A series of 1D, 2D and 3D coordination polymers based on a 5-(benzonic-4-ylmethoxy)isophthalic acid: Syntheses, structures and photoluminescence

Article abstract of DOI:10.1039/c1ce05639e

Seven new coordination polymers, namely, [Zn(HL)(H₂O)] (1), [Zn(HL)(phen)]·1.5H₂O (2), [Zn(HL)(L¹)] (3), [Zn₂(HL)₂(L²)₂]·2H ₂O (4), [Zn(HL)(L³)_0.5

Full text of DOI:10.1039/c1ce05639e

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PAPER
A series of 1D, 2D and 3D coordination polymers based on a 5-(benzonic-4-
ylmethoxy)isophthalic acid: syntheses, structures and photoluminescence†
*
Ying-Ying Liu, Jing Li, Jian-Fang Ma, Ji-Cheng Ma and Jin Yang
*
Received 28th May 2011, Accepted 8th September 2011
DOI: 10.1039/c1ce05639e
Seven new coordination polymers, namely, [Zn(HL)(H2O)] (1), [Zn(HL)(phen)]$1.5H2O (2), [Zn(HL)
(L1)] (3), [Zn2(HL)2(L2)2]$2H2O (4), [Zn(HL)(L3)0.5] (5), [Zn(HL)(L4)] (6) and [Cu2(L)(OH)(H2O)]$
0.5H2O (7) (H3L ¼ 5-(benzonic-4-ylmethoxy) isophthalic acid, phen ¼ 1,10-phenathroline, L1 ¼ 1,2-bis
(1,2,4-triazole-1-yl)ethane, L2 ¼ 1,3-bis(1,2,4-triazole-1-yl)propane, L3 ¼ 1,6-bis(1,2,4-triazole-1-yl)
hexane and L4 ¼ 4,40-bis(1,2,4-triazole-1-ylmethyl)biphenyl), have been hydrothermally synthesized
and characterized by single-crystal X-ray diffraction. In compounds 1–6, the H3L ligand is partially
deprotonated to form HL2ꢀ, while it is completely deprotonated in 7. Compound 1 shows a 3D
framework with 4-connected (42$7$83)2 topology. Compound 2 displays a 1D ribbon structure. The
neighboring ribbons are further linked by hydrogen-bonding interactions to form a 3D supramolecular
architecture. Compound 3 exhibits a 2D undulated sheet. The sheets are further penetrated into each
other to give rise to a 3D polycatenation structure. Compound 4 displays a 2D supramolecular layer
structure. Compound 5 shows a 3D (3,6)-connected (4$8)(4$82$103) net. Compound 6 reveals a 3D
four-fold interpenetrating diamondoid architecture. Compound 7 displays a (3,8)-connected (4$62)
(44$68$812$104) topology. These compounds have been characterized by powder X-ray diffractions
(PXRD) and thermal gravimetric analyses (TGA). In addition, the photoluminescent behaviours of 1–6
have been investigated in detail.
meet the requirements of the coordination geometries of metal
Introduction
atoms in the assembly process. In addition, it can bridge the
central metals to give a series of interesting structures through
complete or partial deprotonation of its three carboxylate
groups. As far as we know, coordination polymers constructed
from H3L and auxiliary N-donor ligands have been scarcely
investigated so far.3 Besides, neutral N-donor ligands, especially
flexible bridging N-donor ligands, also have significant effects on
the construction of coordination polymers.4 In this regard, 1-
substituted bis(1,2,4-triazole) ligands have been found to be one
kind of useful flexible building block in the construction of
coordination polymers with versatile topologies.5
In recent years, considerable efforts have been focused on the
design and synthesis of novel multidimensional coordination
polymers, not only because of their intriguing variety of archi-
tectures and topologies but also because of their tremendous
potential applications in the fields of ion exchange, gas storage,
luminescence and heterogeneous catalysis.1 It is well known that
the construction of coordination polymers is mainly dependent
on the combination of several factors, such as the organic ligand,
solvents, and metal atoms.2 Among them, the anions play an
important role in the construction of novel architectures. Among
various polycarboxylates, 5-(benzonic-4-ylmethoxy)isophthalic
acid (H3L), as a tricarboxylate ligand, is a good candidate for the
construction of coordination polymers. The H3L ligand contains
a hetero-oxygen atom and a –CH2– spacer at the center of the
molecule. Therefore, the two phenylene rings can freely twist to
In this work, seven compounds based on H3L acids and
flexible N-donor ligands have been synthesized under hydro-
thermal conditions, namely, [Zn(HL)(H2O)] (1), [Zn(HL)
Key Lab for Polyoxometalate Science, Department of Chemistry,
Northeast Normal University, Changchun, 130024, People’s Republic of
China. E-mail: jianfangma@yahoo.com.cn; yangjinnenu@yahoo.com.cn;
Fax: +86-431-85098620
† Electronic supplementary information (ESI) available: Selected bond
distances and angles; structure illustrations for compounds 1 and 7;
TGA, luminescence decay and PXRD curves. CCDC reference
numbers 828044–828050. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c1ce05639e
Chart 1 Structures of the bis(1,2,4-triazole) ligands used in this work.
