Germanate with three-dimensional 12 × 12 × 11-ring channels solved by X-ray powder diffraction with charge-flipping algorithm

Article abstract of DOI:10.1021/ic302705f

A new open-framework germanate, denoted as GeO-JU90, was prepared by the hydrothermal synthesis method using 1,5-bis(methylpyrrolidinium)pentane dihydroxide as the organic structure-directing agent (SDA). The structure of GeO-JU90 was determined from synchrotron X-ray powder diffraction (XRPD) data using the charge-flipping algorithm. It revealed a complicated framework structure containing 11 Ge atoms in the asymmetric unit. The framework is built of 7-connected Ge₇ clusters and additional tetrahedral GeO ₃(OH) units forming a new three-dimensional interrupted framework with interesting 12 × 12 × 11-ring intersecting channels. The Ge K-edge extended X-ray absorption fine structure (EXAFS) analysis was performed to provide the local structural information around Ge atoms, giving rise to a first-shell contribution from about 4.2(2) O atoms at the average distance of 1.750(8) A. The guest species in the channels were subsequently determined by the simulated annealing method from XRPD data combining with other characterization techniques, e.g., ¹³C NMR spectroscopy, infrared spectroscopy (FTIR), compositional analyses, and thermogravimetric analysis (TGA). Crystallographic data |(C₁₅N₂H₃₂) (NH₄)|[Ge₁₁O_21.5(OH)₄], orthorhombic Ama2 (No. 40), a = 37.82959 A, b = 15.24373 A, c = 12.83659 A, and Z = 8.

Full text of DOI:10.1021/ic302705f

Article
pubs.acs.org/IC
Germanate with Three-Dimensional 12 × 12 × 11-Ring Channels
Solved by X‑ray Powder Diffraction with Charge-Flipping Algorithm
†
,#
‡,#
∥
,‡,§
,∥
,†
Yan Xu, Leifeng Liu, Daniel M. Chevrier, Junliang Sun,* Peng Zhang,* and Jihong Yu*
†State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012,
China
‡
Berzelii Center EXSELENT on Porous Materials, Department of Materials and Environmental Chemistry, Stockholm University,
Stockholm SE-106 91, Sweden
§
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
∥
Department of Chemistry, Dalhousie University, 15000, Halifax, Nova Scotia, Canada NS B3H 4R2
*
S Supporting Information
ABSTRACT: A new open-framework germanate, denoted as GeO-
JU90, was prepared by the hydrothermal synthesis method using
1,5-bis(methylpyrrolidinium)pentane dihydroxide as the organic
structure-directing agent (SDA). The structure of GeO-JU90 was
determined from synchrotron X-ray powder diffraction (XRPD)
data using the charge-flipping algorithm. It revealed a complicated
framework structure containing 11 Ge atoms in the asymmetric unit.
The framework is built of 7-connected Ge clusters and additional
7
tetrahedral GeO (OH) units forming a new three-dimensional
3
interrupted framework with interesting 12 × 12 × 11-ring
intersecting channels. The Ge K-edge extended X-ray absorption
fine structure (EXAFS) analysis was performed to provide the local
structural information around Ge atoms, giving rise to a first-shell
contribution from about 4.2(2) O atoms at the average distance of 1.750(8) Å. The guest species in the channels were
subsequently determined by the simulated annealing method from XRPD data combining with other characterization techniques,
e.g., 13C NMR spectroscopy, infrared spectroscopy (FTIR), compositional analyses, and thermogravimetric analysis (TGA).
Crystallographic data |(C N H )(NH )|[Ge O (OH) ], orthorhombic Ama2 (No. 40), a = 37.82959 Å, b = 15.24373 Å, c =
1
5
2
32
4
11 21.5
4
12.83659 Å, and Z = 8.
INTRODUCTION
framework structures with large pores, as predicted by Fer
́
ey on
■
8
the basis of the concept of “scale chemistry”. For example,
Crystalline porous materials, especially zeolites with open-
3
b
3f
ASU-16 and SU-12 with 24-ring channels are built of Ge
7
framework structures, are widely used in industry due to thei1r
5d
and (Ge,Si)7 clusters, respectively; FDU-4 with 24-ring
channels is built of Ge clusters; SU-M with mesoporous
0-ring channels is built of Ge10 clusters; JLG-12 with
excellent catalytic, ion-exchange, and adsorption properties.
6b
9
Since these properties strongly depend on the channel system
of the framework structure, much effort has been made to
explore open-framework materials with novel structures in the
3l
3
mesoporous 30-ring channels is built of the combination of Ge
7
7
2
and Ge clusters; FJ-1 with 24-ring channels is built of Ni@
9
past decades. Open-framework germanates are of particular
Ge14 clusters.
interest for their ability to form diverse structures, especially
structures with an extralarge pore.
3
−6
Among the various Ge clusters, the Ge cluster has been
7
In contrast to silicate-
frequently observed in the open-framework germanate
based zeolite materials that contain only tetrahedral primary
building units, open-framework germanates can be constructed
from a variety of Ge-centered coordination polyhedra including
Ge-centered tetrahedra, trigonal bipyramids, and octahedra.
Combination of these flexible coordination modes of the Ge
atom leads to formation of some well-defined clusters including
3
compounds. The Ge cluster is a pseudocubic building unit
7
(
“4−3” subunit) consisting of four GeO tetrahedra, two GeO
4
5
trigonal bipyramids, and one GeO6 octahedron. It has a
maximum connectivity of 7 but is more frequently observed to
have a lower connecting number. A list of germanates with
3
4
3g,l,5
various connection modes of the Ge cluster is given in Table 1.
