Catalytic activity to lithium-thionylchloride battery of different transitional metal carboxylporphyrins

Article abstract of DOI:10.1142/S1088424614500011

The 5-(4-carboxylatomethoxy)phenyl-10,15,20-triphenyl porphyrin (H ₂Pp) and its transition metal complex (MPp, M = Zn²⁺, Co²⁺, Ni²⁺, Cu²⁺) were synthesized and characterized by IR, UV-vis, MS and elem

Full text of DOI:10.1142/S1088424614500011

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2014; 18: 290–296
DOI: 10.1142/S1088424614500011
Published at http://www.worldscinet.com/jpp/
Catalytic activity to lithium-thionylchloride battery of different
transitional metal carboxylporphyrins
Xiangfei Lüa,b, Nan jiang Huc, Jun Lia*, Zeng qi Zhanga and Wei Tangc
aKey Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of
Chemistry & Materials Science, Northwest University, Xi’an, Shaanxi 710069, PR China
bDepartment of Environmental Engineering, College of Resource and Environment Science, Shaanxi University of
Science and Technology, Xi’an, Shaanxi 710021, PR China
cDepartment of Process Equipment Control and Engineering, College of Light Industry and Energy, Shaanxi
University of Science and Technology, Xi’an, Shaanxi 710021, PR China
Received 22 October 2013
Accepted 14 December 2013
ABSTRACT: The 5-(4-carboxylatomethoxy)phenyl-10,15,20-triphenyl porphyrin (H2Pp) and its
transition metal complex (MPp, M = Zn2+, Co2+, Ni2+, Cu2+) were synthesized and characterized by IR,
UV-vis, MS and elementary analysis. Electrocatalytic effects associated with the reduction of thionyl
chloride in a lithium/thionyl chloride (Li/SOCl2) battery containing H2Pp and its transition metal
complex (MPp, M = Zn2+, Co2+, Ni2+, Cu2+) are evaluated by the relative energy of the battery and
discharge time. The results indicate that the energy of Li/SOCl2 battery catalyzed by CuPp and ZnPp is
103.7%, 106.3%, respectively, higher than that of Li/SOCl2 battery in the absence of the porphyrins. The
energy of Li/SOCl2 battery whose electrolyte contains NiPp and CoPp is similar to that of the cell in the
absence of these complexes. It shows that the electronic configuration of the central metal ion influences
a charge-transfer process during the reduction of thionyl chloride. With the increasing numbers of d
electrons of the central metal ion, the catalytic activity of MPps was enhanced. The ZnPp with electronic
configuration d10 of central metal ion exhibits relatively high catalytic activity.
KEYWORDS: transition metal carboxylporphyrin, lithium-thionylchloride battery, electrochemical
properties.
battery have been done to promote the practical energy
INTRODUCTION
of Li/SOCl2 battery [5–8].
There is an urgent need for developing efficient
One possible approach to enhance the cell perfor-
catalyst for lithium-thionylchloride battery since it is one
mance is the addition of catalyst molecules which
of the best primary batteries [1–3]. In spite of lithium-
must be readily oxidizable/reducible and accelerate the
thionylchloride battery with high discharge voltage and
rate of electron transfer. Among these works, using
energy density, its energy in practice that is much lower
macromolecular compounds, especially metal phthalo-
than in the theory is still one of limitations [4]. That is
cyanine (MPc) compounds acting as catalyst attracted
because the system consists of Li anode, a carbon cathode
considerableinterest[9–11]. Choiandco-workersreported
and a LiAlO4-SOCl2 electrolyte, and the Li anode is
on some Schiff base transitional metal compounds shows
prevented from reacting with SOCl2 via the formation
of LiCl passivation film and sulfur. The considerable
research efforts in the field of catalysis for Li/SOCl2
sizeable catalytic activity for the reduction of thionyl
chloride [12]. Xu et al., after comparing different transition
metal phthalocyanine, found the electronic configuration
of the central metal ion strongly influences the catalytic
activity of metal phthalocyanine to Li/SOCl2 battery. They
also predicted that the MPc derivatives whose central
*Correspondence to: Jun Li, email: junli@nwu.edu.cn, tel: +86
298-830-2604, fax: +86 298-830-3798
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CATALYTIC ACTIVITY TO LITHIUM-THIONYLCHLORIDE BATTERY OF DIFFERENT TRANSITIONAL
291
metal ions, such as Zn2+, of electronic configuration d10,
in KBr using a BEQ UZNDX-550. UV-vis spectra were
recorded by a Shimadzu UV-vis-NIR spectrophotometer
(UV-3100). Mass spectrometry analysis was carried out on
a matrix assisted laser desorption/ionization time of flight
mass spectrometer (MALDI-TOF MS, Krato Analytical
Company of Shimadzu Biotech, Manchester, Britain) using
a standard procedure involving 1 mL of the sample solution.
