New CuII and CdII Metal-organic Coordination Polymers with 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole Ligands: Syntheses, Structures and Luminescent Properties

Article abstract of DOI:10.1002/jccs.201400496

Three new complexes {[Cu(L¹)₂(NO₃)₂]H₂O}_oo (1), {[Cu₄(L²)₂(OAc)₈]-CH₃CH₂OH}_oo (2) and [Cd₂(L³

Full text of DOI:10.1002/jccs.201400496

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
New CuII and CdII Metal-organic Coordination Polymers with 1,2,4-triazolo[3,4-b]-
1,3,4-thiadiazole Ligands: Syntheses, Structures and Luminescent Properties
Jian-Zhong Fan, Jin-Ping Li, Li-Peng Zhang, Liu-Gen Zhang and Duo-Zhi Wang*
College of Chemistry and Chemical Engineering, Xinjiang University, Xinjiang Laboratory of Advanced Functional
Materials, Urumqi 830046, P. R. China
(Received: Nov. 16, 2014; Accepted: Jun. 7, 2015; Published Online: Aug. 27, 2015; DOI: 10.1002/jccs.201400496)
Three new complexes {[Cu(L1)2(NO3)2]·H2O}¥ (1), {[Cu4(L2)2(OAc)8]×CH3CH2OH}¥ (2) and
[Cd2(L3)3(NO3)4(H2O)2]¥ (3) (L1 = 4-phenyl-7-(pyridine-3-yl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole,
L2 = 4-(pyridine-3-yl)-7-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole, and L3 = 4-(pyridine-4-yl)-
7-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole) have been synthesized and characterized by elemental
analyses, IR spectra and single crystal X-ray diffraction. The structural analyses reveal that complex 1 is a
neutral 2-D network structure with a 44 topology, 2 has a 1-D neutral coordination chain with a
[Cu2(CH3COO)4] dinuclear structural unit bridged by four acetate ions, and 3 is a neutral rhombohedral
grid structure. All the complexes are air stable at room temperature. Furthermore, the fluorescent proper-
ties of complex 3 and corresponding ligand L3 have been investigated and discussed.
Keywords: Triazole; CuII/CdII complex; Synthesis; Crystal structure.
INTRODUCTION
The rational design and construction of coordination
now, 1,2,4-triazole, especially its derivatives, gains more
interest as ligands to bridge different metal ions to form
functional coordination polymers because of their potential
bridging fashions.16 For example, some complexes con-
taining 1-(9-(1H-1,2,4-Triazol-1-yl)anthracen-10-yl)-1H-
1,2,4-triazole with the luminescent properties have been
documented.17 Previously, we reported a series of bis-
triazole ligands, 9,10-bis(triazol-1-ylmethyl)anthracene
with d10 metal coordination polymers with better lumines-
cence properties,18 and some transition metal-organic coor-
dination complexes with 1,4-bis(1,2,4-triazol-1-ylme-
thyl)naphthalene/4,4¢-bis(1,2,4-triazol-1-ylmethyl)bi-
phenyl have been investigated.19 However, there are rare
reports of ligands based on condensed heterocyclic based
1,2,4-triazole as building blocks for the construction of co-
ordination complexes.
