Efficient Conjugated PolymerâMethyl Viologen Electron Transfer

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Efficient Conjugated Polymer-Methyl Viologen Electron Transfer System for Controlled Photo-Driven Hydrogen Evolution Huan Lu, Rong Hu, Haotian Bai, Hui Chen, Fengting Lv, Libing Liu, Shu Wang, and He Tian ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b00069 • Publication Date (Web): 13 Mar 2017 Downloaded from http://pubs.acs.org on March 14, 2017

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ACS Applied Materials & Interfaces

Efficient Conjugated Polymer− −Methyl Viologen Electron Transfer System for Controlled PhotoDriven Hydrogen Evolution Huan Lu,a Rong Hu,a Haotian Bai,a Hui Chen,a Fengting Lv,a* Libing Liu,a Shu Wanga* and He Tianb* a

Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.

b

College of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China E-mail: [email protected]; [email protected]; [email protected]

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ABSTRACT: Photo-driven hydrogen production has been a good strategy in solar energy utilization. In this work, we use a water-soluble negatively charged polythiophene derivative as photosensitizer to produce

hydrogen

from

aqueous

solution

containing

methyl

viologen

(MV2+),

ethylenediaminetetraacetic acid disodium salt (EDTA) and a colloidal platinum catalyst upon exposure to Xenon lamp (> 420 nm) or natural sunlight. The supramolecular assembly and dis-assembly processes of MV2+ and cucurbit[8]uril (CB[8]) was further used to reversibly “turn-on” and “turn-off” hydrogen generation of the polymer system. This research offers a proof-of-concept to control hydrogen generation in demand, which is an advantage for hydrogen utilization and storage. KEYWORDS: Hydrogen generation, conjugated polymers, light catalysis, self-assembly, switch

1. INTRODUCTION Developing renewable and clean energy sources based on solar energy is extremely urgent in today's world.1-3 Since molecular hydrogen is known as a clean fuel as well as its high specific enthalpy,4-5 photo-driven hydrogen production has been a good strategy in solar energy utilization.6-10 Various inorganic semiconductor-based efficient photocatalytic systems have been designed, and the attempts to achieve efficient hydrogen production from water under visible light are the most striking. In this respect, organic semiconductors exhibit good potential as photosensitizers for developing efficient photocatalytic systems due to their tunability in band gaps. Polymeric carbon nitride has been developed to achieve efficient production of hydrogen from water under visible light.11-12 Organic dyes are also widely used as photosensitizers in photo-induced hydrogen generation systems for their tunable lightabsorption abilities.13-17 Conjugated polymers (CPs) have unique light-harvesting ability and the electrons and holes can move along the backbone in the presence of electron acceptors upon photo-excitation,18-19 which could be utilized to drive photocatalytic reaction for hydrogen evolution from water. Although CPs emerging ACS Paragon Plus Environment

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as materials in organic LEDs,20 field effect transistors21 and photovoltaic cell22 have been widely explored, their applications in artificial photosynthesis or photo-induced hydrogen generation are still scarce. A few of insoluble CP-based linear or porous networks have been designed for photo-driven hydrogen evolution,23-29 however, their insolubility in aqueous solution limits their characterization and electronic communication with electron acceptors, which affects their performance. Up to date, watersoluble conjugated polymers for photo-induced hydrogen generation remain relatively unexplored.30,31 In our previous work, water-soluble CPs with visible light absorption have been synthesized for biosensor, imaging and therapy applications.32,33 In this work, a water-soluble negatively charged polythiophene

