–1
that are vibrations at 1000-600 cm and 600-400 cm . The band at 550-600 cm is typical of the vibration of the Mo O
–1
–1
2
2
–1
entity formed by edge sharing MoO polyhedra building the orthorhombic α-MoO structure. The band at 995 cm is
6
3
–1
characteristic of the vibration of the Mo=O terminal bond [31, 32]. The dominant band at 860 cm is associated with the
vibration of Mo–O–Mo bridging bonds [33-35].
SEM images of the residues obtained by direct calcination of the nanostructures of compound 1 at 700°C shows the
formation of MoO nanoparticles (Fig. 9). As seen in Fig. 9, calcination of the compound obtained by the solvothermal
3
method and sample No. 1 (sonochemical method) yielded nanoparticles of molybdenum trioxide with diameters of 30-40 and
50-60 nm respectively. Calcination of sample No. 5 (sonochemical method) yielded a mixture of plates, rods, and nanoscale
particles while the use of the bulk complex, prepared by reflux, as a precursor afforded micro structures of MoO
3
accompanied by nanoparticles.
CONCLUSIONS
Methanol {2-[(2-hydroxy-1,1-dimethyl-ethylimino)-methyl]phenolato}dioxidomolybdenum(VI) complex (1) was
synthesized by sonochemical irradiation and the solvothermal method and their crystal structures were compared. Compound
1 was characterized by elemental analysis, powder XRD, FT-IR and UV-Vis spectroscopy, TG and DSC analyses. To prepare
compound 1, two methods were used: sonochemical and solvothermal. In the sonochemical method some parameters such as
the type of the solvent, concentrations of initial reagents, and the sonication time were examined and their effects on the
shape, morphology, and size of the structures were investigated. The type of the solvent affected the shape of compound 1, in
the 1:1 mixture of methanol and chloroform some nanorods were obtained, meanwhile in methanol nanoparticles of
compound 1 were obtained. The results show that the morphology and particle sizes of the structures depend on the
concentrations of initial reagents and the ultrasound irradiation time. The optimal size of compound 1 was obtained at
a concentration of 5 mmol in methanol: chloroform and 2.5 mmol in methanol. A decrease in the sonication time led to
a greater agglomeration in both types of solvents. Calcination of compound 1 at 700°C in a furnace and static air atmosphere
for 4 h yields molybdenum trioxide nanoparticles.
Support of this investigation by Vali-e-Asr University of Rafsanjan is gratefully acknowledged.
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