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(phen)]$1.5H2O (2), [Zn(HL)(L1)] (3), [Zn2(HL)2(L2)2]$2H2O
(4), [Zn(HL)(L3)0.5] (5), [Zn(HL)(L4)] (6) and [Cu2(L)(OH)
(H2O)]$0.5H2O (7) (phen ¼ 1,10-phenathroline, L1 ¼ 1,2-bis
Synthesis of [Zn(HL)(H2O)] (1). A mixture of ZnCl2 (0.032 g,
0.23 mmol), H2L (0.050 g, 0.16 mmol), and water (8 mL) was
placed in a Teflon reactor, and the pH value was adjusted to 4.0
by addition of 0.25 mol Lꢀ1 NaOH solution. The mixture was
heated at 140 ꢁC for 3 days, and then it was gradually cooled to
room temperature. The crystals were obtained in a 58% yield.
Anal. Calcd for C16H12ZnO8 (Mr ¼ 397.63): C, 48.33; H, 3.04%.
Found: C, 48.64; H, 2.93%. IR data (KBr, cmꢀ1): 3504 (m), 3112
(m), 2912 (m), 2635 (m), 2514 (m), 1682 (s), 1536 (s), 1455 (m),
1386 (s), 1275 (s), 1136 (s), 1058 (s), 1015 (w), 967 (w), 882 (w),
774 (s), 726 (m), 666 (w).
(1,2,4-triazole-1-yl)ethane, L2
¼
1,3-bis(1,2,4-triazole-1-yl)
propane, L3 ¼ 1,6-bis(1,2,4-triazole-1-yl)hexane and L4 ¼ 4,40-
bis(1,2,4-triazole-1-ylmethyl)biphenyl) (Chart 1). The coordi-
nation modes of the H3L ligands on the ultimate structures
have been discussed. In addition, the luminescent properties for
1–6 have also been investigated.
Experimental
Synthesis of [Zn(HL)(phen)]$1.5H2O (2). A mixture of ZnCl2
(0.032 g, 0.23 mmol), H2L (0.050 g, 0.16 mmol), phen (0.029 g,
0.16 mmol), 1 mL 0.25 mol Lꢀ1 NaOH solution, and water (8
mL) was placed in a Teflon reactor. The mixture was heated at
150 ꢁC for 3 days, and then it was gradually cooled to room
temperature. Colorless block crystals were obtained in a 60%
yield. Anal. Calcd for C28H21ZnN2O8.50 (Mr ¼ 586.84): C, 57.31;
H, 3.61; N, 4.77%. Found: C, 57.14; H, 3.67; N, 4.85%. IR data
(KBr, cmꢀ1): 3471 (s), 3075 (m), 2874 (m), 1682 (m), 1571 (s),
1378 (s), 1245 (m), 1108 (m), 1037 (m), 846 (m), 779 (m), 727 (m),
618 (w), 577 (w).
Materials and measurements
All reagents and solvents for syntheses were purchased from
commercial sources and used as received. The ligand H3L was
synthesized as in a previously reported method.6 The C, H and
N elemental analysis was conducted on a Perkin–Elmer 240C
elemental analyzer. The FT-IR spectra were recorded from
KBr pellets in the range 4000–400 cmꢀ1 on a Mattson Alpha-
Centauri spectrometer. The phase purities of the bulk samples
were identified by X-ray powder diffraction on a Siemens
D5005 diffractometer. TGA was performed on a Perkin–Elmer
TG-7 analyzer. The photoluminescent properties were
measured
on
a
FLSP920
Edinburgh
Fluorescence
Synthesis of [Zn(HL)(L1)] (3). A mixture of ZnCl2 (0.032 g,
0.23 mmol), H2L (0.050 g, 0.16 mmol), L1 (0.026 g, 0.16 mmol),
1 mL 0.25 mol Lꢀ1 NaOH solution, ethanol (2 mL) and water
(6 mL) was placed in a Teflon reactor. The mixture was heated at
120 ꢁC for 3 days, and then it was gradually cooled to room
temperature. Colorless block crystals were obtained in a 47%
yield. Anal. Calcd for C22H18ZnN6O7 (Mr ¼ 543.79): C, 48.59;
H, 3.33; N, 15.45%. Found: C, 48.74; H, 3.38; N, 15.31%. IR data
(KBr, cmꢀ1): 3437 (s), 3148 (m), 3032 (m), 1713 (s), 1606 (s), 1570
(s), 1381 (s), 1265 (s), 1204 (m), 1129 (s), 994 (m), 916 (w), 880
(w), 832 (w), 765 (m), 674 (m), 580 (m).
Spectrometer.
