A new hexamolybdate-based coppera€“2,2a€2-biimidazole coordination polymer serving as an acid catalyst and support for enzyme immobilization

Article abstract of DOI:10.1107/S2053229618013037

The hydrothermal reaction of (NH₄)₃[CoMo₆O₂₄H₆]?·7H₂O (CoMo₆), CuCl₂?·2H₂O and 2,2a€2-biimidazole (H₂biim) led to the formation of a new coordination polymer, namely poly[diaquabis(2,2a€2-biimidazole)hexa-??₃-oxo-octa-??₂-oxo-hexaoxodicopper(II)hexamolybdate(VI)], [Cu₂Mo₆O₂₀(C₆H₆N₄)₂(H₂O)₂]_n (Cu-Mo₆O₂₀), at pH 2a€“3. It is obvious that in the formation of crystalline Cu-Mo₆O₂₀, the original Anderson-type skeleton of heteropolymolybdate CoMo₆ was broken and the new isopolyhexamolybdate Mo₆O₂₀ unit was assembled. In Cu-Mo₆O₂₀, one Mo₆O₂₀ unit connects four [Cu(H₂biim)(H₂O)]²⁺ ions in a pentacoordinate mode via four terminal O atoms, resulting in a tetra-supported structure, and each Cu^II ion is shared by two adjacent Mo₆O₂₀ units. Infinite one-dimensional chains are established by linkage between two adjacent Mo₆O₂₀ units and two Cu^II ions, and these chains are further packed into a three-dimensional framework by hydrogen bonds, ?€a€“?€ interactions and electrostatic attractions. The catalytic performance of this crystalline material used as an efficient and reusable heterogeneous acid catalyst for carbonyl-group protection is discussed. In addition, Cu-Mo₆O₂₀ was applied as a new support for enzyme (horseradish peroxidase, HRP) immobilization, forming immobilized enzyme HRP/Cu-Mo₆O₂₀. HRP/Cu-Mo₆O₂₀ showed good catalytic activity and could be reused.

Full text of DOI:10.1107/S2053229618013037

polyoxometalates
0
A new hexamolybdate-based copper–2,2 -bi-
imidazole coordination polymer serving as an acid
catalyst and support for enzyme immobilization
ISSN 2053-2296
Xiao-Jing Sang, Shu-Li Feng, Ying Lu, Yue-Xian Zhang, Fang Su, Lan-Cui Zhang* and
Zai-Ming Zhu*
Received 1 June 2018
School of Chemistry and Chemical Engineering, Liaoning Normal University, Huanghe Road 850, Dalian, Liaoning
Accepted 14 September 2018
116029, People’s Republic of China. *Correspondence e-mail: zhanglancui@lnnu.edu.cn, chemzhu@sina.com
Edited by J. R. Gal a´ n-Mascar o´ s, Institute of
Chemical Research of Catalonia (ICIQ), Spain
The hydrothermal reaction of (NH
0
0
polymer, namely poly[diaquabis(2,2 -biimidazole)hexa-ꢀ -oxo-octa-ꢀ -oxo-hexa-
3 2
)
[CoMo
O
H
]ꢀ7H
O (CoMo ), CuCl
6
ꢀ2H
O
2
4
3
6
24
6
2
2
and 2,2 -biimidazole (H biim) led to the formation of a new coordination
2
Keywords: isopolyoxometalate; coordination
polymer; acid catalyst; crystal structure; enzyme
immobilization; horseradish peroxidase; POM.
oxodicopper(II)hexamolybdate(VI)], [Cu Mo O (C H N ) (H O) ]
(Cu-
Mo O ), at pH 2–3. It is obvious that in the formation of crystalline Cu-
2
6
20
6
6
4 2
2
2 n
6
20
Mo O , the original Anderson-type skeleton of heteropolymolybdate CoMo
6
6
20
CCDC reference: 1838120
was broken and the new isopolyhexamolybdate Mo O unit was assembled. In
6
20
2
+
Supporting information: this article has
Cu-Mo
6
O
20, one Mo
6
O20 unit connects four [Cu(H biim)(H O)] ions in a
pentacoordinate mode via four terminal O atoms, resulting in a tetra-supported
2 2
supporting information at journals.iucr.org/c
II
structure, and each Cu ion is shared by two adjacent Mo O units. Infinite one-
6
20
dimensional chains are established by linkage between two adjacent Mo O units
6
20
II
and two Cu ions, and these chains are further packed into a three-dimensional
framework by hydrogen bonds, ꢁ–ꢁ interactions and electrostatic attractions. The
catalytic performance of this crystalline material used as an efficient and reusable
heterogeneous acid catalyst for carbonyl-group protection is discussed. In
addition, Cu-Mo O was applied as a new support for enzyme (horseradish
6
20
peroxidase, HRP) immobilization, forming immobilized enzyme HRP/Cu-
Mo O . HRP/Cu-Mo O showed good catalytic activity and could be reused.
6
20
6
20
1
. Introduction
Coordination polymers, as a type of special inorganic complex,
possess novel properties and have been used as catalysts,
support materials and optical and magnetism materials in
many fields (Wang et al., 2014; Sun et al., 2018; Cai et al., 2005;
Fedin et al., 2010). The introduction of nitrogen-containing
ligands can enhance the functions of polymers through the
construction of hydrogen-bond interactions with biological
molecules, such as proteins. In particular, polyoxometalates
(POMs), as polydentate oxygen-donor ligands with high
negative charge, can coordinate with transition metal (TM)
ions or TM-complex units under certain conditions, resulting
in many new structures. Furthermore, POM-based inorganic–
organic hybrid compounds have bifunctional effects, com-
bining organic and inorganic components; on the other hand,
POM anions can not just balance the positive charge of the
TM or TM-complex cations, but can also form hydrogen
bonding and covalent interactions with protein molecules via
exposed O atoms. Because of their diverse structures and
potential applications, POMs have attracted considerable
attention. The design and synthesis of POM-based TM-coor-
dination polymers is still a hot topic.
Enzymes that act as biological catalysts with advantages of
low pollution, high selectivity and high efficiency have been
#
2018 International Union of Crystallography
Acta Cryst. (2018). C74
https://doi.org/10.1107/S2053229618013037 1 of 8

