Hydrothermal syntheses of metal-organic frameworks constructed from aromatic polycarboxylate and 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl

Article abstract of DOI:10.1021/cg101494t

Six new metal-organic frameworks, namely, {[Co(btmb)(HBTC)]?2H ₂O}_n (1), {[Co₃(btmb)₃(BTC) ₂(H₂O)₂]?6H₂O}_n (2), {[Co₃(btmb)₃(BTC)₂(H₂O) ₄]?2H₂O}_n (3), {[Ni₃(btmb) ₃(BTC)₂(H₂O)₄]?2H ₂O}_n (4), [Cu(btmb)(HBTC)]_n (5), and [Cu(btmb)(NDC)]_n (6) (H₃BTC = 1,3,5-benzenetricarboxylic acid, H₂NDC = 1,2-benzenedicarboxylic acid, and btmb = 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl), have been synthesized under hydrothermal conditions. The structure of 1 is a 6-connected self-penetrating three-dimensional (3D) framework with 4⁴?6¹⁰?8 topology. Complex 2 exhibits a trinodal (3,4)-connected topology with a Schlaefli symbol of (6²?8⁴)(6⁴? 8²)(6³). Both complexes 3 and 4 possess 3D pillar-layered structures with a Schlaefli symbol of (6²?8?10 ³)(6⁴?8?10)(6?10²). Complex 5 is also a 3D polymer with a pillar-layered framework, which can be simplified as the (6³)(6⁹?8) topology. Complex 6 shows a 4-connected 3D framework with a Schlaefli notation of (6⁵?8) ₂. Furthermore, complexes 1-6 as heterogeneous catalysts were studied in the green catalysis process of the oxidative coupling of 2,6-dimethylphenol (DMP) to poly(1,4-phenylene ether) (PPE) and diphenoquinone (DPQ). The results show that these complexes exhibit different catalytic activities; both the Cu complexes are catalytically active by showing high conversion of DMP and high selectivity of PPE, and they exhibit great potential as recyclable catalysts.

Full text of DOI:10.1021/cg101494t

ARTICLE
pubs.acs.org/crystal
Hydrothermal Syntheses of MetalꢀOrganic Frameworks
Constructed from Aromatic Polycarboxylate and 4,
4
0
-Bis(1,2,4-triazol-1-ylmethyl)biphenyl
Yajuan Mu, Junhong Fu, Yajing Song, Zhen Li, Hongwei Hou,* and Yaoting Fan
Department of Chemistry, Zhengzhou University, Zhengzhou, Henan 450052, P. R. China
S Supporting Information
b
ABSTRACT: Six new metalꢀorganic frameworks, namely,
{
[Co(btmb)(HBTC)] 2H O} (1), {[Co (btmb) (BTC)
2 n 3 3
3
2 2 2 n 3 3 2 2 4 2
2
(
(
(
H O) ] 6H O} (2), {[Co (btmb) (BTC) (H O) ] 2H O}
3), {[Ni (btmb) (BTC) (H O) ] 2H O} (4), [Cu(btmb)
HBTC)] (5), and [Cu(btmb)(NDC)] (6) (H BTC = 1,3,5-
3
3
n
3
3
2
2
4
3
2
n
n
n
3
benzenetricarboxylic acid, H NDC = 1,2-benzenedicarboxylic
2
0
acid, and btmb = 4,4 -bis(1,2,4-triazol-1-ylmethyl)biphenyl),
have been synthesized under hydrothermal conditions. The
structure of 1 is a 6-connected self-penetrating three-dimensional
4
10
(
(
(
(
1
3D) framework with 4 6 8 topology. Complex 2 exhibits a trinodal (3,4)-connected topology with a Schl €a fli symbol of
3
3
2 4 4 2 3
3
4
6 8 )(6 8 )(6 ). Both complexes 3 and 4 possess 3D pillar-layered structures with a Schl €a fli symbol of
3
3
2
3
2
6 8 10 )(6 8 10)(6 10 ). Complex 5 is also a 3D polymer with a pillar-layered framework, which can be simplified as the
3
3 3
3
3
9
5
6 )(6 8) topology. Complex 6 shows a 4-connected 3D framework with a Schl €a fli notation of (6 8) . Furthermore, complexes
3
3
2
ꢀ6 as heterogeneous catalysts were studied in the green catalysis process of the oxidative coupling of 2,6-dimethylphenol (DMP)
to poly(1,4-phenylene ether) (PPE) and diphenoquinone (DPQ). The results show that these complexes exhibit different catalytic
activities; both the Cu complexes are catalytically active by showing high conversion of DMP and high selectivity of PPE, and they
exhibit great potential as recyclable catalysts.
’
INTRODUCTION
show that flexible bis(triazole) ligands can adopt a variety of
conformations according to the restrictions imposed by the
coordination geometry of the metal ions. So, the flexible bis-
The rational design and construction of novel metalꢀorganic
4
frameworks (MOFs) continues to be a productive research area,
owing to their fascinating structural diversities and potential
(
triazole) ligands can also serve as one kind of most useful
1
organic linker for constructing MOFs with versatile topologies.
Recent investigations have demonstrated that the employ-
ment of mixed organic ligands, especially the mixed polycarbox-
ylate and N-containing ones, during the self-assembly process,
has been widely adopted for the construction of MOFs with
application as new materials. Of the many rational approaches to
the design of these materials, the route of selecting well-designed
organic ligands as building blocks with metal ions or metal
clusters as nodes has been proven to be an efficient strategy.
However, predicting and accurately controlling the framework
array of a given crystalline product still remains a considerable
challenge, due to the fact that the subtle self-assembly process is
frequently influenced by numerous other factors, such as the
5
novel structures and unique properties. Following such a mixed
ligand strategy, to further understand the coordination chemistry
of the flexible bis(triazole) spacer and rigid aromatic polycarbox-
ylate acids, and to explore new materials with beautiful architec-
tures and good physical properties, in this work, we selected the
long flexible bis(triazole) ligand btmb as organic linker in
the presence of H BTC and H NDC as coligands, and we
presence of auxiliary ligands or solvent, concentration, counter2-
anion, temperature, the pH value of the solution, and so on.
Therefore, further studies are required to understand the roles of
these factors in the formation of MOFs.
3
2
hydrothermally synthesized six new MOFs with intriguing
In the design and syntheses of MOFs, aromatic multicarbox-
ylate ligands, especially, benzenedicarboxylate and benzenetri-
carboxylate, are excellent building blocks, not only because of
their various coordination modes to metal ions, resulting from
completely or partially deprotonated sites allowing for the large
diversity of topologies, but also because of the strong coordinat-
ing ability of carboxylates, which can lead to good thermal
stabilities of the materials and increase the possibility of their
structures, {[Co(btmb)(HBTC)] 2H O} (1), {[Co (btmb) -
3
2 2 2 2 n 3 3 2 2 4
2
n
3
3
(
2
[
BTC) (H O) ] 6H O} (2), {[Co (btmb) (BTC) (H O) ]
H O} (3), {[Ni (btmb) (BTC) (H O) ] 2H O} (4),
2 n 3 3 2 2 4 2 n
Cu(btmb)(HBTC)] (5), and [Cu(btmb)(NDC)] (6), where
3
3
3
n
n
Received: November 10, 2010
Revised: April 15, 2011
Published: April 20, 2011
3
functionalization. Meanwhile, the results of previous studies
r 2011 American Chemical Society
2183
dx.doi.org/10.1021/cg101494t
|Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
Table 1. Crystallographic Data and Structure Refinement Details for 1ꢀ6
compound
1
2
3
4
5
6
formula
C
27
H
6
24CoN O
8
C
72
H66Co N
3 18
O
20
C
72
3
H66Co N
18
O
18
C
72
H
66Ni
N
3 18
O
18
C
27
H
20CuN
6
O
6
26 6 4
C H20CuN O
fw
619.45
840.11
293(2)
0.71073
1648.22
293(2)
0.71073
1647.56
293(2)
0.71073
588.03
544.02
293(2)
0.71073
triclinic
P1
T/K
293(2)
293(2)
λ (Mo KR), Å
cryst syst
space group
a/Å
0.71073
monoclinic
0.71073
monoclinic
monoclinic
P2 /c
monoclinic
P2 /c
monoclinic
P2 /c
P2
1
/c
1
1
1
1
P2 /c
12.581(3)
12.583(3)
17.046(3)
90
17.519(4)
10.080(2)
22.931(5)
90
9.5435(19)
14.915(3)
25.142(5)
90
9.5275(19)
14.861(3)
25.048(5)
90
10.169(2)
16.396(3)
15.342(3)
90
8.2582(17)
11.067(2)
14.080(3)
93.68(3)
105.18(3)
92.97(3)
1236.2(4)
2
b/Å
c/Å
R/deg
β/deg
γ/deg
93.32(3)
90
98.72(3)
90
97.06(3)
90
96.92(3)
90
96.09(3)
90
3
V/Å
2694.1(9)
4
4002.5(14)
4
3551.8(12)
2
3520.6(12)
2
2543.4(9)
4
Z
2
θ
max (deg)
27.88
25.00
25.50
25.00
25.00
24.99
ꢀ
3
D
c
/g cm
1.527
1.394
1.541
1.554
1.536
1.462
3
ꢀ1
abs coeff/mm
F(000)
0.700
0.695
0.779
0.881
0.915
0.928
1276
1730
1698
1704
1204
558
GOF
1.123
1.146
1.188
1.163
1.196
1.160
a
R
1
[I > 2σ(I)]
0.0479
0.0836
0.1887
0.0700
0.1343
0.0834
0.1545
0.0720
0.1499
0.0863
0.1787
b
wR
2
(all data)
0.1240
a
b
2
2 2
2 2 1/2
R
1
= ∑||F
o
| ꢀ |F
c
||/∑|F
o
|. wR
2
= [∑w(F
o
ꢀ F
c
) /∑w(F
o
) ]
.
