Diversity of lanthanide(III)-organic extended frameworks with a 4,8-disulfonyl-2,6-naphthalenedicarboxylic acid ligand: Syntheses, structures, and magnetic and luminescent properties

Article abstract of DOI:10.1021/ic2023727

A sulfonate-carboxylate ligand, 4,8-disulfonyl-2,6-naphthalenedicarboxylic acid (H₄-DSNDA), and eight new lanthanide coordination polymers { [ P r 4 ( O H )₄ ( D S N D A )₂ ( H ₂ O )1 2 ] ( H ₂ O )1 0 } n ( 1 ), [ L n (H₂ -DSNDA) _0.5(DSNDA)_0.5(H₂O)₅]_n (Ln = La(2), Nd(3), Sm(4), Eu(5), Gd(6), and Dy(7)), and {[Er(H-DSNDA)(H ₂O)₄](H₂O)}n (8)have been synthesized. Detailed crystal structures of these compounds have been investigated. Compound 1 has a 3D framework featuring the unique cubane-shaped [Pr₄(μ ₃-OH)₄] clusters and is a binodal 4,8-connected network with (4¹⁶·6¹²)(4⁴·6 ²)₂ topology. Compounds 2-7 are isostructural and have 2D layered structures. Compound 8 is also a 2D layer but belongs to different structural types. The luminescence behavior of compound Eu(5)shows that the π-rich aromatic organic ligands efficiently transfer the absorbed light energy to the Eu(III)ions, thus enhancing the overall luminescent properties of compound Eu(5). The magnetic properties of all compounds except for the diamagnetic La(2)compound have been investigated. In addition, elemental analysis, IR spectra, and thermogravimetric analysis of these compounds are also described.

Full text of DOI:10.1021/ic2023727

Article
pubs.acs.org/IC
Diversity of Lanthanide(III)−Organic Extended Frameworks with a
4,8-Disulfonyl-2,6-naphthalenedicarboxylic Acid Ligand: Syntheses,
Structures, and Magnetic and Luminescent Properties
Qing-Yan Liu,*,†,‡ Wu-Fang Wang,† Yu-Ling Wang,† Zeng-Mei Shan,† Ming-Sheng Wang,‡
and Jinkui Tang*,§
†College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, Jiangxi 330022, P. R. China
‡State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences,
Fuzhou, Fujian 350002, P. R. China
§State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences,
Changchun 130022, P. R. China
S
* Supporting Information
ABSTRACT: A sulfonate−carboxylate ligand, 4,8-disulfonyl-2,6-naphthalenedicar-
boxylic acid (H4-DSNDA), and eight new lanthanide coordination polymers
{ [ P r 4 ( O H ) 4 ( D S N D A ) 2 ( H 2 O ) 1 2 ] ( H 2 O ) 1 0
}
( 1 ) , [ L n ( H 2 -
n
DSNDA)0.5(DSNDA)0.5(H2O)5]n (Ln = La(2), Nd(3), Sm(4), Eu(5), Gd(6), and
Dy(7)), and {[Er(H-DSNDA)(H2O)4](H2O)}n (8) have been synthesized. Detailed
crystal structures of these compounds have been investigated. Compound 1 has a 3D
framework featuring the unique cubane-shaped [Pr4(μ3-OH)4] clusters and is a
binodal 4,8-connected network with (416·612)(44·62)2 topology. Compounds 2−7 are
isostructural and have 2D layered structures. Compound 8 is also a 2D layer but
belongs to different structural types. The luminescence behavior of compound Eu(5)
shows that the π-rich aromatic organic ligands efficiently transfer the absorbed light
energy to the Eu(III) ions, thus enhancing the overall luminescent properties of
compound Eu(5). The magnetic properties of all compounds except for the
diamagnetic La(2) compound have been investigated. In addition, elemental analysis, IR spectra, and thermogravimetric analysis
of these compounds are also described.
frameworks displaying interesting solid state dynamics6 and
INTRODUCTION
■
hydrogen-bonded networks through extensive hydrogen
bonds.7 In our work on the synthesis of functionalized
coordination polymers we are interested in the multifunctional
sulfonate−carboxylate ligands.8 The sulfonate−carboxylate
ligand with a strong coordination ability of the carboxylate
group and weak coordination ability of the sulfonate group
simultaneously has received increasing interest recently. 5-
Sulfoisophthalic acid,9 2-sulfoterephthalic acid,10 3-sulfobenzoic
acid,11 and 4-sulfobenzoic acid12 have been employed to
construct coordination polymers with diverse structures and
interesting properties. Nevertheless, there are still relatively few
examples of coordination polymers based on sulfonate−
carboxylate ligands to date. Herein a sulfonate−carboxylate
ligand, 4,8-disulfonyl-2,6-naphthalenedicarboxylic acid (H4-
DSNDA), has been prepared. The H4-DSNDA ligand with a
π-rich naphthalene backbone and two carboxyl and two
sulfonyl functional groups is an effective component in the
design of a diverse range of coordination polymers. However,
the coordination chemistry the H4-DSNDA ligand is seldom
Coordination polymers (CPs) or metal−organic frameworks
(MOFs) from metal ions or metal clusters with multifunctional
organic ligands are currently of great interest due to their
potential applications in catalysis, molecular magnets, photo-
luminescence, adsorption, and phase separation, as well as their
aesthetically appealing structural topology.1 To date, many of
the efforts have so far been devoted to the study of transition-
metal-based coordination polymers. The lanthanide analogues
are also highly sought after because the lanthanide ions possess
a high coordination number and flexible coordination geometry
that can afford structural diversity.2 In addition, lanthanide
compounds can display distinct intrinsic optical and magnetic
properties that are much different from those of transition-
metal compounds.3,4
On the other hand, the organic ligand plays a vital role in the
synthesis of the coordination polymers. Among these reported
organic ligands, carboxylate ligands are some of the most
successful functional ligands. Comparing with carboxylate
ligands, organosulfonate ligands have received much less
attention.5 The sulfonate group with three potential oxygen
coordination sites, which is a weak ligating group, has more
flexible coordination modes, which can form highly flexible
Received: November 1, 2011
Published: January 30, 2012
© 2012 American Chemical Society
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Synthesis of [Ln(H2-DSNDA)0.5(DSNDA)0.5(H2O)5]n (Ln = La(2),
Nd(3), Sm(4), Eu(5), Gd(6), Dy(7)). All six compounds were
prepared by the same method as follows: A mixture of Ln-
(NO3)3·6H2O (Ln = La, Nd, Sm, Eu, Gd, and Dy, 0.1 mmol) and
4,8-disulfonyl-2,6-naphthalenedicarboxylic acid (0.0376 g, 0.1 mmol)
in a 1:1 molar ratio in 10 mL of H2O (pH = 3) was introduced into a
Parr Teflon-lined stainless steel vessel (25 mL). The vessel was sealed
and heated to 140 °C. The temperature was held for 4 days and then
the mixture was cooled naturally to obtain colorless crystals.