polyoxometalates
ꢁ
1
loading (158.7 and 157.5 mg g ) and excellent reusability
Table 1
Experimental details.
were observed. Obviously, the H biim ligand plays an impor-
2
Crystal data
Chemical formula
tant role in the construction of these functional crystalline
materials. H biim has good biological activity (Zhang et al.,
[Cu
1327.07
Triclinic, P1
296
8.065 (3), 10.293 (4), 10.837 (4)
64.090 (5), 75.186 (5), 71.141 (5)
758.8 (5)
2 6 6 6 4 2 2 2
Mo O20(C H N ) (H O) ]
2
M
r
2011; Ye et al., 1999) and possesses four N atoms from two
Crystal system, space group
Temperature (K)
imidazole rings, so that it has a versatile coordination beha-
viour and forms multiple hydrogen bonds. Therefore, the
construction of its complexes was considered to be a tool for
˚
a, b, c (A)
ꢃ, ꢅ, ꢆ ( )
ꢂ
˚
3
V (A )
Z
Radiation type
1
crystal engineering (Tadokoro & Nakasuji, 2000). More
II
importantly, the combination of Cu –H biim cations and POM
Mo Kꢃ
3.87
0.09 ꢄ 0.07 ꢄ 0.06
ꢁ
1
2
ꢀ
Crystal size (mm)
(mm
)
anions can significantly decrease the solubility of the POM,
and such insolubility is a basic requirement for support
materials for enzyme immobilization. In order to construct
Data collection
Diffractometer
Bruker SMART CCD area
detector
Multi-scan (SADABS; Sheldrick,
other types of POM-based TM–H biim coordination polymers
2
Absorption correction
and explore their performance in immobilizing horseradish
peroxidase (HRP), in this work, we attempted to introduce the
2003)
Tmin, Tmax
0.724, 0.795
3875, 2639, 2409
II
Cu –H biim complex into the hexamolybdate (NH ) [Co-
No. of measured, independent and
observed [I > 2ꢇ(I)] reflections
2
4 3
Mo O H ]ꢀ7H O (CoMo ) system under hydrothermal
6
24
6
2
6
R
int
0.011
0.595
conditions. As a result, a new crystalline hexamolybdate-based
˚
ꢁ1
)
(sin ꢂ/ꢄ)max (A
II
Cu –H biim coordination polymer, [Cu Mo (C H N ) (-
2
2
6
6
6
4 2
Refinement
2
H O) O ] , denoted Cu-Mo O , was obtained unexpectedly,
20
2
2
20 n
6
2
2
R[F > 2ꢇ(F )], wR(F ), S
No. of reflections
0.018, 0.042, 1.06
2639
235
2
H atoms treated by a mixture of
independent and constrained
refinement
0.36, ꢁ0.49
and its acid catalytic activity for carbonyl-group protection and
its performance used as a support for HRP immobilization
have been investigated. In addition, the catalytic activity and
reusability of immobilized enzyme HRP/Cu-Mo O , serving
No. of parameters
No. of restraints
H-atom treatment
6
20
as a catalyst in the co-oxidation colour reaction of phenol and
4-aminoantipyrine (4-AAP) with H O , were also researched.
˚
ꢁ3
)
Áꢈmax, Áꢈmin (e A
2
2
Computer programs: SMART (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97
(Sheldrick, 2008), SHELXL2014 (Sheldrick, 2015) and SHELXTL (Sheldrick, 2008).
2
. Experimental
used for large-scale industrial production (DiCosimo et al.,
013; Kikukawa et al., 2018). Although free enzymes exhibit
All chemicals were purchased commercially and used without
2
further purification. (NH ) [CoMo O H ]ꢀ7H O was pre-
4
3
6
24
6
2
high activity as soluble homogeneous catalysts, they are
difficult to isolate from the reaction system, easy to deactivate
and require rigorous reaction conditions. Compared with free
enzymes, immobilized enzymes show high stability, insolubility
and easy separation, which allows them to be used repeatedly
in continuous production. Thus, it is still a long-term task to
develop environmentally friendly and biocompatible enzyme-
support materials with high loading, low cost and high stabi-
lities, including thermal, mechanical and chemical stabilities.
Most importantly, the insolubility of employed supports is vital
for the successful immobilization process. To our knowledge,
POMs have been studied and applied in protein crystallization
pared and characterized according to reported procedures
(Evans & Showell, 1969; Nomiya et al., 1987). HRP (isoen-
zyme C, product P105528, lot K1506050, E.C. 1.11.1.7,
ꢁ
1
300 U mg , R > 3.0, Mw ’ 40 kDa) and 4-AAP were
Z
purchased from Aladdin Biochem Technology Co. Ltd, China.
ꢁ
1
Phosphate buffer solutions (PBS) (0.1 mol l ) with different
pH (3.5–8.5) were prepared using Na HPO , NaH PO or
H PO . The mixture of HRP and Cu-Mo O was centrifuged
2
4
2
4
3
4
6
20
with a TG-16G model centrifuge to obtain immobilized
enzyme HRP/Cu-Mo O . C, H and N elemental analyses
6
20
were performed on a Vario Elcube elemental analyzer. Co, Cu
and Mo were analyzed on a Prodigy XP emission spectro-
ꢁ
1
(Molitor et al., 2016) and protein separation (Chen et al., 2015),
meter. IR spectra were recorded in the range 4000–400 cm
using KBr pellets with a Bruker TENSOR-27 FT–IR spec-
trometer. X-ray powder diffraction (XRPD) data were
but these applied POMs are all water soluble and no water-
insoluble solid POM example used as a support for enzyme
immobilization has been reported except in our recent work
ꢂ
obtained in the 2ꢂ range 5–60 on a Bruker D8 Advance
˚
(Du et al., 2017). Having stated the above, POM-based TM-
diffractometer using Cu Kꢃ radiation (ꢄ = 1.5418 A), with a
ꢂ
coordination polymers obtained by hydrothermal methods can
meet the above requirements and may become a new type of
immobilizing enzyme-support material.
step size of 0.02 . Single-crystal X-ray diffraction data were
collected on a Bruker SMART APEXIIX diffractometer
equipped with graphite-monochromated Mo Kꢃ radiation (ꢄ =
˚
0.71073 A). Thermal analysis (TG–DTA) was carried out on a
Pyris Diamond TG-DTA thermal analyzer in air at a heating
rate of 10 K min . The solid-state UV spectra were recorded
on a PerkinElmer Lambda 35 UV–Vis spectrophotometer.
Liquid UV–Vis absorption spectra were recorded on a
Recently, our group have synthesized two Preyssler-type
II
POM-based Cu –H biim (H biim is 2,2 -biimidazole) coordi-
0
2
2
ꢁ
1
nation polymers with high thermal stability and low solubility,
and firstly used them as supports for enzyme immobilization
Du et al., 2017). A high HRP (horseradish peroxidase)
(
ꢃ
0
2
of 8 Sang et al. Hexamolybdate-based copper–2,2 -biimidazole coordination polymer
Acta Cryst. (2018). C74

