (24 939)
237 (71 200)
235 (101 444)
—
0.016
0.012
0.008
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
DMSO,
298 K
CH3CN,
298 K
CH3OH,
298 K
Solid, 298 K
a
Concentration in DMSO, CH3CN and CH3OH solutions: (M) ¼ 1 ꢂ 10ꢁ5 M. b Determined using quinine sulfate in 0.1 M sulfuric acid (F ¼ 0.546)
for Ag1, Ag2 and rhodamine B chloride in ethanol (F ¼ 0.690) for Cu1 as a standard.
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Fig. 6 Normalized emission spectra of coordination polymers Ag1, Ag2 and Cu1 in DMSO, CH3CN and CH3OH solutions (concentration: (M) z
10ꢁ5 M) at 298 K and 77 K and the corresponding color coordinate diagram of emission.
luminescent lifetimes for Ag1 and Ag2 in the solid state are
determined. The luminescent lifetimes for Ag1 at 298 K and 77
K are 6.27 ms and 16.38 ms, respectively, while those of Ag2 are
7.42 ms and 17.90 ms. The luminescent lifetimes of Ag1 and Ag2
at 77 K are more than twice as those at 298 K in the solid state. A
general trend is that the lifetime of emission of low-temperature
(77 K) is longer than that in room temperature (298 K), which is
attributed to the decrease of thermal vibration and nonradiative
transition at low temperature.27
Coordination polymer Cu1 is different from Ag1 and Ag2 in
the solid state, under UV irradiation, at room temperature, Cu1
emits an intense yellow light. The fascinating and visually
impressive phenomenon of thermochromic luminescence of
Cu1 is revealed by immersing the samples into liquid nitrogen
(77 K). When exposed to UV light, the crystalline solid shows a
color changing process from bright yellow luminescence at
room temperature to red luminescence at low temperature of
liquid nitrogen. Once the samples gradually warmed up to room
temperature, the yellow emission is recovered, indicating a
reversible thermochromic luminescence for Cu1. The variable
temperature luminescence spectrum is shown in Fig. 7. Cu1
shows tunable luminescence at 298 K and 77 K in the solid
state. The emission maximum shis from 576 nm to 646 nm in
Scheme 2 Schematic energy level diagram of coordination polymers
Ag1, Ag2 and Cu1 molecular orbitals ((1) MLCT; (2) d–s transitions, (3)
intraligand transitions).
of coordination polymer Ag2 is longer than Ag1, which due to
the existence of Ag–Ag interaction in Ag2. Meanwhile, one of
carboxyl removed, making the nice coplanar feature of the
structure in Ag2 and improve the mobility of p electrons in
organic aromatic rings, so that it shows the excellent lumines-
cence. Ag2 shows stable luminescence at 298 K and 77 K in the
solid state with the CIE color shis from deep-blue (0.23, 0.27)
to light blue (0.24, 0.33). Both Ag1 and Ag2 display stable blue
luminescent in the solid state at 298 K and 77 K. The
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Fig. 7 Normalized emission spectra of coordination polymers Ag1, Ag2 and Cu1 in the solid state at 298 K and 77 K and the corresponding color
coordinate diagram of emission.
the Cu(I) coordination polymer, characteristic of triplet state
emission.
Thermal analysis and XRPD patterns of Ag1, Ag2 and Cu1
Thermogravimetric experiments were conducted to study the
thermal stability of coordination polymers Ag1, Ag2 and Cu1
(Fig. S9†). The experiments were performed on samples con-
sisting of numerous single crystals in the 25–700 ꢀC range. The
TG curve shows that Ag1 has two weight-loss stages. The loss of
53.49% occurring at the rst step is attributed to decomposition
of 3-Hqlc in the range of 238.1–251.8 ꢀC (calculated 53.44%).