derivative

(poly-(sodium-3,3'-((2-(thiophen-3-yl)ethyl)azanediyl)dipropanoate),

abbreviated as PT, see its chemical structure in Scheme 1) was used as photosensitizer in the photoinduced hydrogen production system, in which methyl viologen (N,N'-dimethyl-4,4'-bipyridinium dichloride, MV2+, see its chemical structure in Scheme 1) was used as electron mediator, while ethylenediaminetetraacetic acid disodium salt (EDTA) was used as the sacrificial electron donor and a colloidal platinum stabilized by polyvinyl alcohol (colloidal of PVA-Pt) as the catalyst. Efficient hydrogen generation from aqueous solution was obtained for this system upon exposure to Xenon lamp (> 420 nm) or natural sunlight. Our previous work showed that the controllably antibacterial activity of CPs could be realized by host–guest interaction of cucurbit[7]uril (CB[7]) and amantadine (AD),34 also photocatalytic activity could be controlled by the assembly and disassembly of cucurbit[8]uril (CB[8]) and MV2+ anchored on the titanium dioxide (TiO2) nanoparticles.35 The supramolecular assembly and dis-assembly processes of MV2+ and cucurbit[8]uril (CB[8]) was further used to reversibly “turn-on” and “turn-off” hydrogen generation of the polymer system.

2. RESULTS AND DISCUSSION PT was synthesized according to the procedure in the literature,36 and it was well-dispersed in water due to carboxylic acid groups in the pendant. The intense and broad absorption band of PT in visible region (400-600 nm) has a large overlap with natural sunlight (Figure S1). Schematic diagram ACS Paragon Plus Environment

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for the photo-driven hydrogen production for the PT system is outlined in Scheme 1. PT, EDTA, MV2+ and colloidal of PVA-Pt are added into the aqueous solution, and MV2+ is attracted to the exterior of PT through electrostatic interactions. Upon light irradiation, the generated electrons and holes depart transfer along the conjugated backbone of PT, followed by the electron transfer from the backbone to MV2+ (MV2+ is reduced to MV+•). Since the electrostatic interaction between MV+• and PT is weaker than that of MV2+ and PT, MV+• is replaced by MV2+ from PT, and then diffuses into the aqueous solution. The electron transfer from MV+• to Pt, then the electron transfer from Pt to proton results in hydrogen generation. Thus, the water is reduced to hydrogen while MV+• is oxidized to MV2+ according to the Equation (1).37 colloidal

2MV • H O

H 2OH - 2MV

(1)

Scheme 1. Schematic diagram for photo-induced hydrogen production from water using PT system, and the chemical structures of PT, MV2+ and its cationic radical (MV+•).

To investigate the electrostatic interaction between PT and MV2+, the zeta potentials (ζ) and hydrodynamic diameter of PT in aqueous solution were firstly measured before and after addition of MV2+ (Figure 1a and 1b). Upon the addition of MV2+, ζ potential of PT turns more positive (-14 ± 1


4

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mV) than that without MV2+ (-30 ± 4 mV), which provides a direct evidence of electrostatic interactions between MV2+ and PT. PT is an amphiphilic macromolecule and exhibits aggregates in water with a hydrodynamic diameter of about 220 nm by dynamic light scatting (DLS) measurement. The transmission electron microscope (TEM) shows PT forms spherical nanoparticles in water (Figure S2). After addition of MV2+, the mean size of PT in aqueous solution was reduced from 220 nm to 78 nm. Both the results of size and ζ potential confirmed the electrostatic interaction between PT and MV2+. Since MV2+ is a highly efficient electron quencher,38 the fluorescence quenching of PT by MV2+ was studied to further confirm their interaction. As shown in Figure 1c, the fluorescence intensity of PT (10 µM) is gradually quenched in the presence of MV2+ with varying concentrations from 0-80 µM, which exhibited the occurrence of electron transfer from PT to MV2+. The Stern-Volmer constant (KSV) was determined by the changes in the fluorescence of PT and calculated via the Stern-Volmer equation (Eq. 2) 39:

= 1 []

(2)

As shown in Figure 1d, at low concentrations of MV2+ (0-10 µM), a linear Stern-Volmer plot was obtained with a KSV value of 6.253×104 M-1. We carried out the quenching experiment with different concentrations of sodium chloride (NaCl). The Ksv was found to decrease with the increase of sodium chloride concentration, which indicates that the electrostatic interaction plays important contribution for the binding of PT with MV2+ (Figure 1e). The fluorescence quenching experiments of PT by MV2+ promoted us to explore whether MV2+ could be reduced into its cationic radical by PT under light irradiation. The mixed aqueous solution of PT, MV2+ and EDTA was sealed in the quartz cell with a rubber stopper. After bubbling with Argon gas for 30 minutes, the quartz cell was exposed to the Xenon lamp. Upon extending irradiation time, the color of the solution turned from light yellow to blue, and then the blue color gradually became darker, which reflect the accumulation of MV+•. As shown in Figure 1f, the enhancement of characteristic absorption peak of MV+• at around 605 nm also reflects the


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accumulation of MV+•.32 These results suggest that the MV2+ is reduced by PT in the presence of EDTA through one-electron process under light irradiation.