polyoxometalates
Lambda 35 UV–Vis spectrophotometer. Circular dichroism
CD) spectra in the wavelength range 190–250 nm were
3.5–8.5) containing different concentrations of HRP. The
mixture was then stirred gently at room temperature, resulting
in a suspension. The suspension was centrifuged, the super-
natant liquid was slowly drawn off and the UV–Vis absor-
bance was measured at ꢄ = 403 nm; meanwhile, the resulting
precipitate was collected and rinsed three times with PBS to
remove nonspecifically adsorbed enzyme, resulting in the
immobilized enzyme, i.e. HRP/Cu-Mo O .
(
obtained on a MOS-500 automatic recording spectro-
polarimeter (Bio Logic, France) at room temperature using a
ꢁ
1
mm cell with a scan rate of 1.0 s nm . The product of the
2
acid-catalyzed reaction was confirmed on a JK-GC112A gas
chromatograph.
6
20
2
.1. Synthesis and crystallization
The Worthington method (Nicell & Wright, 1997; Zhou et
al., 2016; Du et al., 2017) was used to test the activity of the
immobilized HRP, that is, the catalytic activity of the immo-
bilized enzyme HRP/Cu-Mo O was evaluated by co-oxida-
A mixture of (NH ) [CoMo O H ]ꢀ7H O (0.482 g, 0.4 mmol),
4
3
6
24
6
2
H biim (0.054 g, 0.4 mmol) and CuCl ꢀ2H O (0.068 g,
2
2
2
0.4 mmol) in deionized water (20 ml) was adjusted to pH 2–3
6
20
ꢁ
1
tion colour reaction of phenol and 4-AAP with H O (Fig. S1
2 2
with 0.5 mol l HCl and then transferred to a 25 ml Teflon-
lined autoclave and kept at 393 K for 3 d. Dark-green crystals
of Cu-Mo O (yield 58%, based on Mo) suitable for X-ray
diffraction analysis were obtained after cooling to room
temperature and filtering. Analysis calculated for C H N -
Cu Mo O : C 10.86, H 1.22, N 8.45, Cu 9.58, Mo 43.38%;
in the supporting information). The experimental procedure
was as follows: solution A was prepared using 1.4 ml of
6
20
ꢁ ꢁ1
1
0.1 mol l PBS (pH 3.5–8.5) containing 172 mmol l phenol
and 2.46 mmol l 4-AAP, and was mixed with solution B
ꢁ
1
12
16
8
ꢁ
1
consisting of 2 mmol l H O in 1.5 ml of 0.1 mol l PBS,
ꢁ1
2
2
2
6
22
and HRP/Cu-Mo O (5.0 mg) was added to the reaction
6
found: C 11.02, H 1.31, N 8.55, Cu 9.64, Mo 43.43%. IR (KBr,
20
ꢁ1
mixture. The mixture was then centrifuged for 5 min at room
temperature in a centrifuge tube. The rate of red product
formation was proportional to the activity of immobilized
HRP in the test. It can thus be monitored spectrophoto-
metrically by tracing the formation of red product at ꢄ =
cm ): 3443 (m), 3299 (m), 3132 (w), 2923 (w), 1632 (w), 1530
w), 1428 (w), 1380 (w), 1182 (w), 1085 (w), 941 (m), 903 (vs),
32 (s), 592 (s).
(
7
2.2. Structure determination and refinement
ꢁ
1 ꢁ1
s ) was calculated to
catalyst
524 nm. TOF (molproduct mol
Crystal data, data collection and structure refinement
details are summarized in Table 1. Water H atoms were found
according to the residual electron-density peaks around the
determine the activity of the immobilized and free HRP.
attached water O atom, with the O—H distances restrained to
˚
3
. Results and discussion
0.85 (1) A. The remaining H atoms were positioned in
geometrically idealized positions and constrained to ride on
3.1. Synthesis
˚
their parent atoms, with C—H = 0.93 A and N—H = 0.86 A
˚
The heptamolydate (NH ) [Mo O ]ꢀ4H O and simple
4
6
7
24
2
(
H biim), and with U (H) = 1.2U (C,N).
2
inorganic salt Na MoO were both used as the starting
2 4
iso
eq
material and, unfortunately, no crystalline material was
obtained. In contrast, Cu-Mo O was successfully synthesized
2.3. Acid-catalyzed synthesis of cyclohexanone ethylene
6
20
ketal
when (NH ) [CoMo O H ]ꢀ7H O was used as the precursor.
4
3
6
24
6
2
Meanwhile, the elemental analysis results for Co, Cu and Mo
showed that there was no Co in the crystalline sample of
C H N Cu Mo O and the found contents of Cu (9.64%)
One of the most common methods for protecting carbonyl
groups is the condensation of aldehydes or ketones with
alcohols. Selecting the acid-catalyzed synthesis of cyclohexa-
none ethylene ketal from cyclohexanone and glycol in cyclo-
hexane as a model reaction (Greene & Wuts, 1999; Tao et al.,
12 16
8
2
6
22
and Mo (43.43%) were consistent with their calculated values
Cu 9.58% and Mo 43.38%). While no Co was found, this
further proved that the Co centre in the original precursor
Anderson-type CoMo heteropolymolybdate was lost. And
(
2012), the catalytic activity of Cu-Mo O was evaluated. The
6 20
specific experimental process referred to published methods
Li et al., 2014; Liu et al., 2010) and heterogeneous catalyst Cu-
Mo O was easily separated from the organic phase
6
the formation of the isopolyhexamolybdate Mo O unit may
6 20
(
be caused by fragmentation of the skeleton of the CoMo6
6
20
precursor and reassembly of the anion fragment.
containing the product by decantation after reaction. The
catalyst was recovered and reused in a new reaction under
identical experimental conditions by washing with diethyl
ether or acetone.
3.2. Structure analysis
Single-crystal X-ray diffraction analysis reveals that the
asymmetric unit of Cu-Mo O consists of half an [Mo O ]
4ꢁ
6
20
6
20
2.4. Immobilization of enzyme and activity test of immobi-
2+
isopolyanion and one [Cu(H biim)(H O)] coordination
2
2
lized HRP
II
cation composed of one Cu ion, one H biim ligand and one
2
According to literature methods (Lin et al., 2011; Du et al.,
017) and selecting HRP as a model enzyme, the typical
coordinated H O molecule (Fig. 1). The geometry of
2
4
ꢁ
[Mo O ] is obviously quite different from those of other
6 20
2
procedure for preparing Cu-Mo O immobilized HRP
through direct adsorption was as follows: 5.0 mg of ground Cu-
isopolyhexamolybdate anions, such as the famous Lindqvist-
6
20
2
ꢁ 6ꢁ
type POMs [Mo O ] , [Mo O ] , [Mo O ] etc. (Vila-
6 19 6 21 6
8ꢁ
22
ꢁ1
Mo O powder was added to 500 ml of 0.1 mol l PBS (pH
Nadal et al., 2011; Naruke & Yamase, 2005; Takara et al., 1997;
6
20
ꢃ
0
Acta Cryst. (2018). C74
Sang et al.
Hexamolybdate-based copper–2,2 -biimidazole coordination polymer 3 of 8