0
btmb = 4,4 -bis(1,2,4-triazol-1-ylmethyl)bipheny, H BTC =
pH value of the reaction was adjusted to 7.0 with methanolic NaOCH3
solution. Purple crystals were obtained with a yield of 50% (based on Co).
3
1
,3,5-benzenetricarboxylic acid, and H NDC = 1,2-benzenedi-
2
carboxylic acid. The structures and topological analyses of these
complexes, along with the influence of the ligands, metal atoms,
and pH values on the structures of the MOFs are represented and
discussed. The thermal and catalytic properties of these com-
plexes have also been investigated.
Anal. Calcd for C72
Found: C, 51.40; H, 4.00; N, 15.05. IR (cm , KBr): 3426s, 3134m,
3 18
H66Co N O20 (%): C, 51.47; H, 3.96; N, 15.01.
ꢀ
1
3
1
021w, 1616s, 1561s, 1435m, 1366s, 1279m, 1208w, 1129m, 1092w,
0112m, 935w, 879w, 843w, 805w, 762m, 729m, 674m, 651w.
Synthesis of {[Co (btmb) (BTC) (H O) ] 2H O} (3). Com-
3
3
2
2
4
3
2
n
plex 3 was synthesized in a similar way as described for 2, except that the
molar ratio of Co/H BTC/btmb is 3:1:1. Red block crystals of 3 were
obtained with a yield of 45% (based on Co). Anal. Calcd for C H Co
3
’
EXPERIMENTAL SECTION
72
66
3-
N O (%): C, 52.47; H, 4.04; N, 15.30. Found: C, 52.40; H, 4.10; N,
Materials and Characterization. All chemicals were commer-
18 18
ꢀ
1
0
15.28. IR (cm , KBr): 3423s, 3130m, 3033w, 2934w, 1608s, 1558s,
1521s, 1424m, 1370s, 1276m, 1208w, 1129m, 1014m, 940w, 887w,
863w, 804m, 769m, 706m, 676m, 651w.
cially available and used as purchased. Ligand 4,4 -bis(1,2,4-triazol-1-
4
c
ylmethyl)biphenyl (btmb) was prepared according to the literature. IR
data were recorded on a BRUKER TENSOR 27 spectrophotometer
ꢀ
1
with KBr pellets in the region 400ꢀ4000 cm . Elemental analyses
Synthesis of {[Ni
Complex 4 was synthesized in a similar way as described for 2, using
NiCl 6H O (23.7 mg, 0.1 mmol) instead of CoCl 6H O. Green
crystals were obtained with a yield of 65% (based on Ni). Anal. Calcd for
3 3 2 2 4 2 n
(btmb) (BTC) (H O) ] 2H O} (4).
3
(
C, H, and N) were carried out on a Flash EA 1112 elemental analyzer.
Powder X-ray diffraction (PXRD) patterns were recorded using Cu KR1
radiation on a PANalytical X’Pert PRO diffractometer. Thermal analyses
were performed on a Netzsch STA 449C thermal analyzer at the heating
2
2
2
2
3
3
C
72
H
66Ni
3
N
18
O
18 (%): C, 52.49; H, 4.04; N,15.30. Found: C, 52.66; H,
ꢀ
1
ꢀ1
rate 10 °C min in air.
4.15; N, 15.16. IR (cm , KBr): 3441s, 3134w, 1607s, 1559s, 1536s,
1425s, 1425m, 1370s, 1280m, 1209w, 1128m, 1017w, 886w, 861w,
802w, 770m, 727m, 711m, 675m, 652m.
3
Synthesis of {[Co(btmb)(HBTC)] 2H O} (1). A mixture of
CoCl2 6H O (23.7 mg, 0.1 mmol), H BTC (21.0 mg, 0.1 mmol), btmb
31.6 mg, 0.1 mmol), and distilled water (10 mL) was placed in a 25 mL
Teflon-lined stainless steel vessel, and then the pH value was adjusted to
.0 by addition of methanolic NaOCH solution. The mixture was sealed
3
2
n
3
2
3
(
Synthesis of [Cu(btmb)(HBTC)]
n
(5). A mixture of Cu(NO
3 2
)
3
3H O (24.1 mg, 0.1 mmol), btmb (31.6 mg, 0.1 mmol), H
2
3
BTC (21.0
5
mg, 0.1 mmol), and 10 mL of distilled water was placed in a 25 mL
Teflon-lined stainless vessel. The mixture was sealed and heated at
130 °C for three days. After the mixture had been cooled to room
3
and heated at 130 °C for three days. After the mixture had been cooled to
ꢀ
1
room temperature at a rate of 5 °C h , purple crystals of 1 were
3
ꢀ
1
obtained with a yield of 70% (based on Co). Anal. Calcd for C27
H
24Co-
temperature at a rate of 5 °C h , blue crystals of 5 were obtained with a
3
N O (%): C, 52.35; H, 3.91; N, 13.57. Found: C, 52.30; H, 3.98;
yield of 60% (based on Cu). Anal. Calcd for C27
55.15; H, 3.43; N, 14.29. Found: C, 54.97; H, 3.49; N, 14.02. IR (cm
H
20CuN
6
O
6
(%): C,
6
8
ꢀ1
ꢀ1
N, 13.52. IR (cm , KBr): 3510s, 3447s, 3386s, 3143s, 3029w, 2979w,
,
1
1
7
702s, 1629s, 1539s, 1454s, 1436s, 1374s, 1277s, 1200m, 1135m,
109w, 1015m, 1014m, 988m, 938w, 898w, 874w, 842w, 801m, 758s,
19m, 677m, 651w.
KBr): 3132m, 3036w, 1679s, 1614s, 1578m, 1528m, 1489w, 1427m,
1342s, 1248s, 1130s, 1105w, 1073w, 1024w, 1004m, 913w, 843m, 810w,
756s, 723s, 695s, 675m, 633w.
