Crystal structure of meso-substituted pyrazolyl porphyrin complexes and their highly active catalyst for oxidation of alkylbenzenes

Article abstract of DOI:10.1002/aoc.4184

During the past few years, a great deal of effort has been devoted to the anchoring of catalytic oxidation. In this work, three new catalysts CuPp, MnPp and ZnPp by solvothermal methods with 5, 10, 15, 20-tetrakis(4-N-pyrazolyl)-phenyl porphyrin (H_2<

Full text of DOI:10.1002/aoc.4184

Received: 21 September 2017
DOI: 10.1002/aoc.4184
Revised: 22 October 2017
Accepted: 23 October 2017
F U L L P A P E R
Crystal structure of meso‐substituted pyrazolyl porphyrin
complexes and their highly active catalyst for oxidation of
alkylbenzenes
Yahong Yao1,2† | Yanxia Du1† | Jun Li1
| Chen Wang3 | Zengqi Zhang1 | Xin Zhao1
1 Key Laboratory of Synthetic and Natural
During the past few years, a great deal of effort has been devoted to the anchor-
ing of catalytic oxidation. In this work, three new catalysts CuPp, MnPp and
ZnPp by solvothermal methods with 5, 10, 15, 20‐tetrakis(4‐N‐pyrazolyl)‐phe-
nyl porphyrin (H2Pp) and the corresponding metal salts have been synthesized
and structurally characterized. The single crystal structures determined by X‐
ray diffraction show the bond distances of M‐N in porphyrin cores determined
the conformation of porphyrin rings. We explored the catalytic activity of CoPp,
CuPp, MnPp and ZnPp for oxidation of alkylbenzenes. The experimental results
display these products exhibit high catalytic activities and selectivities for oxida-
tion of ethylbenzene to acetophenone, and can be reused by filtration without
appreciable decrease in catalytic activity and selectivity.
Functional Molecule Chemistry of
Ministry of Education, College of
Chemistry & Materials Science, Northwest
University Xi'an, Shaanxi 710069, People's
Republic of China
2 College of Science, Xi'an University of
Architecture and Technology Xi'an,
Shaanxi 710055, People's Republic of
China
3 School of Chemical Engineering,
Northwest University, Xi'an, Shanxi
710069, People's Republic of China
Correspondence
Jun Li, Key Laboratory of Synthetic and
Natural Functional Molecule Chemistry of
Ministry of Education, College of
Chemistry & Materials Science, Northwest
University Xi'an, Shaanxi 710069, People's
Republic of China.
KEYWORDS
catalysis, crystal structure, metalloporphyrin, oxidation of alkylbenzene, porphyrin
Email: junli@nwu.edu.cn
Funding information
National Natural Science Foundation of
China, Grant/Award Number: 21671158
1 | INTRODUCTION
diverse functional materials, such as photonic devices
conductive polymers, chemical sensors, receptors for
Porphyrin and metalloporphyrin molecules with unique
electronic structures and chemical properties have been
extensively exploited as platforms for the study of syn-
thetic and potential application in a wide variety of fields
such as chemistry, physics, material science, engineering,
biology, and medicine.[1–5] Porphyrin as a typical func-
tional discotic molecule can be easily modified by periph-
eral substituents or insertion of metal ion into the
porphyrin ring.[6,7] Accordingly, they have been widely
explored as the building blocks for the construction of
selective catalysis, material for magnetic ordering, and
[8–13]
light‐harvesting materials,
especially as catalyst, a
variety of metalloporphyrins with different substituent
groups were synthesized and showed excellent catalytic
properties.[14–18] The first oxidation system with synthetic
metalloporphyrin as a catalyst was developed by Groves
and co‐workers in 1979.[19] Subsequently, numerous
reports on metalloporphyrin‐catalyzed oxidation systems
have appeared in the literature, as described in previous
reviews.[20–23]
Metal‐catalyzed selective oxidation of organic sub-
strates under mild conditions, with dioxygen, air or tert‐
†These authors contributed equally to this work.
