A. Farokhi, H. Hosseini Monfared / Journal of Catalysis 352 (2017) 229–238
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ating voltage of 10 kV and the textural properties determined from
N2 adsorption isotherms measured on a Belsorp mini II (Japan)
instrument.
The manganese porphyrin was precipitated from the reaction med-
ium by adding HCl (15 mL, 0.10 mol dmÀ3) and cooling the reaction
flask in an ice bath. The precipitate was recovered by centrifuga-
tion and the supernatant, which contained DMF and excess man-
ganese(II) salt, was discarded. The target product, a dark purple-
colored solid, was obtained by washing with HCl (30 mL,
0.10 mol dmÀ3) and purifying by silica column chromatography.
Yield 76% (0.005 g). FT-IR (KBr, cmÀ1): 3427 (s, br, OAH), 2922
(w), 2852 (w),1731 (s, C@O), and 1655 (m, NAC@O). UV–Vis in
2.2. Synthesis of 5,10(or 15)-bis(4-carboxyphenyl)-15(or 10),20-bis(2-
nitrophenyl)porphyrin, H2TCPP-NO2
5,10-bis(4-carboxyphenyl)-15,20-bis(2-nitrophenyl)porphyrin
was synthesized according to the literature [19]. Nitrobenzene
(4.28 ml) and pyrrole (0.14 ml, 2.02 mmol) were added to the solu-
tion of 2-nitrobenzaldehyde (0.10 g, 0.66 mmol) and 4-
carboxybenzaldehyde (0.20 g, 1.36 mmol) in propionic acid
(10 ml). The reaction vessel was shielded from ambient light and
the mixture was heated at 120 °C for 1 h. The solvent was removed
and the solid porphyrin purified by column chromatography on sil-
ica with dichloromethane/acetone/acetic acid (8:2:0.1) as eluent.
The product was a purple colored solid. Yield 6% (0.03 g). UV–Vis
DMF: kmax (log e
, dm3 molÀ1 cmÀ1): 467 (2.96), 560 (2.30) and
605 (2.09).
2.6. Organofunctionalization of SBA-15 (SBA15-NH2)
Mesoporous SBA-15 was synthesized according to the proce-
dure described in the literature [21]. The SBA-15 was activated
under vacuum at 150 °C for 3 h [22]. The mixture of SBA-15 and
3-aminopropyl triethoxysilane (2.17 g, 9 mmol per 3 g of SBA-15)
in 100 cm3 of dry toluene was refluxed under nitrogen for 6 h. Then
Soxhlet extraction with dichloromethane (for 12 h) yielded the
white color NH2-functionalized SBA-15 material (SBA15-NH2). IR
(KBr, cmÀ1): 3441 (m, OAH), 1077 (vs SiAO), 810 (s), and 466 (s).
Anal. found for SBA15-NH2: C, 7.73; H, 1.90; N, 3.56.
in DMF: kmax (log e
, dm3 molÀ1 cmÀ1): 420 (5.34), 515 (4.72), 550
(4.61), 590 (4.51) and 645 (4.37). FT-IR (KBr, cmÀ1): 3433 (s, br,
OAH), 1695 (vs C@O), 1405 (m, CAO), 1244 (s, CAO), 1522 (s,
NO2), 1346 (s, NO2), and 1606 (m, C@C). The high frequency region
of the 1H NMR spectra shows the chemical shifts for pyrrole hydro-
gens (beta-H). 1H NMR (250 MHz, DMSO): d = À3.00 (s, 2H, NAH),
7.60–8.00 (m, 6H, Hb-nitro), and 8.10–8.84 (m, 16H, aryl; m, 2H,
Hb-carboxy). Anal. Calcd for C46H28N6O8: C, 69.69; H, 3.56; N,
10.60. Found: C, 70.33; H, 4.06; N, 10.89.
2.7. Synthesis of SBA15-[MnIII(TCPP-R⁄)Cl]
Covalent binding of the chiral Mn-porphyrin to SBA15-NH2 was
carried out according to a modified reported procedure [26]. In a
round bottom flask, the amino functionalized SBA-15 (0.31 g) and
dicyclohexylcarbodiimide (DCHC) (0.02 g) were suspended in
10 mL of N,N-dimethylformamide (DMF). The solution of [MnIII(-
TCPP-R⁄)OAc] (0.10 g) in DMF (5 mL) was added dropwise to the
suspension and the mixture was refluxed at 140 °C for 8 h. The
resulting solid was isolated and exhaustively washed sequentially
in a Soxhlet extractor with DMF, CH2Cl2 and methanol for remov-
ing the porphyrin bonded by electrostatic interactions to SBA15-
NH2. A brown colored solid product was obtained. Yield 0.405 g.