Crystalline product was filtered, washed with H2O, and dried at
ambient temperature. Yield: 0.011 g, 19% for 2; 0.015 g, 25% for 3;
0.009 g, 16% for 4; 0.017 g, 28% for 5; 0.019 g, 32% for 6; 0.008 g,
13% for 7; based on Ln). Anal. Calcd for C12H15O15S2La (2) (602.27):
C, 23.93; H, 2.51. Found: C, 23.85; H, 2.31. IR spectrum (cm−1, KBr
pellet): 3416 (s), 1704 (s), 1639 (m), 1611 (m), 1550 (vs), 1478 (w),
1415 (vs), 1368 (m), 1135 (m), 1176 (vs), 1053 (s), 928 (w), 857
(w), 819 (m), 804 (m), 788 (m), 719 (w), 656 (w), 604 (m), 515
(m). Anal. Calcd for C12H15O15S2Nd (3) (607.60): C, 23.72; H, 2.49.
Found: C, 23.67; H, 2.44. IR spectrum (cm−1, KBr pellet): 3419 (s),
1700 (s), 1639 (m), 1617 (m), 1560 (s), 1423 (w), 1401 (s), 1360
(m), 1156 (vs), 1067 (s), 951 (m), 860 (m), 791 (w), 619 (w), 546
(w), 604 (m), 516 (m). Anal. Calcd for C12H15O15S2Sm (4) (613.71):
C, 23.48; H, 2.46. Found: C, 23.41; H, 2.35. IR spectrum (cm−1, KBr
pellet): 3412 (s), 1703 (s), 1642 (m), 1613 (m), 1552 (vs), 1479 (w),
1421 (vs), 1371 (m), 1140 (m), 1180 (vs), 1055 (s), 927 (w), 857
(w), 820 (m), 805 (m), 791 (m), 719 (w), 604 (m), 514 (m). Anal.
Calcd for C12H15O15S2Eu (5) (615.32): C, 23.42; H, 2.46. Found: C,
23.31; H, 2.39. IR spectrum (cm−1, KBr pellet): 3412 (s), 1703 (s),
1644 (m), 1614 (m), 1553 (vs), 1478 (w), 1418 (vs), 1372 (m), 1142
(m), 1192 (vs), 1055 (s), 925 (w), 856 (w), 821 (m), 806 (m), 791
(m), 719 (w), 608 (m), 514 (m). Anal. Calcd for C12H15O15S2Gd (6)
(620.61): C, 23.22; H, 2.44. Found: C, 23.25; H, 2.35. IR spectrum
(cm−1, KBr pellet): 3415 (s), 1700 (s), 1652 (m), 1615 (m), 1599
(vs), 1456 (w), 1419 (vs), 1373 (m), 1160 (vs), 1075 (s), 947 (w),
859 (m), 822 (w), 792 (m), 708 (w), 604 (w), 547 (m), 517 (m).
Anal. Calcd for C12H15O15S2Dy (7) (625.86): C, 23.03; H, 2.42.
Found: C, 22.98; H, 2.37. IR spectrum (cm−1, KBr pellet): 3422 (s),
1703 (s), 1642 (m), 1615 (m), 1557 (vs), 1480 (w), 1427 (s), 1373
(m), 1130 (m), 1180 (vs), 1137 (s), 1069 (s), 998 (w), 955 (w), 864
(w), 822 (m), 806 (w), 793 (m), 718 (w), 606 (m), 516 (m).
Synthesis of {[Er(H-DSNDA)(H2O)4](H2O)}n (8). A mixture of
Er(NO3)3·6H2O (0.0461 g, 0.1 mmol) and 4,8-disulfonyl-2,6-
naphthalenedicarboxylic acid (0.0376 g, 0.1 mmol) in a 1:1 molar
ratio in 10 mL of H2O (pH = 3) was introduced into a Parr Teflon-
lined stainless steel vessel (25 mL). The vessel was sealed and heated
to 140 °C. The temperature was held for 4 days, and then the mixture
was cooled naturally to obtain pink crystals. Pink crystalline product
was filtered, washed with H2O, and dried at ambient temperature.
Yield: 0.014 g, 23% based on Er. Anal. Calcd for C12H15O15S2Er
(630.62): C, 22.86; H, 2.40. Found: C, 22.81; H, 2.33. IR spectrum
(cm−1, KBr pellet): 3429 (s), 1685 (s), 1644 (m), 1603 (m), 1409
(vs), 1373 (w), 1277 (m), 1194 (vs), 1162 (s), 1115 (w), 1088 (w),
1054 (s), 1025 (w), 920 (w), 861 (w), 810 (w), 779 (w), 763 (m), 699
(w), 640 (w), 607 (s), 530 (w).
investigated. To the best of our knowledge, only one
compound with H4-DSNDA ligand has been reported very
recently, wherein a molecular supertetrahedron
[Fe16O4(SO4)12(DSNDA)6] based on the mixed-valence
tetranuclear [Fe33+Fe2+(μ3-O)(μ3-SO4)3(CO2)3] clusters is
isolated.13 In this contribution, a series of H4-DSNDA-based
lanthanide coordination polymers has been synthesized and
characterized. The magnetic behavior of all compounds has
been studied with the exception of the diamagnetic La(III)
compound. The luminescence properties of the Eu(III)
compound have also been investigated in detail.
EXPERIMENTAL SECTION
■
Chemicals. All chemicals were of reagent grade and used as
commercially obtained. The starting material 4,8-disulfonyl-2,6-
naphthalenedicarboxylic acid (H4-DSNDA) was prepared following
the previously reported procedure.14
Physical Measurements. Elemental analyses were carried out on
an Elementar Vario EL III analyzer, and IR spectra (KBr pellets) were
recorded on PerkinElmer Spectrum One. Fluorescent spectra were
measured at room temperature with a single-grating Edinburgh EI920
fluorescence spectrometer equipped with a 450-W Xe lamp, an nF900
lamp, and a R928P PMT detector. Magnetic measurements were
carried out on crystalline samples with a Quantum Design MPMS-5
magnetometer. The thermogravimetric measurements were performed
with a Netzsch STA449C apparatus under a nitrogen atmosphere with
a heating rate of 10 °C/min from 25 to 600 °C.
