an active and recyclable catalyst for reduction and oxidation reactions

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peroxydisulfate (NH4)2S2O8 were purchased from Wako Pure Chemical Industries Ltd. 1,4-. Naphthquinone, 2-methyl-1,4-naphthoquinone, 2-hydroxy-1,4- ...

Electronic Supplementary Material (ESI) for ChemComm. This journal is © The Royal Society of Chemistry 2017

Supporting Information

Tuning the Redox Potential of Vitamin K3 Derivatives by Oxidative Functionalization Using Ag (I)/GO Catalyst S. I. El-Hout,a,b H. Suzuki,b S. M. El-Sheikh,a H. M.A. Hassan,c F. A. Harraz,a I.A. Ibrahim,a E. A. ElSharkawy,c S. Tsujimura,d M. Holzinger,e,f and Y. Nishina,b,g*

Nanostructured Materials and Nanotechnology Division, Central Metallurgical Research and Development Institute (CMRDI), P.O. 87 Helwan, Cairo 11421, Egypt.

a

Research Core for Interdisciplinary Sciences, Okayama University, 3 -1-1, Tsushimanaka, Kita-ku, Okayama 700-8530, Japan. b

c

Department of Chemistry, Faculty of Science, Suez University, Suez, Egypt.

Division of Materials Science, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan d

e

Univ. Grenoble Alpes DCM UMR 5250, Grenoble, France

f

CNRS, DCM UMR 5250, F-38000 Grenoble, France

Graduate School of Natural Science and Technology, Okayama University, 3 -1-1, Tsushimanaka, Kita- ku, Okayama 700-8530, Japan. g

* E-mail: [email protected] (Yuta Nishina)

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1. Materials KMnO4, H2SO4, H2O2, HCl, propionic acid, activated alumina, N,N-dimethyl formamide (DMF), potassium peroxydisulfate (K2S2O8), oxone monohydrate, and ammonium peroxydisulfate (NH4)2S2O8 were purchased from Wako Pure Chemical Industries Ltd. 1,4Naphthquinone, 2-methyl-1,4-naphthoquinone, 2-hydroxy-1,4- naphthoquinone, glutaric acid, benzoic acid, p-toluic acid, 4-trifluoromethyl benzoic acid, n-octanoic acid, 3-phenyl propionic acid, and di-tertbutyl peroxide were purchased from Tokyo Chemical Industries Co., Ltd. Silver nitrate (AgNO3), activated carbon (60-100 mesh), synthetic graphite and acetonitrile were purchased from Sigma-Aldrich Co. Acetic acid, propionaldehyde, and dimethyl sulfoxide were purchased from Nacalai Tesque, Inc. 1-Propanol was purchased from Kishida Chemical Co., Ltd. These materials were used without further purification.

2. Characterization tools X-ray diffraction (XRD) patterns were recorded by PANalytical X’Pert-ProMPD using Cu-Kα radiation (= 0.15406 nm) from 2θ = 2–75  at current 45 mA and voltage 40 kV. The XPS analysis was performed on JPS-9030, JEOL using a monochromatic Al -Kα Xray source at 1486.6 eV and operated at 300 W, 12 kV and 25 mA with a base pressure in the XPS analysis chamber of 7×10−8 Pa (5×10−10 Torr). Raman scattering was carried out using single monochromator with a diode pumped single frequency laser and Peltier cooled CCD camera (JASCO, NRS5100). Wavelength and power of laser are 532 nm and 5.7 mW, respectively. The polarized incident beam was focused onto the sample’s surface by objective lens (×100). The spectral resolution was 1.8 cm-1. Transmission electron microscope (TEM) images were recorded using a JEOL JEM-2100F at an acceleration voltage of 200 keV by dispersing a sample in ethanol and dropped on a 200-mesh Cu grid. FT-IR spectra for the new compounds were recorded by IR Tracer-100 FT-IR spectrophotometer, Shimadzu in the range of (4000-400) cm -1. Zeta potential was analyzed by Otsuka Electronics ELSZ-2000. Samples were dispersed in water by sonication for 10 min before analysis. The Ag concentration was analyzed by atomic absorption spectroscopy using a Shimadzu AA-6300 spectrometer and calibrated with 0, 0.05, 0.1, 2

