DESIGN OF DENDRIMERꢀBASED NANOSTRUCTURED CATALYST SYSTEMS
291
Nuclear magnetic resonance analysis was perꢀ
formed on an Avance Bruker spectrometer operating (C
IR, cm–1: 3310 (N–Hst in NH–C(=O)); 2925
Hst); 2860 (C–Hst, CH2–Nst); 1685, 1620, 1555
C–N–H ,
⎯
at a frequency of 400.13 MHz. Chemical shifts were (C=Ost in NH–C(=O)); 1480, 1455 (CH2
,
δ
presented on the
aqueous solutions, 3ꢀ(trimethylsilyl)ꢀ1ꢀpropaneꢀ NH–δC(=O); 990; 870 (N–H ); 765, 725 (CH2 , 625
sulfonic acid (DSS, 0.015) was used as a standard XPS, eV: 285.4 (C 1s, 74.6%), 399.3 (N 1s, 11.6%),
and D2O and DMSOꢀd6 were used as a solvent. The 530.4 (O 1s, 13.8%).
δ
scale relative to TMS (
0.00). For N–H ); 1370, 1335, 1255, 1210, 1175, 1040 (C–Nst iδn
δ
.
δ
γ
δ
purity of the initial dendrimers was determined by
mass spectrometry. The mass spectra were recorded
using an Agilent LCꢀMS 1100 SL instrument with an
electrospray ion (ESI) source in the positiveꢀion
detection mode. The samples were prepared by disꢀ
solving in methanol (99+%, Acros Organics) to have a
concentration of ~10 mg/ml. The spay needle voltage
was set at 3.5 kV. The temperature of the drying gas was
Nanoparticles were synthesized according to a
modified procedure [17].
Synthesis of DABꢀPPIꢀG3ꢀHMDI (1,2/1)ꢀ
Ru(1/8). A suspension of 200 mg of DABꢀPPIꢀG3ꢀ
HMDI(1,2/1) in 135 ml of distilled water and 100 mg
(0.48 mmol) of ruthenium(III) chloride were placed
into a 250ꢀml flask equipped with a condenser and a
magnetic stirrer. The suspension rapidly turned black.
The reaction was run at room temperature over 12 h.
At the end of reaction, the mixture was evaporated to
dryness in a rotary evaporator. The obtained powder,
together with 50 ml of ethanol and 10 ml of water, was
placed into a 100ꢀml flask with a magnetic stirrer and
a condenser. Sodium borohydride in an amount of 182
mg (4.8 mmol) was added to the resulting slurry. This
reaction was also conducted at room temperature over
12 h and was followed by drying in a rotary evaporator.
The obtained powder was washed twice with water and
ethanol and dried in air. The yield of the product (dark
grey powder) was 120 mg (48%).
300 С, and the flow rate was 10 l/min.
°
The Xꢀray photoelectron spectroscopy (XPS) study
of the samples was performed with a LASꢀ3000 instruꢀ
ment equipped with an OPXꢀ150 retardingꢀfield phoꢀ
toelectron analyzer. Photoelectrons were excited by
Xꢀrays from an aluminum anode (Al
K = 1486.6 eV)
at a tube voltage of 12 kV and an emisαsion current of
20 mA. Photoelectron peaks were calibrated by the C
1s carbon line with a binding energy of 285 eV.
Transmission electron microscopy (TEM) and
electron energy loss spectroscopy (EELS) studies of
the samples were performed on a LEO912 AB Omega
electron microscope.
XPS, eV: 285.2 (C 1s, 73.1%), 398.6 (N 1s, 14.6%),
462.4 (Ru 3p3/2, 0.5%); 531.7 (O 1s, 13.8%). UV–
≤
Vis: 9.45% Ru.
Synthesis of Catalysts
Synthesis of DABꢀPPIꢀG1ꢀHMDI (1,2/1)ꢀ
Ru(1/4). The synthesis was performed as described
above. The reactants DABꢀPPIꢀG1ꢀHMDI (1,2/1)
(87 mg) and RuCl3 (100 mg, 0.48 mmol) were mixed
with 20 ml of water. The isolated intermediate product
was suspended in a mixture of 25 ml of ethanol and
5 ml of water followed by reduction with sodium boroꢀ
hydride (182 mg, 4.8 mmol). The resulting black powder
product was obtained with a yield of 90% (122 mg).
XPS, eV: 280.6 (Ru 3d5/2); 282.2 (Ru 3d3/2); 285.0
(C 1s); 399.4, 402.6 (N 1s, 16.4%); 452.2, 460.2,
461.8, 463.4 (Ru3p3/2, 9.0%); 531.0 (O 1s, 74.6%).
UV–Vis: 34.6% Ru.
Ruthenium in the samples was quantified spectroꢀ
photometrically with an Agilent 8453 UV/Vis instruꢀ
ment [17]. First, a set of 10ꢀml aqueous calibration
solutions of RuCl3 with concentrations of 2.2, 2.9, 4.9,
and 7.5 mg/ml were prepared. Samples of DABꢀPPIꢀ
HMDI(1,2/1)ꢀRu(1/8) (2.5 mg) and DABꢀPPIꢀG1ꢀ
HMDI(1,2/1)ꢀRu(1/4) (1 mg) containing ruthenium
were treated with a mixture of 2 ml of concentrated
HCl and 2 ml of 50% hydrogen peroxide. The resulting
solutions were diluted with 6 ml of distilled water each.
A 15ꢀml portion of 0.01 M phenanthroline solution
was added to each of the calibration and sample soluꢀ
tions, and the solutions acquired an emerald green
color. After that, 10 ml of water and 100 mg hydroxyꢀ
lamine hydrochloride were added to each solution and
1
Synthesis of DABꢀPPIꢀHMDI (1,2/1) . A 0.56ꢀg
portion of DAB(NH2)16 (0.33 mmol) and 120 ml of
absolute THF were placed into a 250ꢀml flask
equipped with a condenser and a magnetic stirrer.
Under these conditions, the dendrimer swelled but did
not dissolve. After that, 500
ethylene diisocyanate was added to the flask with conꢀ
tinuous stirring. The reaction was run at 70 over
12 h followed by evaporation of the solvent at 50 in
μ
l (3.19 mmol) of hexamꢀ
°
С
°
С
a rotary evaporator. The product was obtained in the
form of a milkꢀwhite powder with a yield of 1 g (91%).
IR, cm–1: 3320 (N–Hst in NH–C(=O)); 2940 (C–
Hst); 2855 (C–Hst, CH2–Nst); 1770, 1620, 1570
(C=Ost in NH–C(=O); 1480, 1460 (N–H , CH2 ;
C–N–H ); 1440 (CH2, ); 1350, 1340, 1250, 1165,
1070, 1030 (C–Nst in NH–C(=O); 990; 735 (CH2 );
640. XPS, eV: 284.9 (C 1s, 71.4%), 398.7 (N 1s,
16.3%), 530.2 (O 1s, 12.3%).
Synthesis of DABꢀPPIꢀG1ꢀHMDI (1,2/1). The
reaction was conducted according to the same proceꢀ
dure. The reactants were DAB(NH2)4 (500 mg,
1.58 mmol) and hexamethylene diisocyanate
(0.61 ml, 3.8 mmol) in 50 ml of absolute THF. The
product in the form of white powder was obtained with
a yield of 1 g (88%).
δ
δ
δ
δ
γ
1
The total NCO/NH ratio was 1.2 : 1.
2
PETROLEUM CHEMISTRY Vol. 50
No. 4
2010