Ge7X19 (Ge ), Ge X (Ge ), Ge X
(Ge9),
Ge X
7
7
8
20
8
9
25−26
10 28
6
7
It is rare to find the fully connected Ge clusters in the reported
(
Ge ), and Ni@Ge clusters, where X = O, OH, or F. These
7
10
14
large cluster building units can then be linked to each other by
sharing O atoms or through additional primary building units,
Received: December 9, 2012
for instance, GeO tetrahedra to form a variety of open-
4
©
XXXX American Chemical Society
A
dx.doi.org/10.1021/ic302705f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
a
Table 1. Various Connection Modes of Ge Clusters
GeO-JU90 was determined from the powder charge-flipping
7
15
algorithm. It contains 11 independent T atoms, which is one
of the most complicated germanates solved from XRPD. Ge K-
edge extended X-ray absorption fine structure (EXAFS)
analyses were also applied for structural analysis, providing
the local atomic structural information around Ge atoms. The
guest species in the pores were determined by simulated
mode of
linkage
n
connection
example
dimension
1D
ref
2
T
2
3
4
FJ-6
3e
2
P O
unknown
ASU-20-DACH
ASU-20-DAPe
JLG-4
T4
2D
2D
1D
1D
3D
3D
3D
3c
3c
3k
3j
16
13
annealing from XRPD data combining with C NMR
spectroscopy and other characterization techniques.
JLG-5
JLG-12
3l
T2P2
4
SU-44
3g
6b
EXPERIMENTAL SECTION
■
SU-MB
Syntheses of SDAs. The SDA for GeO-JU90, 1,5-bis(N-
methylpyrrolidinium)pentane (MPP(Br) ), was prepared by reacting
2
T PO
4
5
unknown
ASU-12
2
T4P
3D
3D
2D
3D
2D
3D
3D
3D
3D
3D
3a
3b
3c
3f
an excess of N-methylpyrrolidine (97%, Aldrich; 20 g, 234.9 mmol)
ASU-16
with 1,5-dibromopentane (97%, Aldrich; 18.7 g, 81.3 mmol) in 200
1
7
mL of ethanol as a solvent under reflux for 24 h. Then, the solvent
was removed by evaporation under vacuum, and the resulting solid was
washed with diethyl ether until unreacted amine was completely
ASU-19
SU-12
4
T O
5
6
6
6
7
ASU-19
3c
3g
3g
1
13
removed from the solid. The compound was verified by H and
C
4
2
T P
SU-44
NMR. The dibromide salt was converted into the dihydroxide by
4
T PO
SU-8
−
anion exchange in water solution using an OH resin (DOWEX). The
3
2
T P O
PKU-10
3m
3d
extent of exchange was above 90%. The dihydroxide solution was
concentrated by rotovaporation under vacuum with mild heating. The
final concentration was determined by titration using a certified HCl
4
2
T P O
Ge O (OH)·N C H
21
1
0
21
4
6
GeO-JU90
this
work
solution and phenolphthalein. The concentration of MPP(OH) is
2
a
−4
T = tetrahedron, P = trigonal bipyramid, O = octahedron.
1.41 × 10 mol/g.
The SDA for GeO-ITQ-21, 6-azoniaspiro[5.5]undecane
(
C H NBr), was prepared by adding cis-2,6-dimethylpiperidine
compounds, with the only example of the small pore germanate
12 24
3d
(97%, Aldrich; 10 g, 88.3 mmol) to 1,5-dibromopentane (97%,
Aldrich; 20.31 g, 88.3 mmol) in a 1:1 molar ratio in 150 mL of ethanol
in the presence of K CO (13.41 g, 97.2 mmol) and heated under
reflux for 3 days. The product was separated and purified using the
above method. The compound was verified by H and C NMR. The
bromide salt was converted into the hydroxide by anion exchange in
water solution using an OH resin (DOWEX). The extent of exchange
was above 90%. The hydroxide solution was concentrated, and the
Ge O (OH)·N C H . In this work, we use the diquater-
10
21
4
6
21
nary ammonium cation 1,5-bis(methylpyrrolidinium)pentane
as the structure-directing agent and synthesized a novel open-
framework germanate, denoted as GeO-JU90 in a concentrated
2
3
18
1
13
gel system with H O/GeO in a molar ratio of 1.5 in the
2
2
−
absence of HF. Its structure is built of 7-connected Ge clusters
7
and additional tetrahedral GeO (OH) units, forming a novel
3
interrupted open-framework structure.
final concentration was determined by titration using a certified HCl
As is known, the pore size and channel dimension of a
framework structure are crucial factors affecting its application.
Those with three-dimensional channels and ring size between
solution and phenolphthalein. The concentration of C12H24N(OH)
−4
solution is 2.60 × 10 mol/g.
Synthesis of GeO-JU90. Typically, 1.57 g of GeO was dissolved
2
in 26.72 g of MPP(OH) solution. The mixture was stirred until a clear
2
10 and 12 are highly interesting in the catalysis industry. Two
9 10
solution was obtained. Then the water content was controlled by
evaporation of the mixture at 60 °C in an oven. The overall molar ratio
of GeO :MPP(OH) :H O in the representative synthesis gel was
of the most famous examples are zeolites beta and ZSM-5 in
which the former has 12-ring channels and the latter has 10-
ring channels. Both of them are important catalysts but with
very different catalytic properties due to the very different
2
2
2
1
.0:0.25:1.5. The final gel was sealed in a Teflon-lined stainless steel
autoclave and heated at 150 °C for 15 days. After cooling to room
temperature, the white solid was obtained by centrifugation. The
product was washed by distilled water and ethanol and dried at room
temperature.
1
1
channel system. Moreover, the recently reported aluminosi-
12
licate ITQ-39 has intersecting 10- and 12-ring channels.