and 0.15 μM of a standard aqueous Ag nitrate solution. The electrochemical experiments were conducted using a Solartron SI1287 electrochemical interface in a three-electrode system using a glassy carbon electrode as a working electrode, a Pt wire as a counter electrode, and Ag/AgCl electrode as a reference electrode. The cyclic voltammetry (CV) measurements were conducted within a designated potential window at 10 mV/s scan rate. Reaction products were investigated by 1H nuclear magnetic resonance (1H-NMR) using a Varian NMR System 600 MHz using CDCl3 as solvent and tetramethylsilane as internal reference. The new compounds were further characterized using 13C NMR spectroscopy by a Varian NMR System 150 MHz using CDCl3 solvent and a tetramethylsilane as an internal reference. High-resolution Mass Spectra (HR-MS) were measured by JEOL JMS700.

4. Experimental Section 4.1. Preparation of graphene oxide Graphene oxide (GO) was synthesized from graphite by the modified Hummers and Offeman method 1. Typically, 3 g graphite (SP-1) in 150 ml H2SO4 (95%) was stirred for 3 h at 0 °C then 15 g KMnO4 was added slowly with stirring at the same temperature for another 3h. After this, the mixture was heated to 35 °C and stirred for 2 h. The reaction was quenched by adding to ice under harsh stirring for 1h followed by adding 100 ml H2O2 (30 %) slowly with stirring. The solution was washed with 300 ml 10 % HCl, stirred for 30 min and then centrifuged, washed several times using distilled water, and finally, dried at 50 °C under vacuum overnight.

4.2. Preparation of Ag (I)/ GO catalyst The catalyst Ag (I)/GO was synthesized by dispersion of 1 wt. % of GO in 1 ml distilled water for 30 min followed by adding 0.025 mmol AgNO3 and stirring the mixture for 2 h.

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4.3. General procedure for Functionalization of 1,4-Naphthoquinones 0.25 mmol of 2-methyl-1,4-naphthoquinone (1a) and 0.75 mmol (3 equiv.) of propionic acid (2a) in 2 ml acetonitrile (CH3CN) were added to the Ag (I)/GO catalyst solution and then the reaction mixture was stirred, heated to 65 °C. A solution of (NH4)2S2O8 in 1 ml distilled water over a period of 30 min was slowly added to this solution and the stirring continued at this temperature for another 3 h. After completion of the reaction, the reaction mixture was diluted with water (4 ml) and ethyl acetate (10 ml) followed by removing the catalyst using silica gel column and ethyl acetate as eluent and evaporated under vacuum to get the product which analyzed by GC-MS. The recyclability of Ag (I)/GO catalyst was tested by adding 1M NaOH solution slowly to the reaction mixture with stirring for 2 h. Then, filtration of the mixture and washing by CH3CN followed by drying the catalyst in air, at that moment it will be ready for the next run. After each run, the catalyst was removed by the same procedure. 4.4. Electrochemical test using cyclic voltammetry The electrochemical properties of the prepared 1,4-naphthoquinone derivatives were investigated by CV in a three-electrode cell using a glassy carbon electrode (GCE) as a working electrode, Pt wire as a counter electrode, and Ag/AgCl as a reference electrode. The electrochemical studies were performed in an aqueous electrolyte solution composed of compound 3 (0.1 M) and phosphate buffer solution (PBS) at pH 7. The CVs were measured at a scan rate of 10 mV/s.

5. Structural analysis of Ag/GO 5.1. Characterization of Ag (I)/GO catalyst The phase, relative crystallinity, and crystal size of the fresh and reused Ag (I)/GO catalyst were characterized by using XRD in the range 2θ from 5 to 75 as shown in Fig. S1. The XRD pattern shows a typical AgNO3 structure corresponding to JCPDS 43-0649 2.