Synthesis of {[Co (btmb) (BTC) (H O) ] 6H O} (2). Com-
plex 2 was synthesized in a similar way as described for 1, except that the
Synthesis of [Cu(btmb)(NDC)] (6). Complex 6 was synthesized
3
3
2
2
2
3
2
n
n
in a similar way as described for 5, using H NDC (16.6 mg, 0.1 mmol)
2
2
184
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
a
Table 2. Selected Bond Lengths (Å) and Bond Angles (deg) for 1ꢀ6
Complex 1
Co(1)ꢀO(1)
2.0301(15)
2.2688(17)
107.48(7)
93.52(8)
Co(1)ꢀO(2)#1
2.0110(15)
2.149(2)
95.56(7)
89.42(7)
89.92(7)
154.49(6)
91.12(7)
Co(1)ꢀO(3)#2
2.1221(15)
2.1468(19)
156.89(6)
87.37(7)
Co(1)ꢀO(4)#2
Co(1)ꢀN(1)
Co(1)ꢀN(6)#3
O(2)#1ꢀCo(1)ꢀO(1)
O(2)#1ꢀCo(1)ꢀN(6)#3
O(2)#1ꢀCo(1)ꢀN(1)
N(6)#3ꢀCo(1)ꢀN(1)
O(3)#2ꢀCo(1)ꢀO(4)#2
O(2)#1ꢀCo(1)ꢀO(3)#2
O(1)ꢀCo(1)ꢀN(6)#3
O(1)ꢀCo(1)ꢀN(1)
O(2)#1ꢀCo(1)ꢀO(4)#2
N(6)#3ꢀCo(1)ꢀO(4)#2
O(1)ꢀCo(1)ꢀO(3)#2
O(3)#2ꢀCo(1)ꢀN(6)#3
O(3)#2ꢀCo(1)ꢀN(1)
O(1)ꢀCo(1)ꢀO(4)#2
N(1)ꢀCo(1)ꢀO(4)#2
87.07(8)
93.07(7)
179.23(8)
59.60(6)
97.62(6)
88.56(7)
Complex 2
Co(1)ꢀO(4)#1
2.015(3)
Co(1)ꢀO(2)
2.032(4)
2.031(4)
92.64(14)
109.30(16)
180.000(1)
180.0(3)
92.6(2)
Co(1)ꢀN(4)
2.053(5)
2.155(4)
111.83(16)
109.11(17)
91.91(18)
93.0(2)
Co(1)ꢀN(1)
2.057(5)
Co(2)ꢀO(5)
Co(2)ꢀO(7)
Co(2)ꢀN(9)#3
2.163(7)
O(4)#1ꢀCo(1)ꢀO(2)
O(4)#1ꢀCo(1)ꢀN(1)
O(5)ꢀCo(2)ꢀO(5)#2
O(7)ꢀCo(2)ꢀO(7)#2
O(7)ꢀCo(2)ꢀN(9)#3
O(4)#1ꢀCo(1)ꢀN(4)
O(2)ꢀCo(1)ꢀN(1)
O(5)ꢀCo(2)ꢀO(7)
O(5)ꢀCo(2)ꢀN(9)#3
O(7)#2ꢀCo(2)ꢀN(9)#3
O(2)ꢀCo(1)ꢀN(4)
N(4)ꢀCo(1)ꢀN(1)
O(5)#2ꢀCo(2)ꢀO(7)
O(5)#2ꢀCo(2)ꢀN(9)#3
N(9)#3ꢀCo(2)ꢀN(9)#4
110.93(17)
119.69(18)
88.09(18)
87.0(2)
87.4(2)
180.000(1)
Complex 3
Co(1)ꢀO(5)#1
2.040(3)
Co(1)ꢀN(6)#2
2.113(4)
Co(1)ꢀO(8)
2.113(3)
Co(1)ꢀN(1)
2.146(4)
Co(1)ꢀO(1)
2.154(3)
Co(1)ꢀO(2)
2.215(3)
Co(2)ꢀO(3)
2.046(3)
Co(2)ꢀN(7)
2.146(4)
Co(2)ꢀO(7)
2.156(3)
O(5)#1ꢀCo(1)ꢀN(6)#2
O(5)#1ꢀCo(1)ꢀN(1)
O(5)#1ꢀCo(1)ꢀO(1)
N(1)ꢀCo(1)ꢀO(1)
O(8)ꢀCo(1)ꢀO(2)
O(3)#3ꢀCo(2)ꢀO(3)
N(7)#3ꢀCo(2)ꢀN(7)
O(3)ꢀCo(2)ꢀO(7)
90.62(13)
87.97(13)
99.24(10)
86.50(13)
109.67(11)
180.000(1)
180.000(1)
93.72(11)
O(5)#1ꢀCo(1)ꢀO(8)
N(6)#2ꢀCo(1)ꢀN(1)
N(6)#2ꢀCo(1)ꢀO(1)
O(5)#1ꢀCo(1)ꢀO(2)
N(1)ꢀCo(1)ꢀO(2)
O(3)ꢀCo(2)ꢀN(7)#3
N(7)ꢀCo(2)ꢀO(7)#3
N(7)ꢀCo(2)ꢀO(7)
90.81(12)
178.59(13)
93.69(12)
159.49(10)
92.13(12)
89.94(12)
88.88(13)
91.12(13)
N(6)#2ꢀCo(1)ꢀO(8)
O(8)ꢀCo(1)ꢀN(1)
O(8)ꢀCo(1)ꢀO(1)
N(6)#2ꢀCo(1)ꢀO(2)
O(1)ꢀCo(1)ꢀO(2)
O(3)ꢀCo(2)ꢀN(7)
O(3)#3ꢀCo(2)ꢀO(7)
O(7)#3ꢀCo(2)ꢀO(7)
93.68(13)
86.38(13)
167.46(12)
89.18(12)
60.33(10)
90.06(12)
86.28(11)
180.000(1)
Complex 4
Ni(1)ꢀO(5)
2.019(3)
Ni(1)ꢀN(6)#1
2.073(5)
2.107(3)
2.092(5)
91.96(14)
178.02(18)
92.43(15)
159.61(13)
91.55(16)
180.00(14)
180.0
Ni(1)ꢀO(7)
2.073(4)
Ni(1)ꢀN(1)
2.090(5)
Ni(1)ꢀO(3)#2
Ni(1)ꢀO(4)#2
2.183(3)
Ni(2)ꢀO(1)
2.031(3)
Ni(2)ꢀN(9)
Ni(2)ꢀO(8)
2.113(4)
O(5)ꢀNi(1)ꢀN(6)#1
O(5)ꢀNi(1)ꢀN(1)
O(5)ꢀNi(1)ꢀO(3)#2
N(1)ꢀNi(1)ꢀO(3)#2
O(7)ꢀNi(1)ꢀO(4)#2
O(5)ꢀNi(1)ꢀC(32)#2
O(1)ꢀNi(2)ꢀN(9)
O(1)ꢀNi(2)ꢀO(8)
O(8)ꢀNi(2)ꢀO(8)#3
90.25(16)
87.80(17)
98.27(13)
87.52(16)
108.37(14)
128.70(16)
89.73(16)
85.87(14)
180.000(1)
O(5)ꢀNi(1)ꢀO(7)
N(6)#1ꢀNi(1)ꢀN(1)
N(6)#1ꢀNi(1)ꢀO(3)#2
O(5)ꢀNi(1)ꢀO(4)#2
N(1)ꢀNi(1)ꢀO(4)#2
O(1)#3ꢀNi(2)ꢀO(1)
N(9)#3ꢀNi(2)ꢀN(9)
N(9)#3ꢀNi(2)ꢀO(8)
N(6)#1ꢀNi(1)ꢀO(7)
O(7)ꢀNi(1)ꢀN(1)
O(7)ꢀNi(1)ꢀO(3)#2
N(6)#1ꢀNi(1)ꢀO(4)#2
O(3)#2ꢀNi(1)ꢀO(4)#2
O(1)ꢀNi(2)ꢀN(9)#3
O(1)#3ꢀNi(2)ꢀO(8)
N(9)ꢀNi(2)ꢀO(8)
93.30(16)
87.11(16)
168.25(14)
90.16(16)
61.34(12)
90.27(16)
94.13(14)
90.68(16)
89.32(16)
Complex 5
Cu(1)ꢀO(4)#1
1.966(3)
2.366(3)
88.21(15)
90.99(14)
96.01(11)
Cu(1)ꢀO(1)
1.969(3)
Cu(1)ꢀN(4)
1.975(4)
Cu(1)ꢀO(5)#2
Cu(1)ꢀN(1)
1.975(4)
O(4)#1ꢀCu(1)ꢀO(1)
O(4)#1ꢀCu(1)ꢀN(1)
O(4)#1ꢀCu(1)ꢀO(5)#2
N(1)ꢀCu(1)ꢀO(5)#2
156.58(13)
91.75(14)
107.16(12)
91.47(13)
O(4)#1ꢀCu(1)ꢀN(4)
O(1)ꢀCu(1)ꢀN(1)
O(1)ꢀCu(1)ꢀO(5)#2
O(1)ꢀCu(1)ꢀN(4)
N(4)ꢀCu(1)ꢀN(1)
N(4)ꢀCu(1)ꢀO(5)#2
89.79(14)
178.13(15)
86.75(14)
Complex 6
Cu(1)ꢀO(1)
Cu(2)ꢀN(4)
1.961(4)
1.976(6)
Cu(1)ꢀN(1)
O(1)#1ꢀCu(1)ꢀO(1)
2.002(5)
Cu(2)ꢀO(3)
O(1)#1ꢀCu(1)ꢀN(1)
1.956(4)
90.3(2)
180.00(17)
2
185
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
Table 2. Continued
Complex 1
N(1)#1ꢀCu(1)ꢀN(1)
O(3)ꢀCu(2)ꢀN(4)
O(1)ꢀCu(1)ꢀN(1)
89.7(2)
91.7(2)
180.000(2)
88.3(2)
O(3)ꢀCu(2)ꢀO(3)#2
180.000(1)
180.000(1)
O(3)ꢀCu(2)ꢀN(4)#2
N(4)#2ꢀCu(2)ꢀN(4)
a
1
3
Symmetry transformations used to generate equivalent atoms in complex 1: (#1) ꢀx þ 1, ꢀy þ 1, ꢀz þ 2; (#2) ꢀx þ 1, y ꢀ / , ꢀz þ / ; (#3) x þ 1,
2
2
1
1
1
3
y þ 1, z. Complex 2: (#1) x, y ꢀ 1, z; (#2) ꢀx þ 2, ꢀy þ 1, ꢀz þ 1; (#3) x þ 1, ꢀy þ /
2
, z ꢀ /
2
; (#4) ꢀx þ 1, y þ /
2
, ꢀz þ /
2
. Complex 3: (#1) ꢀx
1
1
1
1
þ 2, y ꢀ /
2
, ꢀz þ /
2
; (#2) x þ 1, y þ 1, z; (#3) ꢀx þ 2, ꢀy þ 1, ꢀz þ 1. Complex 4: (#1) x þ 1, y ꢀ 1, z; (#2) ꢀx þ 2, y ꢀ /
2
, ꢀz þ /
2
; (#3) ꢀx þ 2,
1
1
ꢀ
y þ 2, ꢀz. Complex 5: (#1) x ꢀ 1, y, z; (#2) ꢀx, y ꢀ / , ꢀz þ / . Complex 6: (#1) ꢀx þ 1, ꢀy, ꢀz þ 2; (#2) ꢀx þ 1, ꢀy, ꢀz þ 1.