Synthesis of the H4-DSNDA Ligand (Scheme 1). One gram
(4.63 mmol) of naphthalene-2,6-dicarboxylic acid was slowly added to
Scheme 1. Preparation of the H4-DSNDA Ligand
a 25 mL three-neck flask containing 5 mL of fuming sulfuric acid (SO3,
20 wt %) under stirring. Then the reaction mixture was vigorously
stirred at 150 °C for 6 h. After cooling to room temperature, the
mixture was dissolved in deionized water and the acid H4-DSNDA was
precipitated using concentrated HCl. The product was collected by
filtration and dried at 100 °C. Yield: 1.49 g (∼86%) based on
naphthalene-2,6-dicarboxylic acid. IR spectrum (cm−1, KBr pellet):
1243 (s), 1194 (s), 1112 (m), and 1048 (s) (OSO of −SO3H
1
group); 615 (s) (C−S). H NMR (400 MHz, DMSO-d6, δ, ppm):
9.59 (s, the hydrogen atoms at the ortho positions to −SO3H groups)
and 8.49 (s, the hydrogen atoms at the para positions to −SO3H
groups).
X-ray Crystallography. X-ray diffraction data of compounds 1−8
were collected on a Bruker Apex II CCD diffractometer equipped with
graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). Data
reduction was performed using SAINT and corrected for Lorentz and
polarization effects. Adsorption corrections were applied using the
SADABS routine.15 Structures were solved by direct methods and
successive Fourier difference syntheses and refined by the full-matrix
least-squares method on F2 (SHELXTL Version 5.1).16 All non-
hydrogen atoms are refined with anisotropic thermal parameters.
Hydrogen atoms were assigned to calculated positions. Water
hydrogen atoms for compound 1 could not be located in the
difference Fourier map. The R1 values are defined as R1 = Σ∥Fo| − |
Synthesis of {[Pr4(OH)4(DSNDA)2(H2O)12](H2O)10}n (1). A
mixture of Pr(NO3)3·6H2O (0.448 g, 0.1 mmol), 4,8-disulfonyl-2,6-
naphthalenedicarboxylic acid (0.0376 g, 0.1 mmol), and 1,4-
diazabicyclo[2.2.2]octan (0.0221 g, 0.1 mmol) in a 1:1:1 molar ratio
in 10 mL of H2O (pH = 5) was introduced into a Parr Teflon-lined
stainless steel vessel (25 mL). The vessel was sealed and heated to 140
°C. The temperature was held for 4 days, and then the mixture was
cooled naturally to obtain colorless crystals of 1. Colorless crystalline
product was filtered, washed with H2O, and dried at ambient
temperature. Yield: 0.014 g, 33% based on Pr. Anal. Calcd for
C24H56O46S4Pr4 (1772.57): C, 16.26; H, 3.18. Found: C, 16.18; H,
3.11. IR spectrum (cm−1, KBr pellet): 3413 (m), 1641 (s), 1612 (s),
1550 (s), 1479 (m), 1418 (vs), 1369 (m), 1228 (w), 1178 (vs), 1064
(vs), 946 (w), 857 (w), 820 (w), 789 (m), 719 (w), 604 (m), 546 (w),
515 (w).
2
Fc∥/Σ|Fo| and wR2 = {Σ[w(Fo2 − Fc2)2]/Σ[w(Fo )2]}1/2. Details of the
crystal parameters, data collection, and refinement are summarized in
Tables 1 and 2, and selected bond lengths and bond angles are listed in
Table S1, Supporting Information.
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a
Table 1. Crystallographic Data for Compounds 1−4
Pr(1)
La(2)
Nd(3)
Sm(4)
formula
fw
C12H28O23S2Pr2
886.28
296(2)
orthorhombic
Cmcm
C12H15O15S2La
602.27
C12H15O15S2Nd
607.60
C12H15O15S2Sm
613.71
temp (K)
cryst syst
space group
Z
296(2)
296(2)
296(2)
triclinic
P−1
triclinic
triclinic
P−1
2
P−1
2
8
2
a (Å)
21.859(4)
11.5288(18)
21.861(3)
90
7.0471(4)
10.9758(5)
12.2698(6)
84.2890(10)
76.7700(10)
89.5200(10)
919.16(8)
2.176
7.02170(10)
10.9089(2)
12.1681(2)
84.2090(10)
76.6360(10)
89.8110(10)
902.00(3)
2.237
7.013(6)
10.917(9)
12.119(10)
95.919(10)
103.259(10)
90.014(10)
898.1(13)
2.270
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
V (Å3)
90
90
5509.1(16)
2.137
−3
Dcalcd (g·cm )
μ (mm )
−1
3.742
2.633
3.193
3.585
no. of reflns collected
independent reflns
obsd reflns (I > 2σ(I))
F(000)
11 187
3540
8674
12 175
8044
4439
4155
4432
2437
4325
3930
3935
3472
592
598
602
R[int]
0.0839
0.0551
0.0192
0.0315
0.0525
R1 (I > 2σ(I))
wR2 (all data)
0.0194
0.0251
0.0591
0.1389
0.0503
0.0594
0.1684
a
2
2
R1 = Σ∥Fo| − |Fc∥/Σ|Fo| and wR2 = {Σ[w(Fo − Fc2)2]/Σ[w(Fo )2]}1/2
.
a
Table 2. Crystallographic Data for Compounds 5−8
Eu(5)
Gd(6)
Dy(7)
Er(8)
formula
fw
C12H15O15S2Eu
615.32
C12H15O15S2Gd
620.61
C12H15O15S2Dy
625.86
C12H15O15S2Er
630.62
296(2)
monoclinic
P21/m
2
temp (K)
cryst syst
space group
Z
296(2)
triclinic
P−1
296(2)
296(2)
triclinic
triclinic
P−1
2
P−1
2
2
a (Å)
7.0140(18)
10.872(3)
12.083(3)
84.193(3)
76.515(3)
89.976(3)
891.1(4)
2.293
7.00660(10)
10.8551(2)
12.0541(2)
84.2160(10)
76.4690(10)
90.0340(10)
886.54(3)
2.325
7.00090(10)
10.83150(10)
12.01550(10)
95.8500(10)
103.6300(10)
90.1370(10)
880.538(17)
2.361
10.871(2)
6.7535(12)
11.859(2)
90
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
V (Å3)
96.180(2)
90
865.6(3)
2.420
−3
Dcalcd (g·cm )
μ (mm )
−1
3.838
4.060
4.565
5.175
no. of reflns collected
independent reflns
obsd reflns (I > 2σ(I))
F(000)
6522
15 255
15 299
5431
3697
4111
4053
2258
3394
3947
3701
2020
604
606
610
614
R[int]
0.0257
0.0326
0.0341
0.0371
0.0318
0.0752
R1 (I > 2σ(I))
0.0255
0.0286
0.0246
wR2 (all data)
0.0600
0.0892
0.0631
a
2
2
R1 = Σ∥Fo| − |Fc∥/Σ|Fo| and wR2 = {Σ[w(Fo − Fc2)2]/Σ[w(Fo )2]}1/2
.
unsuccessful. Compounds 2−8 were obtained by hydrothermal
reactions of the appropriate Ln(NO3)3 with H4-DSNDA ligand.
