Synthesis, structure and photoluminescent properties of [C 6N2H14][Nd2(C2O 4)2(SO4)2(H2O) 4]·H2O, a new organically templat

Article abstract of DOI:10.1002/zaac.200801309

An organically templated neodymium oxalate-sulfate [C₆N ₂H₁₄][Nd₂(C₂O₄) ₂(SO₄)₂(H₂O)₄] ·H₂O (1) has been synthesized under

Full text of DOI:10.1002/zaac.200801309

ARTICLE
DOI: 10.1002/zaac.200801309
Synthesis, Structure and Photoluminescent Properties of
C N H ][Nd (C O ) (SO ) (H O) ]·H O, a New Organically Templated
[
6
2
14
2
2
4 2
4 2
2
4
2
Neodymium(III) Oxalate-sulfate
[
a]
[a]
[a]
[a]
[a]
[a]
Ning Xu, Yan Xing,* Xianchun Liu, Danhui Song, Ling Ma, and Xiujuan Sun
Keywords: Neodymium; Crystal engineering; OrganicϪinorganic hybrid composites; Luminescence; Open framework
Abstract. An organically templated neodymium oxalateϪsulfate
14][Nd (C (SO (H O) ]·H O (1) has been synthe-
sized under hydrothermal conditions and structurally characterized
dymium(III) ions are interconnected through oxalate and sulfate
groups to form a neodymium oxalateϪsulfate hybrid structure. A
luminescence spectrum of 1 was recorded, and the luminescence
decay time was also measured.
[C
6
N
2
H
2
2
O
4
)
2
4
)
2
2
4
2
by single-crystal X-ray diffraction analysis. In 1, the neo-
Introduction
the hydrothermal synthesis, structural characterization, and
photoluminescent properties of a new neodymium(III)oxal-
ate-sulfate [C N H ][Nd (C O ) (SO ) (H O) ]·H O (1)
Compounds possessing open-framework structures have
been extensively investigated in regard of their important
applications in the areas of catalysis, sorption, and separ-
ation processes. A remarkable variety of open-framework
organically templated inorganic materials have been re-
ported over the last two decades [1]. The research mainly
focused on the metal phosphates [2Ϫ4], phosphites [5Ϫ8],
arsenates [9Ϫ11] and sulfates [12Ϫ17]. Recently, com-
pounds with oxalate anions along with phosphate, phos-
6
2
14
2
2
4 2
4 2
2
4
2
framework.
Experimental Section
Materials and Methods
All chemicals used were of reagent grade and used as received from
commercial sources without further purification. The X-ray powder
phite, and arsenate units attracted much attention because diffraction (XRD) data were collected with a Siemens D5005 dif-
˚
of their novel extended networks formed by the combi- fractometer with Cu-K radiation (λ ϭ 1.5418 A). Elemental analy-
α
nation of organic and inorganic anions [1]. However, in- ses were performed with a PerkinϪElmer 2400 element analyzer.
Inductively coupled plasma (ICP) analyses were carried out with
vestigations on compounds containing both, oxalate and
sulfate units, have been rare.
Research activities in the area of lanthanide sulfates
aroused interest because of their applications in the
separation of rare earth elements [18]. Up to now, various
lanthanide sulfates with open-framework structures have
been reported [18Ϫ27]. The hybrid lanthanide oxalateϪ
a PerkinϪElmer Optima 3300DV spectrometer. Fourier transform
Ϫ1
infrared spectra (FT-IR) were recorded within the 400Ϫ4000 cm
region with a Nicolet Impact 410 FTIR spectrometer using KBr
pellets. The thermogravimetric analyses (TGA) were performed
with a PerkinϪElmer TGA 7 thermogravimetric analyzer in a ni-
Ϫ1
trogen atmosphere with a heating rate of 10 °C·min . The lumi-
nescence excitation and emission spectra were recorded with a HO-
sulfate frameworks, on the other hand, have rarely been RIBA Jobin Yvon FluoroLog-3 spectrofluorometer equipped with
explored hitherto. Mao et al. synthesized La (C O )- a 450 W Xe-lamp as an excitation source and a liquid-nitrogen-
2
2
4
(
SO ) (H O) , in which the lanthanum(III) ions are inter- cooled R5509Ϫ72 PMT as a detector. The time-resolved measure-
4 2 2 3
ment, was done by using the third harmonic (355 nm) of a Spectra-
physics Nd:YAG laser with a 5 ns pulse width and 5 mJ of energy
per pulse as a source, and the Near-IR emission lines were
dispersed with the emission monochromator of a HORIBA Jobin
Yvon FluoroLog-3 equipped with liquid-nitrogen-cooled
R5509Ϫ72 PMT, and the data was analysed with a LeCroy
WaveRunner 6100 1 GHz Oscilloscope. The luminescence lifetime
was calculated using the Origin 7.0 software package.
