Synthesis, crystal structures and luminescence properties of three new cadmium 3D coordination polymers

Article abstract of DOI:10.3390/molecules25112465

The new rigid planar ligand 2,5-bis(3-(pyridine-4-yl)phenyl)thiazolo[5,4-d]thiazole (BPPT) has been synthesized, which is an excellent building block for assembling coordination polymer. Under solvothermal reaction conditions, cadmium ion with BPPT in the

Full text of DOI:10.3390/molecules25112465

molecules
Communication
Synthesis, Crystal Structures and Luminescence
Properties of Three New Cadmium 3D
Coordination Polymers
Hai-Yan Ju 1 , Gang Zhang 1,2, Ming Yang 1,2, De-Zheng Liu *, Yong-Sheng Yang 1,2,* and
,2
3,
Yan-Bo Zhang 1
,2,
*
1
School of Chemistry and Engineering, Wuhan Textile University, 1 Textile Road, Wuhan 430073, China;
juliesky2001@163.com (H.-Y.J.); prayerzg2019@163.com (G.Z.); yangming491@163.com (M.Y.)
Hubei Key Laboratory of Biomass Fibers and Eco-dyeing & Finishing, Wuhan Textile University,
Wuhan 430073, China
Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle, Hubei University of Arts and
Science, Xiangyang 441053, China
2
3
*
Correspondence: liudezheng@hbuas.edu.cn (D.-Z.L.); ysyang@wtu.edu.cn (Y.-S.Y.);
2
006108@wtu.edu.cn (Y.-B.Z.)
ꢀ
ꢁꢂꢀꢃꢄꢅꢆꢇ
Academic Editors: Raquel G. Soengas and Humberto Rodríguez-Solla
Received: 12 April 2020; Accepted: 18 May 2020; Published: 26 May 2020
ꢀ
ꢁꢂꢃꢄꢅꢆ
Abstract: The new rigid planar ligand 2,5-bis(3-(pyridine-4-yl)phenyl)thiazolo[5,4-d]thiazole
BPPT) has been synthesized, which is an excellent building block for assembling coordination
polymer. Under solvothermal reaction conditions, cadmium ion with BPPT in the presence of
(
0
0
various carboxylic acids including (1,1 -biphenyl)-4,4 -dicarboxylic acid (BPDC), isophthalic acid
IP), and benzene-1,3,5-tricarboxylic acid (BTC) gave rise to three coordination complexes, viz,
Cd(BPPT)(BPDA)](BPPT)n ( ), [Cd(BPPT) (IP)] (CH OH) ( ), and [Cd (BPPT) (BTC) (H O) ] ( ).
The structures of , and were characterized by single crystal X-ray diffraction. The IR spectra
as well as thermogravimetric and luminescence properties were also investigated. Complex is a
two-dimensional (2D) network and further stretched to a 3D supramolecular structure through
stacking interaction. The complexes and show 3D framework. The complexes , and exhibited
luminescence property at room temperature.
(
[
1
2
3
3
3
3
2
2
2
1,
2
3
1
π–π
2
3
1,
2
3
Keywords: crystal structure; 3D coordination polymer; luminescence properties
1
. Introduction
In the last twenty years, the design and synthesis of new coordination polymers (CPs) have
become an important research area for their intriguing structures and interesting properties, such as
catalysis [ ], gas storage and separation [ ], photoluminescence [10 12], biomedical uses [13],
and other applications [14 16]. In order to make the CPs have special structures and properties,
it is necessary to synthesize new ligands [17], in which the heteroaromatic thiazolothiazole unit
can be employed as a building block incorporated into organic ligands; the strong stacking
1–
6
7–
9
–
–
π–π
and overlapping of the orbitals in thiazolothiazole unit can afford high electron and hole mobilities,
which are crucial properties for efficient charge transfer in optoelectronic materials [18]; and the
heteroaromatic thiazolothiazole unit has also shown high luminescence properties [19]. On the other
hand, the luminescence properties of coordination polymers with d 10 metal centres Cd(II) have
attracted intense interest because of the potential applications of these compolexes as luminescent
sensing materials [20]. Therefore, the design and synthesis of diverse structural Cd–MOFs or Cd–CPs
with optical properties are highly demanded [21,22].