exhibit excellent catalytic activity to Li/SOCl2 battery
[13, 14]. However, MPc derivatives were difficult to be
purified during the preparation, which would reduce the
catalysis in the Li/SOCl2 battery.
Consideringporphyrinderivativeshavesimilarstructure
of phthalocyanine derivatives, high conjugated structure,
good thermal stability, excellent electron conductivity
and better solubility [15, 16]. Metal porphyrins are
much more environmental compatible compared with
metal phthalocyanines. The role of acidic functionality
is important for the process, as it could enhance the
catalytic activity of metal porphyrin in our several
repeated experiments. The solubility of carboxylporphyrin
may be better than that of the porphyrins containing non-
polar groups in thionyl chloride which showed stronger
adsorption to carboxyl group [17]. In addition, it has
been demonstrated that carboxyl is easy to promote the
formation of MPp·SOCl2 due to the lager p elongation
with low symmetry of carboxylporphyrin [18]. There are,
however, few works discussed or analyzed the factors that
affect the catalytic activity of the system in depth. In fact,
several factors have been proved to influence the catalytic
activity, including the center metal, the peripheral
substituents of porphyrin molecules and axial ligand
[19, 20]. In this paper, catalytic effects relative to thionyl
chloride reduction were examined by evaluating the
relative energy and discharge time in Li/SOCl2 solution
which contained different metal carboxylporphyrins. In
order to better define the influence of different central
metal ions, we focus on the analysis of the electronic
configuration of the central metal ion in the catalytic
activity of the metal carboxylporphyrin compounds.
Synthesis of porphyrin and metal(II) porphyrins
Synthetic routes to porphyrin (H2Pp) and metal
porphyrins (MPp) are shown in Scheme 1 and the
detailed synthetic procedures were as follows:
General procedure for the synthesis of carboxyl-
porphyrin (H2Pp). According to the method reported
previously[21],5-(4-carboxylatomethoxy)phenyl-10,15,-
20-triphenyl porphyrin was synthesized by carrying out
the hydrolysis of 5-(4-ethylacetatatomethoxy)phenyl-
10,15,20-triphenyl porphyrin. H2Pp. Yield 64%. mp:
250°C (decomposed). Anal. calcd. for C46H32N4O3%:
C, 80.21; H, 4.68; N, 8.13%. Found C, 80.15; H, 4.73;
N, 8.09%. UV-vis (CHCl3): lmax, nm 419, 516, 551, 591,
645. FT-IR (KBr): n, cm-1 3437, 2925, 2731, 2362, 1695,
1631, 1398, 1259, 1103, 1037, 966, 806, 680. MS (FAB):
m/z 689.66 (calcd. for [M + H]+ 689.66).
General procedure for the synthesis of MPp
(M = Zn2+, Co2+, Ni2+, Cu2+). 27.0 mg (0.15 mmol) of
M(CH3COO)2 (M = Zn2+, Co2+, Ni2+, Cu2+) was added to
0.05 mmol of the H2Pp dissolved in 20 mL CHCl3 and
5 mL C2H5OH. The mixture was stirred for 24 h at 60°C
and monitored by TCL until the complete disappearance
of the starting material H2Pp. The unreacted solid salt
was filtered and the solvent was removed under vacuum.
The crude product was purified by chromatography on a
silica gel column with CHCl3 and CH3COOH as eluent.
