Electronic Supporting Information

Transcription

1 Electronic Supporting Information Decorating Single Layer Graphene xide with Electron Donor and Acceptor Molecules for Photoinduced Electron Transfer Sushanta K. Das, a Chandra B. KC, a Kei hkubo, b Yasuke Yamada, b Shunichi Fukuzumi b,c,* and Francis D Souza a,* a Department of Chemistry, University of orth Texas, 1155 Union Circle, #305070, Denton, TX , United States; Francis.dsouza@unt.edu b Graduate School of Engineering, saka University, ALCA, Japan Science and Technology Agency (JST), Suita, saka , Japan; Fukuzumi@chem.eng.osaka-u.ac.jp c Department of Bioinspired Science, Ewha Womans University, Seoul, , Korea S1

2 Weight % Temperature ( o C) Fig. S1. TGA plot of ZnPc-SLG-C 60 hybrid. S2

3 1.0 (ii) Raman Intensity (i) Wavenumber (cm -1 ) Fig. S2. Raman spectrum of (i) pristine SLG and (ii) ZnPc-SLG-C 60 hybrid, λ ex = 532 nm. S3

4 Fig. S3. Differential pulse voltammograms of the (a) ZnPc-SLG-C 60, (b) ZnPc-SLG, and (c) SLG-C 60 hybrids in DCB containing 0.1 M (TBA)Cl 4. S4

5 Fig. S4. Femtosecond transient absorption spectra of ZnPc-SLG-C 60 hybrid in DMF by the 390 nm laser. The right panel shows time profile monitored at 1000 nm. S5

6 Fig. S5 Femtosecond transient absorption spectra of ZnPc-SLG hybrid in DMF by the 390 nm laser. The right panel shows time profile monitored at 680 nm. S6

7 Chemicals. SLG was purchased from Graphene Supermarket, Calverton, Y while C 60 was purchased from SES research, Houston, TX. All of the reagents were from Aldrich Chemicals (Milwaukee, WI) while the bulk solvents utilized in the syntheses were from Fischer Chemicals. Tetra-n-butylammonium perchlorate, (n-bu 4 )Cl 4 used in electrochemical studies was from Fluka Chemicals. All the chromatographic materials and solvents were procured from Fisher Scientific and were used as received. All the chromatographic materials and solvents were procured from Fisher Scientific and were used as received. Spectral Measurements. The UV-visible spectral measurements were carried out either on a Shimadzu Model 2550 double monochromator UV-visible spectrophotometer or a Jasco V-670 spectrophotometer. The steady-state fluorescence spectra were measured by using a Horiba Jobin Yvon anolog UV-visible-IR spectrofluorometer equipped with a PMT (for UV-visible) and InGaAs (for IR) detectors. A right angle detection method was used for emission measurements. The 1 H MR studies were carried out on a Varian 400 MHz spectrometer. Tetramethylsilane (TMS) was used as an internal standard. Differential pulse voltammograms were recorded on an EG&G 263A potentiostat/galvanostat using a three electrode system. A platinum button electrode was used as the working electrode. A platinum wire served as the counter electrode and an Ag/Ag + electrode was used as the reference electrode. All the solutions were purged prior to electrochemical and spectral measurements using argon gas. Sample preparation for TGA and Raman experiment: Thermogravimetry analysis was run using a Texas Instruments TGA Q50 instrument. All the samples for the analysis were dried under vacuum. Ramp test were performed under nitrogen atmosphere at 10 o C/min in a tungsten pan. The Raman spectra were measured using Enwave ptronics, Inc., ProRaman-L instrument with 532 nm laser source. All samples for Raman experiment were dried before analysis. Time-resolved Transient Absorption Measurements. Femtosecond laser flash photolysis was conducted using a Clark-MXR 2010 laser system and an optical detection system provided by Ultrafast Systems (Helios). The source for the pump and probe pulses were derived from the fundamental output of Clark laser system (775 nm, 1 mj/pulse and fwhm = 150 fs) at a repetition rate of 1 khz. A second harmonic generator introduced in the path of the laser beam provided 410 nm laser pulses for excitation. A 95% of the fundamental output of the laser was used to generate the second harmonic, while 5% of the deflected output was used for white light S7

8 generation. Prior to generating the probe continuum, the laser pulse was fed to a delay line that provided an experimental time window of 1.6 ns with a maximum step resolution of 7 fs. The pump beam was attenuated at 5 mj/pulse with a spot size of 2 mm diameter at the sample cell where it was merged with the white probe pulse in a close angle (<10 ). The probe beam after passing through the 2 mm sample cell was focused on a 200 mm fibre optic cable, which was connected to a CCD spectrograph (cean ptics, S2000-UV-vis for visible region and Horiba, CP-140 for IR region) for recording the time-resolved spectra ( and nm). Typically, 5000 excitation pulses were averaged to obtain the transient spectrum at a set delay time. The kinetic traces at appropriate wavelengths were assembled from the time-resolved spectral data. anosecond Laser Flash Photolysis. The studied compounds were excited by a polette HE 355 LD pumped by a high energy d:yag laser with second and third harmonics P (tuning range nm, pulse repetition rate 20 Hz, pulse length 7 ns) with the powers of 1.0 to 3 mj per pulse. The transient absorption measurements were performed using a Proteus UV- Vis-IR flash photolysis spectrometer (Ultrafast Systems, Sarasota, FL) with a fibre optic delivered white probe light and either a fast rise Si photodiode detector covering the nm range or a InGaAs photodiode detector covering nm range. The output from the photodiodes and a photomultiplier tube was recorded with a digitizing Tektronix oscilloscope. Data analysis was performed using Surface Xplorer software supplied by Ultrafast Systems. About 1 mg dry samples of ZnPc-SLG-C 60 hybrid was dissolved in 3 ml DMF by sonicating them with a Misonix Ultrasonic Liquid Processor for ten min. Solution was then centrifuged and the clear supernatant used for actual experiment upon 2 purging for 30 min. Synthesis of 2(4 -hydroxyphenyl)fulleropyrrolidine C H Toluene, reflux CH 3 S8