Because of this unique combination of channels, it shows a very
distinct and interesting catalytic property in alkylation of
aromatics with olefins. Thus, it is interesting to see more
structures combining different sizes of channels. Here, we
present GeO-JU90 with a three-dimensional intersecting 12-,
Synthesis of GeO-ITQ-21. A 1.05 g amount of GeO2 was
dissolved in 19.20 g of C H N(OH) solution. After removing 18.10 g
12
24
of water by evaporation, 0.25 g of HF (220 μL, 40 wt % in water) was
added to the mixture and then stirred by hand. The overall molar
composition of GeO :C H N(OH):HF:H O in the gel was
2
12 24
2
1
2-, and 11-ring channel system.
Structures of these open-framework materials can be
1
.0:0.5:0.5:1.5. The final gel was sealed in a Teflon-lined stainless
steel autoclave and heated at 150 °C for 15 days. After cooling to room
temperature, a white solid of GeO-ITQ-21 was filtered, washed by
distilled water and ethanol, and dried at room temperature. GeO-ITQ-
determined routinely by single-crystal X-ray diffraction (SC-
XRD) if the crystals are big enough. However, in many cases
only very fine crystals can be obtained, leaving X-ray powder
diffraction (XRPD) and electron crystallography the most
1
9
2
1 is isomorphous to silicogermanate zeolite ITQ-21 and was used
as a standard reference for EXAFS analysis of GeO-JU90.
13
Structure Solution from Charge Flipping Algorism. XRPD
data were collected using a synchrotron X-ray beam with a radiation
length of 0.827141 Å at the beamline I11, Diamond Light Source, U.K.
Sample was packed in the capillary with a diameter of 0.5 mm, and
data were collected from 2° to 60° in 2θ at room temperature with the
step size of 0.005°. The pattern was indexed as an orthorhombic unit
promising methods for solving the crystal structure. Due to
the sensitivity of germanates under electron beam, electron
crystallography could hardly be helpful except for providing
unit cell parameters. Therefore, exploring XRPD as a possible
technique to reveal the structure for this class of materials is of
great importance. Recently, we successfully solved the structure
2
0
cell using the indexing program Dicvol04 on the first 20 strong peaks
14
of SU-74 from XRPD data. In this work, the structure of
(minimum intensity of 5% of the strongest peak). After extraction of
B
dx.doi.org/10.1021/ic302705f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
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Figure 1. (a) Electron density map obtained from Super Flip with an input space group of Amam. (b) Two sets of overlapped Ge clusters in green
7
and red. (c) Final structure model superimposed on the electron density map obtained with an input space group of Ama2.
Figure 2. Observed (blue), calculated (red), and difference (black) XRPD patterns for Rietveld refinement of as-synthesized GeO-JU90. (Insert)
Patterns in the range from 20° to 45°.
2
1
peak intensity with Jana2006, the charge-flipping method was
The structure obtained is in space group Ama2. However, 56 out of
88 germanium atoms in the structure show the high symmetry of
Amma, which drove the charge-flipping algorithm to the wrong space
group in 6 out of 10 resultant maps. It is also possible that merohedric
twinning with 180° rotation along the a axis occurs due to the nature
of the structure, but different from SC-XRD, twinning does not affect
solving the structure from XRPD data.
22
performed using the software Super Flip to solve the structure.
The resulting electron density map in the space group of Amam is
shown in Figure 1. By assigning the peaks as germanium atoms, the
whole framework structure emerges but with disordering in the middle
part where peaks are relatively weak. The mirror relating two
disordered parts can be removed to convert the space group to Ama2,
which is also the suggested space group from charge flipping in 4 out
of the 10 best results (the other 6 results suggest a space group of
Amam).
Structure Refinement of the Framework. Rietveld refinement
2
4
was applied to all framework atoms using TOPAS with soft restrains
on the distance between bonded germanium and oxygen atoms as well
as between each pair of oxygen atoms bonded to the same germanium
atoms. The topology of GeO-JU90 was determined using the TOPOS
Hence the charge-flipping method was applied again in space group
Ama2. Then the electron density map was converted to atomic
2
3
25
structure using Electron Density Map Analysis (EDMA). All
germanium atoms and some of the oxygen atoms could be found
directly this time. The remaining oxygen atoms and terminal hydroxyl
groups were added to the structure manually based on the
coordination geometry. In the asymmetric unit, there are 11
germanium atoms and 27 oxygen atoms, implying the complexity of
the structure.
package.
Allocation and Refinement of Guest Species. The guest
species were found using the simulated annealing method with
TOPAS. The first 10 carbon atoms were added to random positions
and refined with restrains of minimal distance from framework atoms
to prevent clashing. These carbon atoms assembled into groups after
running simulated annealing. One was located in the channel along the
C
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Inorganic Chemistry
Article
2
8
a axis and had a similar shape as the SDA molecule, while the other
two groups of carbon atoms located in the conjunction part of the
other two channels perpendicular to the a axis could be interpreted as
two separated 1-methypyrrolidine molecules, which may imply
decomposition of the SDA molecule.
obtain scattering paths was the crystal structure of GeO . Fourier
2
2
transforms into R space were performed on k -weighted EXAFS
−1
oscillations in the k range of 2.7−13.0 Å , employing Gaussian
windows, which was then conducted in R space. All fits performed in
the R space include the fitting of the Ge−O distance to the first shell,
To identify organic species in the channel, solid-state 13C MAS
NMR was first carried out on the as-synthesized product. The result
was ambiguous, showing three broad peaks. Later, the organic species
was extracted after dissolving the framework. As detailed in the
following part, the 13C MAS NMR spectrum in the liquid phase
proved that the SDA molecules remained intact after the hydrothermal
process. This means that the two separated 1-methypyrrolidine
molecules were actually connected by a pentane group. However, due
to the high flexibility and low electron density of the alkane chain, it
was not determined directly from simulated annealing. Therefore, two
intact SDA molecules were added as rigid (hydrogen atoms were
omitted, and the corresponding number of electrons was assigned to
carbon and nitrogen atoms). After refining positions and the
configuration of SDA molecules, an additional 8 peaks in the Fourier
EXAFS Debye−Waller factor of σ which accounts for thermal
2
vibration (assuming harmonic vibration) and static disorder (assuming
a Gaussian pair distribution) at an interatomic Ge−O distance away,
the parameter of ΔE which accounts for the error in determining the
o
2
o
edge energy, and the amplitude reduction factor of S
which was
determined by fitting the standard (GeO-ITQ-21) to give a value of
0.99.