CuPp.Yield 92%, mp 250°C (decomposed). Anal. calcd.
for C46H30CuN4O3: C, 73.64; H, 4.03; N, 7.47%. Found
C, 73.67; H, 4.06; N 7.51%. UV-vis (CHCl3): lmax, nm
EXPERIMENTAL
Reagents and materials
The relative energy of Li/SOCl2 battery was used to
evaluate the catalytic activity of the complexes. LiAlCl4/
SOCl2 electrolyte(theconcentrationofLiAlCl4 is1.47M),
lithium pieces and carbon films were provided by Xi’an
Institute of Electromechanical Information Technology,
andotherreagentswerepurchasedfromTianJinChemical
Reagents Company. All solvents and reagents were used
without further purification except pyrrole was distilled
beforeusing. 5-(4-carboxylatomethoxy)phenyl-10,15,20-
triphenyl porphyrin (H2Pp) and metal porphyrins (MPp)
(M = Zn2+, Co2+, Ni2+, Cu2+) were synthesized according
to literature [21]. All chromatographic separations were
carried out on silica gel (180–200 meshes).
Equipment
Elemental analysis (C, H and N) was performed byVario
EL-III CHNOS instrument. FT-IR spectra were registered
Fig. 1. The structure diagram (a) and mode (b) of Li/SOCl2
battery
Copyright © 2014 World Scientific Publishing Company
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X. LÜ ET AL.
416, 540, 575. FT-IR (KBr): n, cm-1 3448, 2964, 2925,
1726, 1633, 1500, 1433, 1340, 1261, 1211, 1170, 1095,
1028, 802, 748, 703. MS (FAB): m/z 749.75 (calcd.
for [M + H]+ 749.75). ZnPp. Yield 95%; mp 250°C
(decomposed). Anal. calcd. for C46H30ZnN4O3: C, 73.46;
H, 4.02; N, 7.45%. Found C, 73.50; H, 4.06; N, 7.47%.
UV-vis (CHCl3): lmax, nm 421, 547, 585. FT-IR (KBr): n,
cm-1 3450, 2962, 2850, 1631, 1485, 1431, 1336, 1363,
1213, 1174, 1070, 999, 800, 752, 700. MS (FAB): m/z
751.82 (calcd. for [M + H]+ 750.16). CoPp. Yield 93%;
mp 250°C (decomposed).Anal. calcd. for C46H30CoN4O3:
C, 74.09; H, 4.06; N, 7.51%. Found C, 74.07; H, 4.09; N,
7.47%. UV-vis (CHCl3): lmax, nm 419, 541, 573. FT-IR
(KBr): n, cm-1 3728, 3444, 2925, 1631, 1409, 1080, 800,
675. MS (FAB): m/z 746.12 (calcd. for [M + H]+ 746.16).
NiPp. Yield 95%; mp 250°C (decomposed). Anal. calcd.
for C46H30NiN4O3: C, 74.12; H, 4.06. Found C, 74.19;
H, 4.02; N, 7.47%. UV-vis (CHCl3): lmax, nm 416, 539,
575. FT-IR (KBr): n, cm-1 3450, 2925, 1712, 1649, 1631,
1502, 1434, 1346, 1265, 1076, 1008, 800, 748, 696. MS
(FAB): m/z 745.79 (calcd. for [M + H]+ 745.17).
cells is made from PTFE material. Carbon films were
used as cathode with the superficial area of 1cm2, and
lithium pieces were used as the counter electrodes. 1mL
LiAlCl4/SOCl2 electrolyte solution containing 2mg metal
carboxylporphyrins was utilized. The discharge tests
for the Li/SOCl2 batteries were evaluated at a constant
resistance 40W, and were stopped when the voltage
reached 2V. All the experiments were implemented in
a glove box under an argon atmosphere (MBRAUN,
MB-BL-01). The structure diagram and mode of Li/
SOCl2 battery is shown in Fig. 1.
RESULTS AND DISCUSSION
Synthesis of the porphyrins
Thesyntheticrouteoftheporphyrinsandcorresponding
metal(II) carboxylporphyrins is illustrated in Scheme 1.
The insertion of metal ion into the porphyrin ring occurs
by reacting the metal-free porphyrin with excess hydrated
M(CH3COO)2 (M = Zn2+, Co2+, Ni2+, Cu2+) in the mixed
solvents of chloroform and acetic acid under 60°C.