Molecules 2020, 25, 2465; doi:10.3390/molecules25112465
www.mdpi.com/journal/molecules

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Here, we have selected a new ligand, namely 2,5-bis(3-(pyridine-4-yl)phenyl)thiazolo[5,4-d]thiazole
BPPT). In the present report, we used BPPT as a ligand to self-assemble with Cd(II) ion and obtained a
(
new three-dimensional coordination polymer, namely [Cd(BPPT)(BPDA)](BPPT)n (
1), [Cd(BPPT) (IP)]
(
CH OH) ( ) and [Cd (BPPT) (BTC) (H O) ] ( ). The structure was characterized by single crystal
2
3
3
3
3
2
2
2
X-ray diffraction. The IR spectra as well as thermogravimetric and luminescence properties were
also investigated.
2
. Results and Discussion
2
.1. The Structure of Complex 1
Single-crystal X-ray diffraction indicated that complex 1 crystallizes in triclinic P-1 space group
and displays a two-dimensional (2D) structure, which contains two BPPT, one deprotonated BPDA
ligand, and one Cd(II) cation in the formula unit. A “Z” shape cavity is formed via the coordination
interaction of Cd(II) (Cd-N and Cd-O) among BPPT and BPDA ligands, which can further propagate
to an infinite 2D lamellar framework. As shown in Figure 1a, a 3D layer-type network architecture is
formed owing to the presence of
exactly one BPPT molecule in the “Z” shape cavity, and the closest distance between two parallel
-stacked BPDA molecules was around 3.56 Å. Each Cd(II) ion, adopting an octahedral geometry,
π–π stacking interactions between the layers. Interestingly, there is
π
is equatorially coordinated by four oxygen atoms from two BPDA ligands and two axially coordinated
nitrogen atoms from BPPT (Figure 1b). The Cd-O bond lengths range over 2.303(2)–2.461(2) Å and the
Cd-N bond length is 2.351(3) Å. Selected bond distances and angles are listed in Table 1. The BPDA
ligands and BPPT ligands are considered as linkers to generate a 4-connected 2D network with sql
topology (Figure 1c).
Figure 1. The 3D network of
network formed in 1 (c).
1 (a), the coordination environment of Cd(II) in 1 (b), and the topological
2
.2. The Structure of Complex 2
The X-ray structural analysis reveals that complex
P21/c, which is a three-dimensional (3D) coordination polymers constructed from BPPT and IP ligands
Figure 2a). The structural unit is made up of one Cd (II) atom, one BPPT ligand, and one IP ligand.
2 crystallizes in the monoclinic space group
(
Cd (II) ions are bridged by IP ligands to form a 2D wavelike network along the a axis (Figure 2b).
It is noteworthy that the Cd (II) is a seven coordinated ion (Figure 2c), in which five oxygen atoms
from IP ligand are in equatorial plane to form a two-dimensional structure (Figure 2b). The Cd-O
◦
◦
bond distances vary from 2.366(16) to 2.393(17) Å. The O-Cd-O bond angles are 53.3(5) –166.5(6) ,
respectively. Two pyridyl nitrogen atoms coordinate with Cd (II) in the axial direction to form a
three-dimensional structure with a Cd-N bond distance of 2.317(18) Å. The N-Cd-N bond angle is

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◦
1
76.5(7) . That is to say, the Cd(II) ions are assembled via bridging carboxylate oxygen atoms in
a 2D plane, and these planes are further interconnected by the BPPT ligand, giving rise to a 3D
framework. The closest distance between two parallel -stacked DPPZ ligands was around 3.55 Å,
π
that is, within the range of π−π interaction. Topological analysis through the olex, the IP ligands,
and BPPT ligands are considered as linkers, then the 3D structure can be classified as a 5-connected
4
4
4
network with (4.8 )(4.6 .8 .10) topology (Figure 2d).
Table 1. Crystal data and structure refinement for 1, 2, and 3.
Complex
1
2
3
Empirical formula
Formula weight
Temperature
C66H40CdN O4S
C35H26CdN O S
C96H61Cd N12O14S6
8
4
4
6
2
3
1249.71
293(2) K
769.08
293(2) K
2113.01
293(2) K
Wavelength
1.54178 A
1.54178 A
1.54178 A
Crystal system, space group
Triclinic, P-1
a = 5.4580(4) Å
α = 76.509(5) deg.
b = 15.3295(9) Å
β = 85.570(6) deg.
c = 16.3168(11) Å
γ = 82.198(5) deg.