Appl Organometal Chem. 2017;e4184.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4184

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YAO ET AL.
butylhydroperoxide as the sole terminal oxidant, is an
economic and green methodology for the synthesis of
epoxides, alcohols, ketones, and aldehydes.[24] Further-
distilled before use. Elemental analyses (C, H and N) were
performed by Vario EL‐III CHNOS instrument. UV‐vis
spectra were measured on a Shimadzu UV 1800 UV‐vis‐
NIR spectrophotometer. UV‐vis diffuse reflectance spectra
(DRS) were recorded on a Shimadzu UV‐3100 spectropho-
tometer by using BaSO4 as a reference. The fluorescence
spectrum was recorded at room temperature on a Hitachi
F4500 fluorescence spectrofluorometer with a xenon arc
lamp as the light source. FT‐IR spectra were obtained on
a BEQUZNDX‐550 spectrometer on samples embedded
in KBr pellets. Mass spectrometry (MS) analysis were car-
ried out on a matrix assisted laser desorption/ionization
time of flight mass spectrometer (MALDI‐TOF MS, Krato
Analytical Company of Shimadzu Biotech, Manchester,
UK). The X‐ray diffraction (XRD) patterns were recorded
on a Bruker D8 diffractometer using graphite monochro-
matic copper radiation (Cu Kα) at 40 kV, 30 mA over
the 2θ range from 20° to 80°. The crystallographic data
sets were collected on a Bruker SMART CCD diffractom-
eter with graphite monochromated Mo Kα radiation (λ =
0.71073 Å). Thermal Analysis (TGA) experiments were
carried out in N2 at a heating rate of 10 °C·min‐1 on a
NETZSCH STA 449C thermal analyzer instrument.
more,
the
catalytic
functionalities
of
the
metalloporphyrins can be easily achieved by modulating
catalytic‐active metal sites and tailoring the peripheral
environments of metalloporphyrins. Design different por-
phyrins and metalloporphyrins provide a new strategy for
seeking novel functional to catalyst. However, over the
last few decades, many catalyst of porphyrins or
metalloporphyrins have been reported with peripheral
substitutes commonly being carboxyl, pyridine or imidaz-
ole groups,[25,26] pyrazolyl‐functionalized porphyrins and
the influence of coordination metal atoms in center of
porphyrin ring on catalytic activity have rarely been
reported.
Our group has been working on the synthesis of differ-
ent metalloporphyrin to research these new materials for
their heterogeneous biomimetic catalysis over the past
several years. In this work, we synthesized and character-
ized four kinds of catalysts CuPp, MnPp and ZnPp by the
ligand 5, 10, 15, 20‐tetrakis (4‐N‐pyrazolyl) phenyl por-
phyrin (H2Pp) (Figure 1). We explored the best catalytic
conditions for ethylbenzene oxidation to acetophenone,
and used the optimal experimental conditions to study
the catalytic activity of CoPp, CuPp, MnPp and ZnPp for
alkylbenzenes oxidation. MnPp exhibits highly efficient
and selective catalytic for alkylbenzenes oxidation.
2.2 | Synthesis
5, 10, 15, 20‐tetrakis (4‐N‐pyrazolyl) phenyl porphyrin
(H2Pp) and CoPp was synthesized and characterized in
our previous report.[27]
2 | EXPERIMENTAL DETAILS
2.1 | Materials and methods
CuPp: Solvothermal reactions of Cu (OAc)2·4H2O
(7.51 mg, 30 mmol) and H2Pp (8.72 mg, 10 mmol) were
in DMF (5 ml) at 90 °C for 72 hours. After cooling down
to room temperature, purple bulk‐shaped crystals were
obtained. Yield 35.2%; Composition [Cu(C56H36N12)
(C2H7N)]). Anal. Calcd for C58H43CuN13: C, 68.69; H,
4.42; N, 18.44%; Found: C, 68.68; H, 4.40; N, 18.47%;
UV‐Vis (DMF) λmax: 428 nm, 549 nm, 604 nm; FT‐IR
(KBr): v, cm‐1, 3331, 2360, 1663, 1505, 1394, 1008, 941.