polymers (CPs) and metal-organic frameworks (MOFs)
have made rapid progress due to their intriguing structural
variety and potential applications such as gas adsorption
and separation, luminescence, ferroelectric, chirality, catal-
ysis, sensors and molecule magnets.1-3 Over the past de-
cade, polydentate aromatic nitrogen heterocyclic ligands
with five-membered rings (azoles) have been well used in
the construction of supramolecular structures.4,5 Among
polyazoles, imidazoles and triazoles ligands have been ex-
tensively used to construct various coordination networks
with diverse topologies and interesting properties.6,7 Much
effort has been invested in the purposeful design and con-
trollable synthesis of these functional complexes. How-
ever, it is still a great challenge to construct target coordina-
tion polymers with desired structures and functional pro-
perties because many factors, such as metal ion, organic
ligand, reagent ratio, solvent, pH value, temperature, and
so on, affect the final results.8-11
In this work, three ligands of condensed hetero-
cyclic based on 1,2,4-triazole: 4-phenyl-7-(pyridine-3-
yl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (L1), 4-(pyri-
dine-3-yl)-7-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-thia-
diazole (L2) and 4-(pyridine-4-yl)-7-phenyl-1,2,4-tria-
zolo[3,4-b]-1,3,4-thiadiazole (L3), (Chart 1), have been
designed and synthesized. The reactions of these ligands
with the corresponding metal salts lead to the formation of
three new metal–organic complexes with 1-D and 2-D
network structures. Herein, we report the syntheses, crys-
tal structures and emission properties of these complexes.
Great efforts have been focused on ligands based on
azole heterocycles, which have both good coordination
ability and diverse coordination modes. 1,2,4-Triazole and
its derivatives are very interesting not only because they
can be used as spin crossover materials which have the po-
tential application in information storage but also because
they can form a variety of novel structural motifs.12-15 Until
* Corresponding author. Email: wangdz@xju.edu.cn
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CHEMICAL SOCIETY
Coordination Polymers of Triazolo-thiadiazole Ligands
In addition, the emission properties of complexe 3 and
ligand L3 have also been investigated in the solid state at
room temperature.
The route of synthesis of ligands L1 - L3
Scheme 2
The structure of ligands L1 – L3
Scheme 1
Preparation of ligand L2
EXPERIMENTAL
4-(pyridine-3-yl)-7-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-
thiadiazole(L2): Ligand L2 was obtained by the similar method
described for L1. Yield: ~60%.1H NMR (CDCl3): d: 9.694 (s, 1H,
pyridine-2), d: 8.676-8.777 (m, 2H, pyridine-4,6), d: 7.524-7.992
(m, 6H, pyridine-5 and benzene); Anal. Calcd for C14H9N5S: C,
60.2; H, 3.25; N, 25.07; Found: C, 60.58; H, 3.19; N, 25.25. IR
(cm- 1, KBr pellets): 3063w, 2999w, 1906w, 1772w, 1622w,
1594w, 1569m, 1514m, 1468m, 1425m, 1440m, 1379m, 1313m,
1274m, 1238m, 1187m, 1156w, 1124w, 1074m, 1024m, 999w,
976m, 955m, 815m, 770m, 691m, 652m, 607m, 495w.
Materials and general methods: All the other reagents
used for the syntheses were commercially available and em-
ployed without further purification. The intermediate of 3-
aryl-4-amino-5-sulfhydryl-1,2,4-triazole (a) was prepared ac-
cording to reported procedures.20 IR spectra were measured on
a Brucker Equinox 55 FT-IR spectrometer with KBr Pellets in
the range of 4000–400 cm-1. Elemental analyses of C, H and N
were performed on a Thermo Flash EA 1112-NCHS-O ana-
lyzer. 1H NMR data were collected using an INOVA-400 NMR
spectrometer. Chemical shifts were reported in relative to
TMS. Solid-state emission and excitation spectra of com-
pounds were measured using a Cary Eclips fluorescence spec-
trophotometer.
Preparation of ligand L3
4-(pyridine-4-yl)-7-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-
thiadiazole(L3): Ligand L3 was obtained by the similar method
described for L1. Yield: ~50%. 1H NMR (CDCl3): d: 8.850 (d, 2H,
pyridine-2,6), d: 8.310~8.326 (m, 2H, pyridine-3,5), d: 7.587-
7.998 (m, 5H, benzene); Anal. Calcd for C14H9N5S: C, 60.2; H,
3.25; N, 25.07; Found: C, 60.38; H, 3.32; N, 25.32. IR (cm- 1, KBr
pellets): 3301w, 3053w, 3024w, 3001w, 1975w, 1898w, 1676w,
1600m, 1512m, 1466m, 1443m, 1313m, 1273m, 1237m, 1218m,
1176m, 1119w, 1098w, 1072m, 1023m, 984m, 956m, 821m, 767m,
715w, 685m, 647m, 608m, 519m, 492w, 476w.