All are 2D layered structures but belong to two structural types.
In compound [Ln(H2-DSNDA)0.5(DSNDA)0.5(H2O)5]n (Ln =
La(2), Nd(3), Sm(4), Eu(5), Gd(6), and Dy(7)) each
lanthanide ion is nine coordinated and surrounded by three
organic ligands. While in compound {[Er(H-DSNDA)-
(H2O)4](H2O)}n (8) the erbium ion is eight coordinated and
surrounded by four organic ligands. No suitable product is
RESULTS AND DISCUSSION
■
Syntheses. Compound {[Pr4(OH)4(DSNDA)2(H2O)12]-
(H2O)10}n (1) was surprisingly obtained by hydrothermal
reaction of Pr(NO3)3 and H4-DSNDA in the presence of 1,4-
diazabicyclo[2.2.2]octan. This finding shows that the presence
of an organic base of 1,4-diazabicyclo[2.2.2]octan is in favor of
formation of the hydroxyl group. Attempts to get single crystals
of other lanthanide compounds by reacting Ln(NO3)3 with H4-
DSNDA in the presence of 1,4-diazabicyclo[2.2.2]octan were
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Figure 1. (a) Coordination environment of Pr(III) centers, and (b and c) coordination polyhedrons around the Pr ions in 1.
obtained using Tb(NO3)3, Ho(NO3)3, or Yb(NO3)3 with the
H4-DSNDA ligand in similar reactions.
(Table S1, Supporting Information), which are comparable to
those in other Pr(III) compounds.17 As shown in Figure 2, four
triply bridging μ3-hydroxyl oxygen atoms link four Pr(III) ions
to form a cubane-shaped tetranuclear [Pr4(μ3-OH)4] SBU
where a Pr4 tetrahedron is embedded in the [Pr4(μ3-OH)4]
unit. It is to be noted that the [Pr4(μ3-OH)4] cubane cluster has
two crystallographically imposed mirror planes of symmetry:
one mirror plane passes through Pr1, Pr1A, O6, and O6E
atoms, and the other passes through Pr2, Pr2A, O7, and O7A
atoms. The Pr1···Pr2, Pr1··· Pr1A, and Pr2··· Pr2A separations
are 3.9216(8), 4.223(2), and 4.0848(16) Å, respectively. As
depicted in Figure 2, four short edges of the Pr4 tetrahedron is
further connected by four carboxylate arms. Each DSNDA4−
ligand locates on an inversion center and exhibits a hexadentate
coordination mode with two bidentate carboxylate groups and
two monodentate sulfonate groups (Scheme 2a). As shown in
Figure 2, each [Pr4(μ3-OH)4] cluster is surrounded by eight
DSNDA4− ligands, which link the [Pr4(μ3-OH)4] clusters to
form a 3D framework with 1D rhombus-shaped channels along
the crystallographic c direction (Figure 3) in which solvent
Crystal Structure of {[Pr4(OH)4(DSNDA)2(H2O)12]-
(H2O)10}n (1). Compound 1 features a 3D framework based
on the unique cubane-shaped [Pr4(μ3-OH)4] cluster as a
secondary building unit (SBU). As shown in Figure 1, there are
two crystallographically unique Pr(III) ions in the asymmetric
unit. Both are nine coordinate. The Pr1 ion is coordinated to
nine oxygen atoms, three (O6, O7, and O7A) from three
hydroxyl groups, two (O2 and O2B) from two carboxylate
groups of the two DSNDA4− ligands, two (O3C and O3D)
from the two sulfonate groups of the two DSNDA4− ligands,
and two (O8 and O9) from the two water molecules (Figure
1a). The Pr2 ion is coordinated to three hydroxyl oxygen atoms
(O6, O7, and O6E), two carboxylate oxygen atoms (O1 and
O1E) from two the DSNDA4− ligands, and four water oxygen
atoms (O10, O11, O12, and O12E) (Figure 1a). The
coordination polyhedrons around the two Pr(III) ions can be
attributed to monocapped square antiprisms with O3D and
O10 at the capped positions, respectively (Figure 1b and 1c).
The Pr−O bond lengths vary from 2.361(6) to 2.679(7) Å
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Figure 3. View of the 3D structure of 1 showing the rhombic channels
(all water molecules are omitted).
Figure 2. Tetranuclear [Pr4(μ3-OH)4] SBU surrounded by eight
DSNDA4− ligands.
Scheme 2. Observed Coordination Modes of the H4-DSNDA
Ligand
Figure 4. View of the binodal (4, 8)-connected topologic network of 1
([Pr4(μ3-OH)4] unit and DSNDA4− ligand represented as green and
pink ball modes, respectively).
which is one of the most important and a unique topology for
connecting regular cubic and tetrahedral building blocks.18
However, structure 1 adopts an uncommon (416·612)(44·62)2
topology. To the best of our knowledge, this topology has not
been observed in coordination polymers yet to date, and the
finding of this unprecedented topology is useful at the basic
level in the crystal engineering of coordination networks.
Notice that the coordination networks of high connectivity
(>6) are extremely rare because of steric constrains, especially
for the fluorite topology, which requires a cubic 8-coordinated
metal center (or metal cluster) and a tetrahedral 4-connected
ligand.19 Interestingly, the present net with 8-connected SBUs
and 4-connected ligand is different from that of the flu net but
related to it. If we take a careful look at the two nodes of the 3D
network of 1, their similarity and difference become apparent.
As shown in Figure 4, the eight 4-connected nodes surrounding
the central 8-connected node form two planes with a dihedral
angle of 90°, which is same as that of the flu net. The 4-
connected node in the flu net is a tetrahedral node. In the
present structure, the DSNDA4− ligand occupies an inversion
center and all the atoms of the DSNDA4− ligand are coplanar
except for the uncoordinated sulfonate oxygen atoms (O4 and
O5). Thus, the DSNDA4− ligand node acts as a planar 4-
connected node, as depicted in Figure 4. As a result, the planar
water and coordinated molecules are located. The free pore
volume is 25.3% when all the water molecules are removed.
