F. Mehrjoyan and M. Afshari
Journal of Molecular Structure 1236 (2021) 130284
2
.2. Synthesis nano NiFe O4 supported phenanthroline Cu(II) complex
2
nickel ferrite MNPs were synthesized by the procedure re-
ported by Maaz et al. [27]. Then an amount of 2 g of the
NiFe O4 nanoparticle was poured into a 250 mL flask contain-
2
ing 50 mL of toluene and was sonicated for 30 min. After the
addition of 3-aminopropyletrimethoxysilane (7.94 mL), the mix-
ture was refluxed for 24 h at 100–110 °C. The resultant parti-
cles (MN@NH ) were separated magnetically, washed thoroughly
2
Scheme 1. Oxidation of 1-phenylethanol using MN@ [NH2–Cu(phen)2] catalyst.
with ethanol, and dried in a vacuum oven. The [Cu(phen) (Cl)] Cl
2
was prepared as previously described [28]. Finally, to synthesize
nano NiFe O4 supported phenanthroline Cu(II) complex, a mix-
2
plexes is the difficulty in product separation and catalyst recycla-
bility relative to heterogeneous catalysts. So in this investigation
in order to overcome these drawbacks, we supported copper(II)-
phenanthroline complex on nickel ferrite and use it as a new het-
erogeneous catalyst for selective oxidation of benzylic alcohols to
corresponding aldehyde (Scheme 1).
ture of MN@NH2 (0.5 g) and 25 ml solution of phenanthroline
Cu(II) complex (0.02 M) was stirred for 24 h. After the nanoparti-
cles were magnetically removed, the nanocomposites were washed
with water and dried under vacuum. A schematic representation of
MN@[NH2–Cu(phen) ] synthesis is shown in Scheme 2.
2
2
.3. Catalytic studies
2. Experimental
In a typical run,
a 25 mL round-bottom flask equipped
2
.1. Materials and methods
with a condenser and magnetic stirrer, was charged with:
MN@[NH2–Cu(phen) ] (0.04 g), benzylic alcohol (1 mmol), and
2
All chemicals were purchased from Sigma-Aldrich or Merck and
H2O2 (6 mmol). This suspension was heated in an oil bath at 50 °C
and the reaction was followed by GC. At the end of the reaction,
the reaction mixture was simply decanted by means of an external
magnet and was purified by silica-gel plate or a silica-gel column
to obtain the pure product. The identities of the products were
confirmed by FT-IR and 1H NMR spectral data.
used as received. Several techniques were employed to analyze and
validate the synthesized catalyst and products. X-ray diffraction
(
XRD) patterns were recorded with a CuKα radiation on a Rigaku
D/MAX RB XRD diffract meter equipped with a curved graphite
monochromator. FT-IR spectra were obtained using Perkin Elmer
BX II FTIR spectrometer. Magnetic properties of all nanoparticles
were measured by a vibrating sample magnetometer (VSM, Megh-
natis Daghigh Kavir Coumpany) at room temperature. The FESEM
images were obtained using a Hitachi Japan S4160 scanning elec-
tron microscope. The TEM images were recorded using a Philips
CM10-HT 100 KV transmission electron microscope. The content of
3. Results and discussion
3.1. Characterization of MN@ [NH2–Cu(phen)2]
The as-synthesized MN@ [NH2–Cu(phen) ] catalyst was charac-
2
copper of the MN@[NH2–Cu(Phen) ] catalyst was determined us-
terized by various techniques.
2
ing an ICP-AES instrument (HORIBAJobinYvon, Longjumeau Cedex,
France). First, the catalyst sample had been dissolved concentrated
hydrochloric acid and after filtration the aqueous solution had con-
verted to aerosols via a nebulizer. The aerosols were transported to
the inductively coupled plasma with argon flow rate of 12 L/min.
GC experiments were performed with a Shimadzu GC-16A instru-
ment using a 2 m column packed with silicon DC-200 or Carbowax
The FT-IR spectrum of MNPs is shown in Fig. 1a. In the
wavenumber range of 400–700 cm–1, two main broad metal–
oxygen bands are seen in the infrared spectra. The higher one ob-
served in the 595 cm–1, is caused by the stretching vibrations of
the tetrahedral metal–oxygen bond. The lowest band observed in
the range 416 cm 1, is caused by the metal–oxygen vibrations in
−
the octahedral sites. Two new a broad peak in the range of 1000–
1250 cm 1 corresponded to the Si–O stretch (Fig. 1b) [29]. The
−
2
0 m and Flame Ionization Detector (FID). Column temperature
was increased at the rate of 10 °C/min and nitrogen had been used
as a carrier gas. The products were identified through their reten-
tion times in comparison with authentic samples. Each peak of the
GC chromatogram was integrated and the actual concentration of
each component was obtained from the pre-calibrated plot of peak
area against concentration. 1HNMR spectra were recorded in CDCl3
on a Bruker Advanced DPX 400 MHz spectrometer.
O–H stretch vibration of surface hydroxyl groups and physico ab-
sorb water were present as broad peaks at 3000–3700 cm 1. The
−
presence of the anchored alkyl groups is confirmed by the aliphatic
−1
weak C-H stretching vibrations appearing at 2932 cm
(Fig. 1b).
The FT-IR spectrum of composite (Fig. 1d), shows the character-
−1
istic peaks at 720 cm
is assigned to the out of plane bend-
ing vibration of C–H bond on the heterocyclic rings. The bands at
Scheme 2. Schematic representation of the formation of MN@[NH2–Cu(phen)2] catalyst.
2