connected through oxalate and sulfate groups to form a no-
vel network with a lanthanum(III)sulfateϪoxalate hybrid
structure [28]. Recently, the first hybrid organicϪinorganic
frameworks based on lanthanide(III)sulfate chains, in-situ
generated oxalate and organic pillars of 1,4-piperazinedia-
cetic acid have been reported [29]. In this work, we report
*
Dr. Y. Xing
Synthesis
E-Mail: xingy202@nenu.edu.cn
[
a] College of Chemistry
[C
6
N
2
H14][Nd
2
(C
2
O
4
)
2
(SO
4
)
2
(H
2
O)
4
]·H
2
O
(1):
To
2 3
Nd O
Northeast Normal University
Changchun 130024, P.R. China
(0.3365 g) and H
2
C
2
O
4
·2H
2
O (0.8825 g) diluted sulfuric acid
558
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2009, 635, 558Ϫ562

[C
6
N
2
2 2 4 2 4 2 2 4 2
H14][Nd (C O ) (SO ) (H O) ]·H O, a New Oxalate-sulfate
˚
Table 1. Crystal data and structure refinement for 1.
Table 2. Selected bond lengths /A and bond angles /° for 1.
Empirical formula
Formula weight
Temperature
C
10
H
24
N
2
Nd
2
O
21
S
2
Nd(1)ϪO(1)
Nd(1)ϪO(2)
Nd(1)ϪO(3)#3
Nd(1)ϪO(8)
Nd(1)ϪO(9)
Nd(1)ϪO(17)
Nd(1)ϪO(18)#1
Nd(1)ϪO(19)
Nd(1)ϪO(20)#2
Nd(2)ϪO(5)
Nd(2)ϪO(6)
Nd(2)ϪO(10)
Nd(2)ϪO(11)
2.567(4)
2.484(4)
2.475(4)
2.410(3)
2.483(4)
2.486(4)
2.512(4)
2.548(4)
2.566(4)
2.444(4)
2.685(4)
2.504(4)
2.459(4)
Nd(2)ϪO(12)
Nd(2)ϪO(13)
Nd(2)ϪO(14)
Nd(2)ϪO(15)#4
Nd(2)ϪO(16)#4
S(1)ϪO(1)
S(1)ϪO(2)
S(1)ϪO(3)
S(1)ϪO(4)
S(2)ϪO(5)
2.505(4)
2.511(4)
2.429(4)
2.486(4)
2.526(4)
1.492(4)
1.491(4)
1.472(4)
1.448(4)
1.484(4)
1.485(4)
1.462(4)
1.470(4)
860.93
293(2) K
0.71069 A
monoclinic
˚
Wavelength
Crystal system
Space group
1
P2 /c
˚
a /A
8.523(5)
28.628(5)
9.306(5)
96.497(5)
2256.1(18)
4
2.535
4.843
1672
0.40 ϫ 0.32 ϫ 0.28
2.31 Ϫ28.24
Ϫ11 Յ h Յ 5
Ϫ38 Յ k Յ 37
Ϫ12 Յ l Յ 12
13707
5224 [R(int) ϭ 0.0548]
Full-matrix least-squares on F2
5224 / 17 / 364
˚
b /A
˚
c /A
β /°
˚
3
Volume /A
S(2)ϪO(6)
S(2)ϪO(7)
S(2)ϪO(8)
Z
Ϫ3
Dcalc /mg·m
Ϫ1
Absorption coefficient /mm
F(000)
Crystal size /mm
θrange /°
Limiting indices
O(1)ϪNd(1)ϪS(1)
O(2)ϪNd(1)ϪS(1)
27.95(8)
27.59(9)
O(5)ϪNd(2)ϪS(2)
O(6)ϪNd(2)ϪS(2)
O(10)ϪNd(2)ϪS(2)
26.81(9)
27.78(9)
103.05(13)
78.03(10)
146.74(10)
71.67(10)
100.32(11)
O(3)#3ϪNd(1)ϪS(1) 80.94(9)
O(8)ϪNd(1)ϪS(1)
O(9)ϪNd(1)ϪS(1)
O(17)ϪNd(1)ϪS(1)