2
2
instead of H BTC. Deep blue crystals of 6 were obtained with a yield of
complexes 1ꢀ3 were performed on Ni or Cu salts, we only
obtained one complex for each kind of metal ions, respectively.
That is to say, cobalt(II) ion is relatively sensitive to the reaction
conditions. For preparation of complex 6, the reaction condition
used in the Experimental Section is the best choice. If the pH
value or the molar ratio of reagents was changed, no crystals were
obtained. All of the complexes 1ꢀ6 are stable in air and are
insoluble in water and common organic solvents such as ethanol,
benzene, acetone, and acetonitrile. In the IR spectra of complexes,
the characteristic bands attributed to the protonated carboxylate
3
5
3
3
1
2% (based on Cu). Anal. Calcd for C H CuN O (%): C, 57.40; H,
26 20 6 4
ꢀ
1
.71; N, 15.45. Found: C, 57.01; H, 3.65; N, 15.42. IR (cm , KBr):
118m, 3037w, 1605s, 1574s, 1533m, 1443w, 1369s, 1281m, 1215w,
128m, 1081w, 1006m, 835w, 805w, 757m, 704w, 673w, 650w.
Crystal Structure Determination. The data of the six complexes
were collected on a Rigaku Saturn 724 CCD diffractomer (Mo KR, λ =
.71073 Å) at the temperature 20 ( 1 °C. Absorption corrections were
0
applied by using a multiscan program. The data were corrected for
Lorentz and polarization effects. The structures were solved by direct
methods and refined with a full-matrix least-squares technique based on
ꢀ
1
ꢀ1
2
6
groups are observed at 1702 cm for 1 and 1679 cm for 5,
F
with the SHELXL-97 crystallographic software package. The
respectively, indicating the incomplete deprotonation of H BTC.
3
hydrogen atoms were assigned with common isotropic displacement
factors and included in the final refinement by using geometrical
restraints. But the hydrogen atoms of water molecules for 3 and 4 were
located from difference Fourier maps and refined with isotropic
displacement parameters. Crystallographic crystal data and structure
processing parameters for complexes 1ꢀ6 are summarized in detail in
Table 1. Selected bond lengths and bond angles are listed in Table 2.
Experimental Procedure for the Catalytic Oxidative Cou-
The absence of such bands in other complexes indicates the
complete deprotonation of aromatic multicarboxylate. This is in
agreement with the result of X-ray single-crystal analysis.
Crystal Structure of {[Co(btmb)(HBTC)] 2H O} (1). Com-
3
2 n
plex 1 crystallizes in the monoclinic space group P2 /c. Each
1
Co(II) atom exhibits a distorted octahedral environment, the
equatorial plane of which comprises four carboxylate oxygen
7
2ꢀ
pling of DMP . One mmol of DMP (122 mg) was dissolved in 3 mL of
atoms from three distinct HBTC anions and two nitrogen
water containing 1 mmol of NaOH (40 mg) and 0.1 mmol of sodium n-
dodecyl sulfate (SDS) (29 mg). 0.01 mmol of complex with appropriate
size was added to the above solution, and the mixture was stirred at
atoms from two btmb ligands occupying the apical site
(
Figure 1a). The CoꢀO/N distances are in the range 2.0104ꢀ
2
.2690 Å, which are in the normal range of those observed in
5
0 °C. Then, 10 μL of H
into the mixture using a microinjector every 15 min (2 times in all). After
h, the reaction was stopped and 1.17 g of NaCl was added. Then the
mixture was transferred into a separatory funnel, and the organic
materials were extracted with CHCl 3 times. The combined organic
2
O
2
(30% aqueous solution) was slowly added
8
2ꢀ
cobalt complexes. The incompletely deprotonated HBTC
ligand acts as a μ -bridge linking three Co(II) atoms, in which
3
8
one carboxylate group adopts the bidentate chelate mode and the
1
1
other adopts a μ -η :η fashion (type I in Scheme 1).
2
3
2ꢀ
Further, the Co(II) atoms are in turn connected by HBTC
extracts were dried with anhydrous MgSO , and the filtrate was
4
to give rise to a two-dimensional (2D) sheet structure along the
bc plane (Figure 1b). The architecture of the 2D sheet is based on
a dinuclear unit [Co (COO) ] with a Co Co distance of
evaporated in vacuo. The products were separated by preparative
TLC performed on dry silica gel plates with ethylether/petroleum ether
2
2
3 3 3
(1:3 v/v) as the developing solvent. The main product, poly(1,4-
4
.474 Å. The sheets are pillared by ligand btmb in a trans
phenylene ether) (PPE), and byproduct, diphenoquinone (DPQ), were
collected and dried in vacuo, repectively.
9
conformation via the CoꢀN connections to generate a pillar-
layered three-dimensional (3D) framework. Better insight into
such an elegant framework can be accessed by the topology
1
13
PPE: H NMR (400 MHz, CDCl
3
) δ: 2.10 (s, 6H), 6.44 (s, 2H). C
NMR (100 MHz, CDCl ) δ: 16.3ꢀ16.8, 114.1, 114.5, 124.4, 124.9,
3
method. In 1, the dinuclear unit [Co (COO) ] acts as nodes, and
1
28.6, 129.0, 131.6, 132.7, 145.6, 146.4, 151.4, 152.2, 154.5, 154.7. IR
2
2
ꢀ
1
the btmb serves as linkers; therefore, the combination of nodes
(cm , KBr): 3429m, 1607s, 1470s, 1306s, 1188s, 1022s, 858m.
and linkers suggests the 6-connected framework with a Schl €a fli
4
10
symbol of 4 6 8. Careful inspection of such a framework
’
RESULTS AND DISCUSSION
3
3
suggests that the net is self-penetrating. As shown in Figure 1c,
Syntheses of the Complexes. Hydrothermal synthesis is a
each six-membered shortest circuit is catenated by two rods of
the same network. Self-penetration is an unusual form of
10
relatively complicated process, and the final products are often
unpredictable under a given set of conditions. The reaction
variables (metal ions, pH value, metalꢀligand ratio, temperature,
etc.) may affect the final products remarkably. In our system, the
central metals, pH value, and metalꢀligand ratio play important
roles in the formation of new complexes. For preparation of
complexes 1ꢀ3, the raw materials are the same, but distinct
structures are obtained for the different pH values or molar ratio
topological entanglement. Thus, 1 can be considered as another
1
1
example of the self-penetrated coordination polymers.
Crystal Structure of {[Co (btmb) (BTC) (H O) ] 6H O}
n
3
3
2
2
2
3
2
(2). As depicted in Figure 2a, there are two types of coordination
environments around the Co(II) atoms in the structure of 2. It
can be clearly seen that the Co1 atom is 4-coordinated, with a
slightly distorted tetrahedral geometry, by two oxygen atoms
3
ꢀ
of Co/H BTC/btmb. However, in the syntheses of complexes
from two different BTC anions and two nitrogen atoms from
3
4
and 5, when the same reaction conditions used to prepare
two btmb ligands. The CoꢀO bond lengths are 2.015(3) and
2
186
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
nitrogen atoms from two btmb ligands (CoꢀN 2.163(7) Å).
3
ꢀ
Each completely deprotonated BTC ligand displaying the
tri(monodentate) coordinated mode (II), as illustrated in
Scheme 1, coordinates to three Co(II) centers. Then the Co(II)
3
ꢀ
cations are bridged by the BTC anions to form a one-
dimensional (1D) ladder structure (Figure 2b).
The btmb ligands in 2 adopt two kinds of conformations. One
12
takes the cis conformation, which links one Co2 atom (at the
ladder center) and one Co1 atom (at the other ladder side) with a
Co2 Co1 distance of 15.00(40) Å (Figure 2c, pink ones).
3
3 3
These Co1 and Co2 atoms are in the same CoꢀBTC layer, while
the other btmb molecule in the trans conformation links Co1
atoms between adjacent layers with a distance of 17.75(42) Å
(
3
blue ones in Figure 2c). These links give rise to the complicated
D framework as shown in topological Figure 2d.