Figure 1. Hydrodynamic diameter distribution and zeta potentials (ζ) of PT in aqueous solution before (a) and after (b) the addition of MV2+. [PT] = 20 µM, [MV2+] = 5 mM. (c) Fluorescence intensity of PT


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in aqueous solution as a function of MV2+ concentration. (d) Stern-Volmer quenching curve of MV2+ to PT, [PT]=10 µM, [MV2+]=0-80 µM, the excitation wavelength is 420 nm. (e) Ksv as a function of NaCl concentration, [NaCl]=0, 0.001, 0.01, 0.1 and 1 M, respectively. (f) UV-Vis absorption spectra change with extending irradiation time of a mixture of PT, MV2+ and EDTA . [PT] = 20 µM, [MV2+] = 5 mM, [EDTA] = 50 mM.

In order to demonstrate the hydrogen generation, colloidal PVA-Pt was introduced to the PT/MV2+/EDTA system. The colloidal of PVA-Pt was prepared according to the reported process.40 A mixture of PT, EDTA, MV2+ and colloidal PVA-Pt was sealed in a Pyrex bottle. After bubbled with argon, the bottle was exposure to the Xenon lamp with a filter λ>420nm at a light power of 50 mW. The gas (200 µL) from reactor was injected into gas chromatography (GC) with an interval of one hour, and the plots of the hydrogen generation were shown in Figure 2a. The production of the hydrogen was calculated according to the H2 normalized curve (Figure S3). The results suggest that hydrogen can generate sustainably even for eight hours (totally about 1.65 µmol). In a sunny autumn day in Beijing, our Pyrex bottle settled with the photo-induced hydrogen production system was irradiated under natural light. The light intensity was measured per hour and the average light power was determined to be about 59 mW at this condition. Efficient hydrogen generation was detected (Figure 2b), and about 1.43 µmol of hydrogen was generated after 6 h irradiation. These results verify the hydrogen generation from water under natural sunlight with PT/MV2+/EDTA/ PVA-Pt system. Apparent Quantum Yield (AQY) which was calculated to be 6.43×10-4 under Xenon lamp.30 The activity calculated of the first hour of the hydrogen generation under Xenon lamp and Solar light are 21.3 mmol/gPT and 22.6 mmol/gPT, respectively, which reflects that our polymer could be used as photosensitizer.41 Of course, the AQY of our system is low compared with that of metal-chelating conjugated polymer systems.30 It is noted that the hydrogen generation exhibits 75% loss after four cycles (Figure S4). We performed the photostability experiment of PT at the same condition as that of hydrogen production. Figure S5 shows that the maximum absorption of PT decreases ACS Paragon Plus Environment