Anal. found for SBA15-[MnIII(TCPP-R⁄)Cl]: C, 16.93; H, 2.21, N,
3.65; Mn, 0.35%.
2.3. Synthesis of 5,10-bis(2-aminophenyl)-15,20-bis(4-
carboxyphenyl)porphyrin, H2TCPP-NH2
Reduction of the nitro groups of the porphyrin was performed
following a reported procedure with modifications [24]. The syn-
thesized H2TCPP-NO2 (0.10 g, 0.13 mmol) was dissolved in concen-
trated hydrochloride acid under nitrogen. After addition of tin(II)
chloride dihydrate (0.28 g, 1.26 mmol) the resulting green mixture
was stirred for 45 min at room temperature and then heated at
65 °C for 30 min. Then the mixture was cooled in ice to 0 °C, con-
centrated aqueous NH3 solution was added slowly to bring pH of
the mixture to 10. The product was extracted by addition of CHCl3
(40 mL) and stirring vigorously for 1 h; the procedure was repeated
twice. The organic fractions were combined, washed with water
and followed by filtration to obtain a dark purple solid. Yield 42%
2.8. Catalytic aerobic oxidation of hydrocarbons
(0.04 g). UV–Vis in DMF: kmax (log
e
, dm3 molÀ1 cmÀ1): 425
The oxidation of hydrocarbons was performed in a 25-mL
round-bottom flask equipped with a condenser in a thermostated
oil bath at 45 °C. In a typical experiment the flask was charged with
the suspension of catalyst SBA15-[MnIII(TCPP-R⁄)Cl] (10.0 mg; con-
(3.94), 515 (3.40), 550 (3.29), 590 (3.18) and 645/650 (3.04). FT-
IR (KBr, cmÀ1): 3422 (s, br, OAH), 3126 (NAH), 1730 (vs C@O),
1607 (m, C@C), 1387 (m, CAO), and 1269 (m, CAO). Anal. Calcd
for C46H32N6O4: C, 75.40; H, 4.40; N, 11.47. Found C, 77.00; H,
2.80; N, 10.55.
tains 63.7 lmol Mn), 5 mL acetonitrile, 0.10 g chlorobenzene as
internal standard, substrate and 5 mmol isobutyraldehyde. Dioxy-
gen was provided using an oxygen balloon. The reaction mixture
was stirred at 45 °C for 8 h. At appropriate intervals, aliquots were
removed and analyzed by GC-FID. The products were identified
with authentic samples and 1H-NMR spectroscopy.
2.4. Synthesis of chiral porphyrin, H2TCPP-R⁄
The solution of diethyl-2,3-O-benzylidene-L-tartrate (0.012 g,
0.041 mmol) and 5,10-bis(2-aminoophenyl)-15,20-bis(4-carboxy
phenyl) porphyrin (0.01 g, 0.014 mmol) in methanol was refluxed
for 2 h and resulting product was washed with water and dried
in air [25]. A dark purple colored oily product was obtained. Yield
15% (0.19 g). FT-IR (KBr, cmÀ1): 3426 (s, br, OAH), 2961 (w), 2780
(w), 1707 (shoulder, C@O), 1627 (m, C@C), 1405 (w, CAO), and
1261 (m, CAO).
3. Results and discussion
3.1. Synthesis of catalyst
The chiral porphyrin H2TCPP-R⁄ and immobilized [Mn(TCPP-R⁄)
Cl] on mesoporous SBA-15 were prepared according to Scheme 1.
5,10(or 15)-bis(4-carboxyphenyl)15(or 10),20-bis(2-nitrophenyl)
porphyrin (cis- or trans-isomer) (H2TCPP-NO2) was prepared
according to the method of Assis [19]. Analysis of the 1H- and
13C-NMR spectra (Figs. S1 and S2 in the ESI) suggests the presence
of the cis and trans isomers which are not possible to separate them
under the conditions used. According to the synthesis route
2.5. Synthesis of [MnIII(TCPP-R⁄)Cl]
Metalation of the porphyrin was performed by the method of
Alder under nitrogen [19]. The mixture of free base porphyrin H2-
TCPP-R⁄ (0.20 mmol) and 10 equivalents manganese(II) chloride
tetrahydrate (2.0 mmol) in DMF (15 mL) was refluxed for 7 h.