Topological analysis was carried out to get insight into the
structure of 2. If Co1 and Co2 are simplified as two kinds of four-
3
ꢀ
connected nodes, and the btmb and BTC ligands are defined
as 2- and 3-connected nodes, respectively, the 3D framework of 2
can be described as a trinodal (3,4)-connected topology with the
2
4
4
2
3
Schl €a fli symbol (6 8 )(6 8 )(6 ).
3
3
Crystal Structures of {[Co (btmb) (BTC) (H O) ] 2H O}
3
3) and {[Ni (btmb) (BTC) (H O) ] 2H O} (4). Similar cell
parameters with the same space group P2 /c (Table 1) and the
3
2
2
4
3
2
n
(
3
3
2
2
4
3
2
n
1
results of crystallographic analyses confirm that 3 and 4 are
isostructural. Thus, only the structure of 3 is described in detail as
a typical example, while the structure of 4 is provided in the
Supporting Information (Figure S1).
As shown in Figure 3a, there are two independent cobalt
3
ꢀ
atoms: Co1 is coordinated by three BTC oxygen atoms, two
btmb nitrogen atoms, and one water molecule to give the
CoO N distorted octahedral geometry, and Co2 also shows
4
2
3
ꢀ
the CoO N octahedral geometry but completed by two BTC
4
2
oxygen atoms, two btmb nitrogen atoms, and two water mol-
ecules. The CoꢀO/N bond lengths are in the range 2.040-
(
3)ꢀ2.215(3) Å. All of the coordination bonds are within normal
3ꢀ
13
distances. In 3, each completely deprotonated BTC serves as
a 3-connected node to coordinate with three Co(II) atoms with
the coordination mode of type III, as illustrated in Scheme 1,
generating a 2D extended network (Figure 3b). In the network,
six Co(II) atoms are bridged by six BTC , forming a macro-
cyclic ring in which the separations of the opposite metal atoms
are 10.149, 14.915, and 26.014 Å, respectively.
3
ꢀ
These 2D layers are further connected by two types of btmb
ligands acting as bridging pillars to build a 3D layer pillar
framework. Both types of the btmb ligands adopt trans con-
formation with different NdonorꢀC
Csp3ꢀN
torsion
sp3 3 3 3
donor
angles (180° for the centrosymmetric ligands and 174.1° for the
noncentrosymmetric ones). As shown in Figure 3c, if Co1 and
Co2 are simplified as two kinds of four-connected nodes, and the
3-
btmb and BTC ligands are defined as a 2- and 3-connected
nodes, respectively, the 3D framework of 3 can be described as
a trinodal (3,4)-connected topology with Schl €a fli symbol of
Figure 1. (a) Coordination environment around the Co(II) centers in 1.
2
ꢀ
(
b) The 2D sheet structure constructed from Co(II) centers and HBTC
2
3
4
2
4 10
3
(6 8 10 )(6 8 10)(6 10 ).
anions. (c) Schematic representation of 4 6 8 topology of complex 1
3 3
3 3
3
3
Crystal Structure of [Cu(btmb)(HBTC)] (5). Single crystal
and the self-penetrated shortest circuits (green, orange, and red).
n
structure analysis reveals that complex 5 is also a pillar-layered 3D
framework, which is similar to the reported structure
4e
2
.032(4) Å, respectively; the CoꢀN bond lengths are 2.053(5)
{[Cu (BTC) (btmb) ] H O} . But there are no lattice water
4 4 4 2 n
3
and 2.057(5) Å, respectively. Co2 adopts a distorted octahedral
CoO N coordination geometry completed by two carboxylate
molecules in complex 5. As shown in Figure 4a, each Cu(II) atom
4
2
is five coordinated by two nitrogen atoms of two btmb ligands
3
ꢀ
2ꢀ
oxygen atoms from two BTC anions (CoꢀO 2.031(4) Å),
and three oxygen atoms from three HBTC anions, taking a
14
two terminal water molecules (CoꢀO 2.155(4) Å), and two
distorted square-pyramidal coordination environment (τ = 0.36).
2
187
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
Scheme 1. Coordinated Mode of the H BTC Ligand
3
The CuꢀN bond lengths are 1.975(4) Å, and the CuꢀO bond
lengths are in the range 1.966(3)ꢀ2.366(3) Å, which are
comparable to those observed for {[Cu(btp)(HBTC) ]
N4 containing btmb (with Ndonor Ndonor 14.58 Å and Cu
3 3 3
3 3 3
Cu 17.28 Å), respectively. Better insight into the present 3D
framework can be accessed by the topological method. Each Cu(II)
2
3
15
2ꢀ
0
.5H O}n (btp = 1,3-bis(1,2,4-triazol-1-yl)propane). Each
atom connects to four other Cu(II) atoms via twoNDC and two
2
2
ꢀ
incompletely deprotonated HBTC ligand serves as a three-
connected node to coordinate with three Cu(II) atoms through
its three carboxylates in monodentate mode (type IV), generat-
ing a 2D (6,3) network, as shown in Figure 4b. Then the 2D
layers are further connected by two kinds of btmb ligands,
forming a 3D layer pillar framework (Figure 4c). Both kinds of
btmb spacers; hence, the Cu(II) atoms can be viewed to be
4-connected nodes. Such connectivity repeats infinitely to give
5
the 3D framework with (6 8) topology (Figure 5c).
3
2
Coordination of Aromatic Multicarboxylate Ligands and
Bis(triazole) Ligand. In complexes 1ꢀ5, H BTC ligand is
3
completely or partially deprotonated under different pH values
and consequently exhibits rich coordination modes. Thus, sev-
eral metal-(H)BTC skeletons (1D ladder, 2D layer) are formed.
btmb ligands adopt a trans conformation with a NdonorꢀC
sp3 3 3 3
Csp3ꢀN
torsion angle of 180°. Though both kinds of btmb
donor
2
ꢀ
have the same conformation with torsion angles of 180°, the
NꢀC torsion angles in these two kinds of
In 1, each incompletely deprotonated HBTC ligand coordi-
N
C
nates to three Co(II) centers, and the Co(II) centers are
donor 3 3 3
sp3 3 3 3 sp3
2
ꢀ
btmb ligands are different. The torsion angles are 5.990° for N1
connected by HBTC anions to form a 2D network. For 2,
3
ꢀ
containing btmb (with N 12.81 Å) or 6.248° for
N
every BTC anion coordinates to three Co(II) centers, and
3
donor 3 3 3 donor
ꢀ
N4 containing btmb (with N
N
13.15 Å), which
Co(II) centers are bridged by BTC anions to form a 1D
3
donor 3 3 3 donor
ꢀ
leads to the different Cu Cu distances (14.19 Å or 14.93 Å)
separated by these two kinds of btmb.
ladder skeleton. In the structures of 3 and 4, each BTC also
3
3 3
coordinates to three M(II) (M = Co or Ni) centers, and the
3
ꢀ
To further understand the structure of the complex, topolo-
M(II) centers are linked by BTC to form a 2D polymeric
2
ꢀ
gical analysis was performed on 5. As discussed above, each
layer, respectively. In the case of 5, the HBTC
anion
2ꢀ
HBTC and btmb ligand links three and two Cu(II) atoms,
coordinates to three Cu(II) centers, and the Cu(II) centers
2
ꢀ
2ꢀ
respectively; accordingly, the HBTC and btmb can be re-
are connected by HBTC anions to furnish a 2D honeycomb
garded as 3- and 2-connected nodes, respectively. As for each
network. When H BTC ligand was replaced by ligand H NDC,
3
2
2ꢀ
2ꢀ
Cu(II) atom, it links three HBTC and two btmb ligands; hence,
the Cu(II) atom can be treated as a 5-connector. According to the
simplification principle, the resulting structure of complex 5 is a
complex 6 was obtained. Each NDC ligand in 6 coordinates
to two Cu(II) centers to generate a 1D zigzag chain. From
the discussion above, the result shows that the coordination
mode of the carboxylate group has an important influence on
the networks constructed by carboxylate ligands and metal
centers.
3
9
binodal (3,5)-connected gra net with a Schl €a fli symbol (6 )(6 8).
3
Crystal Structure of [Cu(btmb)(NDC)] (6). Compared with
n
complex 5, the tricarboxylic acid H BTC ligand is replaced by
3
dicarboxylate ligand H NDC, and a structurally different com-
plex 6 was successfully isolated. In the asymmetry unit
In this study, complexes 1ꢀ6 display a diversity of 3D
frameworks, and the connectivities of the six complexes are
strongly related to the bis(triazole) ligands. In these structures,
the ligand btmb utilizes two exo-N atoms of the triazole units
to coordinate to the metal centers just like a linker. As a result,
the 1D or 2D structures constructed by metal centers and
aromatic multicarboxylate ligands are connected by ligands
btmb to generate 3D frameworks with versartile topologies.