Preparation of {[Cu(L1)2(NO3)2]×H2O}¥ (1): Complex 1
was prepared by dissolving Cu(NO3)2×3H2O (0.3 mmol) and L1
(0.3 mmol) in methanol solution (15 mL), then was refluxed for 3
h. After cooling and filtrated, Blue plate-shaped crystals were
formed after several days with the evaporation of the solvent (ca.
25% yield based on L1). Anal. Calcd for C28H20N12O7S2Cu: C,
44.01; H, 2.64; N, 21.99. Found: C, 44.15; H, 2.58; N, 21.89. IR
(cm- 1, KBr pellets): 3409m, 2363w, 1988w, 1919w, 1845w,
1767w, 1638m, 1613m, 1530m, 1483m, 1426m, 1382m, 1337m,
1196m, 1122m, 1071m, 1049m, 1012m, 975m, 935m, 814m,
778m, 731m, 691m, 607m, 508m, 421w.
Preparation of ligand L1
4-phenyl-7-(pyridine-3-yl)-1,2,4-triazolo[3,4-b]-1,3,4-
thiadiazole(L1): The route of synthesis is shown in Chart 2. The
intermediate of 3-phenyl-4-amino-5-sulfhydryl-1,2,4-triazole (a)
(5 mmol) and nicotinic acid (5 mmol) was added to freshly dis-
tilled POCl3 (20 mL). After heating in an oil bath at 120° for 8
hours, removed excess POCl3 under depress pressure. Poured re-
actor into cold water, neutralized the solution with NaOH to give
raw ligand L1 and recrystallized from absolute ethanol to give
ligand L1 as white crystals. Yield: ~65%. m.p. 239-240 °C. H
1
NMR (CDCl3): d: 9.21 (d, 1H, J = 2 Hz, pyridine-2), 8.86 (dd, 1H,
J = 1.6, 5.2 Hz, phenyl-4), 8.39~8.42 (m, 2H, pyridine-4,6),
8.25~8.28 (m, 1H, pyridine-5), 7.52~7.605 (m, 4H, phenyl-2, 3,
5, 6); Anal. Calcd for C14H9N5S: C, 60.2; H, 3.25; N, 25.07;
Found: C, 60.63; H, 3.22; N, 24.95. IR (cm- 1, KBr pellets):
3325w, 3049w, 2998w, 1992w, 1916w, 1887w, 1809w, 1765w,
1732w, 1693w, 1651w, 1586m, 1571m, 1533w, 1514w, 1480s,
1460s, 1420s, 1380m, 1357m, 1335m, 1308w, 1290m, 1270m,
1244m, 1192m, 1172m, 1123m, 1096w, 1074w, 1049w, 1026m,
998w, 975s, 955s, 922m, 812s, 770s, 721w, 701s, 684s, 672s,
621m, 600m.
Preparation of {[Cu4(L2)2(OAc)8]× CH3CH2OH}¥ (2):
Complex 2 was prepared by dissolving Cu(OAc)2·H2O (0.3
mmol) and L2 (0.3 mmol) in ethanol solution (15 mL) and fil-
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trated. Blue plate-shaped crystals were formed after several days
with the evaporation of the solvent (ca. 19% yield based on L2).
Anal. Calcd for C46H48N10O17S2Cu4: C, 41.50; H, 3.63; N, 10.52.
Found: C, 41.45; H, 3.57; N, 10.62. IR (cm- 1, KBr pellets):
3456w, 2969w, 2930w, 2448w, 1966w, 1621m, 1523m, 1470m,
1431m, 1345m, 1279m, 1237m, 1192m, 1124w, 1096w, 1046w,
1026m, 1001m, 960w, 885w, 818w, 768w, 684m, 625w, 605w.
