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159
crystal data for the complex [VIVO(sal-HBPD)] was reported in our
previous publication [37].
transferred to the desired product (Scheme S1). After 6 h, the
yellow resultant solution was filtered and distilled under high vac-
uum to give a light yellow oil. Yield: 89%. Anal. Calcd (found) for
C10H10O2(%): C, 74.06 (74.09); H, 6.21(6.96). 1H NMR (ı, ppm in
DMSO): 10.42 (s, 1H), 7.71 (d, 1H), 7.61 (t, 1H), 7.18 (d, 1H), 7.06
(t, 1H), 6.09 (m, 1H), 5.46 (d, 1H), 5.30 (d, 1H), 4.71(s, 2H). FT-IR
(cm−1): 3430 ꢀ(O H), 1683 ꢀ(C N), 1620 ꢀ(C C).
2.3. Catalyst characterization
2.3.1. Instrumentation techniques for catalyst characterization
FT-IR spectra (700–30 cm−1 and 4000–650 cm−1) were obtained
on the PerkinElmer 400 ATR-FTIR spectrometer. Microanalysis was
carried out using Elementar Analysen Systeme Vario® MICRO VI
6.2 GmbH. The Gallenkamp melting point apparatus (temperature
range, 0–350 ◦C) was used to measure the melting points. The vana-
dium content was determined using a Thermo Electron (iCAP 6000
Series) inductively coupled plasma-optical emission spectrome-
ter (ICP-OES), and wavelengths with minimum interferences were
chosen (290.88 nm, 292.40 nm, 309.31 nm, 311.07 nm). The poly-
mer microspheres were imaged using a TESCAN Vega TS 5136LM
scanning electron microscope (SEM). Before images were taken;
the beads were coated with a thin film of gold to prevent surface
charging and to protect the surface material from thermal dam-
age by the electron beam. 1H NMR analysis of the ligands and
oxidation products was carried out on a Bruker NMR (400 MHz)
spectrometer (in DMSO-d6 solution). Thermogravimetric analysis
(TGA) was performed using Perkin-Elmer TGA 7 thermogravimetric
analyzer. Typically the samples were heated at a rate of 10 ◦C min−1
under a constant stream of nitrogen gas. The BET surface area
and porosity analysis for the microspherical beads was performed
using a Micromeritics ASAP 2020. Prior to analysis the beads were
degassed for 10 days at 120 ◦C. Atomic force microscopy (AFM)
imaging was performed using a CP-11 Scanning Probe Microscope
from Veeco Instruments in non-contact mode at a scan rate of
2 Hz using a MP11123 cantilever. X-ray photoelectron spectroscopy
(XPS) measurements were performed with a Kratos Axis Ultra X-
ray Photoelectron Spectrometer equipped with a monochromatic
Al K␣ source (1486.6 eV). The base pressure of the system was below
3 × 10−7 Pa. XPS experiments were recorded with 75 W power
source using hybrid-slot spectral acquisition mode and an angu-
lar acceptance angle of 20◦. XPS data analysis was performed with
Kratos version 2 program. EPR spectra were recorded on a Bruker
ESR 300E X-band spectrometer, and the spin Hamiltonian param-
eters were obtained by simulation of the spectra [40].
2.2.2. N,Nꢀ-bis(o-hydroxybenzaldehyde)phenylenediamine
momoner (allylSB)
1.0 g (0.0062 mol) of 3-allyl-2-hydroxybenzaldehyde and o-
phenylenediamine 0.33 g (0.0081 mol) were dissolved in 20 mL
of absolute ethanol. The mixture was heated with stirring at
50 ◦C for 3 h. After cooling to 0 ◦C overnight, formation of yel-
lowish needle-like crystals of N,Nꢀ-bis(o-hydroxybenzaldehyde)
phenylenediamine momoner (allylSB) was observed (Scheme S1),
and the needles were collected by filtration and dried in the
fume hood. Yield: 68%, mp: 151–153 ◦C. Anal. Calcd (found) for
C
26H24N2O2 (%): C, 78.76 (78.78); H, 6.10 (5.90); N, 7.07 (7.43). 1
H
NMR (ı, ppm in DMSO): 12.99 (s, 1H), 8.95 (s, 1H), 7.68 (d, 1H), 7.44
(m, 2H), 7.19 (d, 1H), 6.98 (t, 1H), 5.98–5.85 (m, 1H), 5.20 (s, 1H),
4.60 (s, 1H), 4.18 (d, 2H). FT-IR (cm−1): 3320 ꢀ(O H), 1663 ꢀ(C N),
1632 ꢀ(C C), 1158 (C O).