Monoclinic, P21/c
a = 12.7996 (2) Å
α = 90 deg.
Triclinic, P-1
a = 10.4278(4) Å
α = 88.931(4) deg.
b = 12.5607(7) Å
β = 89.037(4) deg.
c = 18.2058(8) Å
γ = 83.109(4) deg.
Unit cell dimensions
b = 17.9295(3) Å
β = 96.4141(14) deg.
c = 14.5012(2) Å
γ = 90 deg.
3
3
3
Volume
Z, Calculated density
Absorption coefficient
F(000)
1313.77(15) Å
3307.07(8) Å
2366.71(19) Å
3
3
3
1, 1.580 Mg/m
4, 1.559 Mg/m
6.908 mm
1544
1, 1.483 Mg/m
−1
−1
−1
5.324 mm
636
7.147 mm
1057
Crystal size
Theta range for data collection
0.3 × 0.2 × 0.1 mm
0.3 × 0.25 × 0.2 mm
3.47 to 70.99 deg.
−15 ≤ h ≤ 11,
0.3 × 0.2 × 0.14 mm
4.26 to 71.09 deg.
−12 ≤ h ≤ 8,
3.60 to 70.95 deg.
−
5 ≤ h ≤ 6,
−18 ≤ k ≤ 18,
19 ≤ l ≤ 19
Limiting indices
−21 ≤ k ≤ 21,
−15 ≤ k ≤ 15,
−
−16 ≤ l ≤ 17
−22 ≤ l ≤ 22
1
2555/6390
16199/9166
Reflections collected/unique
Completeness to theta
Absorption correction
8494/5078 [R(int) = 0.0331]
[
R(int) = 0.0204]
[R(int) = 0.0426]
97.3%
Semi-empirical from
equivalents
97.5%
Semi-empirical from
equivalents
98.1%
Semi-empirical from
equivalents
Full-matrix least-squares
on Fˆ2
Full-matrix least-squares
on Fˆ2
Full-matrix least-squares
on Fˆ2
Refinement method
Data/restraints/parameters
Goodness-of-fit on Fˆ2
4951/0/376
0.938
6268/6/433
1.061
8917/0/592
1.047
Final R indices [I > 2sigma(I)]
R indices (all data)
Largest diff. peak and hole
R1 = 0.0407, wR2 = 0.1112
R1 = 0.0473, wR2 = 0.1167
0.488 and −0.819
R1 = 0.0388, wR2 = 0.1085
R1 = 0.0416, wR2 = 0.1107
2.027 and −1.389 e.A−
R1 = 0.0725, wR2 = 0.2180
R1 = 0.0797, wR2 = 0.2300
3.271 and −1.542 e.A
3
−3
2
.3. The Structure of Complex 3
According to the single crystal-XRD analysis, complex
3
also crystallized in the monoclinic crystal
system with space group of P21/c and its asymmetric unit contains three Cd(II) ions, three BPPT ligands,
two BTC ligands, and two water molecules. Complex has a 3D structure (Figure 3a). The binding of
3
Cd(II) ions to the organic BTC ligand generates the 2D layer coordination structure, one carboxylic
acids group in the BTC coordinates to Cd (1) ion, and the other two carboxylic groups in the BTC
coordinates to Cd (2) (Figure 3b). The 2D layer interconnected by the BPPT ligand gives rise to a 3D
framework and the closest distance between the two parallel
π-stacked DPTTZ ligands was around
3.57 Å. As shown in Figure 3c, the metal atom Cd (1) is six-coordinate and in an octahedral geometry
coordination environment with two oxygen atoms (O3, O8) from BTC ligands, two water molecules,
and two nitrogen atoms (N3, N3) from BPPT. The Cd (1)-O3 bond length is 2.253(5) Å, the Cd (1)-O8
bond length is 2.346(9) Å, and the Cd (1)-N bond length is 2.319(6) Å. The O-Cd (1)-O angles are in
◦
◦
◦
◦
the range of 82.2(3) –180.00(11) , the N-Cd (1)-O angles are in the range of 88.7(2) –91.3(2) , and the
◦
N-Cd (1)-N angle is 180.0(3) . Each Cd (2) ion is located in an octahedral coordination environment.
Four oxygen atoms from two BTC ligands and two nitrogen atoms from two BPPT ligands in the

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◦
axial direction, the Cd (2)-N bond distance of 2.317(18) Å, and the N-Cd (2)-N bond angle is 176.5(7) .