Preparation of [Cd2(L3)3(NO3)4(H2O)2]¥ (3): Complex 3
was prepared by dissolving Cd(NO3)2×4H2O (0.3 mmol) and L3
(0.3 mmol) in ethanol solution (15 mL) and filtrated. Colorless
plate-shaped crystals were formed after several days with the
evaporation of the solvent (ca. 25% yield based on L3). Anal.
Calcd for C42H31N19O14S3Cd2: C, 37.45; H, 2.32; N, 19.76.
Found: C, 37.50; H, 2.45; N, 19.67. IR (cm- 1, KBr pellets):
3289m, 2973w, 2457w, 1615m, 1516w, 1460m, 1384m, 1291m,
1224m, 1129m, 1101w, 1067m, 1031m, 1004m, 961m, 876w,
836m, 818m, 767m, 719m, 690m, 648m, 605m, 526m, 413w.
X-ray crystallography: X-ray single-crystal diffraction
data for complex 1-3 were collected on a Bruker Smart 1000 CCD
diffractometer at 293(2) K with Mo-Ka radiation (l = 0.71073 Å)
by w -jscan mode. The program SAINT21 was used for integra-
tion of the diffraction profiles. Semi-empirical absorption correc-
tions were applied using SADABS program. All the structures
were solved by direct methods using the SHELXS program of the
SHELXTL package and refined by full-matrix least-squares
methods with SHELXL.22 Metal atoms in each complex were lo-
cated from the E-maps and other non-hydrogen atoms were lo-
cated in successive difference Fourier syntheses and refined with
anisotropic thermal parameters on F2. Hydrogen atoms of carbon
were included in calculated positions and refined with fixed ther-
mal parameters riding on their parent atoms. Crystallographic
data and experimental details for structural analyses are summa-
rized in Table 1. The crystal data file in CIF format was deposited
on CCDC and reference numbers 1005145-1005147 (for complex
1-3, respectively). This data can be obtained from the Cambridge
Crystallographic Data Center, 12 Union Road, Cambridge CB2
1EZ, UK; Fax: +44 1223 336033; E-mail: deposit@ccdc.cam.
ac.uk.
RESULTS AND DISCUSSION
Synthesis and general characterization
L1~L3 were prepared in high yield as white crystal-
line solid by the reaction of 3-aryl-4-amino-5-sulfhydryl-
1,2,4-triazole (a) with different aromatic carboxylic acid.
The structures of L1~L3 were determined by 1H NMR, IR
and elemental analysis.
The complexes 1~3 are stable in air and at ambient
temperature and insoluble in water. Efforts were made to
Table 1. Crystal data and structure refinement summary for complexes 1-3
1
C28H20N12O7S2Cu
764.22
2
C46H48N10O17S2Cu4
1331.22
Monoclinic
P2(1)/c
298(2)
3
C42H31N19O14S3Cd2
1346.81
Triclinic
P-1
Formula
Formular wt
Crystal system
Space group
T/K
Tetragonal
I4(1)/a
298(2)
296(2)
a/Å
12.7134(18)
12.7134(18)
45.328(9)
90.00
14.752(3)
24.415(5)
20.095(6)
90.00
13.691(3)
14.881(3)
14.891(3)
88.89(3)
87.54(3)
74.89(3)
2926.0(10)
2
b/Å
c/Å
a/deg
b/deg
90.00
131.082(18)
90.00
g/deg
V/Å3
90.00
7326(2)
8
5455(2)
4
Z
D/g cm-3
m/mm-1
F(000)
1.386
1.621
1.524
0.769
1.693
0.908
3112
2712
1336
Messured reflns
obsd reflns
Ra/wRb
28550
40537
25716
3222
9581
12498
0.0658/0.3055
0.0743/0.2114
0.0721/0.2764
2 2 1/2
a R = S||Fo| - |Fc|| / S|Fo|; b Rw = [S[w(Fo2 - Fc2)2] / Sw(Fo ) ]
.