9 Fullerene, C 60 (100 mg, mmol), 4-hydroxybenzaldehyde (84 mg, 0.69 mmol) and sarcosine (49 mg, 0.55 mmol) were dissolved in 100 ml dry toluene and refluxed for 12 h under nitrogen. The reaction was then cooled to room temperature and the solvent evaporated. Silica gel column was then run with toluene and ethyl acetate as eluent (9:1) to give the 2-(4 - hydroxyphenyl)fulleropyrrolidine. 1 H MR (CDCl 3, 400 MHz), δ(ppm): (m, 4H, Phenyl H), 4.95(d,1H, pyrrolidine H), 4.85(d, 1H, pyrrolidine H), 4.3(d, 1H, pyrrolidine H), 2.8(s, 3H, -methyl H), Mass- ESI. Calculated: , obtained: Synthetic of 2-hydroxy-9, 16, 23-tri-tertbutylphthalocyaninato zinc(ii) Zn H 4-t-Butylphthalonitrile (695 mg, 3.77 mmol), 4-hydroxyphthalonitrile (90 mg, 0.62 mmol) and ZnCl 2 (257 mg, 1.90 mmol) were kept in 100 ml RB flask under 2 for 20 min. Then DMAE (4 ml) was added and whole mixture was heated at C for 18 h. After cooling the mixture at room temperature, the solution was dissolved with methanol and water (15:5 ml each) and centrifuged for 1.5 h. Thus obtained green coloured residue was dissolved in minimum of chloroform and purified by silica column. The desired compound was obtained as a second fraction eluted by chloroform: Me (90:10 v/v). Yield- 120 mg (25%). 1 H MR (CDCl 3, 400MHz), δ(ppm): 1.55 (m, 27H, -CH 3 ), 7.20 (m, 4H, Ar-H), 7.70 (m, 4H, Ar-H), 7.95 (m, 4H, Ar-H). Mass- ESI. [M+H] +, obtained , calculated Synthesis of ZnPc-SLG-C 60 hybrid About 50 mg single layer graphene layer was taken in a flask with 25 ml thionyl chloride with 1 ml dry DMF. It was then refluxed at 70 o C for 24 hours. The reaction was then cooled to room temperature and all the solvent was taken out. THF was then used to wash out the excess thionyl chloride. The resultant acid chloride derivative of graphene oxide was then dried under S9

10 nitrogen. It was then dissolved in 20 ml of dry DMS and then to the solution was added 10 eq. of hydroxy functionalized fullerene and phthalocyanine in the previous steps. The mixture was heated at 50 o C for 96 h. The reaction was then cooled to room temperature. The mixture was then centrifuged and the supernatant was discarded. This process was repeated and washings were done with methanol, water and dichloromethane until all the unreacted compound was taken out. The final hybrid was then dried under nitrogen and used for further characterization. Synthesis of ZnPc-SLG hybrid Zn C H H In a typical synthesis, about 50 mg single layer graphene layer was taken in a flask with 25 ml oxalyl chloride with 1 ml dry DMF. It was then refluxed at 7 0 o C for 24 hours. The reaction was then cooled to room temperature and all the solvent was taken out. THF was then used to wash out the excess thionyl chloride. The resultant acid chloride derivative of graphene oxide was then dried under nitrogen. It was then dissolved in 20 ml of dry DMS and then to the solution was added 10 eq. of hydroxy functionalized phthalocyanine from the previous step and heated the mixture at 50 o C for 72 hours. Reaction was then brought to room temperature and solvent separated. Excess of the unreacted compound was taken out by sonication followed by centrifugation at least 3 times with water, methanol, and dichloromethane. The resulting hybrid material was then vacuum dried and used for further characterization. S10

11 Synthesis of SLG-C 60 hybrid H 3 C H C H H About 50 mg single layer graphene layer was taken in a flask with 25mL thionyl chloride with 1 ml dry DMF. It was then refluxed at 70 o C for 24 h. The reaction was then cooled to room temperature and all the solvent was taken out. Tetrahydrofuran (THF) was then used to wash out the excess thionyl chloride. The resultant acid chloride derivative of graphene oxide was then dried under nitrogen. It was then dissolved in 20 ml of dry DMS and then to the solution was added 10 equivalents of 2-(4 -hydroxyphenyl)fulleropyrrolidine and heated the mixture at 50 o C for 72 h. Reaction was then brought to room temperature and solvent separated. Excess of the unreacted compound was taken out by sonication followed by centrifugation at least 3 times with water, methanol, and dichloromethane. The resulting hybrid material was then vacuum dried and used for further characterization. S11