The UV-vis spectra of H2Pp and MPps is shown in
Fig. 2. The UV-vis spectra of different MPps were
Electrochemistry
Electrochemical measurements were carried out in
specially designed test cells. The compartment of the
OCH2COOCH2CH3
OCH2COOC2H5
CHO
NH
N
N
BF3 Et2O
CHCl3, N2
DDQ
4
3
+
+
N
H
HN
CHO
OCH2COOH
OCH2COOH
NH
N
N
N
N
M
M(CH3COO)2
CHCl3, EtOH
HN
N
N
MPp(M = Cu2+, Co2+, Ni2+, Zn2+
)
H2Pp
Scheme 1. Synthesis routes of the porphyrins
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CATALYTIC ACTIVITY TO LITHIUM-THIONYLCHLORIDE BATTERY OF DIFFERENT TRANSITIONAL
293
Fig. 4. Relative energy of Li/SOCl2 battery catalyzed by the
metal-free porphyrins
Fig. 2. UV-vis spectra of MPp (M = H2, Cu2+, Co2+, Ni2+, Zn2+)
1 × 10-4 M (CHCl3)
Table 1. TheenergydataofLi/SOCl2 battery
catalyzed by the metal-free porphyrins
Catalyst
Uav, V
C
blank
H2Pp
CuPp
ZnPp
NiPp
CoPp
2.945
2.856
2.995
2.813
2.776
2.810
192.7
192.1
199.8
204.8
181.9
144.4
Mass spectroscopy data of MPps perfectly correspond to
the expected [M + H]+ m/z values. The principal change
in the FI-IR spectra of metal(II) porphyrins compared
with metal-free porphyrins is also the disappearance of
stretching vibration of N−H.
Fig. 3. The discharge curves of the Li/SOCl2 battery
investigated to show the electron transitions between
highest occupied molecular orbital (HOMO) and the
lowest orbital molecular orbital (LUMO) of the metal
carboxylporphyrins. The insertion of metal(II) into the
porphyrin ring caused a violet shift of the corresponding
Soret bands and Q-band for UV-vis spectra, as well as
a decreasing number of Q-bands, due to the symmetry
of the porphyrin ring increases when the H ions of N−H
are replaced by metal(II). There are a relatively strong
B-band and a weak Q-band existing in the electron
absorbance of MPp. To MPp, the stronger band in the
wavelength region of 410–420 nm ascribed to the p–p
transition centred on the macrocycle of porphyrin ring is
the Soret band. The UV-vis spectrum of MPp shows one
Q-band at 529–547 nm, representing the characteristic
band of different metal porphyrins. Compared to the free
carboxylporphyrin, the absorption of MPps indicated
different degree of red shift on Q-band. The Q-band of
ZnPp is at 547 nm, much longer than that of other MPps,
which may be benefit to the reduction of MPp·SOCl2.
Catalytic activity
The discharge curves of Li/SOCl2 battery catalyzed
by different MPps are shown in Fig. 3. It shows that the
catalytic activity of MPp is different, depending on the
metal ions. The battery’s discharge time is 15 min for
CuPp, 17 min for ZnPp, 15 min for NiPp, 11 min for
CoPp and 15.5 min for H2Pp. And the discharge time of
Li/SOCl2 battery catalyzed by metal phthalocyanines is
lengthened 6–12 min [15]. It is indicated that the catalytic
activity of the metal-porphyrins to Li/SOCl2 battery
is higher than that of metal phthalocyanines, when the
central metal ion is same. In order to explain the catalytic
activity of the compounds to Li/SOCl2 battery, the relative
energy of Li/SOCl2 battery was calculated as follows:
The average discharge voltage of Li/SOCl2 battery is:
U∆t
∑
=
(1)
Uav
∆t
∑
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CATALYTIC ACTIVITY TO LITHIUM-THIONYLCHLORIDE BATTERY OF DIFFERENT TRANSITIONAL
295
The energy of Li/SOCl2 battery is:
process of the reduction of SOCl2 catalyzed by MPp
(shown in Fig. 5). The possible routes are proposed
to show the three processes of the reduction of SOCl2
U2
Re
U2
Re
1
1
C = Pdt =
dt =
∆t =
U2 ∆t =
U2 ∆t
∑
∑
∑
∫
∫
Re
40
.
catalyzed by MPp and the reduction of MPp SOCl2
(2)
is the key step: (1) SOCl2 is adsorbed by MPp, and O
atom of SOCl2 coordinates to [M]2+ of MPp, an adduct
where P is the discharge power of the battery, Re is the
constant resistance, U is the voltage discharged in the test.
The relative energy of the battery is:
.
MPp SOCl2 is formed. (2) After that, there are different
.
possible routes that MPp SOCl2 succeeds catalyzing the
reduction of SOCl2. Diverse routes showed that different
.
numbers of electrons are accepted by MPp SOCl2, and
C
X(%) =
×100
(3)
.