The existence of long flexible ligand btmb not only promotes
higher dimensionality but also favors the formation of peculiar
2
(
Figure 5a), there are two independent Cu(II) atoms, but both
of them have the same coordination environment: Cu1 and Cu2
are four-coordinated by two nitrogen atoms from two btmb
ligands (Cu1ꢀN1 2.002(5) Å, Cu2ꢀN4 1.976(6) Å) and two
2ꢀ
oxygen atoms from two NDC anions (Cu1ꢀO1 1.961(4) Å,
Cu2ꢀO3 1.956(4) Å) in a distorted square planar coordination
2
ꢀ
2
1
1
geometry. Each NDC ligand adopting a μ -η :η bridging
mode coordinates to symmetry-related Cu1 and Cu2 atoms to
generate a 1D zigzag chain with the Cu Cu distance of 7.040 Å
2
ꢀ
motifs. For example, in 1, the 2D Co(II)-HBTC layer is
pillared by btmb to generate a pillar-layered 3D framework
with the self-penetrating topology.
3
3 3
(
Figure 5b). These 1D chains are then linked by two kinds of
btmb ligands via CuꢀN coordination bonds, thus leading to the
formation of a 3D framework. Both kinds of btmb ligands adopt
The mixed polycarboxylate and N donor ligands have been
proven to be a useful building block in construction of MOFs
with novel structures and unique properties. For example, the
the same conformation with the same NdonorꢀC
Csp3
ꢀ
sp3 3 3 3
Ndonor torsion angles to that of 5. The Ndonor NꢀC
3 3 3
sp3 3 3 3
3
ꢀ
Csp3 torsion angles are 105.0° for N1 containing btmb (with
Mn(II) and Co(II) frameworks with BTC and bimb ligands
are among the rare examples of MOFs that exhibit high
Ndonor
N
donor
15.10 Å and Cu Cu 18.46 Å) and 90.18° for
3 3 3
3 3 3
2
188
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
Figure 2. (a) Coordination environments around the Co(II) centers in2.
Hydrogen atoms and solvent molecules are omitted for clarity. (b) View of
Figure 3. (a) Coordination environments around theCo(II) centers in 3.
Hydrogen atoms and solvent molecules are omitted for clarity. (b) The
3 2 n
the [Co (BTC) ] ladder. (c) Different conformations of btmb ligands in
3ꢀ
2
D sheet structure constructed from Co(II) centers and BTC anions.
2
. (d) Schematic representation of trinodal (3,4)-connected topology with
2
4
4
2
3
(c) The 3D layer pillar framework of 3. Color code: purple ball,
the topological notation (6 8 )(6 8 )(6 ). Color code: sea-green ball,
3
3
3ꢀ
3-
4-connected Co(II) node; blue ball, 3-connected BTC node; yellow
4-connected Co(II) node; blue ball, 3-connected BTC node; yellow
stick, 2-connected btmb ligand.
stick, 2-connected btmb ligand.
photocatalytic activity for dye degradation under UV light
study was carried out in this work by aromatic multicarboxylate
ligands, and MOFs with different structures and topologies
were obtained. The results of this work provide a nice example
of the construction of MOFs using a mixed ligand strategy. On
the other hand, many factors, such as the stoichiometric ratio of
the components, the pH value, and the versatility of the metal
0
(
(
H BTC = 1,3,5-benzenetricarboxylic acid and bimb = 4,4 -bis-
3
16
1-imidazolyl)biphenyl), and the Ni(II) framework with m-
3
ꢀ
BTC and bpy containing beautiful “S” ribbons shows very
interesting ferromagnetic properties (m-H BTC = 1,2,4-benze-
3
0
17
netricarboxylic acid and bpy = 4,4 -bipyridine). A systematic
2
189
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
Figure 4. (a) Coordination environments around the Cu(II) centers in 5. (b) Infinite 2D (6,3) network constructed from Cu(II) ions coordinated to
2
ꢀ
3
9
HBTC ligands. (c) Schematic representation of binodal (3,5)-connected topology with the topological notation (6 )(6 8). Color code: sea-green
3
2ꢀ
ball, 5-connected Cu(II) node; blue ball, 3-connected HBTC node; yellow stick, 2-connected btmb ligand.
coordination geometries and reaction conditions, can influence
the formation of the final products. So it is still a challenge to
obtain the desired MOFs.
from 308 to 497 °C, corresponding to the losses of btmb and the
2
ꢀ
decomposition of the HBTC . A black amorphous residue of
CuO (observed 13.42%, calculated 12.57%) is remained. The
TGA curve of complex 6 exhibits that it is stable up to 246 °C and
then loses weight from 246 to 606 °C, corresponding to the
Thermal Analyses. To estimate the stability of the coordina-
tion architectures, thermogravimetric analyses (TGA) were
carried out (Figure 6). The phase purities of the bulk samples
were identified by powder X-ray diffraction (Figures S2 in the
Supporting Information). The TGA curve of 1 shows the first
step weight loss (2.91%) at 73.8ꢀ124.5 °C, corresponding to the
loss of a lattice water molecule (calcd: 3.42%), and after that,
from 124.5ꢀ349.5 °C, the second step weight loss (2.91%),
corresponding to the loss of the other lattice water molecule
2
ꢀ
decomposition of btmb and NDC . The remaining weight
corresponds to the formation of CuO (obsd, 14.51%; calcd,
14.86%).
Catalytic Properties of the MOFs. MOFs as catalysts have
attracted increasing attention, motivated by many inherent
advantages, such as the controlled oxidation state of the cation,
the possibility to tune the electron density on the metal as a
contribution of different ligands, multiactive metal centers avail-
able within the molecule, as well as controlled texture (pore size
(
calcd: 2.70%). The removal of the organic components occurs
in the range 349.5ꢀ495.0 °C. The remaining weight corresponds
1
8
to the formation of Co O (obsd, 13.2%; calcd, 13.3%). For 2,
and shape) that may induce some shape selectivity effects.
2
3
the first step weight loss, attributed to the gradual release of six
lattice water molecules and two coordinated water molecules, is
observed in the range 84.5ꢀ317.5 °C (obsd, 8.70%; calcd,
Then we investigated the catalytic activities of complexes 1ꢀ6 in
oxidative coupling reaction of 2,6-dimethylphenol (DMP). The
main product of this reaction, poly(1,4-phenylene ether) (PPE),
is a high-performance engineering plastic with outstanding
chemical and physical properties. In this paper we select the
green oxidative coupling reaction system of DMP in water with
8
.58%). The second step weight loss from 317.4 to 466.3 °C
3
ꢀ
19
corresponds to the decomposition of btmb and BTC , leading
to the formation of Co O as the residue (obsd, 14.81%; calcd,
2
3
1
6.87%). As for complexes 3 and 4, the initial weight losses in the
clean oxidant H O (Scheme S1 in the Supporting Information).
2
2
range 133.8ꢀ283.9 °C and 111.75ꢀ305.9 °C correspond to the
losses of the two lattice water and four coordinated water
molecules (For 3: obsd, 6.85%; calcd, 6.56%. For 4: obsd,
Under the same reaction conditions, complexes 1ꢀ6 show
different catalytic activities. The catalytic data are summarized
in Table 3. On the basis of the above experimental results and
20
7
.24%; calcd, 6.56%), respectively. The further weight losses
previous literature, a plausible reaction mechanism for the
present oxidative coupling reaction was proposed as follows:
DMP is dissolved in the basic aqueous phase to form the
phenolate anion; these phenoxide anions coordinate to M(II)
centers, and then electron transfers from the coordinated phen-
oxide anions to M(II) ions occur, leading to the formation of
represented the decomposition of the anhydrous compounds,
leading to the formation of a brown black residue of Co O3
2
(
obsd, 14.40%; calcd, 15.09%) and a black residue of NiO (obsd,
2.42%; calcd, 13.46%), respectively. The TGA data of complex 5
show that it is stable up to 308 °C and then keeps losing weight
1
2
190
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
Figure 6. TG plots of these MOFs.
Table 3. Catalytic Activities of Complexes 1ꢀ6 for Oxidative
a
Polymerization of DMP
c
conversion of
DMP (%)
yield
selectivity of
PPE (%)
b
catalyst
(%) PPE
1
2
3
4
5
6
60
75
54
56
97
84
90
29
32
44
25
21
88
55
67
13
54
64
78
63
78
72
73
58
d
5
CuCl
2
a
Figure 5. (a) Coordination environments around the Cu(II) centers in
2 2
Reaction conditions: DMP (1 mmol), NaOH (1 mmol), H O (20
6
. Hydrogen atoms are omitted for clarity. (b) Infinite zigzag chain
μL), and catalyst (0.01 mmol) in 3 mL of water for 8 h at 50 °C.