Syntheses of L1–L4. A mixture of 1,2,4-triazole (3.5 g, 50
mmol), NaOH (2.0 g, 50 mmol) and DMF (40 mL) was heated at
60 ꢁC for 1 h, then 1,2-dibromoethane (4.7 g, 25 mmol) was
added. After stirring at 60 ꢁC for 2 h, the mixture was evaporated
in a water bath to a viscous state. The product was extracted by
chloroform three times. The solvent was removed from the
filtrate by rotary evaporation, and a white solid of L1 formed
immediately. The preparations of L2–L4 were similar to that of L1
except that 1,3-dibromopropane for L2, 1,6-dibromohexa-
methylene for L3 and 4,40-bis(chloromethyl)-1,10-biphenyl for L4
were used instead of 1,2-dibromoethane, respectively.
Synthesis of [Zn2(HL)2(L2)2]$2H2O (4). The preparation of 4
was similar to that of 2 except that L2 (0.028 g) was used
Table 1 Crystal data and structure refinements for compounds 1–7
1
2
3
4
5
6
7
Formula
fw
Space group
C16H12ZnO8 C28H21ZnN2O8.50 C22H18ZnN6O7 C46H44Zn2N12O16 C84H72Zn4N12O28 C34H26ZnN6O7 C32H26Cu4O19
397.63
P21/c
11.9530(7)
7.2717(3)
17.7746(8)
90
104.482(5)
90
1495.85(13) 1234.7(8)
4
586.84
543.79
1151.67
ꢀ
P1
1959.02
P21/c
15.1240(7)
13.8252(5)
9.5104(4)
90
102.674(4)
90
1940.10(14)
1
1.677
695.79
P21212
14.9780(5)
32.6149(11)
6.3668(2)
90
968.69
ꢀ
P1
ꢀ
P1
ꢀ
P1
ꢁ
a/A
9.955(5)
8.6590(3)
9.9594(4)
12.8686(6)
94.713(4)
101.475(3)
92.540(3)
1081.82(8)
2
11.8109(6)
13.7859(5)
16.9387(6)
67.887(4)
87.405(4)
71.034(4)
2407.07(20)
2
6.8167(4)
10.8308(5)
12.0167(7)
86.596(4)
83.997(5)
73.499(4)
845.58(8)
1
ꢁ
b/A
10.550(4)
14.073(3)
88.346(2)
69.302(3)
64.914(5)
ꢁ
c/A
a (deg.)
b (deg.)
g (deg.)
90
90
3
ꢁ
V/A
Z
3110.22(18)
4
1.486
2
Dc/g cmꢀ3
F(000)
Observed reflection/unique 6486/3455
1.766
808
1.578
602
1.669
556
1.589
1184
1.902
486
1004
1432
9086/5617
0.0124
1.042
0.0279
0.0745
8204/4916
0.0202
0.880
0.0347
0.0724
17725/10961
0.0264
0.871
0.0347
0.0594
8435/4491
0.0227
0.854
0.0285
0.0563
14173/6632
0.0400
0.748
0.0336
0.0315
6155/3847
0.0200
0.924
0.0281
0.0637
R(int)
0.0262
0.902
0.0335
0.0698
GOF on F2
R1a[I > 2s(I)]
wR2
b
a
b
2
R1 ¼ S||Fo| ꢀ |Fck/S|Fo|. wR2 ¼ |Sw(|Fo|2ꢀ|Fc|2)|/S|w(Fo )2|1/2
.
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instead of phen. Colorless block crystals were obtained in
53% yield. Anal. Calcd for C46H44Zn2N12O16 (Mr
Results and discussion
a
¼
Structure of [Zn(HL)(H2O)] (1)
1151.67): C, 47.97; H, 3.85; N, 14.59%. Found: C, 47.76; H,
3.73; N, 14.43%. IR data (KBr, cmꢀ1): 3437 (s), 3121 (m), 2921
(w), 2621 (s), 1686 (s), 1567 (s), 1369 (s), 1264 (s), 1174 (w),
1136 (m), 998 (m), 897 (m), 777 (m), 736 (m), 673 (m),
646 (m).
As illustrated in Fig. 1a, the Zn(II) ion is five-coordinated by four
carboxylate oxygen atoms from four HL anions and one water
ꢁ
molecule (Zn–O ¼ 1.928(2)–2.459(2) A). Each HL anion coor-
dinates to four Zn(II) atoms in a m4-h1:h1:h0:h1:h0:h1 coordina-
tion mode (Chart 2a). In this way, the Zn(II) centers are
connected by HL anions to yield a 3D framework (Fig. 1b).
Synthesis of [Zn(HL)(L3)0.5] (5). A mixture of ZnCl2 (0.032 g,
0.23 mmol), H2L (0.050 g, 0.16 mmol), L3 (0.035 g, 0.16 mmol), 1
mL 0.25 mol Lꢀ1 NaOH solution, and water (8 mL) was placed in
ꢁ
a Teflon reactor. The mixture was heated at 160 C for 3 days,
and then it was gradually cooled to room temperature. Colorless
block crystals were obtained in a 43% yield. Anal. Calcd for
C84H72Zn4N12O28 (Mr ¼ 1959.02): C, 51.50; H, 3.70; N, 8.58%.