104.16(10) O(11)ϪNd(2)ϪS(2)
70.69(11) O(12)ϪNd(2)ϪS(2)
98.34(10) O(13)ϪNd(2)ϪS(2)
Reflections collected
Reflections unique
Refinement method
Data / restraints / parameters
Goodness-of-fit on F
Final R indices [I>2σ (I)]
R indices (all data)
Largest diff. peak and hole /e·A
O(18)#1ϪNd(1)ϪS(1) 149.09(9) O(14)ϪNd(2)ϪS(2)
O(19)ϪNd(1)ϪS(1) 95.26(9)
O(20)#2ϪNd(1)ϪS(1) 142.78(10) O(16)#4ϪNd(2)ϪS(2) 92.91(10)
O(15)#4ϪNd(2)ϪS(2) 142.50(9)
Symmetry transformations used to generate equivalent atoms:
2
1.043
#
1 Ϫxϩ2, Ϫy, Ϫzϩ1; #2 Ϫxϩ2, Ϫy, Ϫzϩ2; #3 Ϫxϩ1, Ϫy, Ϫzϩ1;
R1 ϭ 0.0374, wR2 ϭ 0.0928
R1 ϭ 0.0456, wR2 ϭ 0.0972
1.755 and Ϫ1.929
1 1
#
2 2
4 x, Ϫyϩ / , zϩ / .
˚
Ϫ3
˚
Table 3. Hydrogen bonds for 1. Lenghts /A and angles /°.
(10.0 mL; 1 mL H
2
SO
4
/10.0 mL H
2
O) was added under constant
DϪH···A
d(DϪH) d(H···A) d(D···A) <(DHA)
stirring to give solution I. 1,4-diazobicyclo[2.2.2]octane (DABCO)
0.9692 g) was added to diluted sulfuric acid (10.0 mL; 0.3 mL
SO /10.0 mL H O) whilst stirring to give solution II. After-
N(9)ϪH(9)···O(16)#2
N(9)ϪH(9)···O(13)#2
0.91
0.91
1.84
2.64
2.09
2.60
2.721(7) 161.7
3.372(6) 138.5
2.905(7) 147.9
3.216(6) 125.9
2.770(5) 164(6)
3.006(7) 153(5)
2.881(6) 167(5)
2.880(6) 150(5)
3.113(6) 122(5)
2.654(6) 164(5)
3.028(6) 151(5)
2.905(6) 160(4)
(
H
2
4
2
N(10)ϪH(10)···O(1W)#1 0.91
wards, solution I was mixed with solution II under constant stir- N(10)ϪH(10)···O(17)
ring. The resulting mixture with a molar ratio of Nd /H SO
O(10)ϪH(3)···O(19)#3
O(10)ϪH(4)···O(1W)#4 0.856(19) 2.22(3)
0.91
O
3
2
4
/
0.850(19) 1.94(3)
2
DABCO/H ·2H O/H O ϭ 1:24.4:4.4:7:1100 was transferred
2
C
2
O
4
2
2
O(1W)ϪH(12)···O(6) 0.842(19) 2.05(2)
into a 30 mL Teflon-lined stainless-steel autoclave and heated at
73 K for 16 h. The resulting pink block-like single crystals of 1
O(1W)ϪH(11)···O(2)#1 0.845(19) 2.12(3)
3
O(1W)ϪH(11)···O(17)#1 0.845(19) 2.59(5)
were collected by filtration, washed with ethanol and dried at room
temperature. Yield: 70 % (with respect to Nd). The inductively
coupled plasma (ICP) and elemental analysis resulted:
O(9)ϪH(2)···O(4)#3
O(9)ϪH(1)···O(5)
0.853(19) 1.82(3)
0.820(19) 2.28(3)
0.879(16) 2.06(2)
0.861(16) 1.845(18) 2.698(5) 170(6)
0.845(19) 1.993(19) 2.834(5) 173(5)
O(11)ϪH(6)···O(18)#1