Better insight into the nature of this intricate framework can
be achieved by application of a topological approach. As
described above, each [Pr4(μ3-OH)4] SBU is surrounded by
eight DSNDA4− ligands and each DSNDA4− ligand bridges four
neighboring [Pr4(μ3-OH)4] SBUs. In this way, the DSNDA4−
ligand and the [Pr4(μ3-OH)4] SBU act as 4- and 8-connected
nodes, respectively, in a ratio of 2:1. Therefore, structure 1 is a
binodal network with 4- and 8-connected nodes. The Schafli
̈
notation is (416·612) for the [Pr4(μ3-OH)4] node and (44·62) for
the DSNDA4− node, giving the whole net symbol (416·612)-
(44·62)2, as depicted in Figure 4. As we know, it is usually
believed that the 4 and 8 connectivities would like to fall into
the fluorite (CaF2) structure of flu-(412·612·84)(46)2 topology,
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Figure 5. (a) Coordination environment of the La(III) center, and (b) coordination polyhedron around the La ion in 2.
4-connected node is surrounded by two 6-membered and four
4-membered shortest circuits. There are six 4-membered
shortest circuits around each 4-connected node in the flu net.
As a result of these essential differences, the topology of the
material changes (412·612·84)(46)2 to (416·612)(44·62)2 topology.
In addition, a related (4, 8)-connected net with (411·614·83)-
(45·6)2 topology has been reported recently, where the
tetranuclear [Cu4(μ3-OH)2] SBU and the 5-sulfoisophthalate
ligand can be represented by cubic and tetrahedral units,
respectively.20 However, the 8-connected node is seriously
distorted from the regular cubic node due to the low symmetry
of the tetranuclear [Cu4(μ3-OH)2] SBU, which lead to the
topological symbol being also different from that of the flu net.
C r y s t a l
S t r u c t u r e
o f
[ L n ( H
-
2
DSNDA)0.5(DSNDA)0.5(H2O)5]n (Ln = La(2), Nd(3), Sm(4),
Eu(5), Gd(6), Dy(7)). Single-crystal X-ray analyses revealed
that compounds 2−7 are isostructural, and the structure of
La(2) is selected and described here representatively to
illustrate their detailed structures. The asymmetric unit of
compound 2 contains one La(III) ion, one-half-occupied H2-
DSNDA2− dianion, one-half-occupied DSNDA4− tetraanion,
and five coordinated water molecules. It is noted that the
compound contains the dianionic H2-DSNDA2− and tetraa-
nionic DSNDA4− ligands, both of which are centrosymmetric.
As depicted in Figure 5, the La(III) ion lies on a general
position and is nine coordinated with an O9 donor set: two
(O1A and O2A) from one carboxylate group of a DSNDA4−
ligand, two (O3 and O8) from two sulfonate groups of one H2-
DSNDA2− ligand and one DSNDA4− ligand, and five from
water molecules. The coordination geometry of the La(III) ion
can be best described as a distorted monocapped square
antiprism with O1A at the capped position (Figure 5b). The
La−O distances range from 2.5104(15) to 2.5846(14) Å
(Table S1, Supporting Information). The uncoordinated
carboxylate groups of H2-DSNDA2− ligand are protonated for
charge balance, as suggested by the strong absorption at about
1700 cm−1 in the IR spectrum. Detailed coordination modes of
the ligands are shown in Scheme 2b and 2c. The DSNDA4−
ligand bridges four La(III) ions by two chelating carboxylate
groups and two monodentate sulfonate groups, displaying a
tetradentate fashion. The La(III) ions are linked by the
tetraanionic DSNDA4− ligands along the a axis, forming a 1D
chain, as shown in Figure 6. Adjacent chains are linked by the
Figure 6. 2D layered structure of 2.
bidentate H2-DSNDA2− ligand with two monodentate
sulfonate groups to give a 2D layer propagating along the ac
plane (Figure 6). The 2D layer is further extended into a 3D
network through extensive hydrogen bonds (Figure S1 and
Table S2, Supporting Information).
Crystal Structure of {[Er(H-DSNDA)(H2O)4](H2O)}n (8).
Compound 8 features a 2D layer that is different from those of
compounds 2−7. There is one unique Er(III) ion in the
asymmetric unit. As shown in Figure 7, the Er(III) ion located
on a mirror plane is coordinated to eight oxygen atoms. The
coordination sphere consists of two monodentate carboxylate
oxygen atoms (O1B and O3C) from two H-DSNDA3− ligands
and two monodentate sulfonate oxygen atoms (O7 and O7A)
from the other two H-DSNDA3− ligands. The remaining
positions are occupied by four coordinated water molecules
(O9, O9A, O10, O11) (Figure 7a). The coordination
environment of the Er(III) ion can be best described as a
trigonal dodecahedron (Figure 7b). The H-DSNDA3− ligand
occupies a mirror plane in which all atoms pass through the
mirror plane except for two pairs of sulfonate oxygen atoms
(O6 and O6D; O7 and O7D). The IR spectrum of 8 shows a
sharp strong absorption at 1685 cm−1, indicating that
protonation of cthe arboxylate group of the H-DSNDA3−
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Figure 7. (a) Coordination environment of the Er(III) center, and (b) coordination polyhedron around the Er ion in 8.
ligand exists, which is needed for charge balance. The H-
DSNDA3− ligand adopts a tetradentate coordination mode with
two monodentate carboxylate groups and one bidentate
sulfonate group (Scheme 2d). The other sulfonate group is
free of coordination and engaged in hydrogen bonding with the
coordinated water molecules. The Er(III) ions are linked by the
H-DSNDA3− ligands to produce a 2D layer propagating along
the bc plane, as shown in Figure 8. The 2D layer has an
about 605 cm−1 for all compounds can be assigned to the C−S
stretching vibrations.
To examine the thermal stability of these compounds and
their structural variation as a function of temperature
thermogravimetric analysis (TGA) was performed on crystal-
line samples of these materials (Figure S3, Supporting
Information). The TGA trace for compound Pr(1) displays a
small gradual weight loss starting at 40 °C, and then a sharp
continual weight loss occurred at 100 °C. The total observed
weight loss between 40 and 155 °C is 16.38%, which is
attributed to release of all 10 solvent water molecules and 6
coordinated water molecules (theoretical 16.25%) and then a
gradual mass loss of 5.82% between 170 and 310 °C, which is
attributed to removal of the remaining six-coordinated water
molecules (theoretical 6.09%). The main framework of the
compound starts to decompose at 380 °C. Compounds 2−7
will show similar thermal behavior since they are isostructural.