The second weight-loss of 13.22% at 452.2–556 ꢀC can be
ascribe to loss the 2-position carboxyl (calculated 13.58%). The
TG curve of Ag2 shows the coordination polymer is very steady
and there is no weight loss until 245.8 ꢀC, the rst weight-loss of
8.01% which corresponding to loss the 3-position carboxyl
(calculated 7.86%) and the following weight-loss of 53.57%
during 338.2–367.2 ꢀC, which is attributed to the decomposition
of the 3-qlc ligands (calculated 53.62%). The remaining weight
of 33.29% for Ag1 and 38.42% for Ag2, corresponds to the
percentage (calculated 32.98% and 38.52%) of the Ag compo-
nents, indicating that the nal product is metal Ag. Through
analyzing the TG curves of Ag1 and Ag2, we deduce that once 2-
position carboxyl coordinates to Ag atom, the sample is very
steady and it begins to lose the weight until 452.2 ꢀC in Ag1. In
the TG curve of Cu1, there are two weight-loss steps. The loss
Fig.
Cu1@PMMA.
8 The comparison TG curves of pure Cu1, PMMA, and
the solid state luminescence spectrum when the temperature is
decreased from 298 to 77 K. The red shi of 70 nm for Cu1 is
large enough to make the color change visible by the naked eye
and the CIE color shis from bright yellow (0.51, 0.48) to red
(0.67, 0.30). Their emission bands could be attributed to triplet
cluster-centered (3CC) excited states, a combination of XMCT
and d–s transitions21 (Scheme 2). The solid state lifetimes at
room temperature is on the scale of microseconds (13.78 and
20.73 ms at 298 K and 77 K respectively), suggestive of their
phosphorescent character. The long decay lifetime displayed by
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Table 4 Luminescence data for coordination polymer Cu1 and Cu1@PMMA
Lifetimes (ms)
Excitation (l, nm)
Emission (lmax, nm)
Integrated area
s1 (ms)
A1%
s2 (ms)
A2%
hsi (ms)
Cu1@0.2% PMMA
Cu1@0.4% PMMA
Cu1@0.6% PMMA
Cu1@0.8% PMMA
Cu1@1.0% PMMA
Cu1@1.2% PMMA
Cu1@1.4% PMMA
360
360
360
360
360
360
360
578
578
578
578
578
578
578
24 862.07
88 384.10
160 371.01
229 682.46
334 392.39
72 764.47
31 401.74
1.17
1.41
1.18
1.01
2.08
1.13
1.03
8.66
8.75
6.44
4.25
2.93
9.42
8.57
35.86
46.05
50.26
83.43
95.63
47.14
43.69
91.34
91.25
93.56
95.75
97.07
90.58
91.43
37.75
45.92
50.18
83.39
95.57
47.03
43.60
lm with optical transfer function.28 As an extension of this
work, we describe the incorporation of the newly designed, and
intensity luminescent Cu1 into PMMA, a low-cost and easily
prepared polymer with excellent optical quality. The excitation
spectrum of the PMMA polymer lms doped with Cu1 at
different concentrations [0.2, 0.4, 0.6, 0.8, 1.0, 1.2 and 1.4% (w/
w)] is shown in Table 4. The emission spectrum of PMMA doped
with coordination polymer Cu1 is at 578 nm (lex ¼ 360 nm). The
lifetimes for coordination polymer Cu1 and the PMMA matrixes
doped with coordination polymer Cu1 are listed in Table 4.
Noticeably, with the increase of the content of coordination
polymer Cu1, the lifetime of the Cu1@PMMA lms increases
and reaches a maximum at 1.0% and then decreases with
further increasing of the content of coordination polymer Cu1
(Fig. 9). It can be attributed to the fact that with a low concen-
tration of coordination polymer Cu1 in the PMMA polymer, the
coordination polymer Cu1 can disperse uniformly in the PMMA
matrix and the PMMA effectively sensitizes the luminescence of
the coordination polymer Cu1. Upon further increasing of the
content of coordination polymer Cu1 to more than 1.0%, some
aggregates formed in the lm and the excition migration
between the Cu1 resulted in the luminescence quenching of
coordination polymer Cu1.29 Noticeably, with the increasing of
the content of Cu1, the lifetime of Cu1@PMMA lms reaches a
maximum at 1.0% (s ¼ 95.57 ms), which is more than eight
times longer than that of Cu1 (s ¼ 13.78 ms). All s values for the
doped polymer systems are higher than coordination polymer
Cu1, indicating that radiative processes are operative in all the
doped polymer lms. Cu1@PMMA is conrmed as a yellow
luminescence polymer lm material.