The Cd (2)-O bond lengths are in the range of 2.255(4) Å–2.398(5) Å. The O-Cd (2)-O angles are in the
◦
◦
range of 55.02(16) –146.95(17) . The BTC ligands and BPPT ligands are considered as linkers, thus the
3
2
4
3
2
2
7
D structure can be classified as a 4, 5-connected network with (4 .6.8 .9)(8.9 .10 )(4 .6 .8) topology
(Figure 3d).
Figure 2. The 3D network of
Cd(II) in ), and the topological network formed in
spheres represent the isophthalic acid (IP ) ligands.
2
(
a
), the 2D [Cd(IP)] n layer in
2 (b), the coordination environment of
2
(c
2 (d); red spheres represent Cd(II) centers, blue
−
Figure 3. The 3D network of
Cd(II) in 3 ( ), and the topological network formed in
spheres represent the benzene-1,3,5-tricarboxylic acid (BTC ) ligands.
3
(
a), the 2D [Cd(BTC)] n layer in
3 (b), the coordination environment of
c
3 (d
); red spheres represent Cd(II) centers, blue
−
2
.4. TGA
TGA was conducted to investigate the thermal stability of complexes
1
,
2
, and
3
. As shown in
◦
Figure 4, the TG curve of
1
displayed no obvious weight loss before 380 C, the weight loss of 49.1%
can be distributed to the removal of BPPT molecule in the “Z” shape cavity (calcd. 35.9%), and the

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◦
framework to decompose at 380–445 C, the remaining weight corresponds to the constitution of CdO
◦
(
4
calcd. 11.8%, found 9.2%) at 700 C. The TGA for complex
.1%) before 75 C, which is associated with the loss of one free methanol molecule. When the
temperature reaches 400 C, the framework of
5.5% (calculated 81.1%) at 700 C can be ascribed to the decomposition of organic matters in complex
2
shows a weight loss of 3.8% (calculated
◦
◦
2
begins to break down gradually. The weight loss of
◦
8
◦
2
. According to the TGA results, complex
3
exhibited no obvious weight loss before 310 C. After that
temperature, the framework begins to decompose. The weight loss of 84.1% (calculated 79.4%) at
◦
7
00 C can be ascribed to the decomposition of organic matters in complex 3.
Figure 4. Thermal gravimetric analysis (TGA) curves of complexes 1–3.
2
.5. IR Analysis
In the IR spectra of complexes
1
,
2
, and
(Figure 5), the broad bands at about 3482 cm 1 for
−
3 2 and
399cm 1 for 3 are assigned to the presence of methanol (2) water molecules (3). All three complexes
−
3
displayed similar FT-IR spectra with only a little variation in the peak position with regards to the
− −1 −1
1
-
C=N (1019 cm ) and -C-S bonds (693 cm and 650 cm ) of the BPPT [23]. The characteristic peaks
−
1
of the deprotonated –COO– symmetry band and the asymmetric band appeared at 1600 cm and
− −1 −1
1
1
423 cm for 2 and 1609 cm and 1438 cm for 3, respectively.
Figure 5. Comparison of FT-IR spectrum of complexes 1, 2, and 3.
2
.6. UV/Vis Analysis
From the spectrum of UV/vis (Figure 6), the maximum absorption of BPPT,
at 330 nm, 340 nm, 330 nm, and 344 nm, respectively. The bands could be assigned to characteristic
* transitions centered on BPPT. Compared with the free ligand BPPT, the absorption peaks of
, and have slightly red-shift, probably attributed to the coordination of the ligands to the Cd ion,
which effectively increases the conjugated extent of the complexes [24].
1, 2, and 3 occurred
π
–
π
1,
2
3

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Figure 6. UV/vis spectrogram of 2, 5-bis(3-(pyridine-4-yl)phenyl)thiazolo[5,4-d]thiazole (BPPT) as well
as complexes 1, 2, and 3 in the solid state.