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Coordination Polymers of Triazolo-thiadiazole Ligands
optimize the reaction conditions for the preparation of
complexes 1~3 by varying the reaction ratios, solvents and
temperatures. Better yields and pure complexes 1 and 2 can
be obtained with the stoichiometric ratio of 1:1 (Cu to L1/
L2) in ethanol solution at room temperature, while complex
1 were obtained with the stoichiometric ratio of 1:1 (Cd to
L3) in methanol solution after being refluxed for 3 h. The
infrared spectra of 1~3 exhibits characteristic absorptions
for corresponding ligands with a slight shift due to coordi-
nation. The absorption bands at about 1382 cm-1 and 1384
cm-1 indicate the existence of the NO3¯ anion in 1 and 3.
The characteristic bands of the coordinated acetate ions ap-
pear at 1621 cm-1 and 1431 cm-1 in 2. L1~L3 and 1~3 all ex-
hibit absorptions corresponding to the framework vibra-
tions of aromatic rings at about 1420-1650 cm-1.
metric unit contains four crystallographically independent
CuII centers, two L2 ligands, eight acetate ions and one eth-
anol molecule. The Cu(1A) ion is coordinated to one N
atom of pyridine from one L2 ligand [Cu(1A)-N(5A) =
2.195(6) Å] and four O atoms from four different acetate
ions; the Cu(1A)–O bond distances range from 1.933(5) to
1.995(5) Å (Fig. 2a). The Cu(2A) ion is coordinated to one
N atom of 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole from a L2
[Cu(2A)-N(3A) = 2.182(6) Å] and four O atoms from four
different acetate ions; the Cu(2A)–O bond distances range
from 1.918(6) to 1.998(5) Å. The Cu(1A) and Cu(2A) cen-
ters form a [Cu2(CH3COO)4] dinuclear structural unit
bridged by four acetate ions, each acetate ion adopts
syn-syn m2 bridged coordination, all the Cu(1A) and
Cu(2A) centers adopt distorted square pyramidal geometry
coordination environment (Fig. 2a), four O atoms form the
equatorial plane of square pyramidal, the N atom is located
on the top in square pyramidal, and the distance between
Cu(1A) and Cu(2A) is 2.638 Å. Other two CuII [Cu(1B)
and Cu(2B)] centers’ coordination environment is similar
to Cu(1A) and Cu(2A), respectively, and the bond dis-
tances of Cu(1B)-N(1B) and Cu(2B)-N(3B) are 2.197(5) Å
and 2.165(6) Å, respectively. The Cu(1B)-O bond dis-
Description of the crystal structure
Structure of {[Cu(L1)2(NO3)2]×H2O}¥ (1)
Complex 1 is a neutral rhombohedral grid (Fig. 1b)
with a 44 topology (Fig. 1c). The centrosymmetric unit con-
tains a CuII center, two L1 ligands and one NO3– anion. The
CuII center is coordinated to two N atoms of 1,2,4-
triazolo[3,4-b]-1,3,4-thiadiazole from distinct L1 ligands
[Cu(1)-N(1) = 1.987(5) Å], two N atoms of pyridine from
distinct L1 ligands [Cu(1)-N(5) = 2.037(5) Å] in the equa-
torial plane and two O atoms from two different NO3– an-
ions [Cu(1)-O(1) = 2.403(7) Å] at the axial positions to
complete its distorted octahedron coordination geometry
with the coordination angles varying from 86.6(3)° to
177.7(3)° (Fig. 1a and Table 2). The NO3– anions not only
participate in coordination but also are used as counter-
anion.
Each L1 ligand links two CuII ions and in turn each
CuII ion connects four ligands forming a layer structure
with 44 grid units, in which all the CuII ions are not located
in one plane (Fig. 1b). Each 44 grid unit is constructed by
four ligands acting as four edges and four CuII ions as four
vertexs. All the lengths of the edges are equal (the edges are
9.088 Å) and both of orthogonal distances are 12.713 Å.