MnPp: MnPp was prepared from MnCl2·4H2O
(5.94 mg, 30 mmol) and H2Pp (8.72 mg, 10 mmol) accord-
ing to the procedures similar to that of compound CuPp.
Yield 36.5%. Composition {Mn[(C56H36N12)(DMF)2Cl]}.
Anal. Calcd for C62H50ClMnN14O2: C, 66.85; H, 4.54; N,
17.62%; Found: C, 66.87; H, 4.53; N, 17.61%; UV‐Vis
(DMF) λmax: 470 nm, 578 nm, 618 nm; FT‐IR (KBr): v,
cm‐1, 3327, 2360, 1646, 1512, 1399, 1002, 937.
All analytical reagents were purchased from commercial
sources and used without further purification expect pyr-
role N, N‐dimethyl formamide (DMF), which was
ZnPp: ZnPp was also prepared from Zn(OAc)2·2H2O
(5.58 mg, 30 mmol) and H2Pp (8.72 mg, 10 mmol) accord-
ing to aforementioned procedures. Yield 43.5%; Composi-
tion [Zn(II)(C56H36N12)]. Anal. Calcd for Zn [C56H36N12]:
C, 71.37; H, 3.85; N, 17.84%; Found: C, 71.35; H, 3.87; N,
17.84%; UV‐Vis (DMF) λmax: 429 nm, 562 nm, 604 nm;
FIGURE 1 Molecule structure of 5, 10, 15, 20‐tetrakis(4‐N‐
Pyrazolyl)phenyl porphyrin (H2Pp)

YAO ET AL.
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FT‐IR (KBr): v, cm‐1, 3429, 2349, 1646, 1529, 1394, 1193,
1048, 998, 937.
(0.005 mmol) and H2O (1.5 ml) was stirred at 80 °C for
20 h. when time up, the identity of the products was deter-
mined by gas‐chromatography (GC), compared with the
authentic samples analyzed under the same conditions.
The yield of products was also obtained by GC analysis
with a flame‐ionization detector (FID) using a capillary
SE‐54 column.
2.3 | X‐ray crystal structure analysis
The crystallographic data of CuPp and MnPp were col-
lected at 296 K by a Bruker SMART CCD diffractometer
with graphite monochromated Mo Kα radiation (λ =
0.71073 Å). Absorption corrections were applied using
SADABS program.[28] The structures were solved by direct
method and refined by full‐matrix least‐squares tech-
niques using the SHELXL‐97 program.[29] Anisotropic
thermal parameters were assigned to all non‐hydrogen
atoms. Hydrogen atoms were placed in geometrically cal-
culated positions. The crystal parameters of CuPp and
MnPp are given in Table 1. Selected bond distances and
angles are listed in Table S1.