2
.7. Luminescence Properties
The luminescence properties of complexes
temperature. The emission spectra are shown in Figure 7, and the complexes
1
,
2
, and
3
were investigated in the solid state at room
, and exhibit
1
,
2
3
luminescence properties, with an emission at 483 nm (excited at 340 nm), 463 nm (excited at 330 nm),
and 489 nm (excited at 344 nm), respectively. To understand the nature of the emission spectra,
the luminescence property of free BPPT ligand was also investigated in the solid state under the same
experimental conditions. The BPPT ligand exhibits one emission band at 455 nm upon excitation at
3
30 nm. This suggests that the emission of
the ligand [25]. By comparing the emission spectra of complexes
we can conclude that the enhancement of luminescence in , and
1
,
2
, and
3
originated from the
π
–
π
* electronic transition of
and the free BPPT ligand,
may be attributed to the ligation
1,
2, and
3
1, 2
3
of ligand to the metal center, which effectively increases the rigidity and reduces the loss of energy by
radiation less decay [26,27]. A detailed spectroscopic study of a possible structure-related luminescent
is underway.
Figure 7. The emission spectra of BPPT, 1, 2, and 3 in the solid state at room temperature.
. Experiment
3
3
.1. Material and Physical Measurements
The organic ligand BPPT was synthesized by modifying the reported procedure using
-(pyridine-4-yl)benzaldehyde [28]. 3-Bromobenzaldehyde, 4-Pyridineboronic acid, dithiooxamide
3
(
Macklin Biochemical Co., Ltd., Shanghai, China) and other reagents (Fuyu Chemical Co., Ltd., Tianjin,
China), were used without further purification. The structures of ligands used in the syntheses
of the coordination polymers are shown in Scheme 1. Elemental analyses for C, H, and N were
performed on a Perkin-Elmer 240C Elemental Analyzer (PerkinElmer, Waltham, MA, USA) at the
analysis center of Nanjing University. FT-IR (Fourier transform infrared) spectra were recorded
−1
in the range of 400–4000 cm on a Bruker Vector 22 FT-IR spectrophotometer (Bruker, Karlsruhe,
Germany) using KBr pellets. Powder X-ray diffraction (PXRD) measurements were carried out on

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a Bruker D Advance X-ray diffractometer (Bruker, Karlsruhe, Germany) using Cu-K
α
radiation
8
(
(
λ = 1.5418 Å). Thermal gravimetric analyses (TGAs) were taken on a Mettler–Toledo thermal analyzer
◦
−1
Mettler–Toledo, Greifensee, Switzerland) under an N2 atmosphere with a heating rate of 10 C
·min
.
The luminescence spectra were measured on a Perkin Elmer LS-55 fluorescence spectrophotometer
(PerkinElmer, Waltham, MA, USA).
Scheme 1. The structures of ligands used in the syntheses of the coordination polymers. BPPT, 2,
0 0
5
-bis(3-(pyridine-4-yl)phenyl)thiazolo[5,4-d]thiazole; BPDC, (1,1 -biphenyl)-4,4 -dicarboxylic acid; IP,
isophthalic acid; BTC, benzene-1,3,5-tricarboxylic acid.
3
.2. Synthesis of 3-(Pyridine-4-yl) Benzaldehyde
3
-Bromobenzaldehyde (1.98 g, 10.72 mmol) was dissolved in 20 mL of 1, 4-dioxane and 20 mL
of water. Then, 4-Pyridineboronic acid (1.26 g, 10.25 mmol) was added and dissolved, followed by
the addition of K CO (4.2 g, 17.36 mmol) and Pd(PPh ) (290 mg, 0.25 mmol). The mixture was
2
3
3 4
◦
refluxed under the protection of N gas and stirred for 72 h at 80 C. After cooling to room temperature,
2
the solvent was removed under reduced pressure to obtain the white solid. The residue was purified
by silica gel column chromatography using petroleum ether and ethyl acetate (v/v, 1/1) as eluent to
1
afford 3-(pyridine-4-yl) benzaldehyde. (Yield, 81.0%). H NMR (400 MHz, CDCl )
δ
10.16–10.08 (m,
3
1
H), 8.72 (d, J = 5.5 Hz, 2H), 8.16 (s, 1H), 7.94 (dd, J = 19.5, 7.7 Hz, 2H), 7.69 (t, J = 7.7 Hz, 1H), 7.55
−1
(
t, J = 6.5 Hz, 2H). IR (KBr pellet cm ): 3029(m), 2826(m), 2730(m), 1949(s), 1690(s), 1601(s), 1583(s),
413(s), 1302(s), 1189(s), 789(s), 654(m), 613(m), 579(m).
