Novel vanadium complexes with rigid carboxylate ligands: Synthesis, structure and catalytic bromine dynamics of phenol red

Article abstract of DOI:10.1016/j.molstruc.2017.07.015

In this work, by selecting appropriate ligands, novel vanadium complexes [V^IVO(2,6-pdc)(Phen)]·3H₂O (1) and [(V^IVO)(C₅H₅N₂O₂)₂H₂O]·2H₂O (2) (2,6-pdc = 2,6-pyridinedicarboxylic acid, Phen = 1,10-Phenanthroline monohydrate) were synthesized by the reaction of V₂(SO₄)₃, 2,6-pdc and Phen (for 1), VO(acac)₂ and C₅H₆N₂O₂ (for 2) via solution or hydrothermal methods. Two complexes were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TG), UV-vis spectroscopy and the single crystal X-ray diffraction. Structural analyses reveal that the vanadium atom has distorted octahedral geometry in 1 and 2 with donor sets of N3O3 and N2O4, respectively. The complexes which catalyze the oxidation of the organic substrate phenol red in the presence of H₂O₂ and bromide exhibited catalytic bromination activity, and the reaction system is considered as an effective model for hydrogen peroxide determination. The reaction rate constant (k) for complexes 1 and 2 can be calculated as 2.13 × 10² and 2.64 × 10² (mol/L)^?2s^?1, respectively.

Full text of DOI:10.1016/j.molstruc.2017.07.015

Accepted Manuscript
Novel vanadium complexes with rigid carboxylate ligands: Synthesis, structure and
catalytic bromine dynamics of phenol red
Yang Wang, Xiao-Meng Lin, Feng-Ying Bai, Li-Xian Sun
PII:
S0022-2860(17)30936-5
10.1016/j.molstruc.2017.07.015
MOLSTR 24042
DOI:
Reference:
To appear in: Journal of Molecular Structure
Received Date: 13 April 2017
Revised Date: 8 July 2017
Accepted Date: 10 July 2017
Please cite this article as: Y. Wang, X.-M. Lin, F.-Y. Bai, L.-X. Sun, Novel vanadium complexes with
rigid carboxylate ligands: Synthesis, structure and catalytic bromine dynamics of phenol red, Journal of
Molecular Structure (2017), doi: 10.1016/j.molstruc.2017.07.015.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
Graphical Abstract
The oxovanadium complexes have been
synthesized and characterized. The catalytic
bromination activity and the practical application
of H O detection have been studied.
2
2

1
ACCEPTED MANUSCRIPT
Journal of Molecular Structure
journal homepage: www.elsevier.com
Novel vanadium complexes with rigid carboxylate ligands: synthesis, structure and
catalytic bromine dynamics of phenol red
a
a
a
b
Yang Wang , Xiao-Meng Lin , Feng-Ying Bai *, Li-Xian Sun *
a
College of Chemistry and Chemical Engineering, Liaoning Normal University, Huanghe Road 850#, Dalian 116029, P.R. China
b
Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004, P.R. China.
ARTICLE INFO
ABSTRACT
IV
Article history:
Received
Received in revised form
Accepted
In this work, by selecting appropriate ligands, novel vanadium complexes [V O(2,6-
IV
pdc)(Phen)]·3H
2
O
(1) and [(V O)(C
5
H
5
N
2
O
2
)
2
H
2
O]·2H
2
O
(2) (2,6-pdc
=
2,6-
pyridinedicarboxylic acid, Phen= 1,10-Phenanthroline monohydrate ) were synthesized by the
reaction of V (SO , 2,6-pdc and Phen (for 1), VO(acac) and C (for 2) via solution or
Available online
2
4
)
3
2
5 6 2 2
H N O
hydrothermal methods. Two complexes were characterized by elemental analysis, IR
spectroscopy, thermogravimetric analysis (TG), UV-vis spectroscopy and the single crystal X-
ray diffraction. Structural analyses reveal that the vanadium atom has distorted octahedral
geometry in 1 and 2 with donor sets of N3O3 and N2O4, respectively. The complexes which
Keywords:
Vanadium (IV) complexes
Crystal structure
Haloperoxidases
2 2
catalyze the oxidation of the organic substrate phenol red in the presence of H O and bromide
exhibited catalytic bromination activity, and the reaction system is considered as an effective
Mimicing bromoperoxidase
Hydrogen peroxide determination
model for hydrogen peroxide determination. The reaction rate constant (k) for complexes 1 and
2
2
-2 -1
2
can be calculated as 2.13×10 and 2.64×10 (mol/L) s , respectively.
2
009 Elsevier Ltd. All rights reserved
.
1
8-20
1
. Introduction
The coordination chemistry of vanadium, in particular with
hydroperoxides, hydrogen peroxide or molecular oxygen.
Vanadium catalysis oxidation with hydrogen peroxide has
attracted great attention because of the functional properties of
this metal in terms of selectivity and reactivity. In addition, it
multidentate ligands, is attracting much attention on account of
its application in various filed such as catalysis, medicine,
electrical conductivity, magnetism, etc.
structures and compositions of inorganic-organic hybrid
materials are derived from the enormous compositional of the
inorganic and organic components.
hybrid vanadium complexes with multidimensional structures are
prepared on account of the particularly variable oxidation states
and coordination geometries of the vanadium atom. Our group
has been working on the synthesis and properties of the
oxovanadium/vanadium complexes for many years.