SEM, NMR, IR, Compositional Analyses, TG, and in Situ
XRPD. Crystal size and morphology were characterized by scanning
electron microscopy (SEM) using a JSM-6700F electron microscope.
The as-synthesized product of GeO-JU90 displays the micrometer size
of flaky crystals with a diameter of about 1−3 μm (Supporting
Information, Figure S1). Liquid-state C and H NMR spectra were
recorded on a MERCURY “300BB”. The solid-state 1 C MAS NMR
spectrum was recorded on a Bruker AVANCE III 400 WB
spectrometer.
13
1
3
difference map were found, which could be water or other small
+
4
cations, e.g., NH . By considering the charge balance that the
The infrared (IR) spectrum was recorded within the 4000−400
cm region on a Nicolet Impact 410 FTIR spectrometer using a KBr
pellet.
framework carries negative charges per unit cell and SDA cations carry
−
1
1
6 positive charges, those peaks were assigned as NH4+ ions which
came from decomposition of SDA molecules. After overall refinement
on both framework and guest species, good fitting was reached as
shown in Figure 2 and Table 2.
Inductively coupled plasma (ICP) analysis was carried out on a
Perkin-Elmer Optima 3300 DV ICP instrument. CHN elemental
analysis was carried out with an Perkin-Elemer 2400 elemental
analyzer.
Thermogravimetric (TG) analysis was performed on a Perkin-Elmer
TGA 7 to study the weight loss associated with decomposition of guest
species. The sample was heated from 25 to 800 °C with a heating rate
of 10 °C/min in air.
The in situ variable-temperature XRPD data of GeO-JU90 were
collected on a Rigaku D/Max-2500 diffractometer with a Cu Kα
radiation source (λ = 1.5418 Å), and the heating rate is 10 °C/min
from room temperature to 500 °C. Patterns were recorded every 20
°C between 200 and 400 °C. The temperature was equilibrated for 2
min prior to each measurement. The 2θ range was 3−50°.
Table 2. Crystal Data and Refinement Details of Structure
Determination of GeO-JU90 from X-ray Powder Diffraction
data collection
synchrotron facility
beamline
Diamond Light Source
I11
capillary, size
wavelength
0.5 mm
0.827141 Å
2−60°
0.005°
2θ range
step size
refinement
empirical formula
unit cell formula
space group
a(Å)
|(C N H )(NH )|[Ge O21.5(OH)4]
Ge88 O204 C120 N24 H320
Ama2
RESULTS AND DISCUSSION
1
5
2
32
4
11
■
Structure of GeO-JU90. The structure of GeO-JU90 was
determined from synchrotron XRPD data using the charge-
flipping algorithm. It reveals that GeO-JU90 crystallizes in the
orthorhombic space group of Ama2 with lattice parameters a =
37.82959
b(Å)
15.24373
c(Å)
12.83659
3
7.82959 Å, b = 15.24373 Å, and c = 12.83659 Å. Each
3
unit cell volume
density
7402.4 Å
asymmetric unit in GeO-JU90 contains 11 crystallographically
independent Ge atoms and 27 crystallographically independent
O atoms, as shown in Figure 3a. The structure is constructed
from Ge clusters and additional tetrahadral GeO (OH) units.
3
2.637 g/cm
2θ range for refinement
2−45°
188
no. of parameters
no. of data points
refinement method
Rp/Rwp/Rexp
Rbrag
7
3
8601
Rietveld refinement
6.650%/9.678%/1.859%
4.781%
GOF
5.205
XAFS Measurement. X-ray absorption fine structure (XAFS)
spectra were collected in transmission mode at the Ge K-edge (11.103
KeV) over the energy range 10.900−11.900 KeV at the hard X-ray
microanalysis (HXMA) beamline of the Canadian Light Source
(
(
Saskatoon, SK, Canada). Powdered samples were measured using a Si
111) monochromator and a rhodium mirror. Samples were packed
into a kapton film pouch for measurements. A Ge standard (GeO-
ITQ-21) was measured simultaneously with each scan (transmission
mode) for the edge energy calibration. XAFS data analysis was
performed with the WinXAS 3.1 software package using a similar data
Figure 3. (a) Asymmetric unit of germanate GeO-JU90 (green, Ge;
26
reduction procedure as reported elsewhere. Theoretical phase and
red, O; gray, H). (b) Coordination environment of Ge cluster (green,
7
scattering amplitudes used for fitting experimental data were obtained
using the FEFF8.2 computational package. The model used to
Ge atoms in Ge cluster; violet, Ge atoms in GeO (OH) units; red, O;
gray, H).
7
3
27
D
dx.doi.org/10.1021/ic302705f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
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Figure 3b shows the coordination environment of the Ge7
cluster. Each Ge cluster connects with seven Ge-centered
7
tetrahedra, of which six are the additional GeO (OH) units and
3
one is a GeO tetrahedron that belongs to the adjacent Ge7
4
cluster. Such 7-connected Ge cluster has rarely been observed
7
in reported germanates, with the only example of germanate
3d
Ge O (OH)N C H containing 7-ring channels.
10
21
4
6
21
In the structure of GeO-JU90, the Ge cluster can be
7
simplified as a polyhedron with seven vertices corresponding to
four GeO tetrahedra, two GeO trigonal bipyramids, and one
4
5
GeO octahedra as shown in Figure 4a. Each of the two Ge7
6
Figure 5. (a) Experimental XAFS data of GeO-JU90 plotted in E
space. (b) Experimental FT-EXAFS (solid line) and best fit (open
circle) in R space. Fitting was done with a k range of 2.7−13.0 Å .