1
3
.3. Synthesis of 2,5-Bis(3-(pyridine-4-yl)phenyl)thiazolo[5,4-d]thiazole (BPPT)
A mixture of 3-(pyridine-4-yl)benzaldehyde (1.83 g, 10.0 mmol) and dithiooxamide (0.60 g,
◦
5
.0 mmol) in DMF (20 mL) was stirred at 150 C for 24 h. The residue was purified by silica gel column
1
chromatography using dichloromethane (DCM) as eluent to afford L (yield, 81.0%). H NMR (400
1
MHz, CHCl ): H NMR (400 MHz, CDCl )
δ 8.73 (dd, J = 4.5, 1.6 Hz, 2H), 8.32 (t, J = 1.7 Hz, 1H), 8.05
3
3
(
ddd, J = 13.4, 7.8, 6.4 Hz, 1H), 7.79–7.70 (m, 1H), 7.67–7.57 (m, 3H), 2.95 (dd, J = 28.8, 22.7 Hz, 1H).
−
1
IR(KBr pellet cm ): 3033(m), 1661(w), 1597(s), 1533(m), 1469(m), 1286(m), 1222(m), 1020(m), 791(s),
6
73(s), 609(s).
3
.4. Synthesis of [Cd(BPPT)(BPDA)](BPPT)n (1)
A mixture of BPPT (15.0 mg, 0.03 mmol), H BPDA (7.2 mg, 0.03mmol), Cd(ClO ) (2.1 mg,
2
4 2
0
.06 mmol), and DMF/water (15 mL, 1:1 v/v) was placed in a 20 mL Teflon-lined stainless steel autoclave.
The mixture was heated under autogenous pressure at 433 K for 72 h and then cooled to room
temperature. Yellow block-shaped crystals were collected by filtration, washed with H O, and dried in
2
air (yield 67%, based on BPPT). Analysis calculated for C H CdN O S : C 63.43, H 3.23, N 8.97%;
6
6
40
8
4 4
−1
found: C 63.40, H 3.27, N 8.96%. IR (KBr pellet cm ): 3043(w), 1569(s), 1524(s), 1451(m), 1386(s),
323(m), 1203(w), 838(m), 773(s), 691(m), 650(m), 627(m).
1

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3
.5. Synthesis of [Cd(BPPT) (IP)] (CH OH) (2)
3
A mixture of BPPT (15.0 mg, 0.03 mmol), H IP (4.8 mg, 0.03mmol), Cd(NO ) (2.1 mg, 0.06 mmol),
2
3 2
and methanol/water (15 mL, 1:1 v/v) was placed in a 20 mL Teflon-lined stainless steel autoclave.
The mixture was heated under autogenous pressure at 433 K for 72 h and then cooled to room
temperature. Yellow block-shaped crystals were collected by filtration, washed with H O, and dried in
2
air (yield 67%, based on BPPT). Analysis calculated for C H CdN O S : C 54.23, H 3.38, N 7.23%;
3
5
26
4
6 2
−1
found: C 54.18, H 3.42, N 7.24%. IR (KBr pellet cm ): 3482(m), 3024(w), 1600(s), 1587(s), 1551(s),
435(m), 1423(m), 1377(s), 1203(m), 1057(m), 1020(w), 755(m), 690(m), 673(m).
1
3
.6. Synthesis of [Cd (BPPT) (BTC) (H O) ] (3)
3 3 2 2 2
A mixture of BPPT (15.0 mg, 0.03 mmol), H BTC (6.3 mg, 0.03 mmol), Cd(NO ) (21.0 mg,
3
3 2
0.06 mmol), and ethanol/water (15 mL, 1:1 v/v) was placed in a 20 mL Teflon-lined stainless steel
autoclave. The mixture was heated under autogenous pressure at 433 K for 72 h and then cooled
to room temperature. Yellow block-shaped crystals were collected by filtration, washed with H O,
2
and dried in air (yield 67%, based on BPPT). Analysis calculated for C H Cd N O S : C 53.98,
9
1
6
61
3
12 14 6
−
H 2.88, N 7.87%; found: C 53.95, H 2.95, N 7.83%. IR (KBr pellet cm ): 3399(w), 1609(s), 1552(s),
1
488(w), 1433(m), 1414(m), 1367(m), 1213(w), 1020(w), 791(w), 690(m), 682(w), 618(w).