polyoxometalates
II
Mo3, respectively. In Cu-Mo O , each Cu ion adopts a
6
20
slightly distorted five-coordinated square-pyramidal geometry
CuN O ) by bonding to two N atoms (N1 and N2) from one
(
H biim ligand, two terminal O atoms [O3 and O8; symmetry
2
3
ii
2
4
ꢁ
code: (ii) ꢁx + 1, ꢁy + 1, ꢁz] from two [Mo O ] isopo-
6
20
lyanions, and one O atom from a water molecule (O1W)
(Fig. 2b). The two Cu1—N bond lengths are 2.021 (3) and
ii
.968 (3) A, and the Cu1—O3 and Cu1—O8 bond lengths are
˚
1
˚
.965 (2) and 2.305 (2) A, respectively. The Cu1—O1W bond
1
length is 1.944 (3) A. Each [Mo O ] unit, acting as a
4
ꢁ
˚
6
20
II
tetradentate ligand, coordinates with four Cu ions through
four terminal O atoms, and further connects to other
4
ꢁ
Mo O ] units one-by-one through edge-sharing O atoms
6 20
[
ii
(triply-bridging atoms O2 and O2 ) between two MoO
octahedra belonging to two different [Mo O ]
6
4ꢁ
units,
forming infinite one-dimensional (1D) zigzag isopolyanion
6
20
Figure 1
The asymmetric unit of the title compound, shown with 50% probability
displacement ellipsoids. All H atoms have been omitted for clarity.
chains (Fig. 2c), and further packing into a three-dimensional
II
(3D) structure (Fig. 2d). As seen from Fig. 2(c), each Cu –
[Symmetry codes: (i) ꢁx + 2, ꢁy + 1, ꢁz; (ii) ꢁx + 1, ꢁy + 1, ꢁz; (iii) x + 1,
4ꢁ
y, z.]
H biim/H O cation links two [Mo O ] isopolyanions, and
20
2
2
6
these complex cations are appended on both sides of the
isopolyanion chain, which strengthens the infinite 1D isopo-
lyanion chain. In the 3D structure, the parallel 1D chains
construct two-dimensional (2D) planes through hydrogen
bonds (Figs. 3a and 3c). In addition, each pair of antiparallel
neighbouring 1D chains in different 2D planes are connected
by face-to-face ꢁ–ꢁ stacking interactions, with the centroid–
4
ꢁ
Qiao et al., 2010), and [Mo O ] is built from six MoO6
6
20
octahedra that can be divided into two groups. Each group is
constructed by edge-sharing MoO octahedra between Mo2/
6
i
Mo2 and Mo3/Mo3 , and face-sharing MoO octahedra
i
6
i
between Mo1/Mo1 and Mo3/Mo3 [symmetry code: (i) –x + 2,
i
ꢁ
y + 1, ꢁz], and the two groups are connected by edge-
˚
sharing and corner-sharing O atoms (Fig. 2a). As shown in
centroid distances being 3.680 A between the imidazole rings
v
i
Fig. 2(a), there exist four triply-bridging O atoms (O6, O6 , O9
vi
R (N2/C2/N4/C6/C5) and R (C4/C3/N1/C1/N3) , and R
1 2 3
i
and O9 ) shared by three MoO octahedra belonging to Mo1/
v
vi
(N3/C1/N1/C3/C4) and R (N2/C2/N4/C6/C5) [symmetry
6
4
i
Mo2 /Mo3, Mo1 /Mo2/Mo3 , Mo1/Mo1 /Mo3 and Mo1/Mo1 /
i
i
i
i
i
codes: (v) x ꢁ 3, y + 1, z; (vi) ꢁx ꢁ 1, ꢁy + 1, ꢁz + 1], together
Figure 2
The crystal structure of Cu-Mo
II
20, showing (a) the crystal structure of the isopolyhexamolybdate anion, (b) the fragment formed by Cu ions and a
6
O
4
–
6 20
[Mo O ] isopolyanion, (c) a 1D chain and (d) a 3D framework generated by infinite 1D zigzag chains. All H atoms have been omitted for clarity.
[Symmetry code: (i) ꢁx + 2, ꢁy + 1, ꢁz.]
ꢃ
0
4
of 8 Sang et al. Hexamolybdate-based copper–2,2 -biimidazole coordination polymer
Acta Cryst. (2018). C74

polyoxometalates
with hydrogen bonds and static electrostatic attractions among
the POM anions and complex cations, generating 2D coordi-
nation polymer layers (Figs. 3b and 3d) in another direction,
and are further alternately packed into a 3D supramolecular
framework (Fig. 2d). In Cu-Mo O , there are two kinds of
Table 2
Hydrogen-bond geometry (A, ).
˚
ꢂ
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
vii
vii
vii
N3—H3Bꢀ ꢀ ꢀO9
N4—H4Bꢀ ꢀ ꢀO8
N4—H4Bꢀ ꢀ ꢀO6
0.86
0.86
0.86
0.85 (1)
0.85 (1)
2.47
2.05
2.41
1.81 (1)
1.97 (1)
3.303 (4)
2.834 (4)
3.013 (4)
2.654 (3)
2.809 (3)
164
151
128
174 (4)
170 (4)
6
2
˚
hydrogen bonds, i.e. N—Hꢀ ꢀ ꢀO [2.834 (4)–3.303 (4) A] and
viii
˚
O1W—H1WAꢀ ꢀ ꢀO4
OW—Hꢀ ꢀ ꢀO [2.654 (3) and 2.809 (3) A] (Figs. 3c and 3d, and
iv
O1W—H1WBꢀ ꢀ ꢀO7
Table 2).
Symmetry codes: (iv) x ꢁ 1; y; z; (vii) ꢁx þ 2; ꢁy; ꢁz þ 1; (viii) ꢁx þ 2; ꢁy; ꢁz.
3.3. Characterization
The characteristic peaks of the polyoxoanion at 941, 903
ꢁ
crystalline phase purity for Cu-Mo O20. The differences in
6
1
and 732 cm in the IR spectrum of Cu-Mo O (Fig. S2 in the
intensity may be due to the preferred orientation of the
crystalline powder samples. The TG–DTA curve from room
temperature to 1273 K of Cu-Mo O is given in Fig. S4 of the
6
20
supporting information) belong to Mo Oterminal and Mo—
Obridging vibrations, respectively (Li et al., 2005; Haso et al.,
6
20
ꢁ
1
2
014), and the bands at 3443–2923 cm are assigned to
characteristic vibrations of O—H, N—H and C—H. The bands
supporting information, which shows that at 303–953 K, the
total weight loss of 23.6% (calculated 22.9%) is consistent with
the removal of two H biim ligands and two water molecules.
ꢁ
1
in the region 1632–1085 cm are associated with the imida-
2
zole ring of H biim. The computer-simulated and experi-
2
An obvious exothermal peak at 706 K is assigned to
combustion of the H biim organic fragments. In the range
2
mental XRPD patterns are illustrated in Fig. S3 of the
supporting information, which shows that all major peaks are
in good agreement with each other, indicating a reasonable
706–953 K, there is no further weight loss, indicating that the
polyanion skeleton of Cu-Mo O is retained.
6
20
Figure 3
The hydrogen bonds and ꢁ–ꢁ interactions in Cu-Mo
b)/(d) the 2D planes consisting of antiparallel neighbouring 1D chains connected by face-to-face ꢁ–ꢁ stacking interactions and hydrogen bonds.
Hydrogen bonds and ꢁ–ꢁ interactions are drawn as dotted and dashed lines, respectively. [Symmetry codes: (iv) x ꢁ 1, y, z; (vii) ꢁx + 2, ꢁy, ꢁz + 1; (viii)
x + 2, ꢁy, ꢁz.]
6
O20, showing (a)/(c) the 2D planes constructed by parallel 1D chains through hydrogen bonds and
(
ꢁ
ꢃ
0
Acta Cryst. (2018). C74
Sang et al.
Hexamolybdate-based copper–2,2 -biimidazole coordination polymer 5 of 8