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by 73% with a blue-shift of 40 nm, and the fluorescence of PT drops below undetectable level under light irradiation for seven hours. Thus, the low AQY and the AQY loss after four cycles of PT system maybe come from the photodegradation of PT polymer. We also explored the pH effect on the hydrogen evolution to further understand the process (Figure 2c). Six samples with different pH value were investigated. After all components were added, the pH value of the solution was measured to be 4.4. The hydrogen generation in the first hour was detected to be 0.56 µmol. Hydrochloric acid was used to regulate the pH of the solution, and after one hour irradiation, the hydrogen evolution was 0.39 µmol and 0.21 µmol for the solutions with pH 4 and pH 3, respectively. The reason possibly comes from the partial acidification of PT in the solutions with pH 4 and pH 3, in which PT exhibits less negative charges and less soluble. In this case the electron transfer between MV2+ to PT is not efficient, which resulted in the decreased hydrogen evolution. Sodium hydroxide aqueous solution was used to regulate the pH of the solution to be 5, 6 and 7. Hydrogen generation at pH 5 and pH 6 was 0.30 µmol and 0.21 µmol, respectively. When pH value was varied to be 7, trace hydrogen was detected. As shown in Figure 2d, after 1 h light irradiation, the solutions with pH 6 and pH 7 exhibited blue and dark blue color, respectively. The blue color of the mixture after irradiation indicated the accumulation of MV+•. However, despite MV2+ could be reduced efficiently at pH 6 and 7, the hydrogen generation was decreased with the increasing of pH based on E(H+/H2)=Eθ(H+/H2)-0.05916×pH (V), since the H+ was more difficult to be reduced for the E(MV2+/ MV+•)(0.443 V vs. NHE)42 that was not pH dependent. It is noted that that the absorption maximum of PT is blue-shifted and the relative intensity of between 400 and 450 nm of PT is increased as the increase of solution pH from 3 to 7 (Figure S6). The blue-shift and increasing relative intensity of between 400 and 450 nm of PT band can be related to the change of its aggregates. At low pH (pH=3), the carboxylic acid group in PT is protonated and PT shows tight aggregation with strong intermolecular π-π interactions in aqueous solution, while at higher pH (pH=7), the carboxylic acids are deprotonated and PT shows losse aggregation.


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Figure

2.

Time-dependent

hydrogen

generation

from

aqueous

solution

containing

PT/MV2+/EDTA/PVA-Pt under Xenon lamp (a) and natural sunlight (b). (c) Hydrogen generation in the solution with varying pH value. (d) Photographs of reaction solutions with varying pH value after 1 hour irradiation. [PT] = 20 µM, [MV2+] = 5 mM, [EDTA] = 50 mM.

We further explored to reversibly “turn-on” and “turn-off” hydrogen generation for PT/MV2+/EDTA/ PVA-Pt system using CB[8] and AD through supramolecular assembly and disassembly processes. MV2+ molecule can form 1:1 complex with CB[8], and then MV2+ can be released upon adding AD molecule since AD and CB[8] forms more stable complex,36 thus the tunability of electron communication between PT and MV2+ or MV2+ and PVA-Pt could be expected by adding CB[8] and AD to PT/MV2+/EDTA/ PVA-Pt system. A mixture of PT, EDTA, MV2+ and colloidal PVAPt was sealed in a Pyrex bottle. After bubbled with Argon, the bottle was exposure to the Xenon lamp ACS Paragon Plus Environment

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with a light power of 50 mW. The gas from the reactor was injected into GC after being irradiated for 2 h and 0.693 µmol hydrogens were detected (Figure 3). After that, CB[8] (2.5 mM) was added into the system, bubbled with Argon before exposure to the Xenon lamp. The hydrogen generation was decreased to 0.066 µmol, which resulted from the assembly of CB[8] and MV+•. Upon adding AD (15 mM) to the system, the hydrogen generation was recovered (0.482 µmol), which resulted from the disassembly of CB[8] and MV+•. The “off” and “on” of hydrogen generation by the assembly and disassembly of CB[8] and MV+• were realized as expected.

Figure 3. Controlled hydrogen generation for PT/MV2+/EDTA/ PVA-Pt system using CB[8] and AD by supramolecular assembly and dis-assembly process. [PT] = 20 µM, [MV2+] = 5 mM, [EDTA] = 50 mM.

To gain insight into the effect of electron transfer process on the reversibly “turn-on” and “turn-off” hydrogen generation, electron communication between PT and MV2+ was firstly studied by adding CB[8]. Unexpectedly, as shown in Figure 4a, the enhancement of characteristic absorption peak of MV+• at around 620nm for PT/MV2+/EDTA system was not blocked through adding CB[8].43 The result suggested that the MV2+ was still reduced by PT through electron transfer under light irradiation even in the presence


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of CB[8]. Thus the reversible “turn-on” and “turn-off” of hydrogen generation must come from the tunability of electron communication between MV+• and PVA-Pt. The possible mechanism is schemed in Figure 4b. MV2+ is reduced to MV+• radical by PT, then the electron transfer from MV+• to Pt is stabled by colloidal PVA. Finally, the electron transfer from Pt to the around proton results in hydrogen generation. With the addition of CB[8], two MV+• are assemblied in the cavity of CB[8],36 and no electron transfer occurs from MV+• to Pt, thus hydrogen is not generated. After that, excess AD is added to remove CB[8] from the system, accompanying with the recovery of hydrogen generation.