Therefore, only one representative La(2) compound is
discussed. Compound La(2) is stable up to 110 °C and then
exhibits two main steps of weight losses. The first step (110−
180 °C) corresponds to release of four coordinated water
molecules (weight loss = measured 12.19%; theoretical
11.96%). The second weight loss in the temperature range
270−310 °C corresponds to loss of the remaining coordinated
water molecule (weight loss = measured 3.13%; theoretical
2.99%). Decomposition of the framework occurs at 400 °C.
Compound Er(8) is not stable and displays a rapid continual
mass loss of 14.71% between 40 and 265 °C, which is attributed
to release of all water molecules (theoretical 14.27%). Collapse
of the framework occurs at 400 °C.
Photoluminescent Properties. Considering the character-
istic luminescent properties of Eu(III)-containing compounds
in the visible region, the solid-state luminescent spectra of
compound Eu(5) were measured at room temperature. As
shown in Figure 9, free H4-DSNDA ligand displays a
photoluminescent emission at 408 nm upon excitation at 350
nm. The photoluminescence of the free ligand has been
assigned as originating from the intraligand (IL) π*−π electron
transitions. The excitation spectrum of compound Eu(5)
exhibits a broad excitation band between 250 and 500 nm, as
depicted in Figure 10. The broad excitation band could be
primarily assigned to the π*−π electron transitions of the
organic ligand. In the excitation spectrum it is also possible to
discern the 7F0 → 5L6 (396 nm) and 7F0 →5D2 (465 nm) intra-
4f6 transitions of the Eu(III) ion (Figure 10),21 although the
Figure 8. 2D layer of 8.
approximate thickness of the 6.87 Å and is extended into a 3D
framework through the interlayered hydrogen bonds between
coordinated water molecules and sulfonate oxygen atoms
(Figure S2 and Table S2, Supporting Information).
FT-IR Spectra and Thermogravimetric Analysis. For
the H4-DSNDA ligand, four characteristic absorption bands at
1243, 1194, 1112, and 1048 cm−1 in the IR spectrum are clearly
observed, which are attributable to the OSO stretching
vibrations of the −SO3H groups. The absorption band at 615
cm−1 assigned to the C−S stretching vibrations was also
detected. The infrared spectra of compounds 1−8 show similar
main characteristic peaks since they all contain the same
organic ligand. The IR spectra of these compounds exhibit
broad absorption bands in the range 3500−3410 cm−1 due to
the presence of water molecules in the structures. The strong
bands at 1360−1650 cm−1 for all compounds are characteristic
of the carboxylate groups. The strong absorption at about 1690
cm−1 for compounds 2−8 indicates the existence of the
protonated carboxylate groups of the organic ligand. The
absorptions in the region 1000−1240 cm−1 for all compounds
are typical of the sulfonate group. The sharp absorptions at
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The 5D0 emission decay curve was monitored within the 5D0
7
→ F2 transition under the excitation wavelength (Figure S4,
Supporting Information). However, the decay curve cannot fit
into the single-exponential function like some reported Eu(III)
coordination compounds25,26 but can be well fit into a double-
exponential function as I = A + B1 exp(−t/τ1) + B2 exp(−t/τ2)
(where τ1 and τ2 are the fast and slow components of the
luminescent lifetimes and A, B1, and B2 are the fitting
5
7
parameters). The lifetimes for D0 → F2 of the Eu(III) ion
were calculated to be τ1 = 0.153 ms and τ2 = 0.474 ms. The
average lifetime of 5D0 → 7F2 for the Eu(III) ion, defined as ⟨τ⟩
27
2
2
= (B1τ1 + B2τ2 )/(B1τ1 + B2τ2), can be determined to be
0.171 ms (fitting parameters B1 = 2066 and B2 = 40.28). The
double-exponential decay behavior of the activator is often
observed when the excitation energy is transferred from the
donor,28 which indicates efficient energy transfer occurs from
the organic ligand to the Eu(III) ion.
Figure 9. Solid-state excitation and emission spectra of the H4-
DSNDA ligand at room temperature.
Magnetic Properties. The dc magnetic susceptibilities for
all compounds except for the La(2) compound were measured
in an applied dc field of 1 or 0.1 kOe. For these compounds the
observed paramagnetism arises uniquely from the 4f Ln(III)
ions. The temperature dependence of the magnetic suscepti-
bility studies for compound Pr(1) has been performed in the
temperature range 2−300 K. The plot of χMT versus T, where
χM is the molar magnetic susceptibility per Pr4 unit, is shown in
Figure 11. At 300 K, the χMT value of 4.81 cm3 K mol−1 is lower
Figure 10. Room-temperature excitation (red) with emission
monitored at approximately 618 nm, and emission (black) spectra
for compound Eu(5) (λex = 350 nm) in the solid state.
intensities of the peaks were very weak. The broad band
overlaps intra-4f6 lines. The absence or negligible intensity of
the intra-4f6 transitions in the excitation spectrum indicates that
the Eu(III) ions are mainly excited via an effective sensitized
process involving the organic ligand excited states, rather than
by direct excitation of the Eu(III) ion. Compound Eu(5)
exhibits a very strong and characteristic emission spectrum of
the Eu(III) ion upon excitation at 350 nm (Figure 10). The
emission bands occurring at 579, 593, 617, 650, and 694 nm
can be assigned to 5D0 → 7FJ (J = 0 1, 2, 3, and 4) transitions. It
is well known that the 5D0 → 7F2 and 5D0 → 7F1 transitions of
the Eu(III) ion are electric-dipole (ED) and magnetic-dipole
(MD), respectively. The former is extremely sensitive to site
symmetry, while the latter whose emission intensity is mainly
dependent on the crystal field around the Eu(III) ion is
Figure 11. Temperature dependence of the χMT product at 1 kOe for
Pr (1). Solid line is the best fit obtained with the model as described in
the text.
than the expected value of 6.4 cm3 K mol−1 for four uncoupled
3
Pr(III) ions (S = 1, L = 5, H4, g = 4/5). χMT gradually
decreases to reach 0.25 cm3 K mol−1 at 2 K, which is probably
the result of a combination of the exchange interaction between
the Pr(III) ions and the progressive depopulation of excited
Stark sublevels. There is no available expression to determine
the magnetic susceptibilities of such 3D system with large
anisotropy. To obtain a rough quantitative estimation of the
magnetic interaction between Pr(III) ions, as a preliminary
treatment, we assumed that owing to the ligand field effects the
5
7
insensitive to site symmetry. The intensity of the D0 → F2
transition is about 3.5 times stronger than that of the 5D0 → 7F1
transition, indicating that the coordination environment of the
Eu(III) ion is asymmetric,22 in agreement with single-crystal X-
5
7
ray analysis. Moreover, the D0 → F0 transition induced by
crystal-field J mixing is also observed in the emission spectrum
of compound Eu(5). According to the electric-dipole selection
rule, the 5D0 → 7F0 emission is only allowed for Cs, Cn, and Cnv
(n = 1, 2, 3, 4, 6) site symmetry.23,24 As described above,
compound Eu(5) crystallizes from the triclinic crystal system
and the Eu(III) ion lies on a general position. Thus, the actual
site symmetry of the Eu(III) ion belongs to the lowest
symmetry of C1. Thus, it is not unreasonable to observe the 5D0
→ 7F0 transition in the emission spectrum of compound Eu(5).