now, our group has synthesized some vanadium complexes such
21
brings anti-cancer and anti-bacterial properties when the aromatic
complexes are introduced by halogen group. The traditional way
for bromine oxidation of aromatic complexes is electrophilic
substitution, but the method is low availability of bromide and
produces a lot of industrial waste which pollutes environment
seriously. Therefore, it will be one of the key topics to search
and synthesize substantial catalyzers with high activity in safe
and non-toxic process. Under the mild condition, natural
vanadium haloperoxidases (V-HPOs) can be applied for realizing
the aim. Regretfully, the natural enzymes as proteins have some
serious disadvantages, for instance, digestion by proteases, easily
denaturationed by environmental changes and expensive
preparation, etc. Therefore, we are trying to find some stable
1-7
The multifarious
8-12
A lot of inorganic-organic
13,14
Up to
as
[V(2,6-pdc) (H O) ]·2H O,
[V(dipic)(Hbdc)(2H O)],
2
2
2
2
2
[
V ((dipic) (H btec)(4H O)]·2H O,
(VO) (bpz*T-O),
2
2
2
2
2
2
VO(bpz*eaT)(SCN)2,
VO(SO )(bpz*P-Me)(H O)
mimicking catalytic bromine dynamics research, which exhibited
the better catalytic bromine activity.
[VO(SO )(bpz*P)(H O)]·H O,
and so on, and has carried out
4
2
2
artificial vanadium complexes to mimics natural vanadium
15-17
22-24
4
2
haloperoxidases.
To our best knowledge, many vanadium
complexes have been synthesized for researching and
understanding the relationship between their structures and
25-27
catalytic activities.
As a part of continuing to work on the
As is known to all, vanadium haloperoxidase (V-HPOs) which
are found in marine algae can expedite the oxidative halogenation
of the aromatic organic complexes in the presence of organic
structures and catalytic bromine activity, it is necessary to
expand and study synthesis, structures and the properties of this
family of the vanadium complexes. Based on these reasons, we

2
IV
synthesized two new vanadium compl
A
ex
C
esCE[VPT
O
E
(2
D
,6- MAN
W
U
e
S
ha
the method in the literatureꢀ
the presence of phenol red solution, buffer solution of NaH PO –
C
ve
R
s
I
tu
P
d
T
ied catalytic bromination dynamics according to
IV
13-17
pdc)(Phen)]·3H O (1), [(V O)(C H N O ) H O]·2H O (2).
the reactions were initiated with
2
5
5
2
2 2
2
2
These complexes were characterized by elemental analysis, IR
spectra, UV–Vis spectroscopy, single-crystal X-ray diffraction
and thermogravimetric analysis (TG). In addition, mimic
catalytic bromination dynamics of the vanadium complexes and
the potential detection of hydrogen peroxide in water were also
studied in this work.
2
4
Na HPO (pH=5.8), KBr, vanadium complex and H O . The UV
2
4
2
2
spectral changes were recorded using
a
UV-1000
spectrophotometer at 5 min intervals. We collected the spectra
data during the reaction. Finally, we calculated the bromine
reaction rate constant of vanadium complexes through the
30
experimental data.
2
. Experimental
Table 1. Summary of crystal data and refinement results for
complexes 1 and 2*
2
.1. Materials and methods
Elemental analyses for C, H, and N were carried out on a
Complexes
1
2
Perkin Elmer 240C automatic analyzer. The infrared spectra was
recorded on a Bruker AXS TENSOR−27 FT−IR spectrometer
Formula
C
19
H
17
N
3
O
8
V
10 16 4 8
C H N O V
−1
with KBr pellets in the range of 4000−400 cm . UV-vis spectra
was recorded on JASCO V-570 spectrometer (200-2000 nm, in
form of solid sample). The X−ray powder diffraction data was
collected on a Bruker AXS D8 Advance diffractometer using Cu–
-
1
M (g mol )
Crystal system
Space group
a (Å)
466. 3
Monoclinic
P2 /c
371.21
Orthorhombic
Pbca
o
Kα radiation (λ = 1.5418 Å) in the 2θ range of 5–60 with a step
1
o
o
size of 0.02 and a scanning rate of 3 /min. Thermogravimetric
analysis (TG) was performed under atmosphere with a heating
14.0293(12)
13.5844(12)
10.5485(9)
90
17.7913(10)
16.9218(2)
20.4769(11)
90
o
-1
rate of 10 C min on a Perkin Elmer Diamond TG/DTA.
b (Å)
2
.2. Synthesis
c (Å)
IV
[
V O(2,6-pdc)(Phen)]·3H O (1) A mixture of V (SO )
2 2 4 3
α (º)
(0.039 g, 0.10 mmol), 2,6-pdc (0.02 g, 0.12 mmol), Phen (0.02 g,
0
.11 mmol), ascorbic acid (V ) (0.02 g, 0.10 mmol) and
C
β (º)
101.2370(10)
90
90
deionized water (10 mL) was loaded into a Pyrex flask. After the
solution was stirred at room temperature for 3 h, the Pyrex flask
was sealed and heated at 100 C for two days, and then cooled to
room temperature. Finally, brown black crystals of the complex
were obtained in ca. 66% yield (0.0301g) based on V. Elemental
Analysis (%) Calcd. For C H N O V: C, 48.93; H, 3.65; N,
γ (º)
90
o
3
V (Å )
1971.8(3)
4
6164.8(6)
16
Z
19
17
3
8
-3
9
.01%. Found: C, 49.76; H, 2.62; N, 9.07%.