3
.7. X-Ray Crystallography
Diffraction data for the complex were collected at 293 (2) K, with a Bruker Smart 1000 CCD
diffractometer using Mo-K
absorption correction was applied to raw intensities [29]. The structure was solved by direct methods
SHELX-97) and refined with full-matrix least-squares technique on F using the SHELX-97 [30].
α radiation (λ = 0.71073 Å) with the ω-2θ scan technique. An empirical
(
2
The hydrogen atoms were added theoretically, and riding on the concerned atoms and refined with
fixed thermal factors. Crystal data, data collection, and structure refinement details are summarized in
Table 1. Suitable single crystals of 1, 2, and 3 were selected and mounted in air onto thin glass fibers.
In these structures, H atoms bonded to C atoms were treated as riding in geometrically idealized
positions, with C-H = 0.93 Å and Uiso (H) = 1.2U eq (C), and the selected bond lengths and angles with
their estimated standard deviations are listed in Table 2.
◦
Table 2. Selected bond lengths (Å) and bond angles ( ) of complex 1, 2, and 3.
Complex 1
Bond
Cd(1)-O(1)
Angle
Dist.
Bond
Cd(1)-N(1)
Angle
Dist.
Bond
Cd(1)-O(2)
Angle
Dist.
2.303(2)
2.351(3)
2.461(2)
◦
◦
◦
( )
( )
( )
O(1)#2-Cd(1)-O(1)
O(1)#2-Cd(1)-N(1)#2 90.11(9)
O(1)#2-Cd(1)-O(2)
N(1)#2-Cd(1)-O(2)
N(1)-Cd(1)-O(2)#2
180.00(12)
O(1)#2-Cd(1)-N(1)
O(1)-Cd(1)-N(1)#2
O(1)-Cd(1)-O(2)
89.89(9)
89.89(9)
55.11(8)
O(1)-Cd(1)-N(1)
N(1)-Cd(1)-N(1)#2
N(1)-Cd(1)-O(2)
O(1)-Cd(1)-O(2)#2
90.11(9)
180.0
89.93(9)
124.89(8)
124.89(8)
90.07(9)
90.07(9)
O(1)#2-Cd(1)-O(2)#2 55.11(8)
Complex 2
Bond
Dist.
Bond
Dist.
Bond
Dist.
N(4)-Cd(1)#1
Cd(1)-N(1)
Cd(1)-O(3)#5
Angle
2.317(18)
2.324(18)
2.381(17)
O(3)-Cd(1)#2
Cd(1)-O(2)
Cd(1)-O(4)#5
Angle
2.381(17)
2.364(16)
2.393(17)
Cd(1)-N(4)#3
Cd(1)-O(1)#4
Cd(1)-O(1)
Angle
2.317(18)
2.366(16)
2.522(16)
◦
◦
◦
( )
( )
( )
N(4)#3-Cd(1)-N(1)
176.5(7)
N(4)#3-Cd(1)-O(2)
94.7(6)
N(1)-Cd(1)-O(2)
87.4(6)

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Table 2. Cont.
N(4)#3-Cd(1)-O(1)#4 90.8(6)
N(4)#3-Cd(1)-O(3)#5 86.5(7)
O(1)#4-Cd(1)-O(3)#5 93.7(6)
N(1)-Cd(1)-O(1)#4
N(1)-Cd(1)-O(3)#5
N(4)#3-Cd(1)-O(4)#5 90.3(7)
O(1)#4-Cd(1)-O(4)#5 148.2(6)
N(1)-Cd(1)-O(1)
O(3)#5-Cd(1)-O(1)
85.7(6)
93.7(7)
O(2)-Cd(1)-O(1)#4
O(2)-Cd(1)-O(3)#5
N(1)-Cd(1)-O(4)#5
O(3)#5-Cd(1)-O(4)#5 54.6(6)
O(2)-Cd(1)-O(1)
125.9(5)
140.2(6)
92.7(7)
O(2)-Cd(1)-O(4)#5
N(4)#3-Cd(1)-O(1)
O(1)#4-Cd(1)-O(1)
85.7(6)
92.9(6)
72.7(6)
86.1(6)
166.5(6)
53.3(5)
139.0(5)
O(4)#5-Cd(1)-O(1)
Complex 3
Bond
Cd(1)-O(3)
Cd(2)-O(2)#2
Cd(2)-N(1)
Dist.
Bond
Cd(1)-N(5)
Cd(2)-N(2)
Cd(2)-O(6)#3
Angle
Dist.