Figure 4. (a) Ge cluster consisting of one GeO octahedron (red),
7
6
two GeO trigonal bipyramids (yellow), and four GeO tetrahedra
5
4
−1
(
green). (b) Layer built of Ge7 clusters and extra tetrahedral
GeO (OH) units (violet). (c) Framework structure with a three-
3
dimensional channel system constructed by assembling the layers. (d)
Simplified topological view of the framework, Ge7 (green), two
GeO (OH) units (violet), and six GeO (OH) units (violet).
Table 3. EXAFS Fitting Results for GeO-ITQ-21 and GeO-
JU90 with a k Range of 2.7−13.0 Å−
1
3
3
2
2
sample
RGe−O(Å)
CN
σ (Å )
ΔEo
GeO-ITQ-21
GeO-JU90
1.739(5)
1.750(8)
4.0(1)
4.2(2)
0.0027(5)
0.0048(7)
−1(1)
−4(2)
clusters is directly connected by corner sharing to form a sort of
dimer as shown in Figure 4b. Such dimers are further
connected by additional GeO (OH) units to build up a layer.
The layers possessing 11-ring channels perpendicular to
3
confirming that only GeO tetrahedra exist in GeO-ITQ-21.
4
themselves (along the a axis) are further assembled via bridging
However, for GeO-JU90 sample, the first-shell contribution is
4.2(2) from O atoms at an average distance of 1.750(8) Å,
suggesting that other Ge-centered polyhedra, such as GeO5
GeO (OH) units to form the three-dimensional open-frame-
3
work germanate. A large pore space consisting of two 12-ring
channels perpendicular to the a axis is created between two
layers. Thus, the framework structure has an interconnected
three-dimensional channel system of 11 × 12 × 12-rings
trigonal bipyramids and GeO octahedra, may coexist with
6
GeO tetrahedra. The result is in agreement with the obtained
4
structure of GeO-JU90 containing one GeO , two GeO , four
6
5
(
Figure 4c).
GeO , and four GeO (OH) out of the 11 independent Ge
4 3
To simplify the structure, topology analysis was carried out
Figure 4d and Supporting Information, Table S1). The extra
atoms, with an average coordination number (CN) of Ge−O of
4.36 and average Ge−O distance of 1.7693 Å. The Debye−
(
2
tetrahedral GeO (OH) units complicated the connectivity of
Waller factor σ (evaluation of the ordering of Ge local
3
2
9
2
the Ge cluster. If the Ge cluster was chosen as the uninode, its
environment ) for GeO-ITQ-21 (0.0027(5) Å ) is smaller
7
7
2
connectivity could become 17. Thus, we decided to use three
different nodes representing Ge7 clusters (green), two
GeO (OH) units (violet), and six GeO (OH) units (violet).
than that of GeO-JU90 (0.0048(7) Å ), indicating that the local
structure around the Ge atoms in the GeO-JU90 framework is
more disordered than that of GeO-ITQ-21.
3
3
2
2
The net obtained has the point symbol of {3.4 .5 .6}-
SDA Molecules in the Channel. The lack of strong
interaction between the ogranic species and the framework
makes the organic species less ordered in the structure, which
introduces difficulty in solving their structure initially. Although
from synchrotron XRPD data the organic species was later
allocated by real-space method-simulated annealing, it is
necessary to confirm the result using other techniques.
Solid-state 13C MAS NMR spectroscopy was used to verify
the organic species. Due to the low resolution, only three broad
peaks (δ 17.1−27.3, 50.1, and 61.0−67.3) are present in the
spectrum (Supporting Information, Figure S2), which can be
interpreted as either the SDA molecule or the 1-methylpyr-
5
3
6
5 2 8
{
3.4 .5 .6 } {4 .5 .6 } and transitivity of [3 6 9 5]. After
2
simplification, it is clear that the Ge cluster connects to one of
7
the other Ge clusters directly and connects to as many as 16
7
clusters though the other nodes.
EXAFS Analysis. Ge K-edge EXAFS analysis was performed
to analyze the local structural information around the Ge
atoms. The resultant experimental spectrum and best fitting are
shown in Figure 5 and Table 3. GeO-ITQ-21 was selected as a
standard reference for the edge energy calibration. The fitting
result for GeO-ITQ-21 exhibits a first-shell contribution from
about 4.0(1) O atoms at an average distance of 1.739(5) Å,
E
dx.doi.org/10.1021/ic302705f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
1
3
odine molecule. Then liquid-state C NMR was carried out to
get a spectrum with higher resolution. The as-synthesized GeO-
JU90 compound was first dissolved in 5 M HF solution to
liberate the organic species, and then the solution was
neutralized by addition of 2 M sodium hydroxide solution
and further extracted with CH Cl . After evaporating the
from about 4.2(2) O atoms at the average distance of 1.750(8)
Å, which is in agreement with the obtained structure. The
framework structure consisting of 7-connected Ge clusters and
7
additional GeO (OH) units can be described as an assembly of
3
layers with intra 11-ring pores to form a three-dimensional
structure with intersecting 12 × 12 × 11-ring channels. The
organic species in the channel can be determined by the
simulated annealing method and was further confirmed by
NMR, IR, compositional analyses, and TG analysis. The SDA
molecules could not be removed from the channels while
keeping the framework intact. This work not only shows a
germanate with a novel structure and interesting channel
system but also demonstrates a powerful way for structure
solution of complex structures by combing XRPD with the
charge-flipping algorithm, simulated annealing, and EXAFS
characterization.
2
2
1
3
solvent, the liquid-state C NMR measurement was performed
on the residual solid dissolved in D O (0.5 mL). The resultant
C NMR spectrum (δ 23.5, 24.5, 25.1, 51.3, 66.1, and 67.5) is
identical to that of MPP(Br) in D O solution (δ 20.6, 23.8,
5.5, 50.7, 66.1, and 66.9) (Supporting Information, Figure S3),
suggesting that the MPP cations remain intact in the structure
of GeO-JU90.