3 | RESULTS AND DISCUSSIONS
3.1 | Crystal structures
CuPp crystallizes in the triclinic system with a space
group of P‐1. The asymmetric unit contains one Cu (II)
Pp‐complex and one dimethylamine molecule (DMF
decomposition) (Figure 2a). The copper atom resides at
the center of porphyrin macrocycle. The dihedral angles
between the neighboring pyrrole rings are 6.865(230)°,
2.4 | Catalytic oxidation procedure
All the oxidation reactions were carried out in a sealed
vial. A mixture of alkylbenzenes (1 m mol), tert‐
butylhydroperoxide (TBHP, 0.8 mmol), catalyst
TABLE 1 The crystal parameters of CuPp and MnPp
Compounds
CuPp
MnPp
Empirical formula
C58H43CuN13
C62H50ClMnN14O2
Formular weight
Wavelength(Å)
θ range (°)
Crystal system
Crystal size(mm)
T (K)
985.59
1113.55
0.71073
1.22‐25.04
Tetragonal
0.26 × 0.21 × 0.17
296(2)
0.71073
2.47‐25.10
Triclinic
0.24 × 0.21× 0.16
296(2)
Space group
a (Å)
P‐1
P4(3)
10.737(3)
15.388(4)
16.730(4)
102.176(5)
93.409(5)
90.779(5)
2696.2(12)
2
16.654(6)
16.654(6)
19.517(7)
90
b (Å)
c (Å)
α (°)
β(°)
90
γ (°)
V (Å3)
90
5413(4)
4
Z
Dcalc ((mg/m3)
1.24
1.366
F(0 0 0)
1022
2312
μ(mm‐1)
0.455
0.353
R1, wR2 [I >2σ(I)]
R1, wR2 (all data)
Goof(F2)
0.0972, 0.2802
0.1658,0.3392
1.029
0.0721, 0.2027
0.0979, 0.2345
1.044
FIGURE 2 (a) And (b) the coordination environment of cu(II)
and structure conformation of CuPp. (the hydrogen atoms are
omitted for clarity, cu, red; N, blue; C, gray)

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YAO ET AL.
4.827(244)°, 13.444(185)° and 11.717(231)°, respectively.
The peripheral four substituent groups extend along the
porphyrin plane and the angles between the two contra-
puntal pyrazolyl are 42.7951(230)° and 35.904(183)°,
respectively. The porphyrin macrocycle in CuPp displays
a distorted conformation (Figure 2b).
Analysis of the CuPp reveals that phenyl rings and
pyrazolyl ring could form weak C‐H···π contact as hydro-
gen donor. C‐H···π interactions (Figure S2, green dotted
line) between the phenyl C atom and pyrrole rings and
the C‐H···π (Figure S2, red dotted line) of pyrazole C atom
and adjacent porphyrin macrocycles interlink the mole-
cules to form 1D chain structure (Figure 3a). The
neighbouring chains connect by π···π interactions (green
dashed lines) between the pyrazolyl of two adjacent por-
phyrin rings to form 2D layer structure (Figure 3b). The
layers link each other by π···π interactions between por-
phyrin macrocycles to construct a 3D structure (Figure 3
c). The distances of C‐H···π interactions are in supporting
information (Figure S2).
FIGURE 3 (a) 1D chains structure of CuPp; (b) 2D layers
structure of CuPp; (c) 3D structure of CuPp. (the hydrogen atoms
are omitted for clarity; the C‐H···π and π···π interactions are
indicated by dotted lines)
FIGURE 4 (a) And (b) the coordination environment of Mn(III)
and structure conformation of MnPp. (the hydrogen atoms are
omitted for clarity, Mn, rose; N, blue; C, gray; cl, green)

YAO ET AL.
5 of 10
MnPp crystallizes in the tetragonal system with a
32.214(396)°, respectively. The porphyrin macrocycle in
MnPp displays a little distorted conformation (Figure 4b).
In the structure of MnPp, there are two kinds of C‐
H··π interactions and two kinds of hydrogen bonds. The
C‐H···π interactions are: the pyrazolyl C atom and adja-
cent porphyrin macrocycle and the hydrogen bonds are
Cl‐C···H bonds and Cl‐O···H bonds to construct a 3D
structure (Figure 5).
The bond distances from M (at the center of a
distorted nonplanar porphyrin macrocycle) to pyrrole N
are Cu‐N(1) 1.995(5) Å, Cu‐N(2) 1.979(6) Å, Cu‐N(3)
1.993(6) Å, Cu‐N(4) 1.996(6) Å in CuPp and Mn‐N(2)
2.013(2) Å, Mn‐N(4) 2.014(2) Å, Mn‐N(3) 2.020(2) Å,
Mn‐N(1) 2.021(2) Å in MnPp, respectively. This is differ-
ent from the literature,[27] the Co–N bond distances are
space group of P4 (3). The asymmetric unit contains the
MnPp‐complex and two DMF molecules (Figure 4a).