polyoxometalates
supporting information). The optimal conditions determined
from Figs. S5(a–c) are as follows: a reaction time of 4 h, a
ketone/alcohol ratio of 1:1.4 and a catalyst (based on Mo)/
cyclohexanone molar ratio of 1/200. Under the optimal
conditions, a 92% conversion of cyclohexanone is obtained
using 10 ml of cyclohexane as the water-carrying agent at
II
reflux temperature. In light of the Cu ion being a good and
homogeneous Lewis acid for the catalytic reaction (Wang et
II
al., 2014), the introduction of Cu into the POM skeleton with
the aid of an organic ligand can play an important role in the
catalytic reaction. Meanwhile, the catalyst Cu-Mo O can be
6
20
recycled because of its insolubility and its acid catalytic
activity is almost unchanged after three cycles (Fig. S6 in the
supporting information). Additionally, the acid dissociation of
the water molecule that coordinates to the Cu cation was
considered to be the other part contributing to the catalytic
Figure 4
Enzyme loading (curve a) and immobilized enzyme activity (curve b) for
Cu-Mo O20 at different pH values.
6
II
activity. Furthermore, the skeleton structure of Cu-Mo O
6
20
3
.4. Acid catalytic activity of Cu-Mo O20
6
may lead to the pseudo-liquid phase feature (a very remark-
able property of heteropoly acids when they are used as solid
catalysts is the formation of a ‘pseudoliquid phase’; Lee et al.,
1992), which can improve the acid strength of the compound.
The above results illustrate that Cu-Mo O is fairly stable and
As we know, protection of carbonyl groups as acetals or
ketals under acid catalysis is an important strategy during
multiple organic reactions (Greene & Wuts, 1999). The
commonly used catalysts are traditional protonic acids, e.g.
anhydrous HCl, H SO etc., or Lewis acids, such as the simple
6
20
2
4
its main skeleton is retained before and after reaction, which
can be further proved by powder X-ray diffraction (XRPD)
(Fig. S7 in the supporting information).
metal salts FeCl and CuCl . These acids cannot be reused or
3
2
recycled and can produce large amounts of waste and pollu-
tion, in particular, HCl or H SO may cause serious corrosion
2
4
of equipment. Thus, development of more efficient, recyclable
and environmental pollution-free catalysts is a long-term goal
(Tao et al., 2012; Liu et al., 2010). In our previous work, we
reported the good acid catalytic performances of inorganic–
organic hybrid materials constructed from Strandberg-type
inorganic anions {P Mo } (Li et al., 2014) and Strandberg-type
2
5
organophosphomolybdate clusters {(C H PO ) Mo } (Wang et
6
5
3 2
5
3
.5. Factors affecting HRP loading on Cu-Mo O and the
6 20
al., 2014). Herein, the acid catalytic activity of Cu-Mo O
6
20
II
activity of HRP/Cu-Mo O
6
20
based on isopolyoxometalate and Cu complex units was
evaluated by the synthesis of cyclohexanone ethylene ketal,
and the chemical equation of the catalytic reaction is shown in
Scheme 1. The effect of the reaction factors, including reaction
time, reactant molar ratio and dosage of catalyst, on the
conversion of cyclohexanone has been discussed (Fig. S5 in the
The influence of pH, concentration of HRP solution and
immobilized time on enzyme loading were studied (Figs. 4
and 5). From a comprehensive consideration of enzyme
loading (curve a in Fig. 4) and immobilized enzyme activity
(curve b in Fig. 4), an optimal pH of 7.5 for HRP immobili-
Figure 5
The influences of (a) concentration of HRP solution and (b) immobilized time on enzyme loading at pH 7.5 at room temperature. The concentration of
ꢁ
1
HRP solution for (a) was 3.1 mg ml and the immobilized time for (b) was 10 h.
ꢃ
0
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of 8 Sang et al. Hexamolybdate-based copper–2,2 -biimidazole coordination polymer
Acta Cryst. (2018). C74

polyoxometalates
S10 in the supporting information for Cu-Mo O and HRP/
6
20
Cu-Mo O , respectively, the IR characteristic peaks are
6
20
basically the same, and the main diffraction peaks are
consistent, indicating that the structural skeleton of Cu-
Mo O is retained, also reflecting that HRP is only adsorbed
6
20
on the surface of Cu-Mo O , and does not enter into the
6
20
crystal lattices of the support. In order to evaluate the effect of
Cu-Mo O on the secondary structure of HRP, the CD
6
20
spectra of the free HRP solution and the eluting HRP
desorbed from HRP/Cu-Mo O were recorded (Fig. S11 in
6
20
the supporting information), where the curve profiles coincide
well with each other for free and desorbed HRP, showing that
the secondary structure of the enzyme is retained.
Moreover, the satisfying catalytic activity of HRP/Cu-
Mo O is still retained after eight catalytic cycles (Fig. 6), and
Figure 6
The relative activity of HRP/Cu-Mo
6
20
6
O
20 after being used eight times.
the activity decrease may be caused by some HRP leaching
during repeated washing and prolonged exposure to high
concentrations of substrate (Qiu et al., 2010). Compared with
the reported immobilized HRP by pore adsorption (Zhou et
al., 2013), HRP/Cu-Mo O possesses better reusability.
zation was confirmed. As can be seen from Figs. 5(a) and 5(b),
the HRP concentration and immobilization time are
ꢁ
1
.1 mg ml and 10 h, respectively. Under these optimum
6
20
3
conditions, the amount of immobilized HRP reached a
Meanwhile, HRP/Cu-Mo O is also a potential material for
6
20
ꢁ
6
ꢁ1
H O detection, and the linear range is from 2.35 ꢄ 10 to
2
2
maximum of 300.1 mg g , which can be calculated from the
ꢁ
ꢁ4 ꢁ1
1
4.0 ꢄ 10
mol l (Fig. 7). Additionally, to exclude the
possibility for peroxidase activity of the carrier itself, i.e. pure
Cu-Mo O without any HRP was selected as a catalyst for the
equation: HRP loading (mg g ) = (c ꢁ c)V/W (Chao et al.,
o
s
2013) and the standard curve of HRP (Fig. S8 in the
supporting information). The maximum of HRP loading on
6
20
ꢁ
1
Cu-Mo O (300.1 mg g ) is significantly higher than those on
same co-oxidation colour reaction of phenol and 4-AAP with
H O to obtain a blank value, the result showing that carrier
6
20
II
our reported Preyssler-type POM-based Cu coordination
2
2
ꢁ
1
Cu-Mo O has little effect on the catalytic reaction under
6 20
polymers (158.7 and 157.5 mg g ; Du et al., 2017), but a
longer immobilization time was needed for Cu-Mo O . In
addition, compared with other organically functionalized
identical reaction conditions. It was found that the red colour
of the reaction solution will appear slowly after a long time
(about 10 h).
6
20
ꢁ
1
supports, such as mesoporous organosilica (126 mg g ) and
ꢁ
1
modified chitosan (82.66 mg g ) (Zhou et al., 2013; Monier et
al., 2010), Cu-Mo O also has a higher loading capacity for
HRP. Moreover, the structure of Cu-Mo O is unchanged
6
20
4
. Conclusion
6
20
before and after immobilizing HRP. As shown in Figs. S9 and
The new isopolyhexamolybdate-based crystalline material Cu-
Mo O was successfully synthesized from the Anderson-type
cobalt hexamolybdate CoMo under hydrothermal conditions.
6
20
6
II
Cu-Mo O is a Cu coordination polymer with a 3D structure
6
20
composed of unbounded 1D chains which were constructed by
4
ꢁ
Mo O ] isopolyanions and [Cu(H biim)(H O)] complex
6 20 2 2
2+
[
cations. Cu-Mo O has good acid catalytic activity towards
6
20
ketalation of cyclohexanone with glycol and it also exhibits a
stronger adsorbtion ability towards HRP than our previously
II
reported two cases of Preyssler-type POM-based Cu –H biim/
2
H O coordination polymers and some other inorganic–organic
2
hybrid compounds, and the maximum immobilized HRP
ꢁ
1
loading reaches 300.1 mg g . The immobilized enzyme HRP/
Cu-Mo O is stable and can be reused in catalytic processes.
6
20
Moreover, HRP/Cu-Mo O can be applied to detect trace
20
6
amounts of H O with a linear response ranging from 2.35 ꢄ
2
2
ꢁ6
ꢁ4
ꢁ1
10
to 4.0 ꢄ 10 mol l .
Figure 7
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2
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A(blank, ꢄ = 524 nm). The reaction time was 5 min. Pure Cu-Mo
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1
(
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6 20
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of 8 Sang et al. Hexamolybdate-based copper–2,2 -biimidazole coordination polymer
Acta Cryst. (2018). C74