Fig. 9 The emission spectra of PMMA polymer doped with coordi-
nation polymer Cu1 in 0.2–1.4% at 298 K under excitation at 360 nm.
45.74% occurring at the rst step is attributed to the sublima-
tion of I2 and lose the weight of 3-position carboxyl in the range
ꢀ
of 237.8–320.4 C (calculated 45.29%). The second weight-loss
of 31.63% at 320.4–402.9 ꢀC corresponds to the decomposi-
tion of quinoline (calculated 33.76%). The remaining weight of
22.63% for Cu1, the observed weight loss of 22.63% is in good
agreement with the calculated value (20.95%), indicating that
the nal product is CuO.
The XRPD patterns for coordination polymers Ag1, Ag2 and
Cu1 are shown in Fig. S10.† The diffraction peaks of both
simulated and experimental patterns match well in key posi-
tions, indicating thus the phase purities of coordination poly-
mers Ag1, Ag2 and Cu1.
Properties of PMMA polymer doped with coordination
polymer Cu1
TG analysis of Cu1@PMMA lm exhibits no weight-loss in the
temperature range of 25–285 C in contrast to that for coordi-
Conclusion
ꢀ
nation polymer Cu1 (Fig. 8). Furthermore, TG analysis of In summary, three 1D coordination polymers [Ag(2,3-Hqldc)]n
ꢀ
Cu1@PMMA lm shows a slight increase of 48 C in compar- (Ag1), [Ag(3-qlc)]2n (Ag2) and [CuI(3-Hqlc)]n (Cu1) were
ison with the pure PMMA, which suggests that the thermal successfully synthesized under hydro(solvo) thermal methods
stability of the Cu1@PMMA lm is essentially improved by based on quinoline-2,3-dicarboxylic acid (H2qldc). Through
doping coordination polymer Cu1. The IR spectra of Cu1, controlling the temperature makes the ligand H2qldc decar-
PMMA and Cu1@PMMA are shown in Fig. S11.†
boxylation and results in the formation of 3-Hqlc ligand. Aer
Based on the excellent luminescence of Cu(I) coordination decarboxylation, the nice coplanar feature of the structure in
polymers, making it incorporated into polymer matrixes Ag2 can enhance the luminescent efficiency. Both Ag1 and Ag2
represents a new class of materials. The materials can serve as display stable blue luminescent in the solid state and in
ideal candidates in the pursuit of application in farm plastic- solvents (DMSO, CH3CN and CH3OH) at 298 K and 77 K. The
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luminescent lifetimes of Ag1 and Ag2 at 77 K are longer than at 12 (a) Z. M. Hudson, C. Sun, M. G. Helander, Y. L. Chang,
298 K both in the solid state and in solvents. The quantum
yields of Ag1 and Ag2 are much higher than those of free ligand.
The superior photoluminescent properties make coordination
polymers Ag1 and Ag2 promising materials for the development
Z. H. Lu and S. Wang, J. Am. Chem. Soc., 2012, 134, 13930;
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changing the temperature from 298 K to 77 K in the solid state,
the luminescence variation from bright yellow to red indicating
thermochromic luminescence for Cu1. In extending work, Cu1
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Acknowledgements
This work was supported by the National Natural Science
Foundation of China (Grant 21371040 and 21171044), the
National key Basic Research Program of China (973 Program,
no. 2013CB632900), and the Fundamental Research Funds for
the Central Universities (Grant no. HIT. IBRSEM. A. 201409),
also Program for Innovation Research of Science in Harbin
Institute of Technology (PIRS of HIT no. A201416 and B201414).
¨
¨
Renement, University of Gottingen, Gottingen, Germany,
1997; (b) G. M. Sheldrick, SHELXL 97 Program for Crystal
¨
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Structure Solution, University of Gottingen, Gottingen,
Germany, 1997.
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