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Figure 4. (a) UV-Vis absorption spectra change with extending irradiation time for PT/MV2+/EDTA system in the presence of CB[8]. (b) Schematic diagram of controlled hydrogen generation mechanism using CB[8] and AD by supramolecular assembly and dis-assembly process.


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3. CONCLUSION In conclusion, we successfully use a water-soluble negatively charged polythiophene derivative as photosensitizer to produce hydrogen under visible light irradiation. Hydrogen production was achieved both under Xenon lamp and nature sunlight. The pH effect on the hydrogen generation was also investigated, and the mechanism of the hydrogen production process was proposed. Conjugated polymers with adjustable energy band gap and water-soluble ability may contribute to substantial improvement and advance in hydrogen production. The supramolecular strategy was further used to reversibly “turn-on” and “turn-off” hydrogen generation of the polymer system, which is an advantage for hydrogen utilization and storage.

ASSOCIATED CONTENT Supporting Information. Experimental procedures, additional Table S1 and Figures S1- S2. This material is available free of charge via the Internet at http://pubs.acs.org/.

AUTHOR INFORMATION Corresponding Author *Email: [email protected] (S.W.); [email protected] (L.L.); [email protected] (H. T.)

ACKNOWLEDGEMENTS The authors are grateful to the Major Research Plan of China (No. 2013CB932800), the National Natural Science Foundation of China (Nos. 21533012, 91527306).

REFERENCES


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(1)

Page 14 of 19

Esswein, A. J.; Nocera, D. G. Hydrogen Production by Molecular Photocatalysis. Chem. Rev. 2007, 107, 4022-4047.

(2)

Kleidon, A.; Miller, L.; Gans, F. Physical Limits of Solar Energy Conversion in the Earth System. Springer New York, 2015.

(3)

Rajeshwar, K.; McConnell, R.; Harrison, K.; Licht, S.; Solar Hydrogen Generation, Springer New York, 2008.

(4)

Lewis, N. S.; Nocera, D. G. Powering the Planet: Chemical Challenges in Solar Energy Utilization. Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 15729-15735.

(5)

Gray, H. B. Powering the Planet with Solar Fuel. Nat. Chem. 2009, 1, 7.

(6)

Fujishima, A.; Honda, K. Electrochemical Photolysis of Water at a Semiconductor Electrode. Nature 1972, 238, 37-38.

(7)

Schneider, J.; Matsuoka, M.; Takeuchi, M.; Zhang, J.; Horiuchi, Y.; Anpo, M.; Bahnemann, D. W. Understanding TiO2 Photocatalysis: Mechanisms and Materials. Chem. Rev. 2014, 114, 99199986.

(8)

Grewe, T.; Meggouh, M.; Tüysüz, H. Nanocatalysts for Solar Water Splitting and a Perspective on Hydrogen Economy. Chem. Asian J. 2016, 11, 22-42.

(9)

Yang, M.; Zhang, N.; Pagliaro, M.; Xu, Y. Artificial Photosynthesis over Graphene– Semiconductor Composites. Are We Getting Better? Chem. Soc. Rev. 2014, 43, 8240-8254.

(10) Han, Z.; Eisenberg, R. Fuel from Water: The Photochemical Generation of Hydrogen from Water. Acc. Chem. Res. 2014, 47, 2537-2544. (11) Wang, X.; Maeda, K.; Thomas, A.; Takanabe, K.; Xin, G.; Carlsson, J. M.; Domen, K.; Antonietti. M. A Metal-Free Polymeric Photocatalyst for Hydrogen Production from Water under Visible Light. Nat. Mater. 2009, 8, 76-80. (12) Wang, X.; Maeda, K.; Chen, X.; Takanabe, K.; Domen, K.; Hou, Y.; Fu, X.; Antonietti, M. Polymer Semiconductors for Artificial Photosynthesis: Hydrogen Evolution by Mesoporous Graphitic Carbon Nitride with Visible Light. J. Am. Chem. Soc. 2009, 131, 1680-1681. ACS Paragon Plus Environment