Found: C, 51.39; H, 3.73; N, 8.61%. IR data (KBr, cmꢀ1): 3133
(m), 3045 (w), 2948 (s), 2865 (s), 2488 (w), 1714 (s), 1544 (s), 1410
(m), 1280 (s), 1275 (m), 1130 (s), 1001 (s), 892 (m), 858 (m),
771 (m), 673 (m), 641 (m).
Synthesis of [Zn(HL)(L4)] (6). The preparation of 6 was similar
to that of 5 except that L4 (0.035 g) was used instead of L3.
Colorless block crystals were obtained in a 35% yield. Anal.
Calcd for C34H26ZnN6O7 (Mr ¼ 695.79): C, 58.69; H, 3.77; N,
12.07%. Found: C, 58.79; H, 3.70; N, 12.01%. IR data (KBr,
cmꢀ1): 3549 (m), 3478 (s), 3414 (s), 3137 (s), 3053 (s), 2979 (m),
2851 (w), 1705 (s), 1621 (s), 1558 (s), 1502 (m), 1405 (s), 1320 (m),
1268 (m), 1240 (m), 1132 (s), 1056 (m), 999 (m), 965 (w), 940 (w),
888 (w), 782 (s), 734 (m), 674 (m), 647 (m).
Synthesis of [Cu2(L)(OH)(H2O)]$0.5H2O (7). The preparation
of 7 was similar to that of 1 except that CuCl2$2H2O (0.057 g)
was used instead of ZnCl2, and the temperature was changed into
130 ꢁC. Blue crystals were obtained in a 52% yield. Anal. Calcd
for C32H26Cu4O19 (Mr ¼ 968.69): C, 39.68; H, 2.70%. Found: C,
39.74; H, 2.66%. IR data (KBr, cmꢀ1): 3386 (s), 2501 (m), 1679
(m), 1544 (s), 1400 (s), 1294 (s), 1238 (m), 1138 (m), 1044 (m), 962
(w), 912 (w), 765 (s), 692 (w), 599 (w).
X-ray crystallography
Crystallographic diffraction data for compounds 1–7 were
recorded on a Oxford Diffraction Gemini R CCD with
ꢁ
graphite-monochromated Mo-Ka radiation (l ¼ 0.71073 A) at
293 K. Absorption corrections were applied using multi-scan
technique. All the structures were solved by Direct Method of
SHELXS-97 and refined by full-matrix least-squares techniques
using the SHELXL-97 program within WINGX.7 Non-
hydrogen atoms were refined with anisotropic temperature
parameters. The hydrogen atoms attached to carbons were
generated geometrically. The hydrogen atoms of hydroxyl and
water molecules were located from difference Fourier maps and
refined with isotropic displacement parameters. The detailed
crystallographic data and structure refinement parameters for
1–7 are summarized in Table 1. Selected bond distances and
angles and hydrogen bonds for the compounds are given in the
ESI (Tables S1–S2)†.
Fig. 1 (a) ORTEP diagram showing the coordination environment of
the Zn(II) atom in 1. Symmetry codes: #1 ꢀx + 2, ꢀy, ꢀz + 2; #2 x, ꢀy ꢀ 1/
2, z ꢀ 1/2; #3 ꢀx + 1, y + 3/2, ꢀz + 3/2. (b) View of the 3D structure. (c)
Schematic diagram (OLEX) showing the 3D (42$7$83)2 net of 1.
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Actually, in order to simplify the intricate structure of 1, both the
Zn(II) atom and HL anion can be considered as 4-connected
nodes, respectively (Fig. S1†). From a topological perspective,
the 3D framework of 1 can be described as a 4-connected net with
polycatenated framework of 3 was obtained. The Zn(II) atom is
five-coordinated by three carboxylate oxygen atoms from two
HL anions, and two nitrogen atoms from two L1 ligands
(Fig. 3a). The HL anion shows a m2-h0:h1:h0:h0:h1:h1 coordina-
tion mode (Chart 2c). Two crystallographically unique L1 ligands
lie about inversion centers. The Zn(II) atoms are linked by HL
anions and L1 ligands to generate a deeply corrugated 2D (4,4)
sheet (Fig. 3b). The open space within each sheet provides the
chance for the parallel polycatenation of the (4,4) sheets (Fig. 3c).
Each sheet is penetrated by two others (one above and one
below) which have parallel but not coincident mean planes,
leading to an overall 3D entanglement (Fig. 3d). As far as we
know, only a few examples of 2D / 3D structures entangled in
parallel mode have been observed up to now.9
2
3
8
€
a Schlafli symbol of (4 $7$8 )2 (Fig. 1c). In addition, there are
intermolecular hydrogen-bonding interactions between the water
molecule and the carboxylate O atoms. These hydrogen bonds
further stabilize the structure of the 3D framework (Table S2†).