supporting information
supporting information
Acta Cryst. (2018). C74 [https://doi.org/10.1107/S2053229618013037]
A new hexamolybdate-based copper–2,2′-biimidazole coordination polymer
serving as an acid catalyst and support for enzyme immobilization
Xiao-Jing Sang, Shu-Li Feng, Ying Lu, Yue-Xian Zhang, Fang Su, Lan-Cui Zhang and Zai-Ming
Zhu
Computing details
Data collection: SMART (Bruker, 2005); cell refinement: SMART (Bruker, 2005); data reduction: SAINT (Bruker, 2005);
program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014
(Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication:
SHELXTL (Sheldrick, 2008).
(I)
Crystal data
Cu Mo
= 1327.07
Triclinic, P1
[
M
2
6
O
20(C
6 6 4 2 2 2
H N ) (H O) ]
Z = 1
F(000) = 630
D = 2.904 Mg m
x
r
−3
a = 8.065 (3) Å
b = 10.293 (4) Å
c = 10.837 (4) Å
α = 64.090 (5)°
β = 75.186 (5)°
γ = 71.141 (5)°
Mo Kα radiation, λ = 0.71073 Å
Cell parameters from 2954 reflections
θ = 2.1–31.0°
µ = 3.87 mm
T = 296 K
−1
Block, green
0.09 × 0.07 × 0.06 mm
3
V = 758.8 (5) Å
Data collection
Bruker SMART CCD area detector
diffractometer
2639 independent reflections
2409 reflections with I > 2σ(I)
phi and ω scans
R
int = 0.011
Absorption correction: multi-scan
θmax = 25.0°, θmin = 2.1°
(
SADABS; Sheldrick, 2003)
h = −9→9
k = −12→5
l = −12→11
T
3
min = 0.724, Tmax = 0.795
875 measured reflections
Refinement
2
Refinement on F
Hydrogen site location: mixed
Least-squares matrix: full
H atoms treated by a mixture of independent
and constrained refinement
2
2
R[F > 2σ(F )] = 0.018
2
2
2
2
wR(F ) = 0.042
w = 1/[σ (F
o
) + (0.0182P) + 0.8925P]
2
2
S = 1.06
where P = (F
o
+ 2F )/3
c
2
2
2
639 reflections
35 parameters
restraints
(Δ/σ)max = 0.002
Δρmax = 0.36 e Å
Δρmin = −0.49 e Å
−
3
−
3
Acta Cryst. (2018). C74
sup-1

supporting information
Extinction correction: SHELXL2014
Sheldrick, 2015),
(
*
2
3
-1/4
Fc =kFc[1+0.001xFc λ /sin(2θ)]
Extinction coefficient: 0.00089 (19)
Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance
matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles;
correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate
(isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
2
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å )
x
y
z
Uiso*/Ueq
Mo1
Mo2
Mo3
Cu1
O1
O2
O3
O4
O5
O6
O7
O8
O9
O10
N1
N2
N3
H3B
N4
H4B
C1
C2
C3
H3A
C4
H4A
C5
H5A
C6
H6A
O1W
H1WA
H1WB
0.98397 (3)
0.60552 (3)
1.36521 (3)
0.74909 (5)
0.8072 (3)
0.4604 (3)
0.4304 (3)
1.1704 (3)
0.7053 (3)
1.2507 (3)
1.5341 (3)
0.9664 (3)
0.9035 (3)
1.3870 (3)
0.9166 (4)
0.7007 (4)
1.0422 (4)
1.0674
0.7703 (4)
0.8209
0.9213 (4)
0.8025 (4)
1.0407 (5)
1.0670
1.1183 (5)
1.2061
0.5996 (5)
0.5169
0.33719 (3)
0.61615 (3)
0.35113 (3)
0.03949 (4)
0.3884 (2)
0.4673 (2)
0.7745 (2)
0.2611 (2)
0.6093 (3)
0.3138 (2)
0.1920 (3)
0.1694 (2)
0.4712 (2)
0.4373 (3)
−0.1542 (3)
0.0549 (3)
−0.2950 (3)
−0.3268
−0.0341 (4)
−0.0913
−0.1711 (4)
−0.0553 (4)
−0.2745 (4)
−0.2928
−0.3617 (4)
−0.4497
0.1512 (4)
0.2391
0.03177 (3)
−0.14598 (3)
−0.13694 (3)
0.26078 (4)
−0.0564 (2)
−0.0845 (2)
−0.1873 (2)
−0.0937 (2)
−0.3023 (2)
0.0931 (2)
−0.1027 (2)
0.1693 (2)
0.1197 (2)
−0.3123 (2)
0.3601 (3)
0.4419 (3)
0.5499 (3)
0.6323
0.6520 (3)
0.7249
0.4888 (3)
0.5341 (3)
0.3394 (4)
0.2589
0.4566 (4)
0.4707
0.5058 (4)
0.4661
0.01070 (8)
0.01038 (8)
0.01252 (8)
0.01640 (10)
0.0153 (5)
0.0130 (5)
0.0171 (5)
0.0160 (5)
0.0205 (5)
0.0139 (5)
0.0221 (5)
0.0179 (5)
0.0137 (5)
0.0261 (6)
0.0219 (6)
0.0208 (6)
0.0255 (7)
0.031*
0.0277 (7)
0.033*
0.0193 (7)
0.0188 (7)
0.0294 (9)
0.035*
0.0315 (9)
0.038*
0.0259 (8)
0.031*
0.6412 (5)
0.5920
0.7698 (4)
0.795 (5)
0.689 (4)
0.0962 (4)
0.1384
0.0086 (3)
−0.076 (2)
0.066 (4)
0.6357 (4)
0.7013
0.0923 (3)
0.088 (4)
0.0306 (9)
0.037*
0.0286 (6)
0.031 (11)*
0.034 (12)*
0.042 (4)
Acta Cryst. (2018). C74
sup-2