̂
Pr(III) ion may exhibit a splitting of mj energy levels (H =
2
̂
ΔJZ), resulting in the magnetic susceptibility equation below
previously reported by McPherson and co-workers.29 Thus, χPr
can be described as eq 1.
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χ
occurring between Nd(III) ions, in combination with
considerable spin−orbit effects.
Magnetic susceptibility measurements of Sm(4) and Eu(5)
were performed in an applied magnetic field of 0.1 kOe in the
2−300 K range. They are shown in Figure 13 for Sm(4) and
Ln
χ =
2 2
1 − (2zJ′/Ng β )χ
(2)
Ln
In this expression Δ is the zero-field splitting parameter and N,
g, β, and k have their usual meanings. Using the above equation
and considering the molecular field approximation with zJ′ as
the total exchange parameter between Pr(III) ions we can fit
our experimental data with eq 2. The best fitting of the
susceptibility data in the temperature range 2−300 K gives zJ′ =
−1.79 cm−1, Δ = 0.33 cm−1, g = 0.73, and R2 = 0.99929. The
negative value of zJ′ indicates that an overall antiferromagnetic
interaction between Pr(III) ions is operative.
The plot of χMT versus T for compound Nd(3) in the
temperature range 2−300 K, where χM is the molar magnetic
susceptibility per Nd(III) unit, is shown in Figure 12. At 300 K,
Figure 13. Temperature dependence of the χMT product at 0.1 kOe
for Sm(4). Solid line is the best fit obtained with the model as
described in the text.
Figure 12. Temperature dependence of the χMT product at 0.1 kOe
for Nd(3).
the χMT value of 1.26 cm3 K cm−1 is lower than the expected
value of 1.64 cm3 K cm−1 for one insulated Nd(III) ion (S = 3/
2, L = 6, 4I9/2, g = 8/11). χMT gradually decreases to reach 0.49
cm3 K cm−1 at 2 K, which is probably the result of a
combination of the exchange interaction between the Nd(III)
ions and the progressive depopulation of excited Stark
sublevels.30 There is no available expression to determine the
magnetic susceptibilities of such 2D system with large
anisotropy. To obtain a rough quantitative estimation of the
magnetic interaction between Nd(III) ions, as a preliminary
treatment, we assumed that owing to the ligand field effects, the
Figure 14. Temperature dependence of the χMT product at 0.1 kOe
for Eu(5). Solid line is the best fit obtained with the model as
described in the text.
̂
Nd(III) ion may exhibit a splitting of mj energy levels (H =
2
̂
ΔJZ), resulting in a magnetic susceptibility equation in which
Figure 14 for Eu(5). The χMT values of 0.31 (Sm(4)) and 1.42
cm3 K mol−1 (Eu(5)) are much higher than the theoretical
values of 0.088 and 0 cm3 K mol−1 for one isolated Sm(III) (S =
5/2, L = 5/2,6H5/2, g = 2/7) and Eu(III) ions (S = 3, L = 3, 7F0,
g = 5) in the ground state, respectively, because not only the
ground state of these two metal ions but also the first (6H7/2 for
χNd can be described as eq 3.
Unfortunately, however, combining eqs 2 and 3 we cannot gain
a satisfied result. As is well known, due to the presence of
thermally populated excited state and large magnetic anisotropy
for most lanthanide ions, the fitting of the susceptibility curve is
difficult. The low-temperature magnetization measurement as a
function of the field for Nd(3) is represented in Figure S5,
Supporting Information; the magnetization increases rapidly at
low field before a gradual linear increase. The magnetization
does not saturate but reaches 1.19 μB at 1.8 K in a field of 7 T.
This value is much lower than the expected saturation value of
3.27 μB, which is indicative of antiferromagnetic coupling
7
Sm(III) and F1 for Eu(III)) and even higher exited states can
be populated at room temperature.31 The rapid decrease in the
χMT values for both compounds upon lowering the temper-
ature are mainly due to thermal depopulation of the excited
levels. The typical nonmagnetic ground state 7F0 is observed at
low temperatures for Eu(5) as suggested by the χMT value of
0.013 at 1.8 K.31 The molar magnetic susceptibilities can be
expressed by eqs 4 and 5, respectively, which take into account
both the ground state and the exited states (6HJ, J = 7/2, 9/2,
11/2, 13/2, 15/2 for Sm(4); 7FJ, J = 1, 2, 3, ..., 6 for Eu(5)).32
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In these two expressions x = λ/kT (λ is the spin−orbit coupling
parameter), the zJ′ parameter based on the molecular field
approximation
The best fit gives g = 0.98, λ = 254 cm−1, zJ′ = −2.63 cm−1, and
R2 = 0.99148 for Sm(4) in the range 2−300 K. For Eu(5) the
parameters are g = 1.14, λ = 323 cm−1, zJ’ = −6.58 cm−1, and R2
= 0.99935 in the range 2−300 K. The negative zJ′ values are
indicative of the antiferromagnetic interaction between the
Ln(III) ions in both compounds. The field dependence of the
magnetization at 1.8 K for Sm(4) reveals a gradual linear
increase of the magnetization (Figure S5, Supporting
Information). The magnetization does not saturate but reaches
0.26 μB in a field of 7 T, which is much lower than the expected
saturation value of 0.84 μB for each Sm(III) ion.