D
calc (Mg m )
1.544
1.600
IV
0
.54×0.44×0.03
0.34×0.3×0.23
[
(V O)(C H N O ) H O]·2H O (2) VO(acac) (0.0265 g, 0.1
Crystal size (mm)
F(000)
5
5
2
2 2
2
2
2
mmol) and 5-pyrazol-1H-pyrazol-3-carboxylic acid (0.025 g, 0.2
mmol) were mixed and stirred for 3 h in a solution of 95%
methanol (8 mL) at room temperature. After two days, purple
crystals of complex were obtained. Yield (based on V): 0.036g,
8.78%. Anal. Calc. For C H N O V: C, 32.35; H, 4.3; N,
5.09. Found: C, 32.35; H, 4.28; N, 15.05.
924
0.556
3056
0.691
-1
µ (Mo-Kα) / mm
θ (°)
4
1
10 16 4 8
1.48 to 25.00
9785
1.94 to 28.32
38066
Reflections collected
Independent reflections
Parameters
2
.3. X-ray crystallographic determination
3471
7662
Suitable single crystals of the three complexes were mounted
on glass fibers for X-ray measurement, respectively. Reflection
data was obtained at room temperature with a Bruker AXS
SMART APEX II CCD diffractometer (Bruker AXS, Karlsruhe,
Germany) with graphite-monochromated Mo-K alpha radiation (l
0.7107 Å) and a ω scan mode. All measured independent
reflections (I > 2 sigma (I)) were used in the structural analysis
and semi-empirical absorption corrections were applied using the
277
409
-3
∆
(ρ) (e Å )
1.827 and -0.833
1.093
0.780 and -0.771
1.063
Goodness-of-fit
=
a
b
b
R
1
0.0660(0.0749)
0.0514(0.0780)
a
b
b
28
wR2
0.2025(0.2116)
0.1470(0.1650)
SADABS program. The structures were solved by the direct
method using SHELXL-97.
29
a
2
o
2
c
2
2
o
2
1/2
b
All non-hydrogen atoms were
* R = ΣF – F /ΣF , wR = [Σw(F –F ) /Σw(F ) ] ;F >4σ(F ).
o
c
o
2
o
o
refined anisotropically and by temperature factor with the full-
matrix least squares method. Hydrogen atoms of the organic
frameworks were fixed at calculated positions with isotropic
thermal parameters and refined using a riding model. Hydrogen
atom of free water molecules were found in difference Fourier
map. For complex 1, it should be noted that one of the O3W
from free water was full occupancy and the other two O1W and
O2W were disordered and split into two position with occupancy
Based on all data.
3
. Results and discussion
.1. Synthesis
We have successfully synthesized complexes 1 and 2 with a
3
hydrothermal reaction for 1 and the solution reaction for 2, as
shown in Scheme 1. Starting material V (SO ) was used to
synthesize complex 1, while VO(acac) was used for 2. The
complex 1 with 2,6-pdc as ligand has been synthesized by
hydrothermal methods at 100 °C, it was interesting to note that
the chemical valence of the central metal vanadium has been
changed. A possible reason was that the higher temperature
could lead to V(III) atom being oxidized into a V(IV) atom by
the oxygen from air. All of the complexes were synthesized for
2
4
3
0
.7:0.3. Crystal data and structure refinements were shown in
2
Table 1. The selected bond lengths and bond angles were giving
in TableS1-S2. Hydrogen bonds of the complexes 1 and 2 were
given in TableS3-S4.
2
.4. Measurement of mimic catalytic bromination dynamics in
solution

3
*
the first time. In addition, both complexes
room temperature, and can be easily soluble in DMF.
A
we
C
re
C
al
E
l
P
st
T
ab
E
le
D
at MAfo
N
r 2
vanadium.
U
c
S
an
C
b
R
e c
I
aused by the d→d transition of the central metal
P
T
Table 2 Characteristic UV-Vis bands (nm) for complexes 1-2
Complexes
π-π*
1
2
216, 266
376, 452
742
219, 262
294
LMCT
d-d*
549, 786
3
.6. Structural description of complexes 1-2
Scheme 1: The reaction route of the complexes 1 and 2.
IV
[
V O(2,6-pdc)(Phen)]·3H O (1) Structural analyses reveal that
2
the complex crystallize in the monoclinic, space group P2 /c.
1
3
.2. IR spectra
The IR spectras of the complexes 1 and 2 were listed in
The molecular structure of the complex 1 is shown in Figure 1a.
IV
It consists of one V atom, a terminal oxygen atom, one 2,6-pdc
(
Fig.S1-S2). The broad absorption bands centered in region of
IV
-
1
ligand, one Phen ligand, three free water molecules. V is six-
3
426 and 3437 cm were assigned to the stretching vibrations of
coordinate with one nitrogen atom (N3) from the 2,6-pdc ligand,
two oxygen atoms (O1, O4) from the 2,6-pdc ligand, two
nitrogen atom (N1, N2) from Phen ligand and a terminal oxygen
atom (O5) to form a distorted octahedral geometry. 2,6-pdc
ligands adopt tridentate chelating coordination and Phen ligand
adopt bidentate chelating coordination mode. V-O bond lengths
ranged from 2.035(3) to 2.137(8) Å. V-N bond lengths ranged
from 2.029(4) to 2.320(3) Å. The bond length of V=O (O5) was
the unassociated O–H in the water molecules. The peaks at 3088
-
1
and 3083 cm were attributed to the C–H stretching vibrations of
the benzene rings, pyridine rings or pyrazole rings. The bands
-
-
belonged to asymmetric ν (COO ) and symmetric ν (COO )
as
s
-
1
vibrations of the carboxyl group were in 1653 and 1349 cm for
complex 1 and in 1647 and 1324 cm for complex 2. The
stretching vibration of V=O was varied at approximately 982 cm
for 1 and 964 cm for 2ꢁ as expected. The band at 577 cm for
-
1
-
1
-1
-1
2
was characteristic of the stretching vibrations of V–Owater. The
-
1
-1
1
.592(3) Å, which was shorter than the single bond of V-O.
bands at 543 cm for 1 and 540 cm for 2 were attributed to the
stretching vibration of V–Ocarboxyl. Absorptions at 440 and 470
cm were characteristic of the stretching vibration of V–N.