The manganese atom resides at the center of porphyrin
macrocycle, two chloric atoms coordinate with the man-
ganese atom and respective accounts for 1/2 of manga-
nese atoms, the manganese atom are trivalent in MnPp.
The bond distances from Mn(III) (at the center of a sad-
dle‐distorted nonplanar porphyrin macrocycle) to the Cl
atoms are 2.385(2) Å and 2.4619(14) Å, respectively. The
dihedral angles between the neighboring pyrrole rings
are 9.470(133)°, 7.891(146)°, 3.580(148)° and 5.862(107)°,
respectively. The peripheral four substituent groups
extend along the porphyrin plane and the angles between
the two contrapuntal pyrazolyl are 47.363(282)° and
FIGURE 5 (a) 1D chains structure of MnPp (b) 2D layers
structure of MnPp; (c) 3D structure of MnPp. (the hydrogen
atoms are omitted for clarity; the C‐H···π interactions are indicated
by dotted line)
FIGURE 6 (a) And (b) are the FT‐ IR and UV–vis spectras of
CuPp, MnPp and ZnPp in solid

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YAO ET AL.
Co‐N(1) 1.938(9) Å, Co‐N(2) 1.946(8) Å, Co‐N(3) 1.950(9)
Å, Co‐N(4) 1.948(9) Å in CoPp which are significant dif-
ference, and the angles between the two contrapuntal
pyrazolyl are 31.499(221) ° and 77.327(207) °, respectively.
Furthermore different size of Cu(II), Co(II) and Mn(III)
metal at the center of porphyrin macrocycle make differ-
ent the coordination model between metal ions and N
atoms, and then lead to change in geometry of the por-
phyrin molecule. The porphyrin macrocycle in MnPp
and CuPp displays a little distorted conformation due to
the size of copper (II) and manganese (III) ions and simi-
lar M–N distances. However, the smaller size of the cobalt
ion causes a considerable saddle‐type deformation of the
porphyrin ring in order to accommodate the shorter Co–
N coordination bonds. In the literature,[30] the Co–N bond
distances is range from 1.802(6)‐1.987(5) Å, the porphyrin
macrocycle is close to a perfect plane.
to 300 °C should be attributed to solvent molecules. With
the temperature increased, the curve is followed by a
steady platform up to 427 °C; after this, the network starts
to decompose. However, ZnPp exhibits a relatively steady
plateau up to 426 °C before decomposition of the network.
So that stable state can be maintained for the CuPp and
MnPp below 427 °C, and for the ZnPp below 426 °C.
The phase purity of CuPp, MnPp and ZnPp were ver-
ified by powder X‐ray diffraction studies, which have
revealed that the diffraction patterns of the fresh samples
are consistent with the simulated ones (Figure S5).
3.3 | The FT‐ IR spectra and solid‐state
UV–vis spectra
The FT‐ IR spectra of CuPp, MnPp and ZnPp showed sim-
ilar characters (Figure 6a), and a new band appeared
around 1000 cm‐1 was assigned to M‐N vibration, while
δ(NH) of the porphyrin ring bands at 972 cm‐1 were
absent in compounds CuPp, MnPp and ZnPp. The bands
ascribed to the stretching vibration of –C=N– at 1654,
1669, 1650 and 1645 cm‐1 were observed in the IR spectra
of H2Pp, CuPp, MnPp and ZnPp respectively. The UV–vis
spectra of CuPp, MnPp and ZnPp were examined in the
3.2 | Thermogravimetric and X‐ray power
diffraction (PXRD) analysis
Thermogravimetric analysis (TGA) was taken to examine
the thermal stability of the compounds. As can be seen in
Figure S4, a weight loss of the CuPp and MnPp from 25 °C
TABLE 2 Selective oxidation of ethylbenzene catalyzed by MnPp
Entry
Catalysta
T(°C)
[O]
Solventb
Yields(%)c
Selectivity(%)d
1
CoPp
80
TBHP
H2O
88
>99
2
CuPp
ZnPp
80
80
80
80
80
65
80
65
65
80
80
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
H2O2
H2O
79
56
99
27
6
>99
>95
>99
>90
>78
>99
>99
>78
>99
>99
>78
3
H2O
4
MnPp
H2Pp1
Blank
MnPp
MnPp
Blank
MnPp
MnPp
Blank
H2O
5
H2O
6
H2O
7
CH3CN
CH3CN
CH3CN
H2O
83
82
5
8
9
10
11
12
70
70
4
H2O
H2O2
H2O
Conditions:
amixture of catalyst (0.005 mmol), ethylbenzene (0.05 mmol), and oxidant (0.5 mmol);
b2.5 ml solvents;
cBased on GC analysis;
dSelective oxidation of ethylbenzene to acetophenone

YAO ET AL.