Structure of [Zn(HL)(phen)]$1.5H2O (2)
When phen was introduced into the reaction system of 1, a quite
different ribbon structure of 2 was obtained. The Zn(II) ion of 2 is
six-coordinated by four oxygen atoms from three HL anions (Zn–
ꢁ
O ¼ 1.991(1)–2.304(2) A) and two nitrogen atoms (Zn–N ¼ 2.095
ꢁ
(1)–2.143(2) A) from one phen ligand (Fig. 2a). The HL anion
exhibits a m3-h1:h1:h0:h1:h0:h1 coordination mode (Chart 2b). The
Zn(II) atoms are linked via HL anions to form a 1D ribbon
structure (Fig. 2b). The chelating phen ligands are located on both
rims of the ribbon. Adjacent ribbons are further connected by
face-to-face p–p interactions between phen ligands (with average
Structure of [Zn2(HL)2(L2)2]$2H2O (4)
When L1 was replaced by L2, a completely different compound 4
was obtained. As shown in Fig. 4a, there are two kinds of crys-
tallographically unique Zn(II) centers in the structure. Each Zn
(II) cation is coordinated by two oxygen atoms from two HL
anions, and two nitrogen atoms from two L2 ligands in a slightly
distorted tetrahedral geometry. Two HL ligands show m2-h0:h1:
h0:h1:h0:h0 and m2-h1:h1:h0:h1:h0:h0 coordination modes,
respectively (Chart 2d and 2e). The L2 ligands bridge adjacent Zn
(II) atoms to give a dimeric unit [Zn(L2)2Zn] with the Zn/Zn
ꢁ
face-to-face distance of 3.34 A and centroid-to-centroid distance
ꢁ
of 3.53 A), resulting in a 3D supramolecular architecture (Fig. 2c).
Moreover, there exist hydrogen-binding interactions among
adjacent ribbons (Table S2†). The lattice water molecules and the
uncoordinated carboxylic group of the HL anion act as hydrogen
donors (O7/O3#5 ¼ 2.5806(18) A, O1W/O1 ¼ 2.968(3) A,
ꢁ
ꢁ
O1W/O1#6 ¼ 3.017(3) A, O2W/O2 ¼ 2.932(6) A, ꢀx + 1,
ꢀy + 1, ꢀz + 1; #5 x ꢀ 1, y + 1, z + 1; #6 ꢀx, ꢀy + 1, ꢀz + 2). These
hydrogen bonds further stabilize the 3D supramolecular archi-
tecture of 2.
#4
#4
ꢁ
ꢁ
2
ꢁ
distance of 9.956 A. As shown in Fig. 4b, the [Zn(L )2Zn] dimers
are further connected by HL anions to give a 1D ribbon struc-
ture. The dangling 4-carboxybenzyloxy groups of HL anions
locate on both rims of the ribbon structure. The 1D ribbon
structures of 4 are further stacked by the face-to-face p–p
interactions between the phenyl rings of adjacent HL anions
(with face-to-face and centroid-to-centroid distances of 3.32 and
Structure of [Zn(HL)(L1)] (3)
When the flexible bis(1,2,4-triazole) ligand L1 was utilized in
3.66 A, respectively) to generate a 2D supramolecular network
ꢁ
place of the chelating phen ligand of 2, a 2D / 3D
(Fig. 4c). In addition, the intermolecular hydrogen-bonding
Chart 2 Coordination modes of the HL2ꢀ and L3ꢀ ligands in compounds 1–7.
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Fig. 2 (a) ORTEP diagram showing the coordination environment of
the Zn(II) atom in 2. Symmetry codes: #1 x ꢀ 1, y, z; #2 ꢀx, ꢀy + 2, ꢀz + 2.
(b) View of the 1D chain of 2. (c) View of the 3D supramolecular
architecture of 2 formed by p–p stacking interactions of neighboring
chains.
interactions among adjacent chains further stabilize the 2D
supramolecular network of 4.
Structure of [Zn(HL)(L3)0.5] (5)
When the L2 anion of 4 was replaced by L3, a different 3D
structure of 5 was obtained. As shown in Fig. 5a, the Zn(II) cation
is coordinated by three oxygen atoms from three HL anions, and
one nitrogen atom from one L3 ligand in a slightly distorted
tetrahedral geometry. The L3 ligand lies about an inversion
center. The HL anion is partly deprotonated, and displays a m3-
h1:h1:h0:h1:h0:h0 coordination mode (Chart 2f). Neighboring Zn
(II) atoms are linked by HL anions to generate a 2D layer. The 4-
carboxybenzyloxy groups of HL anions, as the dangling arms,
locate at both sides of the layer (Fig. 5b). The layers are further
Fig. 3 (a) Coordination environment of the Zn(II) atom in 7. Symmetry
codes: #1 x, y + 1, z + 1. (b) View of the 2D undulated layer. (c) The 2D /
3D parallel interpenetration of the layers in 3. (d) Schematic represen-
tation of the 2D / 3D polycatenation of different (4,4) motifs.
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connected by L3 ligands to give a 3D framework. If Zn(II) atoms
and HL anions can be considered as four-connected and three-
connected nodes, respectively, the structure of 5 can be
symbolized as a 3D (4$8)(4$82$103) net with two kinds of
nonequivalent points (Fig. 5c).