Because of the inverse trans effect of the V=O (O5), the bond
length of V-N2 (2.320(3) Å) was slightly longer than that of V-
N1 (2.142(3) Å).
-
1
3
.3. Thermal analysis
In the packing structure, there are two kinds of hydrogen
...
In order to examine the thermal stability of the complex 1-2,
bonding: (i) hydrogen bonding of C-H O: between the carbon
atom from 2,6-pdc ligands (C15, C17) and the oxygen atoms
from 2,6-pdc ligands (O2) and terminal oxygen (O5): C15-
thermogravimetric analysis (TG) was carried out at a heating rate
o
of 10 C /min under nitrogen in the temperature range of 30-1000
o
...
#2
...
#3
C (Fig.S3-S4). For 1, the initial loss of 34.5 % before 515 ºC
H15 O5 , C17-H17 O2 (#2 -x+1,-y,-z+1; #3 -x+1,y+1/2,-
…
was assigned to the departure of three free water molecules and
partial framework collapse of Phen, the second weight loss in the
z+3/2). (ii) hydrogen bonding of O-H O: between the O (donor)
and the
O
(donor): O(1W) -H(1D)...O(2W), O(1B)-
o
#8 #7 #7
range of 515-1000 C was due to the release of remainder
H(1F)...O(3W) , O(2W)-H(2C)...O(3) , O(2B)-H(2F)...O(3) ,
O(3W)-H(3C)...O(1) , O(3W)-H(3D)...O(1W) (#2 -x+1,-y,-
z+1; #5 x,y,z+1; #7 -x+1,y-1/2,-z+1/2; #8 x,-y+1/2,z-1/2). By
#2
#5
framework of Phen and a coordinated 2, 6-pdc ligand. The final
residue of the complex corresponded to the oxide of vanadium.
...
#2
(24.45%) For 2, the initial weight loss of 13.68% before 292 ºC
the hydrogen bonding of C15-H15 O5 , two adjacent molecules
IV
was assigned to the departure of two free water molecules and a
[V O(2,6-pdc)(Phen)] were connected to form a dimer with a
o
coordinated water (calc: 14.55%). The second step up to 909 C
closed twelve number ring structure. (Figure 1b) Then, through
...
#3
(obs: 68.3%) was attributed to the removal of two coordinated 5-
the hydrogen bonding of C17-H17 O2 , the dimer was further
connected to form a 2D sheet structure which was parallel with
cb. The formation of the dimer was more stable through the
connection of the above hydrogen bonds. (Figure 1c).
pyrazol-1H-pyrazol-3-carboxylic acid. (calc: 67.4%) The final
residue of the complex corresponded to the oxide of vanadium.
(18.02%)
3
.4. PXRD analysis
In order to confirm whether the crystal structures were truly
representative of the bulk materials, the PXRD patterns of the
complexes 1-2 were recorded, as shown in the Fig.S5-S6. The
phase of the corresponding complex was considered as purities
owning to the agreement of the peak positions. The different
intensity may be due to the preferred orientation of the powder
samples.
3
.5. UV-Vis spectra
The UV–vis absorption spectras of the complexes 1-2 (Fig.S7-
Figure 1: a: The molecular structure of the complex 1; b: The
biopolymers structure of 1; c: A view of a 2D supramolecular
S8) were recorded in the form of solid sample and their
characteristic of the UV-vis bands were listed in Table 2. They
have similar absorption patterns. Bands at 216 and 266 nm for 1,
and 219 and 262 nm for 2 were attributed to the π-π* transition of
the ligands. The bands at 376 and 452 nm for 1, 294 nm for 2
were assigned to the LMCT (ligand to metal charge transfer)
transition. The broad peaks at 742 nm for 1 and 549 and 786 nm
network structure formed by the hydrogen bonds.
IV
[
(V O)(C H N O ) H O]·2H O (2) The complex crystallize
5 5 2 2 2 2 2
in the orthorhombic, space group Pbca. The molecular structure
of the complex 2 was shown in Figure 2a. It comprised two

4
identical
crystallographically
independ
A
en
C
t
CE
m
P
o
T
lec
E
u
D
les MAin
N
th
U
e r
S
an
C
ge
R
o
I
f
P
1.966- 2.228 Å, ones of the
T
[
(VO)(C H N O ) H O] and four free water molecules. Each
5
5
2
2 2
2
V-N were about 2.029- 2.320 Å.
Table 3 Hydrogen bonds (Å) for complex 1
Complex 1
molecule was composed of one vanadium atom, two 5-pyrazol-
H-pyrazol-3-carboxylic acid molecules, one coordinated water,
a terminal oxygen atom and two free water molecules, in which
1
IV
V
was six-coordinate with two oxygen atoms (O9, O11) and
two nitrogen atoms (N1, N3) from the 5-pyrazol-1H-pyrazol-3-
carboxylic acid molecules, one oxygen atom (O8) from the
coordinated water, and a terminal oxygen atom (O7) to form a
D–H···A
d(D–H)/Å d(H···A)/Å
d(D···A)/Å
3.264(2)
ꢂD–H···A/°
#2
C(15)-H(15)···O(5)
0.93
2.57
131.9
distorted octahedral geometry.