2
ꢀ
b
constructed from Cu(II) ions coordinated to NDC ligands. (c)
Topological representation of the 4-connected topology with the
topological notation (6 8)
Conversions and isolated yields based on the DMP; average of
c
d
two runs. Selectivity = 100[PPE]/([PPE] þ [DPQ]). Second reuse.
5
2
. Color code: sea-green ball, 4-connected
3
2ꢀ
Cu(II) node; blue stick, 2-connected NDC ligand; yellow stick,
-connected btmb ligand.
complexes have an obvious comparative advantage in the
oxidative coupling of DMP.
2
In addition, the coordination environments of metal centers
also influence the catalytic activities. In general, a lower coordi-
nation number leads to a higher catalytic activity. And the
coordinated water molecules in the complexes are easy leaving
groups and can be readily replaced by the substrate; thus, it is
easier for the phenolate anion to enter the metal coordination
sphere when metal centers are coordinated by water molecules,
further enhancing the catalytic activity. For example, complexes
1ꢀ3 with the same reactants but different coordination geome-
tries exhibit different catalytic properties. Specifically, in 1, there
is only one type of six-coordinated Co(II) center. The results
show that complex 1 affords a moderate catalytic effect, while the
Co(II) centers in complex 2 have two different coordination
environments. One is four-coordinated, and the other is six-
coordinate with one coordinated water molecule. Complex 2
gives relatively high conversion and yield of PPE among the three
complexes. The Co(II) centers in complex 3 also have two kinds
of coordination modes, but both of them are six-coordinated with
one or two coordinated water molecules. Complex 3 provides
relatively high selectivity of PPE among the three complexes. On
the other hand, the pore size also exerts a profound influence on
the catalytic activities. The larger the pore is, the better the
catalytic activity is. Concretely, large cavities in complexes could
phenoxyl radicals. The resultant M(I) ions were reoxidized to
M(II) ions by H O (M = Cu, Co, or Ni). The CꢀO coupling of
2
2
these phenoxyl radicals yields the linear polymer PPE; the CꢀC
coupling of these phenoxyl radicals results in the byproduct DPQ
(Scheme S2 of the Supporting Information).
All the complexes have a 3D porous framework; however,
the catalytic activities of these complexes possess big differ-
ences. From Table 3, we found that complexes 5 and 6 show
better activities than complexes 1ꢀ4 in this system. The results
indicated that Cu(II)-containing complexes have good cataly-
tic activities in the oxidative coupling reaction. The contrasting
reaction using CuCl as catalyst only gives trace amounts of
2
PPE. The reason is that the N/O donor ligands interact with
metal ions to provide a delocalized electronic system within
complexes, which induce the modification of the electronic
properties of the molecules. This favors the coordination of
DMP to metal centers to form the proposed active metal
1
8f,21
species and the subsequent polymerization of DMP.
Likewise, Reedijk and co-workers have also shown that a series
of Cu(II) complexes incorporating structurally related N,O-
containing ligands underwent this polymerization more effi-
2
2
ciently than copper(II) salts. This suggests that the copper
2
191
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
accommodate more substrates binding to Cu(II) centers to
facilitate this oxidative coupling, and thus, the higher yield of
PPE is observed. This is also in agreement with the experimental
result. For example, the pore volumes for 1ꢀ3 are 274.8, 554.1,
’ AUTHOR INFORMATION
Corresponding Author
*
Fax: (86) 0371-67761744. E-mail: houhongw@zzu.edu.cn.
3
and 81.9 Å (2 > 1 > 3), respectively, which are calculated by
PLATON. The yields of PPE also follow the order 32% for 1,
’
ACKNOWLEDGMENT
This work was financially supported by the National Natural
4
4% for 2, and 25% for 3. We also found that complexes 3 and 4
provide similar results. This may be due to the fact that they are
isostructural. Comparing the two copper complexes, it is found
that the Cu(II) centers in complex 5 have higher coordination
numbers than those of 6, but complex 5 generally shows the
highest activity within this system. This is possibly attributed to a
Science Foundation (Nos. 20971110 and 91022013), Program
for New Century Excellent Talents of Ministry of Education of
China (NCET-07-0765), the Outstanding Talented Persons
Foundation of Henan Province, and The Ministry of Science
and Technology of China for the International Science Linkages
Program (2009DFA50620).
3
little larger pore volume of 5 (pore volume for 5, 53.0 Å ; for 6,
3
4
5.0 Å ) and the nature of coordinated anions, which may favor
the coordination of the substrate to Cu(II) centers to promote
the oxidative coupling reaction. It is evident that the metal
centers, coordinated anions, pore sizes, and coordination geo-
metries of the structures have great influence on the catalytic
activities. As a result, further structure modification for MOFs
could be realized through objective molecular design and synth-
esis, and then enhance the catalytic properties for desired
applications.
Taking into account that complex 5 was high catalytically
active in the green catalysis process of the oxidative coupling of
DMP, we take the complex as an example to study the stability
after catalytic reaction. After completion of the polymerization,
simple filtration of the reaction mixture allowed the separation
of the solid-state catalyst from the product-containing solu-
’
REFERENCES
(
1) (a) Han, S. S.; Goddard, W. A., III. J. Am. Soc. Chem. 2007,
129, 8422. (b) Kaczorowski, T.; Justyniak, I.; Lipinska, T.; Lipkowski, J.;
Lewinski, J. J. Am. Chem. Soc. 2009, 131, 5393. (c) Eddaoudi, M.; Moler,
D. B.; Li, H.; Chen, B.; Reineke, T. M.; O’Keeffe, M.; Yaghi, O. M. Acc.
Chem. Res. 2001, 34, 319. (d) Fang, Q. R.; Zhu, G. S.; Xue, M.; Sun, J. Y.;
Wei, Y.; Qiu, S. L.; Xu, R. R. Angew. Chem., Int. Ed. 2005, 44, 3845.
(e) Yamauchi, Y.; Yoshizawa, M.; Fujita, M. J. Am. Chem. Soc. 2008,
130, 5832. (f) Xu, J.; Pan, Z. R.; Wang, T. W.; Li, Y. Z.; Guo, Z. J.; Batten,
S. R.; Zheng, H. G. CrystEngComm 2010, 12, 612. (g) Zhang, F. W.; Li,
Z. F.; Ge, T. Z.; Yao, H. C.; Li, G.; Lu, H. J.; Zhu, Y. Y. Inorg. Chem. 2010,
49, 3776.
(
2) (a) Yoshizawa, M.; Nagao, M.; Umemoto, K.; Biradha, K.; Fujita,
M.; Sakamoto, S.; Yamaguchi, K. Chem. Commun. 2003, 1808. (b) Chen,
B.; Fronczek, F. R.; Maverick, A. W. Chem. Commun. 2003, 2166.
tion. After washing with CHCl several times, the catalyst was
3
characterized by powder XRD. The XRD patterns of the
catalyst before and after catalytic reaction are the same, which
indicates that the structural integrity of complex 5 was main-
tained during the catalytic process (Figure S3 of the Support-
ing Information). Then the complex was reused for the next
cycle. The result showed that complex 5 could be used for the
next cycle without significant loss of selectivity and only a slight
loss of conversion was observed. The slight loss of conversion
may be caused by the loss of the catalyst during the recovery
process. The complex exhibits a great potential as recyclable
catalyst.
(
c) Batten, S. R.; Murray, K. S. Coord. Chem. Rev. 2003, 246, 103. (d)
Chen, B.; Ma, S.; Zapata, F.; Fronczek, F. R.; Lobkovsky, E. B.; Zhou,
H. C. Inorg. Chem. 2007, 46, 1233. (e) Chen, S. M.; Lu, C. Z.; Zhang,
Q. Z.; Liu, J. H.; Wu, X. Y. Eur. J. Inorg. Chem. 2005, 423. (f) Cho, S. H.;
Ma, B.; Nguyen, S. T.; Hupp, J. T.; Albrecht-Schmitt, T. E. Chem.
Commun. 2006, 2563.
(
3) (a) Ye, B. H.; Ding, B. B.; Weng, Y. Q.; Chen, X. M. Cryst. Growth
Des. 2005, 5, 801. (b) Qi, Y.; Che, Y. X.; Zheng, J. M. Cryst. Growth Des.
008, 8, 3602. (c) Zhu, S. R.; Zhang, H.; Zhao, Y. M.; Shao, M.; Wang,
2
Z. X.; Li, M. X. J. Mol. Struct. 2008, 892, 420. (d) Su, Z.; Xu, J.; Fan, J.;
Liu, D. J.; Chu, Q.; Chen, M. S.; Chen, S. S.; Liu, G. X.; Wang, X. F.; Sun,
W. Y. Cryst. Growth Des. 2009, 9, 2801. (e) Du, M.; Jiang, X. J.; Zhao, X. J.
Inorg. Chem. 2007, 46, 3984.
(4) (a) Mu, Y. J.; Song, Y. J.; Wang, C.; Hou, H. W.; Fan, Y. T. Inorg.