Structure of [Cu2(L)(OH)(H2O)]$0.5H2O (7)
As shown in Fig. 7a, the asymmetric unit contains two crystal-
lographic Cu(II) atoms. The Cu1 cation is coordinated by three
oxygen atoms from three L anions, one m3–OH and one water
molecule. Cu2 is coordinated by three oxygen atoms from three
L anions and two m3–OH. Cu1 and Cu2 ions have distorted
square pyramidal environments, in agreement with the structural
index s values of 0.383 for Cu1 and 0.263 for Cu2, respectively
(s ¼ 0 and 1 for perfect square-pyramidal and trigonal-bipyra-
midal geometries, respectively).11 Due to the Jahn–Teller
effect, the Cu–O distance at the axial site (Cu1–O1W 2.287(3)
Structure of [Zn(HL)(L4)] (6)
Each Zn(II) center in 6 is five-coordinated by three oxygen atoms
from two HL anions, and two nitrogen atoms from two L4
ligands (Fig. 6a). The HL anion shows a m2-h1:h1:h0:h1:h0:h0
coordination mode (Chart 2e). The Zn/Zn separations bridged
4
ꢁ
by the HL anion and L ligand are 9.82 and 18.14 A, respectively.
Zn(II) ions are bridged by HL anions and L4 ligands to give a 3D
diamond framework (Fig. 6b). Because of the spacious nature of
the single network, the potential voids are filled via mutual
interpenetration of identical 3D frameworks, generating a four-
fold interpenetrating architecture (Fig. 6c). According to
topology classification, this diamondoid architecture belongs to
Class Ia (all the independent nets are related by a single vector
and the whole interpenetrating arrays are generated by trans-
lating a single net 3 times),10 with the translating vector of [001]
ꢁ
6.37 A.
Fig. 4 (a) Coordination environments of the Zn(II) atoms in 4.
Fig. 5 (a) Coordination environment of the Zn(II) atom in 5. Symmetry
#1
#2
#1
#2
Symmetry codes: ꢀx + 1, ꢀy + 1, ꢀz + 1; ꢀx + 2, ꢀy + 1, ꢀz. (b)
View of the 1D chain structure of 4. (c) View of the 2D supramolecular
layer connected by face-to-face p–p interactions.
codes: ꢀx + 2, y + 1/2, ꢀz + 3/2; ꢀx + 2, ꢀy, ꢀz + 2. (b) Repre-
sentation of the 2D Zn-HL layer. (c) Schematic diagram (OLEX) of the
(4$8)(4$82$103) network of 5.
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ꢁ
and Cu2–O7 2.374(2) A) is much longer than those of equatorial
ꢁ
planes (1.9156(15)–1.9935(15) A). All of the coordination bonds
an eight-connected node, and the L anion was considered as
a three-connected node (Fig. S2†), the topology of this 3D
framework can thus be described as a (4$62)(44$68$812$104) net
(Fig. 7c).
show typical values for the Cu(II) ion. As shown in Fig. 7b, two
m3–OH groups link four Cu(II) ions to form a rhombus-like tet-
ranuclear unit. The separation of Cu2/Cu2#4 ions is 3.027 A,
ꢁ
indicating the existence of a weak Cu/Cu interaction.12 Each L
anion bridges three tetranuclear units in a m6-h1:h1:h1:h1:h1:h1
coordination mode (Chart 2g). In this way, L anions linked the
neighboring tetranuclear [Cu4O10] units to generate a 3D
framework. If the tetranuclear [Cu4O10] unit was considered as
Effect of organic ligands on the complex structure
From the structure description above, we can see that the neutral
ligand has a significant effect on the complex structure.
Compound 1 displays a 3D framework. In comparison with 1, the
introduction of neutral N-donor ligands (phen, L1, L2, L3 and L4)
in 2–6 not only replaces the coordinated water molecule of the Zn
(II) ion, but also changes the coordination modes of the HL
anions. When the secondary N-donor ligand phen was utilized,
Fig. 7 (a) Coordination environments of the Cu(II) atoms in 7.
Symmetry codes: #1 ꢀx + 4, ꢀy + 1, ꢀz + 3; #2 x, y ꢀ 1, z; #3 ꢀx + 2, ꢀy +
2, ꢀz + 2; #4 ꢀx + 2, ꢀy + 1, ꢀz + 2; #5 x ꢀ 1, y, z ꢀ 1. (b) View of the
[Cu4O10] unit. (c) View of the 3D (3,8)-connected framework with (4$62)
(44$68$812$104) topology.
Fig. 6 (a) Coordination environment of the Zn(II) atom in 6. Symmetry
codes: #1 ꢀx + 3/2, y + 1/2, ꢀz + 1; #2 x + 1/2, ꢀy + 1/2, ꢀz ꢀ 1. (b) View
of a single diamond structure of 6. (c) View of the four-fold inter-
penetrating diamond diagram (OLEX) of 6.