Our structural analysis suggests that part of the SDA
molecules decompose to smaller species, i.e., NH4+ ions during
hydrothermal synthesis. The FTIR spectrum of GeO-JU90
2
1
3
2
2
2
2
+
(
Supporting Information, Figure S4) shows peaks at around
−1
+
3d
ASSOCIATED CONTENT
3
000 and 1470 cm which can be attributed to NH ions.
4
■
−
1
The absorption bands at 834, 785, and 736 cm can be
*
S
Supporting Information
SEM images, solid-state 13C MAS NMR spectra, liquid-state
assigned to asymmetric stretching vibrations of Ge−O bonds.
The peaks at 581 and 532 cm are attributed to the
symmetrical stretch of Ge−O bonds. A Ge−O bending
vibration is observed at 483 and 454 cm .
The number of SDA molecules and NH4 cations in the
structure was examined by compositional analyses. ICP analysis
gives the contents of Ge as 52.8 wt %, while elemental analyses
give the contents of C, H, and N as 12.27, 2.75, and 2.70 wt %,
respectively. These compositional analysis results are in
agreement with the empirical formula, |(C N H )(NH )|
−
1
13
C NMR spectra, IR spectrum, TG curves, in situ XRPD
patterns, and nets that describe the underlying topology of
GeO-JU-90. This material is available free of charge via the
Internet at http://pubs.acs.org.
−1
3d,30
+
AUTHOR INFORMATION
Corresponding Author
Phone: +86-431-85168608 (J.Y.); +4686747481 (J.S.); 001-
02-494 3323 (P.Z.). Fax: +86-431-85168608 (J.Y.); 001-902-
94 1310 (P.Z.). E-mail: jihong@jlu.edu.cn (J.Y.); junliang.
sun@pku.edu.cn (J.S.); peng.zhang@dal.ca (P.Z.).
Author Contributions
These authors contributed equally to this work
■
*
9
4
1
5
2
32
4
[
Ge O (OH) ], given by the crystal structure determined
11 21.5 4
from XRPD data (calculated value Ge, 54.37; C, 12.26; H, 2.74;
N, 2.86 wt %). The fact that the C/N ratio of 5.30 is
significantly lower than the C/N ratio of 7.5 for the
MPP(OH) molecule confirms the presence of NH4 cations
as additional counterions decomposed from MPP(OH) during
#
+
2
Author Contributions
2
hydrothermal synthesis.
The TG curve of GeO-JU90 (Supporting Information,
Figure S5) shows a weight loss of 1.9% between 25 and 165
This manuscript was written through contributions of all
authors. All authors have given approval to the final version of
the manuscript.
°
C, which corresponds to removal of the physically adsorbed
water molecules. The weight loss of 20.95% between 165 and
00 °C in the TG curve corresponds to release of NH3,
Notes
The authors declare no competing financial interest.
8
decomposition of SDA molecules, and loss of OH terminal
groups in the form of water molecules (calcd 20.04%). In situ
XRPD analysis indicates that the structure collapses at 300 °C
with decomposition of SDAs (Supporting Information, Figure
S6).
ACKNOWLEDGMENTS
■
This project was supported by the National Natural Science
Foundation of China and the State Basic Research Project of
China (Grant No. 2011CB808703). We also are thankful for
support from the Swedish Research Council (VR) and the
Swedish Governmental Agency for Innovation Systems
CONCLUSIONS
A novel three-dimensional open-framework germanate GeO-
JU90 has been hydrothermally prepared using 1,5-bis-
■
(
VINNOVA) through the Berzelii Center EXSELENT and
the Discovery Grant from NSERC Canada. We thank Beamline
I11 in Diamond Light Source, U.K., for XRPD data collection
and the Canadian Light Source for XAFS measurements. The
Canadian Light Source is financially supported by NSERC
Canada, CIHR, NRC, and the University of Saskatchewan.
Synchrotron technical support from Yang Xinxin at the
Shanghai Synchrotron Radiation Facility and Ning Chen at
the Canadian Light Source is also acknowledged.
(
methylpyrrolidinium)pentane dihydroxide as the structure-
directing agent in the concentrated gel system. The framework
structure of GeO-JU90 was solved from synchrotron XRPD
data using the charge-flipping algorithm. It reveals that the
structure contains 11 crystallographically independent Ge
atoms and 27 crystallographically independent O atoms,
which is one of the most complicated germanate structures.
The framework structure is built of 7-connected Ge clusters
7
REFERENCES
1) (a) Cheetham, A. K.; Fer
■
and additional GeO (OH) units forming a three-dimensional
3
(
1
́
ey, G.; Loiseau, T. Angew. Chem., Int. Ed.
interrupted open-framework with intersecting 12 × 12 × 11-
ring channels. The Ge K-edge EXAFS analysis provides the
local structural information around the Ge atoms in the
framework structure. It gives rise to the first-shell contribution
999, 38, 3268−3292. (b) Davis, M. E. Nature 2002, 417, 813−821.
(
c) Wang, Z.; Yu, J.; Xu, R. Chem. Soc. Rev. 2012, 41, 1729−1741.
(2) (a) Jiang, J.; Yu, J.; Corma, A. Angew. Chem., Int. Ed. 2010, 122,
3186−3212. (b) Yu, J.; Xu, R. Acc. Chem. Res. 2010, 43, 1195−1204.
F
dx.doi.org/10.1021/ic302705f | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
́
̃
(13) (a) Sun, J.; Bonneau, C.; Cantín, A.; Corma, A.; Díaz-Cabanas,
(
3) (a) Li, H.; Eddaoudi, M.; Richardson, D. A.; Yaghi, O. M. J. Am.