’
CONCLUSIONS
Chim. Acta 2010, 365, 167. (b) Hu, J. Y.; Li, J. P.; Zhao, J. A.; Hou, H. W.;
Fan, Y. T. Inorg. Chim. Acta 2009, 362, 5023. (c) Meng, X. R.; Song,
Y. L.; Hou, H. W.; Han, H. Y.; Xiao, B.; Fan, Y. T.; Zhu, Y. Inorg. Chem.
In summary, we have synthesized and characterized six new
MOFs based on aromatic polycarboxylate and a long flexible
bis(triazole) ligand, which show rich structural features. The
results of this study illustrate that the coordination modes of
carboxylate ligand and the nature of the neutral ligands play
important roles in the construction of MOFs. The catalytic
activities of the complexes indicate that the copper complexes
may be good catalysts for the oxidative coupling of 2,6-dimethyl-
phenol (DMP). It is anticipated that more metal complexes
containing neutral ligands and aromatic carboxylate anions with
interesting structures as well as physical properties will be
synthesized.
2
004, 43, 3528. (d) Ren, C.; Liu, P.; Wang, Y. Y.; Huang, W. H.; Shi,
Q. Z. Eur. J. Inorg. Chem. 2010, 5545. (e) Ren, C.; Hou, L.; Liu, B.; Yang,
G. P.; Wang, Y. Y.; Shi, Q. Z. Dalton Trans. 2011, 40, 793.
(5) (a) Yang, E. C.; Liu, Z. Y.; Shi, X. J.; Liang, Q. Q.; Zhao, X. J.
Inorg. Chem. 2010, 49, 7969. (b) Wang, X. L.; Bi, Y. F.; Lin, H. Y.; Liu,
G. C. Cryst. Growth Des. 2007, 7, 1086.
(
(
6) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.
7) Zhang, E. P.; Hou, H. W.; Han, H. Y.; Fan, Y. T. J. Organomet.
Chem. 2008, 693, 1927.
8) (a) Qi, Y.; Luo, F.; Che, Y. X.; Zheng, J. M. Cryst. Growth Des.
008, 8, 606. (b) Bai, H. Y.; Ma, J. F.; Yang, J.; Zhang, L. P.; Ma, J. C.; Liu,
(
2
Y. Y. Cryst. Growth Des. 2010, 10, 1946. (c) Yang, W. B.; Lin, X.; Blake,
A. J.; Wilson, C.; Hubberstey, P.; Champness, N. R.; Schr €o der, M. Inorg.
Chem. 2009, 48, 11067. (d) Wang, L.; Gu, W.; Deng, J. X.; Liu, M. L.; Xu,
N.; Liu, X. Z. Anorg. Allg. Chem. 2009, 636, 1124.
’
ASSOCIATED CONTENT
(
9) (a) Li, C. Y.; Liu, C. S.; Li, J. R.; Bu, X. H. Cryst. Growth Des. 2007,
S
Supporting Information. X-ray crystallographic files in
b
7, 286. (b) Gao, E. Q.; Xu, Y. X.; Yan, C. H. CrystEngComm 2004, 6, 298.
(10) (a) Sun, H. L.; Gao, S.; Ma, B. Q.; Batten, S. R. CrystEngComm
2004, 6, 579. (b) Martin, D. P.; Supkowski, R. M.; LaDuca, R. L. Cryst.
CIF format and powder X-ray patterns for 1ꢀ6. This material is
available free of charge via the Internet at http://pubs.acs.org.
2
192
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193

Crystal Growth & Design
ARTICLE
Growth Des. 2008, 8, 3518. (c) Ma, L. F.; Wang, L. Y.; Wang, Y. Y.;
Batten, S. R.; Wang, J. G. Inorg. Chem. 2009, 48, 915.
(11) (a) Chen, S. S.; Fan, J.; Okamura, T.; Chen, M. S.; Su, Z.; Sun,
W. Y.; Ueyama, N. Cryst. Growth Des. 2010, 10, 812. (b) Yang, G. S.; Lan,
Y. Q.; Zang, H. Y.; Shao, K. Z.; Wang, X. L.; Su, Z. M.; Jiang, C. J.
CrystEngComm 2009, 11, 274. (c) Blatov, V. A.; Carlucci, L.; Ciani, G.;
Proserpio, D. M. CrystEngComm 2004, 6, 377.
(
12) (a) Fan, J.; Yee, G. T.; Wang, G. B.; Hanson, B. E. Inorg. Chem.
006, 45, 599. (b) Tan, H. Y.; Zhang, H. X.; Ou, H. D.; Dang, B. S. Inorg.
Chim. Acta 2004, 357, 869.
13) (a) Liu, Y. Y.; Ma, J. F.; Yang, J.; Su, Z. M. Inorg. Chem. 2007,
6, 3027. (b) Liu, F. C.; Zeng, Y. F.; Jiao, J.; Bu, X. H.; Ribas, J.; Batten,
2
(
4
S. R. Inorg. Chem. 2006, 45, 2776. (c) Yu, Q.; Li, C. P.; Zhang, Z. H.; Du,
M. Polyhedron 2009, 28, 2347.
(14) (a) Addison, A. W.; Rao, T. N.; Reedijk, J.; Rijn, J. V.;
Verschoor, G. C. J. Chem. Soc., Dalton Trans. 1984, 1349. (b) Burchell,
T. J.; Eisler, D. J.; Puddephatt, R. J. Inorg. Chem. 2004, 43, 5550.
(
15) Yang, E. C.; Feng, W.; Wang, J. Y.; Zhao, X. J. Inorg. Chim. Acta
010, 363, 308.
16) Wen, L. L.; Wang, F.; Feng, J.; Lv, K. L.; Wang, C. G.; Li, D. F.
Cryst. Growth Des. 2009, 9, 3581.
17) Yan, Y.; Wu, C. D.; He, X.; Sun, Y. Q.; Lu, C. Z. Cryst. Growth
Des. 2005, 5, 821.
18) (a) Fujita, M.; Kwon, Y. J.; Washizy, S.; Ogura, K. J. Am. Chem.
Soc. 1994, 116, 1151. (b) Tannenbaum, R. Chem. Mater. 1994, 6, 550.
c) Seo, J. S.; Whang, D.; Lee, H.; Jun, S. I.; Oh, J.; Jeon, Y. J.; Kim, K.
2
(
(
(
(
Nature 2000, 404, 982. (d) Kondo, M.; Shimamura, M.; Noro, S.;
Minakoshi, S.; Asami, A.; Seki, K.; Kitagawa, S. Chem. Mater. 2000,
12, 1288. (e) Fujita, M.; Umemota, K.; Yoshizawa, M.; Fujita, N.;
Kusukawa, T.; Biradha, K. Chem. Commun. 2001, 509. (f) Han, H. Y.;
Zhang, S. J.; Hou, H. W.; Fan, Y. T.; Zhu, Y. Eur. J. Inorg. Chem.
2
2
006, 1594. (g) Xiao, B.; Hou, H. W.; Fan, Y. T. J. Organomet. Chem.
007, 692, 2014.
(19) (a) Liu, Y.; Pang, Q. H.; Meng, X. G.; Liu, F. R.; Li, J. M.; Du, J.;
Hu, C. W. J. Appl. Polym. Sci. 2010, 118, 2043. (b) Sadeghi, F.; Tremblay,
A. Y.; Kruczek, B. J. Appl. Polym. Sci. 2008, 109, 1454. (c) Li, X. H.;
Meng, X. G.; Pang, Q. H.; Liu, S. D.; Li, J. M.; Du, J.; Hu, C. W. J. Mol.
Catal. A: Chem. 2010, 328, 88. (d) Sakar, D.; Cankurtaran, O.; Karaman,
F. Plast., Rubber Compos. 2008, 37, 276.
ꢀ
(
20) (a) Boldron, C.; AromI, G.; Challa, G.; Gamez, P.; Reedijk, J.
Chem. Commun. 2005, 5808. (b) Saito, K.; Tago, T.; Masuyama, T.;
Nishide, H. Angew. Chem., Int. Ed. 2004, 43, 730. (c) Baesjou, P. J.;
Driessen, W . L.; Challa, G.; Reedijk, J. J. Am. Chem. Soc. 1997,
1
19, 12590. (d) Gao, J.; Reibenspies, J. H.; Martell, A. E. Inorg. Chim.
Acta 2002, 338, 157.
21) Maurya, M. R.; Jain, I.; Titinchi, S. J. J. Appl. Catal. A: Gen. 2003,
49, 139.
22) Guieu, S. J .A.; Lanfredi, A. M. M.; Massera, C.; Pach ꢀo n, L. D.;
Gamez, P.; Reedijk, J. Catal. Today 2004, 96, 259.
(
2
(
2
193
dx.doi.org/10.1021/cg101494t |Cryst. Growth Des. 2011, 11, 2183–2193