5-pyrazol-1H-pyrazol-3-
carboxylic acid molecules adopt bidentate chelating coordination
mode, the dihedral angle of two five number rings between (V1
O11 C1 C2 N1) and (V1 O9 C6 C7 N3) is 81.34 (8)°. V-O bond
lengths ranged from 1.599(2) to 2.192(2) Å. The bond length of
V=O was shorter than V-O obviously. V-N bond lengths ranged
#3
C(17)-H(17)···O(2)
0.93
2.55
3.380(3)
2.778(4)
148.00
166(5)
3
0.827(19)
1.97(2)
O(1W)-H(1D)···O(2W)
#
8
0.82(2)
0.848(19)
0.83(2)
2.56(4)
1.97(2)
2.24(9)
2.38(3)
2.00(2)
3.157(10)
2.806(3)
2.931(8)
3.076(3)
2.826(4)
166(5)
131(5)
171(5)
141(12)
143(4)
O(1B)-H(1F)···O(3W)
from 2.192(2) to 2.066(3) Å. O-V-O bond angles ranged from
#7
O(2W)-H(2C)···O(3)
O(2B)-H(2F)···O(3)
O(3W)-H(3C)···O(1)
o
8
3.27(9) to 168.83(10) , O-V-N bond angles ranged from 73.34(9)
o
#
7
to 161.99(10) , N-V-N bond angles ranged from 91.89(10) to
4.96(10) . It should be pointed out that distortion of two ligands
o
9
#
2
0.822(18)
0.838(18)
in a molecular is different which maybe bacause free water is
asymmetric distribution and build the different H-bonding.
#5
O(3W)-H(3D)···O(1W)
In the packing structure, there are three kinds of hydrogen
.
..
* Symmetry code:#2 -x+1,-y,-z+1; #3 -x+1,y+1/2,-z+3/2; #5 x,y,z+1; #7 -
x+1,y-1/2,-z+1/2; #8 x,-y+1/2,z-1/2
bonding: (i) hydrogen bonding of C-H O: between the C atom
from 5-pyrazol-1H-pyrazol-3-carboxylic acid molecules (C16),
and the O atom from free water molecule (O4W): C16-
Table 4 Hydrogen bonds (Å) for complex 2
.
..
#6
H16E O4W (#6: -0.5+x, y, 0.5-z). (ii) hydrogen bonding of O-
Complex 2
…
H O: between the O atom from free water molecule (O1W,
O2W), 5-pyrazol-1H-pyrazol-3-carboxylic acid molecules (O4,
O6, O10, O12), coordinated water (O2, O8) and terminal oxygen
D–H···
A
d(D–H)/Å
.819(9)
d(H···A)/Å
1.762 (11)
d(D···A)/Å ꢂD–H···A/°
…
…
#7
#2
0
2.581(3)
2.730(2)
2.829(3)
2.792(3)
2.513(3)
2.697(2)
2.941(3)
2.781(3)
2.742(3)
2.800(3)
2.663(3)
2.739(3)
3.349(10)
173(3)
166(3)
167(3)
173(3)
177(3)
174(3)
143(2)
158(3)
157(4)
165(4)
172(6)
173(6)
150.87
atoms (O1, O7): O1W-H1WA O10, O1W-H1WB O12 (#7: 1-
O8–H8C···O1W
O8–H8D···O1
.
..
#1
x, y+0.5, 0.5-z), O2W-H2WA O4 (#1: 1-x, 1-y, 1-z), O2W–
…
#8
…
0.819(9)
0.86(3)
0.86(3)
1.927(13)
1.98(3)
H2WB O6
(#8: 1.5-x, y+0.5, z), O8–H8D O1, O8–
#
2
H8C···O1W ( #2: 1.5-x, -0.5+y, z), O2–H2A···O2W, O2–
H2C···O7 (,#5: 1.5-x, 1-y, 0.5+z). (iii) hydrogen bonding of N-
#
3
#
5
N2–H2···O6
N4–H4···O3
.
..
H O: between the N from 5-pyrazol-1H-pyrazol-3-carboxylic
acid molecules (N2, N4, N6, N8) and the O from 5-pyrazol-1H-
pyrazol-3-carboxylic acid molecules (O3, O6, O9, O11): N2–
#3
1.94(3)
0
.824(10)
0.827(9)
.878(10)
0.83(3)
.809(10)
1.690(10)
1.873(11)
2.190(19)
1.99(3)
O2–H2A···O2W
#
3
#3
H2···O6 , N4–H4···O3 (#3: 1.5-x, 1-y, z-0.5), N6–H6···O11,
...
#5
O2–H2C···O7
N8–H8···O9. By the hydrogen bonding of N6-H6 O11 and O2-
H2C O7 , the adjacent molecules [(V O)(C H N O ) H O]
.
..
#5
IV
5
5
2
2 2
2
0
N6–H6···O11
were connected to form an infinite 1D chain structure.(Figure 2b)
…
#7
Moreover, by the hydrogen bonding of O1W-H1WB O12 and
N8–H8···O9
…
#2
O8-H8C O1W the 1D chain structures are further connected to
form a 2D sheet structure.(Figure 2c)
0
1.98(2)
O1W–H1WA···O10
#
7
0.815(10)
0.816(10)
0.817(10)
0.960
2.005(15)
1.852(13)
1.927(12)
2.4778
O1W–H1WB···O12
#
1
O2W–H2WA···O4
#
8
O2W–H2WB···O6
#
1
C16–H16E···O4W
Symmetry code: #1: 1-x, 1-y, 1-z; #2: 1.5-x, -0.5+y, z; #3:1.5-
x, 1-y, z-0.5; #5: 1.5-x, 1-y, 0.5+z; #6: -0.5+x, y, 0.5-z; #7: 1-
x, y+0.5, 0.5-z; #8: 1.5-x, y+0.5, z
3
.7. Mimic catalytic bromination dynamics studies of the
vanadium complexes
As mentioned above, in the presence of bromide and H O ,
2
2
vanadium complexes can mimic a haloperoxidases reaction in
which vanadium complex catalyze the bromination of organic
31-35
substrates.