Bond
Cd(1)-O(8)
Cd(2)-O(1)
Cd(2)-O(5)#3
Angle
Dist.
2.253(5)
2.255(4)
2.325(6)
2.319(6)
2.303(5)
2.367(5)
2.346(9)
2.309(4)
2.398(5)
◦
◦
◦
Angle
( )
( )
( )
O(3)#1-Cd(1)-O(3)
O(3)#1-Cd(1)-N(5)
O(3)#1-Cd(1)-O(8)#1 82.2(3)
N(5)-Cd(1)-O(8)#1
N(5)#1-Cd(1)-O(8)
O(2)#2-Cd(2)-N(2)
O(2)#2-Cd(2)-N(1)
O(2)#2-Cd(2)-O(6)#3 146.95(17)
N(1)-Cd(2)-O(6)#3
O(1)-Cd(2)-O(5)#3
180.00(11)
91.3(2)
O(3)#1-Cd(1)-N(5)#1 88.7(2)
O(3)-Cd(1)-N(5)#1
N(5)#1-Cd(1)-N(5)
N(5)#1-Cd(1)-O(8)#1 90.0(4)
O(3)-Cd(1)-O(8)
O(8)#1-Cd(1)-O(8)
N(2)-Cd(2)-O(1)
O(1)-Cd(2)-N(1)
O(1)-Cd(2)-O(6)#3
N(2)-Cd(2)-O(5)#3
91.3(2)
180.0(3)
O(3)-Cd(1)-N(5)
O(3)-Cd(1)-O(8)#1
O(3)#1-Cd(1)-O(8)
N(5)-Cd(1)-O(8)
O(2)#2-Cd(2)-O(1)
N(2)-Cd(2)-N(1)
N(2)-Cd(2)-O(6)#3
88.7(2)
97.8(3)
97.8(3)
90.0(4)
122.65(17)
71.0(2)
90.0(4)
90.0(4)
95.93(19)
88.3(2)
82.2(3)
180.000(1)
87.30(18)
83.8(2)
89.97(17)
99.5(2)
90.31(18)
90.4(2)
144.07(16)
O(2)#2-Cd(2)-O(5)#3 91.94(17)
N(1)-Cd(2)-O(5)#3 88.3(2)
O(6)#3-Cd(2)-O(5)#3 55.02(16)
Symmetry transformations used to generate equivalent atoms:
1
−
: #2
x, y
−
x
−
1,
−
−
y + 1,
z + 3/2.
−
z + 1.
2
: #1 x + 1, y + 1, z; #2
−
x, y + 1/2,
−
z + 3/2; #3 x
−
1, y
−
1, z; #4
−
x,
−
y + 1,
−
z + 1; #5
−
1/2,
3
: #1
−
x + 1, y + 1, z + 1 #2
−
−
−
x + 2, −y + 1, −z; #3 −x + 1, −y + 1, −z; #4 −x + 1, −y + 2, −z; #5 x, y − 1, z − 1, #6 x, y + 1, z + 1.
4
. Conclusions
The new rigid planar ligand BPPT has been synthesized, by introducing different rigid carboxylic
acids BPDC, IP, and BTC as auxiliary ligands; three Cd(II) CPs have been synthesized successfully
under solvothermal conditions. The complexes , and show a 3D framework and have good
thermal stability. In addition, complexes , and exhibit luminescence properties. We hope that
1,
2
3
1
,
2
3
this new BPPT ligand can obtain more novel structures. Studies toward the preparation of new
CPs or MOFs, especially further studies of luminescence properties including the three complexes,
are underway.
Author Contributions: Y.-S.Y. designed the research and wrote the manuscript. H.-Y.J., M.Y., and G.Z. performed
the experiments. D.-Z.L. and Y.-B.Z. participated in analyzing data and contributed to the revisions of the
manuscript. All authors have read and agreed to the published version of the manuscript.
Funding: This research was funded by Wuhan Textile University, grant number: 195014 and 017/192223; Hubei
Superior and Distinctive Discipline Group of “Mechatronics and Automobiles” (No. XKQ2019009); Natural Science
Foundation of Hubei Province (2016CFB334) and National Natural Science Foundation of China (No. 21204087).
Acknowledgments: We acknowledge Shiping Yan from Nankai Univerisity and Gongjun Chen from Shandong
Normal University, they provide the technical support and help us analysis the results.
Conflicts of Interest: The authors declare no conflict of interest.
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2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
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