Chem. Soc. 1998, 120, 8567−8568. (b) Plevert, J.; Gentz, T. M.; Laine,
A.; Li, H.; Young, V. G.; Yaghi, O. M.; O’Keeffe, M. J. Am. Chem. Soc.
001, 123, 12706−12707. (c) Plevert, J.; Gentz, T. M.; Groy, T. L.;
O’Keeffe, M.; Yaghi, O. M. Chem. Mater. 2003, 15, 714−718.
d) Beitone, L.; Loiseau, T.; Ferey, G. Inorg. Chem. 2002, 41, 3962−
966. (e) Zhang, H.; Zhang, J.; Zheng, S.; Yang, G. Inorg. Chem. 2003,
́
M. J.; Moliner, M.; Zhang, D.; Li, M.; Zou, X. Nature 2009, 458,
1154−1157. (b) Gramm, F.; Baerlocher, C.; McCusker, L. B.;
Warrender, S. J.; Wright, P. A.; Han, B.; Hong, S. B.; Liu, Z.;
Ohsuna, T.; Terasaki, O. Nature 2006, 444, 79−81. (c) Xie, D.;
Baerlocher, C.; McCusker, L. J. Appl. Crystallogr. 2008, 41, 1115−
2
́
(
́
1
121. (d) Baerlocher, C.; Gramm, F.; Massu
He, Z.; Hovmoller, S.; Zou, X. Science 2007, 315, 1113−1116.
14) Inge, A. K.; Huang, S.; Chen, H.; Moraga, F.; Sun, J.; Zou, X.
Cryst. Growth Des. 2012, 12, 4853−4860.
15) Baerlocher, C.; McCusker, L.; Palatinus, L. Z. Kristallogr. 2007,
22, 47−53.
16) Kirkpatrick, S.; Gelatt, C. D., Jr.; Vecchi, M. P. Science 1983,
20, 671−680.
17) Corma, A.; Chica, A.; Guil, J. M.; Llopis, F. J.; Mabilon, G.;
Perdigon-Melon, J. A.; Valencia, S. J. Catal. 2000, 189, 382−394.
18) Zones, S. I.; Burton, A. W.; Lee, G. S.; Olmstead, M. M. J. Am.
Chem. Soc. 2007, 129, 9066−9079.
19) Corma, A.; Díaz-Cabanas, M. J.; Martínez-Triguero, J.; Rey, F.;
̈
ger, L.; McCusker, L. B.;
3
4
2
̈
2, 6595−6597. (f) Tang, L.; Dadachov, M. S.; Zou, X. Chem. Mater.
(
005, 17, 2530−2536. (g) Christensen, K. E.; Shi, L.; Conradsson, T.;
Ren, T.; Dadachov, M. S.; Zou, X. J. Am. Chem. Soc. 2006, 128,
(
2
(
2
1
4238−14239. (h) Shi, L.; Bonneau, C.; Li, Y.; Sun, J.; Yue, H.; Zou,
X. Cryst. Growth Des. 2008, 8, 3695−3699. (i) Guo, B.; Inge, A. K.;
Bonneau, C.; Sun, J.; Christensen, K. E.; Yuan, Z.; Zou, X. Inorg. Chem.
2
011, 50, 201−207. (j) Pan, Q.; Li, J.; Christensen, K. E.; Bonneau, C.;
(
Ren, X.; Shi, L.; Sun, J.; Zou, X.; Li, G.; Yu, J.; Xu, R. Angew. Chem., Int.
Ed. 2008, 47, 7868−7871. (k) Pan, Q.; Li, J.; Ren, X.; Wang, Z.; Li, G.;
Yu, J.; Xu, R. Chem. Mater. 2008, 20, 370−372. (l) Ren, X.; Li, Y.; Pan,
Q.; Yu, J.; Xu, R.; Xu, Y. J. Am. Chem. Soc. 2009, 131, 14128−14129.
́
́
(
(
̃
(
m) Su, J.; Wang, Y.; Wang, Z.; Liao, F.; Lin, J. Inorg. Chem. 2010, 49,
765−9769.
4) (a) Li, H.; Yaghi, O. M. J. Am. Chem. Soc. 1998, 120, 10569−
0570. (b) Conradsson, T.; Dadachov, M. S.; Zou, X. Microporous
Mesoporous Mater. 2000, 41, 183−191. (c) Medina, M. E.; Iglesias, M.;
Monge, M. A.; Gutierrez-Puebla, E. Chem. Commun. 2001, 2548−
549. (d) Villaescusa, L. A.; Lightfoot, P.; Morris, R. E. Chem.
Rius, J. Nature 2002, 418, 514−517.
(
(
9
(
1
20) Boultif, A.; Louer, D. J. Appl. Crystallogr. 2004, 37, 724−731.
21) Petricek, V.; Dusek, M.; Palatinus, L. JANA2006, a Crystallo-
graphic Computing System; Institute of Physics, Academy of Sciences of
the Czech Republic: Prague, Czech Republic, 2000.
́
(
22) Palatinus, L.; Chapuis, G. J. Appl. Crystallogr. 2007, 40, 786−
90.
23) van Smaalen, S.; Palatinus, L.; Schneider, M. Acta Crystallogr.
003, A59, 459−469.
24) Young, R. The Rietveld Method; Oxford University Press:
Oxford, 1993; pp 1−39.
25) Blatov, V. IUCr CompComm Newslett. 2006, 7, 4−38. TOPOS is
available at http://www.topos.ssu.samara.ru.
26) (a) MacDonald, M. A.; Zhang, P.; Qian, H.; Jin, R. J. Phys.
2
7
(
2
(
Commun. 2002, 2220−2221. (e) Villaescusa, L. A.; Wheatley, P. S.;
Morris, R. E.; Lightfoot, P. Dalton Trans. 2004, 820−824. (f) Xu, Y.;
Fan, W.; Chino, N.; Uehara, K.; Hikichi, S.; Mizuno, N.; Ogura, M.;
Okubo, T. Chem. Lett. 2004, 33, 74−75.