supporting information
2
Atomic displacement parameters (Å )
11
22
33
12
13
23
U
U
U
U
U
U
Mo1
Mo2
Mo3
Cu1
O1
O2
O3
O4
O5
O6
O7
O8
O9
O10
N1
N2
N3
N4
0.00964 (14)
0.01055 (14)
0.01202 (14)
0.0205 (2)
0.0134 (11)
0.0120 (11)
0.0161 (12)
0.0148 (11)
0.0213 (12)
0.0132 (11)
0.0199 (13)
0.0186 (12)
0.0130 (11)
0.0269 (14)
0.0239 (15)
0.0228 (15)
0.0262 (16)
0.0320 (17)
0.0201 (17)
0.0202 (17)
0.033 (2)
0.00824 (14)
0.00962 (14)
0.01383 (15)
0.0121 (2)
0.0148 (11)
0.0151 (11)
0.0150 (12)
0.0154 (12)
0.0219 (13)
0.0125 (11)
0.0208 (13)
0.0111 (11)
0.0122 (11)
0.0349 (15)
0.0169 (15)
0.0196 (15)
0.0206 (16)
0.0306 (18)
0.0138 (17)
0.0172 (17)
0.021 (2)
0.01472 (15)
0.01067 (14)
0.01426 (15)
0.0155 (2)
0.0190 (12)
0.0124 (11)
0.0188 (12)
0.0234 (12)
0.0172 (12)
0.0166 (12)
0.0283 (14)
0.0219 (12)
0.0171 (12)
0.0168 (12)
0.0223 (16)
0.0163 (15)
0.0250 (17)
0.0149 (15)
0.0188 (18)
0.0161 (17)
0.034 (2)
−0.00114 (10)
−0.00216 (10)
−0.00256 (11)
0.00063 (17)
−0.0011 (9)
−0.0038 (9)
−0.0014 (10)
−0.0027 (9)
−0.0053 (10)
−0.0017 (9)
0.0009 (10)
−0.0046 (9)
−0.0028 (9)
−0.0090 (12)
−0.0009 (13)
−0.0003 (12)
0.0009 (13)
−0.0002 (14)
−0.0036 (14)
−0.0065 (14)
0.0026 (17)
0.0066 (16)
0.0049 (16)
−0.0009 (18)
0.0070 (12)
−0.00385 (10)
−0.00322 (10)
−0.00265 (11)
−0.00799 (17)
−0.0050 (9)
−0.0036 (9)
−0.0062 (9)
−0.0029 (9)
−0.0009 (10)
−0.0049 (9)
−0.0068 (10)
−0.0082 (10)
−0.0030 (9)
−0.0044 (10)
−0.0073 (13)
−0.0074 (12)
−0.0148 (13)
−0.0101 (13)
−0.0069 (14)
−0.0040 (14)
−0.0087 (17)
−0.0157 (18)
−0.0083 (16)
−0.0041 (17)
−0.0196 (13)
−0.00442 (11)
−0.00288 (11)
−0.00763 (12)
−0.00461 (17)
−0.0080 (10)
−0.0044 (10)
−0.0050 (10)
−0.0131 (10)
−0.0076 (11)
−0.0057 (9)
−0.0142 (11)
−0.0009 (10)
−0.0065 (10)
−0.0083 (11)
−0.0060 (13)
−0.0047 (13)
−0.0031 (14)
−0.0053 (14)
0.0003 (14)
C1
C2
C3
C4
C5
C6
O1W
−0.0017 (14)
−0.0151 (18)
−0.0123 (19)
−0.0095 (16)
−0.0181 (18)
−0.0145 (12)
0.029 (2)
0.028 (2)
0.034 (2)
0.0431 (17)
0.022 (2)
0.0219 (19)
0.034 (2)
0.041 (2)
0.0231 (19)
0.025 (2)
0.0167 (14)
0.0300 (15)
Geometric parameters (Å, º)
Mo1—O1
Mo1—O8
Mo1—O9
Mo1—O4
Mo1—O9
Mo1—O6
Mo1—Mo3
Mo1—Mo1
Mo2—O5
Mo2—O3
Mo2—O6
Mo2—O2
Mo2—O2
Mo2—O1
Mo2—Mo3
Mo3—O10
Mo3—O7
1.730 (2)
Cu1—O8
O2—Mo3
O2—Mo2
2.305 (2)
iv
ii
1.739 (2)
1.868 (2)
1.961 (2)
2.230 (2)
2.320 (2)
3.1621 (11)
3.1980 (14)
1.701 (2)
1.746 (2)
1.853 (2)
2.007 (2)
2.236 (2)
2.332 (2)
3.3005 (12)
1.699 (2)
1.720 (2)
1.938 (2)
2.236 (2)
1.965 (2)
1.853 (2)
2.230 (2)
2.367 (2)
1.337 (4)
1.383 (5)
1.336 (4)
1.384 (4)
1.344 (4)
1.374 (5)
0.8600
ii
O3—Cu1
O6—Mo2
O9—Mo1
O9—Mo3
N1—C1
N1—C3
N2—C2
N2—C5
N3—C1
N3—C4
N3—H3B
N4—C2
N4—C6
N4—H4B
i
i
i
i
i
i
ii
i
1.337 (5)
1.378 (5)
0.8600
Acta Cryst. (2018). C74
sup-3

supporting information
Mo3—O4
Mo3—O2
Mo3—O6
Mo3—O9
1.932 (2)
1.938 (2)
2.330 (2)
2.367 (2)
3.3005 (12)
1.944 (3)
1.965 (2)
1.968 (3)
2.021 (3)
C1—C2
C3—C4
1.453 (5)
1.362 (5)
0.9300
0.9300
1.356 (5)
0.9300
0.9300
0.848 (10)
0.847 (10)
iii
C3—H3A
C4—H4A
C5—C6
C5—H5A
C6—H6A
O1W—H1WA
O1W—H1WB
i
i
Mo3—Mo2
Cu1—O1W
ii
Cu1—O3
Cu1—N2
Cu1—N1
iii
O1—Mo1—O8
O1—Mo1—O9
O8—Mo1—O9
O1—Mo1—O4
O8—Mo1—O4
O9—Mo1—O4
O1—Mo1—O9
O8—Mo1—O9
O9—Mo1—O9
O4—Mo1—O9
O1—Mo1—O6
O8—Mo1—O6
O9—Mo1—O6
105.53 (10)
99.82 (10)
101.97 (11)
98.42 (10)
99.33 (10)
146.97 (9)
93.92 (9)
160.21 (9)
77.76 (10)
73.73 (9)
164.31 (9)
89.31 (9)
81.63 (8)
73.66 (8)
71.01 (8)
119.19 (8)
116.11 (8)
111.74 (7)
35.38 (6)
48.38 (5)
47.29 (6)
98.47 (7)
141.00 (8)
42.95 (7)
107.11 (7)
34.80 (6)
71.83 (5)
75.714 (13)
103.81 (11)
105.88 (11)
99.09 (10)
99.76 (10)
96.41 (10)
145.72 (9)
157.22 (10)
98.12 (9)
76.26 (9)
71.39 (9)
O2 —Mo3—Mo1
107.91 (7)
47.03 (5)
44.76 (6)
142.83 (9)
91.19 (8)
107.00 (7)
41.02 (6)
33.08 (5)
79.92 (5)
77.48 (2)
88.80 (10)
171.61 (13)
91.04 (10)
97.25 (11)
172.79 (11)
82.40 (12)
92.83 (11)
90.16 (9)
95.57 (11)
93.43 (11)
131.51 (11)
146.84 (12)
104.30 (9)
108.61 (9)
171.89 (14)
108.63 (10)
151.38 (11)
103.60 (10)
85.69 (7)
O6—Mo3—Mo1
i
O9 —Mo3—Mo1
i
i
O10—Mo3—Mo2
O7—Mo3—Mo2
i
i
O4—Mo3—Mo2
i
i
i
i
iii
O2 —Mo3—Mo2
i
O6—Mo3—Mo2
i
i
O9 —Mo3—Mo2
i
Mo1—Mo3—Mo2
O1W—Cu1—O3
ii
O1W—Cu1—N2
ii
O3 —Cu1—N2
O4—Mo1—O6
O1W—Cu1—N1
i
ii
O9 —Mo1—O6
O1—Mo1—Mo3
O8—Mo1—Mo3
O9—Mo1—Mo3
O4—Mo1—Mo3
O3 —Cu1—N1
N2—Cu1—N1
O1W—Cu1—O8
ii
O3 —Cu1—O8
N2—Cu1—O8
N1—Cu1—O8
Mo1—O1—Mo2
Mo3 —O2—Mo2
Mo3 —O2—Mo2
Mo2—O2—Mo2
Mo2—O3—Cu1
Mo3—O4—Mo1
Mo2 —O6—Mo1
Mo2 —O6—Mo3
Mo1—O6—Mo3
Mo1—O8—Cu1
Mo1—O9—Mo1
Mo1—O9—Mo3
i
O9 —Mo1—Mo3
O6—Mo1—Mo3
O1—Mo1—Mo1
O8—Mo1—Mo1
O9—Mo1—Mo1
i
iv
i
iv
ii
i
ii
i
ii
O4—Mo1—Mo1
i
i
O9 —Mo1—Mo1
i
i
O6—Mo1—Mo1
Mo3—Mo1—Mo1
O5—Mo2—O3
O5—Mo2—O6
i
i
i
133.36 (11)
102.24 (10)
133.99 (10)
86.86 (8)
106.1 (3)
111.6 (2)
142.1 (3)
106.2 (3)
113.6 (2)
i
i
O3—Mo2—O6
i
O5—Mo2—O2
O3—Mo2—O2
i
i
Mo1 —O9—Mo3
i
O6 —Mo2—O2
C1—N1—C3
C1—N1—Cu1
C3—N1—Cu1
C2—N2—C5
C2—N2—Cu1
ii
O5—Mo2—O2
ii
O3—Mo2—O2
i
ii
O6 —Mo2—O2
ii
O2—Mo2—O2
Acta Cryst. (2018). C74
sup-4