MPp SOCl2 is reduced. (3) Finally, intermediates turn
C0
into MPp.
The overall catalytic activity of the compounds
to lithium battery depends on the competitive and
cooperative reduction process of MPp SOCl2. With
where C stands for the energy of the battery, C0 stands
for the energy of the battery in the absence of complexes.
The energy of Li/SOCl2 battery whose electrolyte
contains CuPp and ZnPp is approximately 103–106%
higher than that of the cell in the absence of complexes.
By contrast with three kinds of compounds above, H2Pp,
NiPp and CoPp are inactive, and the energy of the Li/
SOCl2 battery whose electrolyte contains them is similar
to that of the cell in the absence of complexes. The results
indicate that the electronic configuration of metal ions
([M]2+) is the key factor affecting the catalytic activity of
the compounds in Li/SOCl2 battery.
The relative energy(X) of Li/SOCl2 battery reflects the
catalytic activity of MPp clearly (as shown in Fig. 4).
It shows that the relative energy of Li/SOCl2 battery
catalyzed by CuPp and ZnPp is 103.7%, 106.3% higher,
respectively, than that of Li/SOCl2 battery in the absence
of complexes. These consequences are also listed in the
Table 1. Furthermore, this conclusion is well consistent
with the previous results of discharge curves.
.
the same peripheral substituents, the three routes are
primarily controlled by the electronic configuration of
the central metal ions of the compounds. Among the
catalysis process, the second step plays a predominant
role owing to that the electron configuration of central
metal. As to Zn2+Pp, whose configuration of d electron is
3d10 and have the great trend to stabilize square planar of
complex, so it will enhance the process of the formation
of [Zn+Pp]−, S, SO2 and Cl- during the reduction of Zn2+
Pp·SOCl2, therefore enhancing the catalytic reaction.
Cu2+Pp also has similar catalysis. Therefore, ZnPp and
CuPp exhibit excellent catalytic activity to Li/SOCl2
battery. But to Ni2+Pp and Co2+Pp, whose d electronic
configuration are 3d8 and 3d7, respectively and did
not have enough energy to stabilize square planar of
porphyrin, a series of intermediates MPp·SOCl2 cannot
immediately be reduced to MPp, Ni2+Pp and Co2+Pp are
inoperative as a result.
During the discharge of the Li/SOCl2 battery, the
electrode reaction of Li/SOCl2 battery is as follows:
Li = Li+ + e
(4)
(5)
SUMMARY
2SOCl2 + 4e = 4Cl- + SO2 + S
The influence of the electronic configuration of
the central metal ion on catalytic activity of metal
carboxylporphyrin to Li/SOCl2 battery has been shown
in this paper. The metal porphyrins with electronic
configuration d7 and d8 of the central metal ion are
inactive. The compounds (MPp) with electronic configu-
ration d9 and d10 of central metal ions, exhibit relatively
high catalytic activity as a result of the strong trend to
stabilize square planar of complexes during the reduction
In the above reaction, the Li+ ions around the lithium
electrode migrate to the carbon electrode surface and
react with the Cl- anion:
Li+ = Cl- = LiCl
(6)
Due to the low solubility of lithium chloride crystallite
in SOCl2 electrolyte, as the discharge goes on, the
amount of lithium chloride crystallite deposited on the
carbon electrode is increased. It can affect the electrode
kinetics of the cathode discharge reaction and also causes
a voltage delay owing to its overly passive nature. The
different metal porphyrins as possible catalysts affect the
rate of electron transfer in the above reaction.
Mechanisms of Li/SOCl2 battery catalyzed by metal
phthalocyanines and metal-porphyrins have been
demonstrated in some papers [22, 23]. On the basis of
the results and the mechanism of the catalytic reduction
by metal porphyrins demonstrated by Doddapaneni and
Bernstein, the possible routes are proposed to show the
.
of MPp SOCl2.
Acknowledgements
This research was financially supported by the
National Nature Science Foundation of China
(21271148), Scientific Research Program Funded by
Shaanxi Provincial Education Department (Program No.
2013JK0660), Natural Science Foundation of Shaanxi
province (2013JQ2026) and Shaanxi University of
Science and Technology Scientific Research Foundation
for doctor (BJ11-19).
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