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Page 15 of 19

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(13) Cambié, D.; Bottecchia, C.; Straathof, N. J. W.; Hessel, V.; Noël T. Applications of ContinuousFlow Photochemistry in Organic Synthesis, Material Science, and Water Treatment. Chem. Rev. 2016, 116, 10276-10341. (14) Freemantle, M. Ionic Liquids May Boost Clean Technology Development. Chem. Eng. News 1998, 76, 32-37. (15) Grätzel, M. Artificial Photosynthesis: Water Cleavage into Hydrogen and Oxygen by Visible Light. Acc. Chem. Res. 1981, 14, 376-384. (16) Du, P.; Knowles, K.; Eisenberg, R. A Homogeneous System for the Photogeneration of Hydrogen from Water Based on a Platinum(II) Terpyridyl Acetylide Chromophore and a Molecular Cobalt Catalyst. J. Am. Chem. Soc. 2008, 130, 12576-12577. (17) Li, Q.; Che, Y.; Ji, H.; Chen, C.; Zhu, H.; Ma, W.; Zhao, J. Ortho-Dihydroxyl-9,10-Anthraquinone Dyes as Visible-Light Sensitizers That Exhibit a High Turnover Number for Hydrogen Evolution. Phys. Chem. Chem. Phys. 2014, 16, 6550-6554. (18) Hoofman, R. J. O. M.; de Haas, M. P.; Siebbeles, L. D. A.; Warman. J. M. Highly Mobile Electrons and Holes on Isolated Chains of the Semiconducting Polymer Poly(Phenylene Vinylene). Nature 1998, 392, 54-56. (19) Zhou, Q.; Swager, T. M. Fluorescent Chemosensors Based on Energy Migration in Conjugated Polymers: The Molecular Wire Approach to Increased Sensitivity. J. Am. Chem. Soc. 1995, 117, 12593-12602. (20) AlSalhi, M. S.; Alam, J.; Dass, L. A.; Raja, M. Recent Advances in Conjugated Polymers for Light Emitting Devices. Int. J. Mol. Sci. 2011, 12, 2036-2054. (21) Wu, J.-S.; Cheng, S.-W.; Cheng, Y.-J.; Hsu, C.-S. Donor–Acceptor Conjugated Polymers Based on Multifused Ladder-Type Arenes for Organic Solar Cells. Chem. Soc. Rev. 2015, 44, 1113-1154. (22) Zhan, X.; Zhu, D. Conjugated Polymers for High-Efficiency Organic Photovoltaics. Polym. Chem. 2010, 1, 409-419.