Figure 16. Temperature dependence of the χMT product at 1 kOe for
Dy(7).
rises to reach a maximum value of 16.47 cm3 K cm−1 at 27 K,
below which the χMT product decreases sharply to reach a value
of 12.69 cm3 K cm−1 at 2.5 K. This behavior is characteristic of
a system with ferromagnetic interactions. The decrease of χMT
at low temperature is likely due to a combination of
depopulation of excited Stark sublevels, large magnetic
anisotropy, and intermolecular magnetic coupling. The large
spin S and magnetic anisotropy D values intrinsic to the Dy(III)
ion make its compounds attractive for design of single-molecule
magnets, which is a hot topic of the single-molecule magnet
community very recently.33 To examine the spin dynamics the
temperature dependencies of the alternating-current (ac)
magnetic susceptibility for compound Dy(7) were collected
at zero direct-current (dc) field with an ac field of 3 Oe with
oscillating frequencies, given in Figure S8, Supporting
Information, as plots of χ′ and χ″ versus T. However, no
imaginary component of the ac susceptibility χ″ was observed,
which clearly excludes an SMM behavior for compound Dy(7)
above 2.5 K.
The temperature dependence of the magnetic susceptibility
of compound Gd(6) was determined in the 2−300 K
temperature range. The result is represented in Figure 15 as
Figure 15. Temperature dependence of the χMT product at 0.1 kOe
for Gd(6).
The thermal variation of the χMT product for Er(8) is shown
in Figure 17. At 300 K, χMT is equal to 11.80 cm3 K cm−1,
a χMT versus T curve (χM being the molar paramagnetic
susceptibility per Gd(III)). At 300 K, χMT is 8.21 cm3 K cm−1,
which is higher than the expected corresponding value of 7.87
cm3 K cm−1 for one Gd(III) (S = 7/2, L = 0, 8S7/2, g = 2.0). χMT
gradually decreases to 6.75 cm3 K cm−1 at 2 K. The decrease of
χMT when lowering the temperature indicates clearly the
presence of an antiferromagnetic interaction between the
8
Gd(III) ions. It is well known that Gd(III) has a S7/2 ground
state without first-order orbital momentum. The magnetic
susceptibility is almost isotropic and follows the Curie−Weiss
law χ = C/(T − θ). A fit of the Curie−Weiss law (Figure S6,
Supporting Information) between 2 and 90 K yields C = 7.28
cm3 K cm−1 and θ = −0.73 K, further confirming the possibility
of weak antiferromagnetic exchange. The field dependence of
the magnetization of Gd(6) was collected at low temperature as
shown in Figure S7, Supporting Information. The magnet-
ization eventually reaches a value of 7.85 μB at 1.8 K and 7 T
with near saturation.
Figure 17. Temperature dependence of the χMT product at 0.1 kOe
for Er (8).
The result of the magnetic susceptibility of compound Dy(7)
in the 2.5−300 K temperature range is represented in Figure 16
as a χMT versus T curve. At 300 K, the χMT value is 14.18 cm3
K cm−1, which is the same as the expected value of 14.17 cm3 K
cm−1 for one magnetically isolated Dy(III) (S = 5/2, L = 5,
6H15/2, g = 4/3) ion. Upon cooling, the χMT product gradually
which is the value expected (11.48 cm3 K cm−1) for one Er(III)
4
ion (S = 3/2, L = 6, I15/2, g = 6/5). On lowering the
temperature χMT gradually decreases to 10.44 cm3 K cm−1 at 50
K, probably the result of mainly thermal depopulation of the
Er(III) excited states (Stark sublevels of the 4I15/2 state). Below
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50 K, χMT decreases down to 5.80 cm3 K cm−1 at 2 K. The
decrease of χMT between 50 and 2 K is associated with
antiferromagnetic intramolecular exchanges. The field depend-
ence of the magnetization of Er(8) was collected at low
temperature as shown in Figure S7, Supporting Information.
Magnetization eventually reaches a value of 6.10 μB at 1.8 K and
7 T without clear saturation.
.-H.; Gao, H.-L.; Cui, J.-Z.; Zhao, B. CrystEngComm 2011, 13, 1870.
́
(d) Henry, N.; Costenoble, S.; Lagrenee, M.; Loiseau, T.; Abraham, F.
CrystEngComm 2011, 13, 251. (e) Cai, B.; Yang, P.; Dai, J.-W.; Wu, J.-
Z. CrystEngComm 2011, 13, 985.
(4) (a) Jiang, H.-L.; Tsumori, N.; Xu, Q. Inorg. Chem. 2010, 49,
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O. M. J. Am. Chem. Soc. 1999, 121, 1651. (c) Liu, T.-F.; Zhang, W. J.;
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CONCLUSIONS
■
A 4,8-disulfonyl-2,6-naphthalenedicarboxylic acid (H4-
DSNDA) ligand and a series of lanthanide coordination
polymers based on the H4-DSNDA ligand have been
synthesized and characterized. Compound 1 is a 3D framework
with (416·612)(44·62)2 topology featuring the unique cubane-
shaped [Pr4(μ3-OH)4] cluster. Compounds 2−7 are 2D layered
structures. Compound 8 has a 2D layer different from those of
compounds 2−7. Compound Eu(5) shows the characteristic
red luminescence, the emission spectrum being in good
agreement with the crystal structure. Finally, the magnetic
behavior of the compounds is discussed in detail.
̂ ́
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ASSOCIATED CONTENT
* Supporting Information
■
S
X-ray structure data in CIF format, table of bond lengths and
angles, table of hydrogen bonds, 3D hydrogen-bonded
structures, TG curves, luminescence decay curve of compound
Eu(5), M vs H/T magnetic data, and ac magnetic
susceptibilities of compound Dy(7). This material is available
free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: qyliuchem@hotmail.com (Q.-Y.L.); tang@ciac.jl.cn
(J.T.).
■
(11) (a) Miao, X.-H.; Zhu, L.-G. CrystEngComm 2009, 11, 2500.
(b) Prochniak, G.; Videnova-Adrabinska, V.; Daszkiewicz, M.;
Pietraszko, A. J. Mol. Struct. 2008, 178, 891.
(12) (a) Yuan, R.-X.; Xiong, R.-G.; Xie, Y.-R.; You, X.-Z.; Peng, S.-
M.; Lee, G.-H. Inorg. Chem. Commun. 2001, 4, 384. (b) Li, X.; Li, Y.-
Q.; Wu, X.-S. Inorg. Chem. Commun. 2008, 11, 774. (c) Zhang, L.-P.;
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(13) Papadaki, I.; Malliakas, C. D.; Bakas, T.; Trikalitis, P. N. Inorg.
Chem. 2009, 48, 9968.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the NNSF of China (Grants
20901033 and 21101081), the Scientific Research Foundation
for the Returned Overseas Chinese Scholars (State Education
Ministry), the Provincial NSF of Jiangxi (2009GZH0056), and
the Project of Education Department of Jiangxi Province
(GJJ10016 and GJJ11381).
(14) Qing, S.; Huang, W.; Yan, D. React. Funct. Polym. 2006, 66, 219.
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