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Fig. S1. XRD of the Ag (I)/GO catalyst.

The presence of Ag ions on GO surface was further examined by XPS. Two peaks located at 373.9 and 367.9 eV are assigned as Ag3d5/2 and Ag 3d3/2, which belong to Ag+ of Ag(I)/GO catalyst (Fig. S2c).

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Fi g. S2. XPS spectra (a), (b), and (c) are the full scan, C1s, and Ag 3d for Ag(I)/GO catalyst, respectively.

Additional information about the structure of graphene can be extracted from the Raman spectrum. Fig. S4 shows the Raman spectra of the Ag (I)/GO catalyst. Both the position and intensity of D and G bands are highly susceptible to the structural changes of the carbon matrix, and there are several factors affecting the position and intensity of D and G bands, such as doping, layer numbers, defects, strains, substrates, etc.3 The peaks appeared at 1350 and 1592 cm−1 were attributed to sp3 (D band) and sp2 (G band) hybridization carbon atoms, respectively. In addition, the peak at 556 cm−1 ascribed to the modes in Ag+ suggesting the presence of Ag (I) on the surface of GO. The ratio of D band and G band (ID/IG) is an indicator of the defects present on graphene structure. The ID/IG ratio of the Ag 6

(I)/GO catalyst was found to be 1.02.

Fig. S3. Raman spectra for Ag (I)/GO catalyst

Table S1. Zeta potential analysis of fresh and recovered Ag (I)/ GO catalyst. Zeta potential (mV) Fresh Ag (I)/ GO

-32.83

Recovered Ag (I)/ GO

-25.09

6. Screening of the reaction conditions We studied the effect of catalyst dose on the product yield of alkylation of 1a as shown in Table S2. By using 0.05 equiv. of Ag (I) ions in catalyst, it gave 50 % yield of product 3a (Entry 1) which increased to 92 % by increasing the conc. of Ag (I) ions to 0.1 equiv. (Entry 2). Further increasing in the conc. of Ag (I) ions leads to 7

decreasing the product yield to 38, 30 and 27 % (Entries 3-5) at concentrations 0.2, 0.3 and 0.5 equiv., respectively. A yield product of 83 % was achieved by using AgOAc as Ag (I) precursor while duplicating the amount of GO to 2 wt% has no effect on the yield (Entries 6 and 7). It is clear that Ag (I) ions are the active species in this reaction where the yield decreased to 23 % by using metallic Ag on GO instead of Ag (I) ions (Entry 8). We carried out the reaction in presence of AgNO3 only which produced 58 % of 3a whereas, performing the reaction in the absence of Ag (I) ions and using GO as catalyst, traces of 3a was formed and this observation directed us to understand the importance of both Ag (I) and GO where physical adsorption of Ag (I) ions with the oxygen functional groups on GO surface may enhance the product yield of this reaction (Entries 9 and10).

Table S2. Optimization of catalyst dosing.a O

O

+

Ag(I)/GO (Ag: x mol%)

HO O

O

1a

Entry

2a (3.0 equiv.)

(NH4)2S2O8 (2 equiv.) H2O/CH3CN, 65 °C, 3 h

O

3a

Catalyst dose

Conversion of 1a (%)

Yield of 3a (%)b

1

Ag (I) / GO (Ag: 5 mol%)

90

50

2

Ag (I) / GO (Ag: 10 mol%)

95

92

3

Ag (I) / GO (Ag: 20 mol%)

100

38

4

Ag (I) / GO (Ag: 30 mol%)

99

30

5

Ag (I) / GO (Ag: 50 mol%)

100

27

6

Ag (I) / GO (Ag: 10 mol%)c

97

83

7

Ag (I) / GO (Ag: 10 mol%)d

94

81

8

8

Ag/ GO (Ag: 10 mol%)

97

23

9

AgNO3 (Ag: 10 mol%)

99

58

10

GO (Ag: 0 mol%)

76

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