(
5) (a) Li, H.; Eddaoudi, M.; Yaghi, O. M. Angew. Chem., Int. Ed.
(
1
2
999, 38, 653−655. (b) Bu, X.; Feng, P.; Stucky, G. D. Chem. Mater.
000, 12, 1505−1507. (c) Sun, K.; Dadachov, M. S.; Conradsson, T.;
(
Zou, X. Acta Crystallogr., Sect. C 2000, 56, 1092−1094. (d) Zhou, Y.;
Zhu, H.; Chen, Z.; Chen, M.; Xu, Y.; Zhang, H.; Zhao, D. Angew.
Chem., Int. Ed. 2001, 40, 2166−2168. (e) Xu, Y.; Fan, W.; Elangovan,
S. P.; Ogura, M.; Okubo, T. Eur. J. Inorg. Chem. 2004, 4547−4549.
Chem. Lett. 2010, 1, 1821−1825. (b) MacDonald, M. A.; Zhang, P.;
Chen, N.; Qian, H.; Jin, R. J. Phys. Chem. C 2011, 115, 65−69.
(c) Padmos, J. D.; Zhang, P. J. Phys. Chem. C. 2012, 116, 23094−
23101.
(27) (a) Ankudinov, A. L.; Ravel, B.; Rehr, J. J.; Conradson, S. D.
Phys. Rev. B 1998, 58, 7565−7576. (b) Simms, G. A.; Padmos, J. D.;
Zhang, P. J. Chem. Phys. 2009, 131, 214703.
(
f) Medina, M. E.; Iglesias, M.; Snejko, N.; Gutier
́
rez-Puebla, E.;
Monge, M. A. Chem. Mater. 2004, 16, 594−599. (g) Attfield, M. P.; Al-
Ebini, Y.; Pritchard, R. G.; Andrews, E. M.; Charlesworth, R. J.; Hung,
W.; Masheder, B. J.; Royal, D. S. Chem. Mater. 2007, 19, 316−322.
(28) Haines, J.; Cambon, O.; Philippot, E.; Chapon, L.; Hull, S. J.
Solid State Chem. 2002, 166, 434−441.
(
2
h) Ren, T.; Xiao, P.; Xing, X.; Christensen, K. E. Cryst. Res. Technol.
010, 45, 1035−1040.
6) (a) Medina, M. E.; Gutier
(29) Sevillano, E.; Meuth, H.; Rehr, J. J. Phys. Rev. B 1979, 20, 4908−
(
́
rez-Puebla, E.; Monge, M. A.; Snejko,
4911.
N. Chem. Commun. 2004, 2868−2869. (b) Zou, X.; Conradsson, T.;
(30) (a) Tarte, P.; Pottier, M. J.; Proces, A. M. Spectrochim. Acta
1973, 29A, 1017−1027. (b) Paques-Ledent, M. Th. Spectrochim. Acta
Klingstedt, M.; Dadachov, M. S.; O’Keeffe, M. Nature 2005, 437, 716−
1
976, 32A, 383−395. (c) Conradsson, T.; Zou, X. D.; Dadachov, M. S.
7
19. (c) Christensen, K. E.; Bonneau, C.; Gustafsson, M.; Shi, L.; Sun,
Inorg. Chem. 2000, 39, 1716−1720.
J.; Grins, J.; Jansson, K.; Sbille, I.; Su, B.; Zou, X. J. Am. Chem. Soc.
2
008, 130, 3758−3759. (d) Inge, A. K.; Peskov, M. V.; Sun, J.; Zou, X.
Cryst. Growth Des. 2012, 12, 369−375. (e) Lorgouilloux, Y.; Paillaud,
J.-L.; Caullet, P.; Bats, N. Solid State Sci. 2008, 10, 12−19. (f) Bonneau,
́
C.; Sun, J.; Sanchez-Smith, R.; Guo, B.; Zhang, D.; Inge, A. K.; Eden,
M.; Zou, X. Inorg. Chem. 2009, 48, 9962−9964.
(
7) Lin, Z.; Zhang, J.; Zhao, J.; Zheng, S.; Pan, C.; Wang, G.; Yang, G.
Angew. Chem., Int. Ed. 2005, 44, 6881−6884.
(
8) Fer
́
ey, G. J. Solid State Chem. 2000, 152, 37−48.
(
9) (a) Higgins, J. B.; LaPierre, R. B.; Schlenker, J. L.; Rohrman, A.
C.; Wood, J. D.; Kerr, G. T.; Rohrbaugh, W. J. Zeolites 1988, 8, 446−
52. (b) Newsam, J. M.; Treacy, M. M. J.; Koetsier, W. T.; de Gruyter,
C. B. Proc. R. Soc. London 1988, A, 420, 375−405.
10) (a) Kokotailo, G. T.; Lawton, S. L.; Olson, D. H.; Meier, W. M.
4
(
Nature 1978, 272, 437−438. (b) Olson, D. H.; Kokotailo, G. T.;
Lawton, S. L.; Meier, W. M. J. Phys. Chem. 1981, 85, 2238−2243.
(
11) Jae, J.; Tompsett, G. A.; Foster, A. J.; Hammond, K. D.;
Auerbach, S. M.; Lobo, R. F.; Huber, G. W. J. Catal. 2011, 279, 257−
68.
12) Tom, W.; Sun, J.; Wan, W.; Oleynikov, P.; Zhang, D.; Zou, X.;
Moliner, M.; Gonzalez, J.; Martínez, C.; Rey, F.; Corma, A. Nat. Chem.
012, 4, 188−194.
2
(
2
G
dx.doi.org/10.1021/ic302705f | Inorg. Chem. XXXX, XXX, XXX−XXX