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a structurally different compound 2 was obtained. In 2, phen
occupies the coordinate sites of Zn(II) ion, and generates a 1D
chain structure.13 The structural differences of compounds 3–6 are
closely related to the spacers of bis(1,2,4-triazole) ligands. Due to
the presence of different spacers, –(CH2)2–, –(CH2)3–, –(CH2)6–
and –CH2–(phenyl)2–CH2– in L1, L2, L3 and L4, respectively, the
neutral N-donor ligands display different lengths, geometries and
flexibilities. As a result, these different properties of the N-donor
ligands result in the differences of their complex frameworks.14
For example, in 3, 5 and 6, Zn(II) centers are bridged by L1, L3 and
L4 ligands to form chains, whereas two Zn(II) ions are bridged by
L2 ligands to generate a [Zn2(L2)2] loop in 4.
3386 cmꢀ1 for 7 are attributable to the O–H stretching frequency
of the water molecules.4d
Thermal analysis
To characterize the compounds more fully in terms of thermal
stability, the thermal behaviors of 1–7 were examined by TGA.
The experiments were performed on samples consisting of
numerous single crystals with a heating rate of 10 ꢁC minꢀ1
(Fig. S3†).
For compound 1, the weight loss corresponding to the release
of a lattice water molecule is observed from 147 to 233 ꢁC (obsd
5.10%, calcd 4.53%). The anhydrous compound begins to
On the other hand, the structures of the compounds are
strongly related to the coordination modes of H3L ligands (Chart
2). In compound 1, the m4-HL anions are partly deprotonated,
and link Zn(II) ions to give a 3D framework. In compounds 2–4
and 6, the HL anions bridge Zn(II) atoms to generate 1D chains
in different bidentate coordination modes. In 5, m4-HL anions
connect Zn(II) atoms to give a 2D layer. In 7, the L anion
coordinates to six Cu(II) centers to form a (3,8)-connected (4$62)
(44$68$812$104) topology.
ꢁ
decompose at 362 C. The remaining weight corresponds to the
formation of ZnO (obsd 20.2%, calcd 20.47%). For 2, the first
weight loss corresponding to the release of a water molecule is
observed before 115 ꢁC (obsd 2.4%, calcd 4.60%), and the
ꢁ
departure of organic components occurs from 296 C. For 3–6,
the decomposition of organic components occurs at 331–565,
276–550, 236–645 and 298–570 ꢁC, respectively. Compound 7
releases its water molecule from room temperature to 160 ꢁC
(obsd 3.7%, calcd 5.57%), and the anhydrous compound begins
ꢁ
to decompose at 284 C.
IR spectra
Luminescent properties
In the IR spectrum of compounds 1–6, the vibration bands at
1682 cmꢀ1 for 1, 1682 cmꢀ1 for 2, 1713 cmꢀ1 for 3, 1686 cmꢀ1 for
4, 1714 cmꢀ1 for 5 and 1705 cmꢀ1 for 6 were observed, which
indicates the incomplete deprotonation of the H3L ligand.3a The
peaks around 1536 and 1386 cmꢀ1 for 1, 1571 and 1378 cmꢀ1 for
2, 1570 and 1381 cmꢀ1 for 3, 1567 and 1369 cmꢀ1 for 4, 1544 and
1410 cmꢀ1 for 5, 1558 and 1405 cmꢀ1 for 6, and 1544 and 1400
cmꢀ1 for 7 can be attributed to the asymmetric and symmetric
vibrations of the carboxylate groups. The broad bands centered
around 3504 cmꢀ1 for 1, 3471 cmꢀ1 for 2, 3437 cmꢀ1 for 4 and
Solid-state luminescent studies were carried out for compounds
1–6 and free ligands H3L, phen, L1, L2, L3 and L4 (Fig. 8, Fig. S4†
and Table 2). The emission bands for the free ligands are prob-
ably attributable to the p* / n or p* / p transitions.15
The emission spectra of compounds exhibit emissions at about
413 nm (lex ¼ 358 nm) for 1, 424 nm (lex ¼ 372 nm) for 2, 426 nm
(lex ¼ 372nm) for 3, 423nm(lex ¼ 352nm) for 4, 395nm(lex ¼ 353
nm) for 5 and 462 nm (lex ¼ 353 nm) for 6. The luminescent decay
curves are well fitted into a single-exponential function with s ¼
0.92 ns for 1, 3.60 ns for 3, 2.01 ns for 4 and 1.93 ns for 5. The decay
curves can be fitted with a double-exponential decay function with
s1 ¼ 1.91 ns (61.72%) and s2 ¼ 10.14 ns (38.28%) for 2; s1 ¼ 1.29 ns
(34.76%) and s2 ¼ 6.73 ns (65.24%) for 6. The emissions of
compounds 1–6 are mainly based on the organic ligands.
The emissions of compounds 1, 3–5 may originate from the
corresponding HL anions, because similar emissions are
observed for H3L ligand (lem ¼ 392 and 412 nm, lex ¼ 364 nm).
The luminescent lifetimes of these compounds are very close to
the ones of the free H3L ligand [s1 ¼ 1.22 ns (65.6%) and s2 ¼
3.78 ns (34.4%)].16 The broad peaks for 2 and 6 exhibit a red-shift
with respect to the free H3L, phen (380 nm, lex ¼ 325 nm, s ¼
1.39 ns) and L4 ligands [443 nm, lex ¼ 305 nm, s1 ¼ 0.88 ns
Fig.