Herein, we have also researched the bromination
Figure 2 a: The molecular structure of the complex 2; b: An infinite
chain structure of 2; c: A view of a 2D network structure formed by
the hydrogen bonds.
reaction activities of complexes 1-2 using phenol red as organic
substrate, which was converted to bromophenol blue during the
reaction. The reactive process is shown in Scheme 2. The
solution of complex 1 was added to the standard reaction of
bromide in phosphate buffer with phenol red as a trap for
oxidized bromine resulted in the visible color changing of the
solution from yellow to blue. The UV absorption spectra
Compared with other similar complexes, from the Table S3, it
is found that V(IV) complexes were usually six-coordinate, there
were N3O3 or N2O4 coordinate mode. The bond length of the
V=O was about 1.592-1.603 Å, the bond lengths of the V-O were

5
recorded a decrease in absorbance of the peak a
A
t 4
C
43
C
n
E
m
P
in
TED
ue MANUSCRIPT
v
irt
of the loss of phenol red and an increase of the peak at 592 nm
with production of the bromophenol blue shown in Figure 3,
showing that 1 performs significant catalytic activity. The results
of the mimic catalytic activities for 2 are similar to that of 1.
O
O
O
O
S
S
Br
Br
O
O
KBr, V Complex
OH
OH
H O
2
2
Br
Br
OH
OH
Scheme 2: Reactive process of the bromination reaction for the
complexes.
Figure 4: A series of linear calibration plots of the absorbance at 592
nm dependence of time for different concentration of the complex 1.
-
1
-1
Condition used: pH=5.8, c(KBr)=0.4 mol·L , c(H O )=1 mol·L ,
2
2
-
4
-1
-4
-1
-5
c(phenol red)=10 mol·L . c(complex 2×10 mol·L )= a: 10 ; b:
-
5
-5
-5
-5
2
×10 ; c: 3×10 ; d: 4×10 ; e: 5×10 .
Figure 3: oxidative bromination of phenol red catalyzed by 1.
Spectral changed at 10 min intervals. The reaction mixture
-
1
contained phosphate buffer (pH=5.8), KBr (0.4 mol·L ), H O (1
2
2
-
1
-4
-1
-4
-1
mol·L ), phenol red (10 mol·L ) and complex 1 (2×10 mmol·L ).
Figure 5: –log (dc/dt) dependence of –logc for 1 in DMF-H O at
2
In order to study the catalytic reaction process, taking
complex 1 as an example to execute kinetic studies of the
mimicking bromination reaction. Changing the reaction time and
concentration of the complex 1, a series of linear calibration plots
of the absorbance at 592 nm were obtained, according to
relationship of the UV absorbance data with the different reaction
time.(Figure 4) Then, the catalytic reaction kinetic equation
about dc/dt= k·cx·c y·c z was dealt with log into lg(dc/dt)=lgk
o
3
0±0.5 C
2
3
+
xlgc+ylgc +zlgc . We used dA/dt data (where A = absorbance
2 3
at 592 nm) corresponding to the concentration change of the
oxidovanadium complexes, as the function of -log (dc/dt) vs.
variable of –logc (where c = concentration of complex) to obtain
36-38
a straight line (Figure 5)
We can know the the slope (1.091)
and intercept (2.260) through the straight line. The slope
confirmed that the reaction order was first-order reaction
dependence on vanadium. On the basis of the intercept, we can
calculate the reaction rate constant (k) of complex 1 was
Figure 6: A series of linear calibration plots of the absorbance at 592
2
-2 -1
2
.13×10 (mol/L) s . Similar plots for 2 was generated in the
nm dependence of time for different concentration of the complex 2.
same way (Figure 6-7), and values of the slope and the intercept
was 1.089 and 1.974 ꢁ respectively. According to similar
calculating method, The reaction rate constant (k) for complex 2
-1
-1
Condition used: pH= 5.8, c(KBr)= 0.4 mol·L , c(H O )= 1 mol·L ,
2
-1
2
-4
-1
-4
-5
c(phenol red)= 10 mol·L . c(complex 4×10 mol·L )= a: 2×10 ; b:
-5
-5
-5
-4
4
×10 ; c: 6×10 ; d: 8×10 , e: 10
2
-2 -1
was 2.64×10 (mol/L) s .

6
ACCEPTED MAN
H
U
yd
S
ro
C
ge
R
n
I
peroxide play an important role in our daily life,
P
T
industry, pharmaceutical production and clinical physic,
especially in catalytic reaction.
39-42
Based on the view, we have
studied the dependence of H O2 concentration upon the
2
bromination catalytic reaction to create a new H O detection
2
2
method. As shown in the experiment results, the oxidation
reaction catalyzed by the vanadium complexes is H O
2
2
concentration-dependent, and the absorbance at 592 nm presents
a linear dependence on the concentration of H O along with the
2
2
formation of bromophenol blue.
A series of lines dependent on c(H O ) at 5 min intervals
2
2
(among 20-45 min) were plotted for 1 (Figure 9). In the
detection of hydrogen peroxide, we need to ensure accuracy of
2
the detection and the time as short as possible. The R of the
Figure 7: –log (dc/dt) dependence of –logc for 2 in DMF-H O at
2
2
lines with different reaction time was calculated, R
=0.987ꢁ
o
20min
3
0±0.5 C
2
2
2
R25min2=0.9415
ꢁ
R30min =0.9531
ꢁ
R35min =0.9576
ꢁ
2
Vanadium complexes played an important role in the catalytic
R40min =0.965ꢁR45min =0.9709. To get best linear relationship
and shortest time, we chosen 20 min as the reaction time for the
detection of H O .
reaction. For further research, we proposed a cyclic catalytic
brominated reaction mechanism based on a large number of
experimental results. (Figure 8) The tetravalent vanadium
complex was easily oxidized to form an oxidovanadium
2
2
-
intermediate by H O as an oxidation regent. Br was oxidized
2
2
rapidly by the oxidovanadium intermediate, while at the same
+
+
-
time X (X =HOBr/Br /Br mixture) was formed with the losing
2
3
-
+
of OH , in which (X ) further brominated oxidized phenol red
into bromophenol blue. Although the details of the mechanism
still need more experimental proof, the study on application of
the vanadium complex has a great prospect.