O(11)ϪH(5)···O(1)
O(12)ϪH(7)···O(20)#3
O(12)ϪH(8)···O(7)#5
(
7
C
10
H
24
N
2
Nd
.45; N 3.25; H 2.81; found: O 39.25; Nd 33.40; C 13.83; S 7.58;
N 3.12; H 2.70.
2 21 2
O S ) calcd. (%): O 39.03; Nd 33.51; C 13.95; S
0.849(19) 1.94(2)
2.781(6) 171(5)
Symmetry transformations used to generate equivalent atoms:
1
3
#
1 Ϫxϩ1, Ϫy, Ϫzϩ1; #2 Ϫxϩ2, yϪ /
2 2
, Ϫzϩ / ; #3 Ϫxϩ1, Ϫy,
Crystal Structure Determination
Ϫzϩ2; #4 x, y, zϩ1 #5 xϪ1, y, z
A
0
suitable single crystal of
.40 ϫ 0.32 ϫ 0.28 mm was selected for single-crystal X-ray dif-
fraction analysis. The intensity data were collected with a Siemens with the Cambridge Crystallographic Data Centre as supplemen-
1
with the dimensions
SMART CCD diffractometer using graphite-monochromatic
tary publication number CCDC-695257. Copies of the data can be
obtained free of charge on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK [Fax: ϩ44-1223-336-033; E-mail:
deposit@ccdc.cam.ac.uk].
˚
Mo-K
α
radiation (λ ϭ 0.71069 A). Data processing was ac-
complished with the SAINT program [30]. All absorption correc-
tions were performed using a multi-scan method. The structures
were solved by direct methods with the SHELXTL 97 software
package [31]. All non-hydrogen atoms were refined anisotropically.
Hydrogen atoms on oxygen and nitrogen atoms were found in Results and Discussion
Fourier difference maps and organic hydrogen atoms were placed
in geometrically preset positions. Crystal and experimental data are
listed in Table 1. Selected bond lengths and angles are listed in
The agreement between the experimental and simulated
XRD patterns indicated the phase purity of 1 (Figure 1).
Table 2 and hydrogen bonding parameters are given in Table 3. The difference in reflection intensities between the simu-
Crystallographic information of compound 1 has been deposited lated and experimental patterns was due to the variation in
Z. Anorg. Allg. Chem. 2009, 558Ϫ562
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
559

N. Xu, Y. Xing, X. Liu, D. Song, L. Ma, X. Sun
ARTICLE
Figure 1. Simulated and experimental powder X-ray diffraction
patterns of 1.
preferred orientation for the powder sample during collec-
tion of the experimental XRD data.