8 Solid-state emission spectra of compounds 1–6 at room
temperature.
Table 2 Wavelengths of the emission maximums and excitation (nm), and the luminescent lifetimes (ns) of 1–6 and ligands
Compound
1
2
3
4
5
6
lem (nm)
lex (nm)
s (ns)
413
358
0.92
424
372
1.91,10.14
phen
380
426
372
3.60
L1
437
326
423
352
2.01
L2
408
320
395
353
1.93
L3
414
312
462
353
1.29,6.73
L4
443
ligand
H3L
lem (nm)
lex (nm)
s (ns)
392,412
364
1.22,3.78
325
1.39
305
0.88,6.78
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and Y.-Y. Liu, Cryst. Growth Des., 2010, 10, 1946; (d)
W.-Q. Kan, J. Yang, Y.-Y. Liu and J.-F. Ma, Polyhedron, 2011,
30, 2113.
(88.6%) and s2 ¼ 6.78 ns (11.35%)], respectively. On the basis of
the emission peaks and the luminescent lifetimes, the N-donor
ligands and O-donor anions may show contributions to the
broad fluorescent emissions of 2 and 6 simultaneously.17
5 (a) L. Yi, X. Yang, T. Lu and P. Cheng, Cryst. Growth Des., 2005, 5,
1215; (b) D.-Z. Wang, C.-S. Liu, J.-R. Li, L. Li, Y.-F. Zeng and
X.-H. Bu, CrystEngComm, 2007, 9, 289; (c) Y.-Y. Liu, L. Yi,
B. Ding, Y.-Q. Huang and P. Cheng, Inorg. Chem. Commun., 2007,
10, 517; (d) B. Ding, Y.-Y. Liu, Y.-Q. Huang, W. Shi, P. Cheng,
D.-Z. Liao and S.-P. Yan, Cryst. Growth Des., 2009, 9, 593; (e)
X.-L. Tong, D.-Z. Wang, T.-L. Hu, W.-C. Song, Y. Tao and
X.-H. Bu, Cryst. Growth Des., 2009, 9, 2280; (f) N. Liang, J. Wang,
D. Yuan, B. Li and H. Li, Inorg. Chem. Commun., 2010, 13, 844;
(g) P. I. M. List, S. J.-L. Oldenbroek, E. N. Lugthart,
G. A. Albada, P. Gamez, J. G. Haasnoot, S. J. Teat, O. Roubeau,
I. Mutikainen and J. Reedijk, Inorg. Chim. Acta, 2011, 370, 164; (h)
X. He, J.-J. Liu, H.-M. Guo, M. Shao and M.-X. Liu, Polyhedron,
2010, 29, 1062; (i) K. Liu, W. Shi and P. Cheng, Dalton Trans.,
2011, 40, 8475.
Conclusion
In summary, seven coordination polymers based on 5-(benzonic-
4-ylmethoxy)isophthalic acid have been prepared and charac-
terized through single-crystal X-ray diffraction analyses. These
compounds show fascinating 2D and 3D frameworks with
various topologies. The structural diversities of the complexes
indicate that this flexible tricarboxylate is a good candidate for
the construction of coordination polymers with fascinating
motifs. It is anticipated that other new coordination polymers
with intriguing structures as well as physical properties may also
be synthesized through using this ligand.
6 Y. H. He, Y. L. Feng, Y. Z. Lan and Y. H. Wen, Cryst. Growth Des.,
2008, 8, 3586.
7 (a) G. M. Sheldrick, SHELXS-97, Programs for X-ray Crystal
€
€
Structure Solution; University of Gottingen: Gottingen, Germany,
1997; (b) G. M. Sheldrick, SHELXL-97, Programs for X-ray Crystal
Acknowledgements
€
€
Structure Refinement; University of Gottingen: Gottingen,
Germany, 1997; (c) L. J. Farrugia, WINGX, A Windows Program
for Crystal Structure Analysis, University of Glasgow, Glasgow,
UK, 1988.
We thank the National Natural Science Foundation of China
(Grant No. 21071028, 21001023), the Science Foundation of Jilin
Province (20090137, 20100109), the Fundamental Research
Funds for the Central Universities, the Specialized Research
Fund for the Doctoral Program of Higher Education, the
Training Fund of NENU’s Scientific Innovation Project and the
Analysis and Testing Foundation of Northeast Normal
University for support.
8 (a) A. F. Wells, Three-dimensional Nets and Polyhedra; Wiley-
Interscience: New York, 1977; (b) A. F. Wells, Further Studies of
Three-Dimensional Nets; ACA Monograph 8; American
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O. V. Dolomanov, A. J. Blake, N. R. Champness and M. Schroder,
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CrystEngComm, 2011, 13, 3811, and refs. therein.
10 Y.-Y. Liu, J.-F. Ma, J. Yang, J.-C. Ma and G.-J. Ping,
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