(IV)
Figure 8: The catalytic brominated reaction mechanism for V
complex.
Figure 9: The relationship between the amount of hydrogen peroxide
and the absorbance of the reaction with different time. Condition
-
1
-5
-1
used: pH=5.8, c(KBr)=0.4 mol·L , c(complex)=4×10 mol·L ,
-
4
-1
c(phenol red)=10 mol·L , V(H O )= 1.3, 1.5, 1.7, 1.9, 2.1, 2.3 mL,
c(H O )= 1.273, 1.47, 1.665, 1.86, 2.057, 2.253 mol·L .
2
2
-
1
2
2
Table 4 Kinetic data for the complexes in DMF–H O at
2
o
3
0±0.5 C
-
1 -2 -1
Complex
m
b
k(mol L ) s
2
1
1.091
2.260
2.13×10
2
2
1.089
1.974
2.64×10
-
1
Conditions used: c(phosphate buffer) =50 mmol·L , pH =5.8, c(KBr)
-
1
-4
-1
=
0.4 mol·L , c(phenol red) =10 mol·L . ‘‘x’’ is the reaction order
of the vanadium complex; ‘‘b’’ is the intercept of the line; ‘‘k’’ is the
reaction rate constant for the vanadium complex
Above the experimental results showed that (i) the reaction
orders of the vanadium complexes in the bromination reaction are
all close to 1, confirming appreciatively the first-order
dependence on vanadium; (ii) the reaction rate constants of the
two complexes is 2>1 (Table 4). Different ligand lead to
different catalytic reaction activity of the vanadium complexes.
In complex 1 and 2, the complex with coordinated water has
higher catalytic activity, such as 2, attributed to low bond energy
of the V-OH2O and easy dissociation of water, resulting in easier
formation of the intermediate. These results show that the
catalytic activity of the complexes may have great connection
with their structural characterization.
Figure 10: The linear relationship between the amount of hydrogen
peroxide and the absorbance of the reaction of complex 1. Condition
-
1
-5
-1
used: pH= 5.8, c(KBr)= 0.4 mol·L , c(complex)= 4×10 mol·L ,
-
4
-1
c(phenol red)= 10 mol·L , V(H O )= 1.3, 1.5, 1.7, 1.9, 2.1, 2.3 mL,
c(H O )= 1.273, 1.47, 1.665, 1.86, 2.057, 2.253 mol·L .
2
2
-1
2
2
From Figure 10, every line denotes a linear relationship
between the amount of hydrogen peroxide and the absorbance of
the reaction system at given time with complex 1 as catalyzer.
3
.8. The effect of the concentration of H O on bromination
2 2

7
1
7 D. X. Ren, N. Xing, H. Shan, C. Chen, Y. Z. Cao and Y. H. Xing,
According to the same method, and the linear d
A
at
C
a o
C
f
E
ab
P
so
TED
ce MANUSCRIPT
rb
an
Dalton Trans., 2013, 42, 5379-5389.
8 M. Isupov, A. Dalby, A. Brindley, T. Izumi, T. Tanabe and J.
Littlechild, J. Mol. Biol., 2000, 299, 1035-1049.
9 J. Littlechild and E. Garcia-Rodriguez, Coord. Chem. Rev., 2003,
237, 65-76.
20 M. Almeida, S. Filipe, M. Humanes, M. F. Maia, R. Melo, N.
dependence of c(H O ) from other complex is also obtained
2
2
1
(
Figure S9). The detection limit value of the concentration H O
2 2
is estimated to be 1.019 mol/L for 1 and 1.098 mol/L for 2 by
extension of the line. All these observations further confirm that
the catalytic reaction system can be used as a potential method
for the detection of H O .
1
Severino, J. A. L. da. Silva, J. J. R. Frau´sto da Silva and R. Wever,
Phytochemistry, 2001, 57, 633-642
2
2
2
1 A. Colettia, P. Gallonia, A. Sartorelb, V. Contea and B. Florisa,
Catalysis Today, 2012, 192, 44-55.
2 N. Teshima, M. Kuno, M. Ueda, H. Ueda, S. Ohno and T. Sakai,
Talanta, 2009, 79, 517-522.
3 F. Natalio, R. Andre´, A. F. Hartog, B. Stoll, K. P. Jochun, R.
Wever and W. Tremel, Nat. Nanotechnol., 2012, 7, 530-535.
24 M. Sandy,J. N. Carter-Franklin, J. D. Martin and A. Butler, Chem.
Commun., 2011, 47, 12086-12088.
4
. Conclusion
2
In this work, by selecting appropriate ligands, two new
vanadium complexes have been successfully synthesized for the
first time. In order to investigate their applicability, we tested the
bromination reaction activities with phenol red as organic
substrate in the presence of H O , KBr, and a phosphate buffer
2
2
2
2
5 M. Kosugi, S. Hikichi, M. Akita and Y. Moro-oka, Inorg. Chem.,
solution to explore the model oxovanadium complexes
mimicking the active center of VHPO and the further study the
1
999, 38, 2567-2578.
2
6 M. Etiennc, Coord. Chem. Rev., 1996, 156, 201-236.
H O detection system which is simple and sensitive. We will
2
2
27 M. Herberhod, G. Frohmader, T. Hofmann and W. Milius, J.
investigate deeply the application of the vanadium complexes as
catalysts in the future.
Darkwa, Inorg. Chim. Acta, 1998, 267, 19-25.
8 G. M. Sheldrick. SADABS, Program for Empirical Absorption
Correction for Area Detector Data, University of Götingen, Götingen,
Germany, 1996.