The uncoordinated water molecules are located at the cavi-
ties of the sheets.
Structure of {[Cu4(L2)2(OAc)8]×CH3CH2OH}¥ (2)
Complex 2 crystallizes in the monoclinic symmetry
space group P2(1)/c. Crystallographic data and experimen-
tal details for structural analyses were summarized in Table
1, and the selected bond distances and angles were listed in
Table 2. The X-ray diffraction analysis shows that 2 has a
1-D neutral coordination chain (Fig. 2b). In 2, the asym-
Fig. 1. View of (a) the coordination environment of
CuII ions in 1. (b) 2-D (4,4) network structure of
1 (H atoms are omitted for clarity). (c) 44 to-
pology of 1.
J. Chin. Chem. Soc. 2015, 62, 786-792
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Table 2. Selected Bond Distances (Å) and Angles (deg) for Complexes 1-3
Complex 1
Cu(1)-N(1)
Cu(1)-O(1)
1.987(5)
2.403(7)
94.9(3)
86.6(3)
91.3(2)
Cu(1)-N(5)#3
2.037(5)
N(1)#2-Cu(1)-N(1)
N(5)#3-Cu(1)-N(5)#4
N(1)-Cu(1)-O(1)
N(5)#4-Cu(1)-O(1)
N(1)#2-Cu(1)-N(5)#3
N(1)#2-Cu(1)-O(1)
N(5)#3-Cu(1)-O(1)
89.35(19)
87.18(19)
86.4(2)
95.32(19)
Complex 2
Cu(1A)-O(5A)
Cu(1A)-O(3A)
Cu(1A)-N(1A)
Cu(2A)-O(4A)
1.933(5)
1.971(6)
2.195(6)
1.918(6)
1.979(5)
2.165(6)
1.943(5)
1.990(5)
1.914(5)
1.993(5)
89.0(2)
89.1(2)
95.8(2)
103.1(3)
86.80(16)
84.14(16)
89.2(2)
Cu(1A)-O(1A)
1.949(5)
1.995(5)
2.182(6)
1.935(6)
1.998(5)
1.928(5)
1.971(5)
2.197(5)
1.916(5)
2.009(5)
90.7(2)
89.1(2)
90.8(2)
94.4(2)
86.51(15)
78.39(15)
87.9(2)
88.6(2)
91.2(3)
Cu(1A)-O(7A)
Cu(2A)-N(3A)#1
Cu(2A)-O(8A)
Cu(2A)-O(2A)
Cu(1B)-O(1B)
Cu(1B)-O(3B)
Cu(1B)-N(1B)
Cu(2B)-O(4B)
Cu(2B)-O(6B)
O(1A)-Cu(1A)-O(3A)
O(1A)-Cu(1A)-O(7A)
O(1A)-Cu(1A)-N(1A)
O(7A)-Cu(1A)-N(1A)
O(1A)-Cu(1A)-Cu(2A)
O(7A)-Cu(1A)-Cu(2A)
O(8A)-Cu(2A)-O(6A)
O(8A)-Cu(2A)-O(2A)
O(8A)-Cu(2A)-N(3A)#1
O(2A)-Cu(2A)-N(3A)#1
O(8A)-Cu(2A)-Cu(1A)
O(2A)-Cu(2A)-Cu(1A)
Cu(2A)-O(6A)
Cu(2B)-N(3B)#3
Cu(1B)-O(5B)
Cu(1B)-O(7B)
Cu(2B)-O(8B)
Cu(2B)-O(2B)
O(5A)-Cu(1A)-O(3A)
O(5A)-Cu(1A)-O(7A)
O(5A)-Cu(1A)-N(1A)