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solid state (Figure 6b) at room temperature. The UV–vis
spectrum of CuPp is characterized by a Soret band at
364 nm and only one Q band at 539 nm, there are one
Soret band at 456 nm and 370 nm, two Q bands at 574‐
614 nm and 554‐599 nm for MnPp and ZnPp, respectively.
The decreased number of Q bands in the spectra of
metalloporphyrins is owing to the symmetry increase of
porphyrin ring after metal ions coordinating with the N
atoms of porphyrin. The delocalized π bonds of ZnPp
and CuPp decreased the average electron density of the
porphyrin, which increased the energy for electron transi-
tion, leading to a blue shift in the Soret band. Further-
more Mn(III) ion insertion into the free‐base porphyrin
elicited a large bathochromic shift of the Soret band com-
pared with H2Pp (Soret band at 390 nm and four Q band
at 513‐644 nm), which might be attributed the charge
transfer between the a1u(π) and a2u(π) orbital of the por-
phyrin ring to the eg(dπ) orbitals of manganese (III) cen-
ter metal.[31,32]
To shed further light on the catalytic activities, time‐
dependent experiments were also carried out at different
time (within 30 hours). Figure 7a was the time‐yield plot
for the oxidation of ethylbenzene. It showed that these
catalysts exhibited strong catalytic activities. The yield of
acetophenone increased sharply at the beginning of
20 hours, and the increasing tendency of yield became
leveling off when exceeded 20 hours.
3.4.2 | Catalysts reuse
We assessed the catalytic activities and reuse of CoPp,
CuPp, MnPp and ZnPp according to the above selected
conditions. The results (Table 2) showed that these cat-
alysts efficiently catalyzed the conversion of ethylben-
zene to the only product acetophenone quantitatively
in 88%, 79%, 99% and 56% yield, respectively. After reac-
tion finished, solid CoPp CuPp, MnPp and ZnPp was
3.4 | Catalytic properties
3.4.1 | Conditions optimization
The optimal reaction conditions for ethylbenzene cataly-
sis were investigated by the influences of reaction temper-
ature, oxidant and solvent according to prior reports in
the literature.[33,34] A series of experiments was carried
out by choosing MnPp as catalyst, with the model test
for ethylbenzene oxidization. Blank experiments in the
absence of catalyst were carried out for easy comparison.
Table 2 are summarized the results catalyzed, it was obvi-
ous that four metalloporphyrins display much higher cat-
alytic activity than the molecular H2Pp catalyst for the
oxidation of ethylbenzene. The yield of acetophenone in
solvent of CH3CN with 83% conversion (Table 2, entry
7) were higher than that of in solvent of H2O (Table 2,
entry 10) at 65 °C. However, the activity was remarkably
improved in the solvent of H2O and almost the same in
solvent of CH3CN when the temperature rose to 80 °C,
corresponding to 99% and 82% conversion, (Table 2, entry
4 and 8) respectively. Furthermore, for a better under-
standing of the role of oxidant on the catalytic reaction,
different oxidant was investigated in solvent of H2O at
80 °C (Table 2, entry 4 and 11). The use of TBHP leads
to significantly higher yields compared with H2O2. From
these experiments, the optimal reaction conditions for
ethylbenzene oxidation to acetophenone was in solvent
of H2O at 80 °C using tert‐butylhydroperoxide (TBHP)
as the oxidant. Compare with the reported literature,[35]
the yield of acetophenone was increased by 22% in such
condition.