2
Acknowledgements
2
9 G. M. Sheldrick. SHELX-97, Program for Crystal Structure
This work was supported by the grants of the National
Natural Science Foundation of China (Nos. 21571091,
Analysis, University of Gottingen: Gottingen, Germany, 1997.
30 E. Verhaeghe, D. Buisson, E. Zekri, C. Leblanc, P. Potin and Y.
Ambroise, Anal. Biochem., 2008, 379, 60-65.
2
1371086) and Guangxi Key Laboratory of Information
3
3
1 M. R. Maurya, Coord. Chem. Rev., 2003, 237,163-181.
2 A. Messerschmidt and R. Wever, Proc. Natl. Acad. Sci. U S A,
Materials, Guilin University of Electronic Technology, P.R.
China (Project No. 151002-K) for financial assistance for
financial assistance.
1
996, 93, 392-396.
33 S. Patra, S. Chatterjee, T. Kr. Si and K. K. Mukherjea, Dalton
Trans., 2013, 42, 13425-13435.
3
3
4 V. Conte and B. Floris, Inorg. Chim. Acta, 2010, 363, 1935-1946.
5 G. J. Colpas, B. J. Hamstra, J. W. Kampf and V. L. Pecoraro, J. Am.
References and notes
Chem. Soc., 1996, 118, 3469-3478.
6 G. Zampella, J. Y. Kravitz, C. E. Webster, P. Fantucci, M. B. Hall,
H. A. Carlson, V. L. Pecoraro and L. D. Gioia, Inorg. Chem., 2004, 43,
127-4136.
7 T. N. Mandal, S. Roy, A. K. Barik, S. Gupta, R. J. Butcher and S.
K. Kar, Polyhedron, 2008, 27, 3267-3274.
8 A. Pohlmann, S. Nica, T. K. K. Luong and W. Plass, Inorg.Chem.
Commun., 2005, 8, 289-292.
9 O. Bortolini, V. Conte, C. Chiappe, G. Fantin, M. Fogagnolo and S.
Maietti, Green Chem., 2002, 4, 94-96.
0 Z. Li, X. H. Zheng, Q. L. Sheng, Z. Y. Yang and J. B. Zheng, RSC
Adv., 2016, 6, 11218-11225.
1 H. H. Deng, G. W. Wu, D. He, H. P. Peng, A. L. Lin, X.H. Xia and
W. Chen, Analyst, 2015, 140, 7650-7656.
2 C. Perez, J. P. Monserrat, Y. Chen and S. M. Cohen, Chem.
1
2
3
4
J. C. Pessoa. Inorg. Biochem., 2015, 147, 4.
3
V. Conte, B. Floris, Inorg. Chim. Acta, 2010, 1935,1946.
V. Conte, B. Floris, Dalton Trans, 2011, 40, 1419.
N. Taniyama, Y. Ohki and K. Tatsumi, Inorg Chem., 2014, 53,
4
3
5
438-5446.
J. Kauppila, L. Lund, T. Laiho, M. Salomäki, J. Kankare and J.
Lukkari, J. Mater. Chem. C, 2014,2, 3602-3609.
F. Marchetti, C. Pettinari, C. D. Nicola, R. Pettinari, A. Crispini,
M. Crucianelli and A. D. Giuseppe, Appl. Catal., A 2010, 378, 211-220.
5
3
6
3
7
8
9
W. Plass, Coord. Chem. Rev., 2011, 255, 2378-2387.
S. H. Feng and R. R. Xu, Acc. Chem. Res., 2001, 34 (3), 239–247.
Z. Shi, S. Feng, S. Gao, L. R. Zhang, G. Y. Yang, J. Hua, Angew.
4
4
Chem., Int. Ed. 2000, 39(13), 2325-2327.
0 Z. Shi, S. Feng, L. Zhang, G. Yang, J. Hua, Chem. Mater. 2000,
2(10), 2930-2935.
1
4
1
Commun., 2015, 51, 7116-7119.
11 M. Schindler, F. C. Hawthorne, W. H. Baur, Chem. Mater. 2000,
1
2(5), 1248-1259.
Supplementary data
1
2 Z. M. Dai, Z. Shi, G. H. Li, D. Zhang, W. S. Fu, H. Y. Jin, W. Xu,
S. H. Feng, Inorg. Chem., 2003, 42, 7396-7402.
3 R. Zhang, J. Liu, C. Chen, Y. H. Xing, Q. L. Guan, Y. N. Hou, X.
Wang, X. X. Zhang and F. Y. Bai, Spectrochim. Acta, Part A, 2013, 115,
76-482.
4 R. Zhang, X. X. Zhang, F. Y. Bai, C. Chen, Q. L. Guan, Y. N. Hou,
X. Wang and Y. H. Xing, J. Coord. Chem., 2014, 67, 1613-1628.
5 X. D. Feng, X. X. Zhang, Z. N. Wang, J. Song, Y. H. Xing and F. Y.
Bai, New J. Chem., 2016, 40, 1222-1229.
6 C. Chen, Q. Sun, D. Ren, R. Zhang, F. Y. Bai and Z. Shi, Cryst.
Eng. Commun., 2013, 15, 5561-5573.
1
Figures of Infrared spectra, TG analysis, PXRD, UV-Vis
spectrum, hydrogen bonds of complexes, Coordination modes
and bond lengths (Å) range compare with other complexes,the
bond lengths (Å) and angles (°) are presented in the
supplementary material. CCDC: 1496249 and 1496250.
4
1
1
1

ACCEPTED MANUSCRIPT
•
•
Syntheses and crystal structures of two novel vanadium complexes
catalyze the bromination reaction of the organic substrate phenol red in the presence of
H O
2
2
•
detection of H O
2 2