The structure of 1 is based on a network of neodymium-
Figure 2. ORTEP view of the structure of 1 showing the atom labe-
ling scheme (50 % thermal ellipsoids).
centered polyhedral NdO , sulfur-centered tetrahedral sul-
9
fate and oxalate units. The asymmetric unit contains two
neodymium atoms, two oxalate groups, two sulfate groups,
one protonated 1,4-diazobicyclo[2.2.2]octane (DABCO)
molecule, four coordinated and one free water molecule
(Figure 2). Of the two neodymium atoms, Nd(1) is sur-
rounded by nine oxygen atoms, in which four oxygen atoms
2Ϫ
are from two sulfates, four from two oxalates (C O4 ), and
2
one from a water molecule. Nd(2), on the other hand, is
nonacoordinated by two oxygen atoms from one sulfate,
2
Ϫ
four from two oxalates (C O ), and three from water mol-
2
4
ecules. The average NdϪO bond lengths [Nd(1)ϪO ϭ
˚ ˚
.503 A, Nd(2)ϪO ϭ 2.505 A], are in good agreement with
2
those reported earlier [29]. Two sulfur atoms form the cen-
ters of the tetrahedral sulfate groups. The SϪO bond
Figure 3. Structures of the zigzag chain along the c-axis (a), the
lengths in the SO tetrahedra are in the range 1.448(4) to hybrid organic-inorganic layer in the ac plane (b) and the frame-
4
˚
work of 1 (c). Blue dots indicate nonaconnected neodymium atoms;
red, yellow, dark gray and dark blue dots suggest atoms oxygen,
sulfur, carbon and nitrogen, respectively.
1
.492(4) A, with OϪSϪO bond angles in the range 104.0(2)
to 111.6(2)°.
As shown in Figure 3a, the neodymium atoms are linked
through μ -oxalate to form an infinite zigzag chain along
4
the c direction. These neodymium oxalate chains are con-
nected by the sulfate groups to give rise to a layer structure,
as shown in Figure 3b. Finally, these layers, parallel to the
ac plane, are further linked to the neodymium oxalate
chains through sulfate groups, resulting in an interesting
framework structure (Figure 3c). The DABCO cations and
water molecules are located in the cavities of the frame-
work. It is well known that multipoint hydrogen-bond inter-
actions are necessary for the phase formation and stability
of open architectures. This was also found for the present
study, where strong interactions exist between the hydrogen
atoms attached to nitrogen and the framework oxygen
atoms. In addition, water molecules participate in hydrogen
bonding through OWaterϪH···O bonds. The important hy-
drogen bond interactions are presented in Table 3.
The IR spectrum (Figure 4) shows the ν(NϪH) and
Ϫ1
ν(OϪH)bands in the range 3431Ϫ2602 cm . The strong Figure 4. IR spectrum of 1.
560
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© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2009, 558Ϫ562

6 2 2 2 4 2 4 2 2 4 2
[C N H14][Nd (C O ) (SO ) (H O) ]·H O, a New Oxalate-sulfate
absorption signals at 1598 and 1474 cmϪ1 correspond to
the antisymmetric and symmetric stretching bands for the
carboxylate groups of the oxalate anion. The absorption
bands associated with the sulfate groups appear in the
Ϫ1
region from 1158 to 616 cm
.
The thermogravimetric analysis (TGA) of 1 (Figure 5)
displays a weight loss from room temperature to 250 °C,
corresponding to the evacuation of lattice and coordinated
water molecules (calcd.: 10.46 %; observed: 10.31 %). From
2
4
50 to 800 °C, two periods of sharp weight loss (calcd.:
1.16 %; observed: 40.59 %) due to the loss of protonated
DABCO, CO and SO are observed. The powder X-ray
2
2
diffraction pattern of the sample heated at 800 °C corre-
sponds to Nd O (SO ) (JCPDS file card No. 48Ϫ1829).
2
2
4
Figure 6. Emission (λex ϭ 355 nm) spectrum for 1 in solid-state at
room temperature.
Acknowledgement
This work was supported by the Training Fund of NENU’S
Scientific Innovation Project (No. NENU-STC07004) and the
Analysis and Testing Foundation of Northeast Normal University.
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[
8
[
4
4
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4
4
4
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Z. Anorg. Allg. Chem. 2009, 558Ϫ562
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
561

N. Xu, Y. Xing, X. Liu, D. Song, L. Ma, X. Sun
ARTICLE
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7
Received: September 23, 2008
Published Online: January 23, 2009
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