O(3A)-Cu(1A)-N(1A)
O(5A)-Cu(1A)-Cu(2A)
O(3A)-Cu(1A)-Cu(2A)
O(4A)-Cu(2A)-O(6A)
O(4A)-Cu(2A)-O(2A)
O(4A)-Cu(2A)-N(3A)#1
O(6A)-Cu(2A)-N(3A)#1
O(4A)-Cu(2A)-Cu(1A)
O(6A)-Cu(2A)-Cu(1A)
92.1(2)
96.0(3)
99.1(2)
83.34(16)
81.04(16)
98.9(2)
89.50(16)
81.00(15)
Complex 3
Cd(1)-N(10)#1
2.307(7)
2.315(7)
2.358(8)
2.493(15)
2.289(6)
2.330(7)
2.416(11)
2.578(11)
91.0(3)
103.8(3)
85.0(3)
79.2(3)
87.7(3)
68.6(6)
91.2(4)
113.0(6)
96.4(3)
94.0(3)
91.1(4)
86.1(3)
81.0(3)
82.4(5)
78.1(3)
48.6(4)
Cd(1)-N(6)
Cd(1)-O(11)
Cd(1)-O(1)
Cd(1)-O(7)
Cd(2)-N(11)#2
Cd(2)-O(12)
Cd(2)-O(5)
2.315(7)
2.327(9)
2.360(11)
2.54(2)
2.319(9)
2.437(15)
2.452(11)
Cd(1)-N(6)
Cd(1)-N(9)
Cd(1)-O(8)
Cd(2)-N(1)
Cd(2)-N(12)
Cd(2)-O(10)
Cd(2)-O(4)
N(10)#1-Cd(1)-O(11)
N(10)#1-Cd(1)-N(9)
O(11)-Cd(1)-N(9)
N(6)-Cd(1)-O(1)
N(10)#1-Cd(1)-O(8)
O(1)-Cd(1)-O(8)
N(6)-Cd(1)-O(7)
O(1)-Cd(1)-O(7)
N(1)-Cd(2)-N(11)#2
N(1)-Cd(2)-O(12)
N(12)-Cd(2)-O(12)
N(12)-Cd(2)-O(10)
N(1)-Cd(2)-O(5)
O(10)-Cd(2)-O(5)
N(11)#2-Cd(2)-O(4)
O(5)-Cd(2)-O(4)
N(6)-Cd(1)-O(11)
N(6)-Cd(1)-N(9)
N(10)#1-Cd(1)-O(1)
O(11)-Cd(1)-O(1)
N(6)-Cd(1)-O(8)
N(10)#1-Cd(1)-O(7)
N(9)-Cd(1)-O(7)
O(8)-Cd(1)-O(7)
N(11)#2-Cd(2)-N(12)
N(11)#2-Cd(2)-O(12)
N(1)-Cd(2)-O(10)
O(12)-Cd(2)-O(10)
N(12)-Cd(2)-O(5)
N(1)-Cd(2)-O(4)
N(12)-Cd(2)-O(4)
93.7(3)
88.7(3)
88.6(3)
90.4(5)
83.6(3)
89.3(4)
72.2(5)
44.4(6)
96.1(3)
77.6(4)
84.1(3)
73.9(5)
89.7(3)
93.4(3)
86.8(3)
Symmetry codes, for 1: #2 = -x + 1, -y + 1/2, z + 0; #3 = -y + 1/4, x +1/4, -z + 1/4; #4 = y +
3/4, -x + 1/4, -z+1/4.
for 2: #1 = -x, y + 1/2, -z + 3/2; #3 = -x + 1, y + 1/2, -z + 1/2.
for 3: #1 = x, y + 1, z + 1; #2 = x, y-1, z.
790
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J. Chin. Chem. Soc. 2015, 62, 786-792

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Coordination Polymers of Triazolo-thiadiazole Ligands
tances range from 1.928(5) to 1.990(5) Å, while the
Cu(2B)-O bond distances range from 1.914(5) to 2.009(5)
Å. The distance between Cu(1B) and Cu(2B) is 2.641 Å.