supporting information
O5—Mo2—O1
O3—Mo2—O1
O6 —Mo2—O1
84.46 (10)
170.22 (9)
83.37 (9)
76.79 (8)
73.17 (8)
147.98 (8)
92.04 (7)
43.33 (7)
105.98 (6)
34.67 (6)
83.25 (6)
105.13 (12)
103.31 (11)
98.59 (11)
102.58 (11)
99.05 (10)
143.45 (9)
158.41 (10)
96.44 (10)
73.93 (8)
72.48 (8)
90.22 (10)
163.34 (10)
71.06 (9)
83.52 (8)
68.49 (7)
119.29 (8)
119.71 (9)
36.00 (6)
C5—N2—Cu1
C1—N3—C4
C1—N3—H3B
C4—N3—H3B
C2—N4—C6
C2—N4—H4B
C6—N4—H4B
N1—C1—N3
N1—C1—C2
N3—C1—C2
N2—C2—N4
N2—C2—C1
N4—C2—C1
C4—C3—N1
C4—C3—H3A
N1—C3—H3A
C3—C4—N3
C3—C4—H4A
N3—C4—H4A
C6—C5—N2
C6—C5—H5A
N2—C5—H5A
C5—C6—N4
C5—C6—H6A
N4—C6—H6A
Cu1—O1W—H1WA
Cu1—O1W—H1WB
140.0 (2)
107.4 (3)
126.3
126.3
107.6 (3)
126.2
i
O2—Mo2—O1
ii
O2 —Mo2—O1
i
i
O5—Mo2—Mo3
O3—Mo2—Mo3
126.2
i
i
O6 —Mo2—Mo3
110.8 (3)
116.3 (3)
132.8 (3)
110.7 (3)
115.8 (3)
133.5 (3)
108.7 (3)
125.7
125.7
107.0 (3)
126.5
126.5
108.7 (3)
125.7
125.7
106.9 (3)
126.6
126.6
125 (3)
115 (3)
i
O2—Mo2—Mo3
ii
i
O2 —Mo2—Mo3
i
O1—Mo2—Mo3
O10—Mo3—O7
O10—Mo3—O4
O7—Mo3—O4
iii
O10—Mo3—O2
iii
O7—Mo3—O2
iii
O4—Mo3—O2
O10—Mo3—O6
O7—Mo3—O6
O4—Mo3—O6
iii
O2 —Mo3—O6
i
O10—Mo3—O9
i
O7—Mo3—O9
i
O4—Mo3—O9
iii
i
O2 —Mo3—O9
i
O6—Mo3—O9
O10—Mo3—Mo1
O7—Mo3—Mo1
O4—Mo3—Mo1
H1WA—O1W—H1WB
108 (4)
i
i
O8—Mo1—O1—Mo2
O9—Mo1—O1—Mo2
O4—Mo1—O1—Mo2
135.03 (15)
29.57 (16)
−122.78 (15)
−48.67 (15)
−64.4 (4)
−92.25 (14)
−13.94 (15)
−10.07 (19)
93.81 (16)
−111.59 (16)
−179.13 (17)
175.10 (16)
−144.49 (12)
115.81 (14)
−91.91 (10)
159.76 (9)
30.7 (2)
Mo1 —Mo1—O9—Mo3
97.56 (16)
0.3 (4)
−175.7 (2)
179.0 (3)
3.1 (4)
−0.4 (4)
−178.9 (4)
0.4 (4)
176.5 (2)
180.0 (3)
−3.9 (4)
0.0 (4)
−179.5 (4)
0.5 (5)
178.9 (4)
179.9 (4)
−1.7 (7)
−0.1 (4)
C3—N1—C1—N3
Cu1—N1—C1—N3
C3—N1—C1—C2
Cu1—N1—C1—C2
C4—N3—C1—N1
C4—N3—C1—C2
C5—N2—C2—N4
Cu1—N2—C2—N4
C5—N2—C2—C1
Cu1—N2—C2—C1
C6—N4—C2—N2
C6—N4—C2—C1
N1—C1—C2—N2
N3—C1—C2—N2
N1—C1—C2—N4
N3—C1—C2—N4
C1—N1—C3—C4
i
O9 —Mo1—O1—Mo2
O6—Mo1—O1—Mo2
Mo3—Mo1—O1—Mo2
i
Mo1 —Mo1—O1—Mo2
O1—Mo1—O8—Cu1
O9—Mo1—O8—Cu1
O4—Mo1—O8—Cu1
i
O9 —Mo1—O8—Cu1
O6—Mo1—O8—Cu1
Mo3—Mo1—O8—Cu1
i
Mo1 —Mo1—O8—Cu1
i
O1—Mo1—O9—Mo1
i
O8—Mo1—O9—Mo1
i
O4—Mo1—O9—Mo1
i
i
O9 —Mo1—O9—Mo1
−0.001 (1)
Acta Cryst. (2018). C74
sup-5

supporting information
i
O6—Mo1—O9—Mo1
72.26 (9)
35.09 (9)
5.65 (17)
−102.68 (15)
128.26 (16)
97.56 (16)
169.82 (16)
132.65 (12)
Cu1—N1—C3—C4
N1—C3—C4—N3
C1—N3—C4—C3
C2—N2—C5—C6
Cu1—N2—C5—C6
N2—C5—C6—N4
C2—N4—C6—C5
173.8 (3)
−0.1 (5)
0.3 (4)
−0.7 (4)
−175.1 (3)
0.7 (5)
i
Mo3—Mo1—O9—Mo1
i
O1—Mo1—O9—Mo3
O8—Mo1—O9—Mo3
i
i
O4—Mo1—O9—Mo3
i
i
O9 —Mo1—O9—Mo3
i
O6—Mo1—O9—Mo3
−0.4 (4)
i
Mo3—Mo1—O9—Mo3
Symmetry codes: (i) −x+2, −y+1, −z; (ii) −x+1, −y+1, −z; (iii) x+1, y, z; (iv) x−1, y, z.
Hydrogen-bond geometry (Å, º)
D—H···A
D—H
H···A
D···A
D—H···A
v
v
v
N3—H3B···O9
N4—H4B···O8
N4—H4B···O6
0.86
0.86
0.86
0.85 (1)
0.85 (1)
2.47
2.05
2.41
1.81 (1)
1.97 (1)
3.303 (4)
2.834 (4)
3.013 (4)
2.654 (3)
2.809 (3)
164
151
128
174 (4)
170 (4)
vi
iv
O1W—H1WA···O4
O1W—H1WB···O7
Symmetry codes: (iv) x−1, y, z; (v) −x+2, −y, −z+1; (vi) −x+2, −y, −z.
Acta Cryst. (2018). C74
sup-6