2.2.3. Poly[allylSB-co-EGDMA] beads
The functional monomer N,Nꢀ-bis(o-hydroxybenzaldehyde)-
phenylenediamine 4 g (0.01 mol), crosslinker ethyleneglycol
dimethacrylate
(EGDMA)
2 mL
(0.0075 mol)
and
azo-
bis(isobutyronitrile) (AIBN) 0.2 g (0.001 mmol) were stirred in
5 mL of toluene. In a separate 250 mL round bottom flask an
aqueous phase containing polyvinylalcohol (PVA) (0.025 g) and
NaCl (0.07 g) in 100 mL of water was stirred at 280 rpm. The
solution was warmed up to 70 ◦C to allow the dissolution of PVA
and NaCl. The organic phase was added dropwise to the aqueous
phase under constant stirring, and the reaction was allowed to
proceed for 24 h under an argon atmosphere (Scheme S1). The
mixture was cooled to room temperature and the resultant beads
were collected by filtration, washed with hot DMF and methanol
and then dried at 50 ◦C overnight. The beads were then sieved with
a mesh sieve of diameter ≤ 300 M to attain the required beads
diameter. Anal. found (%): C, 56.66; H, 7.47; N, 5.29. FT-IR (cm−1):
3410 ꢀ(O H), 1722 ꢀ(C O), 1645 ꢀ(C N).
2.4. Catalytic test
2.4.1. Metal content determination and leaching studies
2.2.4. Poly[allylSB-co-EGDMA]-VO beads
Vanadium content on the poly[allylSB-co-EGDMA]-VO beads
was determined by weighing out 0.025 g into a vial, and 10 mL of
TraceSelect HNO3 (69%) was added [41]. This mixture was heated
up to a temperature of 40 ◦C for 12 h to leach out the vanadium.
The acid-leached solution was then diluted with deionized-distilled
water to 100 mL, filtered with 0.45 M filters and analyzed by ICP-
OES. Vanadium leached during the oxidation reaction was also
determined in the same manner. However, the reaction prod-
ucts were evaporated to dryness before the acids were added for
digestion. The quantity of vanadium leached out from the poly-
mer matrix was determined by evaporating the solvents from the
reaction mixture followed by digesting with nitric acid. After appro-
priate dilutions, the vanadium content was determined by ICP-OES
Poly[allylSB-co-EGDMA] beads (2 g) were swollen in 30 mL of
DMF for 2 h. To this was added excess VOSO4·3H2O (1 g, 4.6 mmol)
in DMF (Scheme S1). The mixture was heated to 60 ◦C and
stirred overnight. The resultant blue–green beads were filtered and
washed several times with DMF and MeOH, and then dried at 50 ◦C
overnight. Anal. found (%): C, 48.44; H, 6.99; N, 4.20; V, 2.83. FT-IR
(cm−1): 1723 ꢀ(C O), 1659 ꢀ(C N), 957 ꢀ(V O), 419 ꢀ(V O),351
ꢀ(V N).
2.2.5. Synthesis of [VIVO(sal-HBPD)]
The unsupported vanadium complex [VIVO(sal-HBPD)] was syn-
thesized by dissolving [VIVOSO4] 0.16 g (0.001 mol) into a solution
of N,N-bis(o-hydroxybenzaldehyde)phenylene diamine (sal-HBPD)
Schiff base 1.28 g (0.004 mol) in 25 mL of methanol [37] (Scheme
S2). The reaction was allowed to proceed for 6 h at 50 ◦C. The pre-
cipitate formed was filtered and washed with excess methanol
and ethanol. The product [VIVO(sal-HBPD)] was then dried in a
desiccator over silica gel. Yield: 93.1%, mp: > 300 ◦C. FT-IR (cm−1):
1627 ꢀ(C N), 1161 ꢀ(C O), 990 ꢀ(V O). Anal. Calcd (found) for
2.4.2. GC-FID/MS conditions
Toward the determination of the initial and residual con-
centrations of the selected sulfur compound in the organics,
approximately 0.2 mL aliquots of liquid samples were withdrawn
from the reactor at fixed time intervals (30 min) and analyzed
using a gas chromatograph. Prior to analysis, GC conditions
were optimized to efficiently separate the products from the
reactants in the Zebron Phenomenex ZB-5MSi, capillary column
C40H34N4O9V2 (%): C, 58.83(60.28); H, 4.20(3.93); N, 6.86(6.87).
Further information regarding the synthesis, characterization and