FIGURE 7 (a) Time‐yield plot for the oxidation of ethylbenzene
catalyzed by CoPp, CuPp, MnPp and ZnPp; (b) the yield after three
cycles. (conditions: The ethylbenzene oxidation was performed in solvent
of H2O at 80 °C using TBHP as the oxidant, yields determined by GC)

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YAO ET AL.
TABLE 3 Selective oxidation of alkylbenzenes catalyzed by the four complexes in H2O
Entry
Substrate
Product
Catalyst
Yields(%)
TON
Selectivity(%)
1
CoPp
86
1720
98
2
CuPp
ZnPp
MnPp
CoPp
CuPp
ZnPp
MnPp
CoPp
CuPp
ZnPp
MnPp
71
49
91
72
65
43
79
70
61
38
73
1420
980
85
82
99
98
99
86
99
99
99
82
99
3
4
1820
1440
1300
860
5
6
7
8
1580
1400
1220
760
9
10
11
12
1460
Conditions: Alkylbenzenes (0.1 mmol), TBHP (0.15 mmol), catalyst (0.005 mmol), H2O (2.5 ml) were stirred at 80 °C for 20 h. Conversion (%) and selectivity (%)
were determined by GC on an SE‐54 column.

YAO ET AL.
9 of 10
easily recovered by centrifuging and filtration and sub-
sequently used in successive runs with only slightly
decreased in catalytic efficiency. As showed in the
Figure 7b, the catalytic activity showed no obvious
decreased after three cycles.
synthesized and characterized. The distances of M‐N
bonds in center of the porphyrin rings determine the con-
formation of porphyrin macrocycle. The results of ther-
mogravimetric showed they possessed ideal thermo‐
stability. In addition, the higher catalytic efficiency
observed for MnPp in comparison with the CoPp, CuPp
and ZnPp. These results demonstrated that the metal
atoms in center of porphyrin macrocycle determine the
catalytic activity of metalloporphyrin, and the catalytic
activity order is MnPp>CoPp>CuPp>ZnPp.
3.4.3 | Catalytic oxidation of
alkylbenzenes
These complexes catalytic oxidation of alkylbenzenes
were examined according to a procedure similar to that
for the oxidation of ethylbenzene. GC analysis (Table 3)
displayed that the compounds efficiently catalyzed these
chemical transformations. MnPp was the highest catalytic
activity for alkylbenzenes oxidation, and their selectivity
were over 99% indicating the products were almost the
only one. The conversion of 1‐phenylpropane was as high
as 91% which was far more than that of diphenylmethane
and 1, 2, 3, 4‐tetrahydronaphalene. Followed by CoPp and
then CuPp, in which the conversions were slightly
decreased but the selectivity was still quite high and
maintained more than 98%. However, ZnPp showed low
catalytic activity compared to that for MnPp, CoPp and
CuPp, which alkylbenzenes oxidation yields for
alkylbenzenes reduced to about 40%.
ACKNOWLEDGEMENT
This work has been supported by the NNSF (No.
21271148), Scientific Research Program Funded by
Shaanxi Provincial Education Department (No.
15JK1736), Natural Science Foundation of Shaanxi prov-
ince (No. 2014JM2054) and Northwest University Scien-
tific Research Foundation (No. 12NW24).
ORCID
Jun Li http://orcid.org/0000-0002-1474-6239
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How to cite this article: Yao Y, Du Y, Li J, Wang
C, Zhang Z, Zhao X. Crystal structure of meso‐
substituted pyrazolyl porphyrin complexes and
their highly active catalyst for oxidation of
alkylbenzenes. Appl Organometal Chem. 2017;
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