Two dinuclear Cu(II) structural units are all bridged
by ligands L2, so the complex 2 assembled into two infinite
1-D supramolecular chains (Fig. 2b), and the neighboring
non-bonding distance of Cu···Cu connected by L2 are 9.896
and 9.889 Å, respectively.
mode, Cd–O lengths of 2.360(11) Å] and one O atom from
a water molecule [Cd(1)–O(11) = 2.327(9)]. The Cd(2)
center’s coordination environment is similar to Cd(1): just
two nitrogen atoms belonging to two pyridine of distinct L3
ligands [the Cd–N lengths are 2.330(7) and 2.319(9) Å, re-
spectively], one N atom of 1,2,4-triazolo[3,4-b]-1,3,4-
thiadiazole from a L3 ligand [Cd(2)-N(1) = 2.289(6) Å],
three oxygen atoms from two distinct NO3– anions and one
O atom from a water molecule of which the coordination
modes are similar to those coordinated to Cd(1)center.
Each L3 ligand links two CdII ions and in turn each CdII ion
connects three ligands forming a layer structure, in which
all the CdII ions are located in one plane.
Structure of [Cd2(L3)3(NO3)4(H2O)2]¥ (3)
Complex 3 crystallizes in the triclinic space group
P-1. In 3, the asymmetric unit contains two crystallographi-
cally independent CdII centers, three L3 ligands, four NO3
–
anions and two water molecules. As shown in Fig. 3a, the
seven-coordinated environment of Cd(1) (Fig. 3a) center is
as follows in detail: two nitrogen atoms belonging to two
1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole of distinct L3 li-
gands [the Cd–N lengths are all within normal range,
2.315(7) and 2.358(8) Å, respectively], one N atom of
pyridine from distinct L3 ligands [Cd(1)-N(10) = 2.307(7)
Å], three oxygen atoms from two distinct NO3– anions [one
NO3– anion adopts bidentate chelating coordination mode,
Cd–O lengths of 2.493(15) and 2.540(2) Å, respectively,
Luminescent properties
Aromatic organic molecules and mixed inorganic–or-
ganic hybrid coordination polymers are promising lumi-
nescent materials for their potential applications, such as
light-emitting materials (LEDs).23,24 The emission spectra
of L3 and complex 3 in the solid state at room temperature
were investigated (see Fig. 4). L3 exhibits a weak blue fluo-
rescent emission band around 410 nm upon excitation at
–
another NO3 anion adopts monodentate coordination
Fig. 2. View of (a) the coordination environment of
CuII ions in 2. (b) two 1-D chains of the com-
plex 2 (H atoms are omitted for clarity).
Fig. 3. View of (a) the coordination environment of
CdII ions in 3. (b) 2-D network structure of 3 (H
atoms are omitted for clarity).
J. Chin. Chem. Soc. 2015, 62, 786-792
© 2015 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.jccs.wiley-vch.de
791

Article
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350 nm. Complex 3 exhibits an intense blue fluorescent
emission band around 465 nm upon excitation at 350 nm.
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CONCLUSIONS
In summary, three metals (Cu and Cd) metal-organic
complexes with 4-phenyl-7-(pyridine-3-yl)-1,2,4-triazolo
[3,4-b]-1,3,4-thiadiazole (L1), 4-(pyridine-3-yl)-7-phenyl-
1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (L2), and 4-(pyri-
dine-4-yl)-7-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole
(L3) have been synthesized and structurally characterized.
Moreover, the fluorescence properties of complexe 3 dis-
play strong blue fluorescent emission at room temperature.
This approach may be useful for the construction of a vari-
ety of new transition metal complexes and luminescent co-
ordination polymers with novel structures that have the po-
tential of leading to new fluorescent materials.
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ACKNOWLEDGEMENT
This work was financially supported by the National
Nature Science Foundation of China (No. 21361026).
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792
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© 2015 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2015, 62, 786-792