15


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 19

(23) Yanagida, S.; Kabumoto, A.; Mizumoto, K.; Pac, C.; Yoshino, K. Poly(P-Phenylene)-Catalysed Photoreduction of Water to Hydrogen. J. Chem. Soc., Chem. Commun. 1985, 8, 474-475. (24) Jensen, B. W.; Fraser, K.; Ong, C.; Forsyth, M.; MacFarlane, D. R. Conducting Polymer Composite Materials for Hydrogen Generation. Adv. Mater. 2010, 22, 1727-1730. (25) Sprick, R. S.; Bonillo, B.; Clowes, R.; Guiglion, P.; Brownbill, N. J.; Slater, B. J.; Blanc, F.; Zwijnenburg, M. A.; Adams, D. J.; Cooper, A. I. Visible-Light-Driven Hydrogen Evolution Using Planarized Conjugated Polymer Photocatalysts. Angew. Chem., Int. Ed. 2016, 55, 1792-1796. (26) Schwab, M. G.; Hamburger, M.; Feng, X.; Shu, J.; Spiess, H. W.; Wang, X.; Antonietti, M.; Müllen, K. Photocatalytic Hydrogen Evolution Through Fully Conjugated Poly(Azomethine) Networks. Chem. Commun. 2010, 46, 8932-8934. (27) Zhang, Z.; Long, J.; Yang, L.; Chen, W.; Dai, W.; Fu, X.; Wang, X. Organic Semiconductor for Artificial Photosynthesis: Water Splitting into Hydrogen by A Bioinspired C3N3S3polymer Under Visible Light Irradiation. Chem. Sci. 2011, 2, 1826-1830. (28) Kailasam, K.; Mesch, M. B.; Möhlmann, L.; Baar, M.; Blechert, S.; Schwarze, M.; Schröder, M.; Schomäcker, R.; Senker, J.; Thomas, A. Donor–Acceptor-Type Heptazine-Based Polymer Networks for Photocatalytic Hydrogen Evolution. Energy Technol. 2016, 4, 744-750. (29) Sprick, R. S.; Jiang, J.-X.; Bonillo, B.; Ren, S.; Ratvijitvech, T.; Guiglion, P.; Zwijnenburg, M. A.; Adams, D. J.; Cooper, A. I. Tunable Organic Photocatalysts for Visible-Light-Driven Hydrogen Evolution. J. Am. Chem. Soc. 2015, 137, 3265-3270. (30) Li, L.; Hadt, R. G.; Yao, S.; Lo, W.-Y.; Cai, Z.; Wu, Q.; Pandit, B.; Chen, L. X.; Yu, L. Photocatalysts Based on Cobalt-Chelating Conjugated Polymers for Hydrogen Evolution from Water. Chem. Mater. 2016, 28, 5394-5399. (31) Jiang, D.; Choi, C.; Honda, K.; Li, W.; Yuzawa, T.; Aida, T. Photosensitized Hydrogen Evolution from Water Using Conjugated Polymers Wrapped in Dendrimeric Electrolytes. J. Am. Chem. Soc. 2004, 126, 12084-12089.


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(32) Zhu, C.; Liu, L.; Yang, Q.; Lv, F.; Wang, S. Water-Soluble Conjugated Polymers for Imaging, Diagnosis, and Therapy. Chem. Rev. 2012, 112, 4687-4735. (33) Yuan, H.; Wang, B.; Lv,

F.; Liu, L.; Wang, S. Conjugated-Polymer-Based Energy-Transfer

Systems for Antimicrobial and Anticancer Applications. Adv. Mater. 2014, 26, 6978-6982. (34) Bai, H.; Yuan, H.; Nie, C.; Wang, B.; Lv, F.; Liu, L.; Wang, S. A Supramolecular Antibiotic Switch for Antibacterial Regulation. Angew. Chem., Int. Ed. 2015, 54, 13208-13213. (35) Zhang, Q.; Qu, D.; Wang, Q.; Tian, H. Dual-Mode Controlled Self-Assembly of TiO2 Nanoparticles Through A Cucurbit[8]Uril-Enhanced Radical Cation Dimerization Interaction. Angew. Chem., Int. Ed. 2015, 54, 15789-15793. (36) Xing, C.; Xu, Q.; Tang, H.; Liu, L.; Wang, S. Conjugated Polymer/Porphyrin Complexes for Efficient Energy Transfer and Improving Light-Activated Antibacterial Activity. J. Am. Chem. Soc. 2009, 131, 13117-13124. (37) Kiwi, J.; Grätzel, M. Hydrogen Evolution from Water Induced by Visible Light Mediated by Redox Catalysis. Nature 1979, 281, 657-658. (38) Chen, L.; McBranch, D. W.; Wang, H. L.; Hegelson, R.; Wudl, F.; Whitten, D. C. Highly Sensitive Biological and Chemical Sensors Based on Reversible Fluorescence Quenching in A Conjugated Polymer. Proc. Natl. Acad. Sci. U. S. A. 1999, 96, 12287-12292. (39) Kim, O. K.; Je, J. S. One Dimensional Energy/Electron Transfer through a Helical Channel. J. Am. Chem. Soc. 2006, 128, 4532-4533. (40) Toshima, N.; Yonezawa, T. Bimetallic Nanoparticles—Novel Materials for Chemical and Physical Applications. New J. Chem. 1998, 22, 1179-1201. (41) Martindale, B. M.; Hutton, G. M.; Caputo, C.; Reisner, E. Solar Hydrogen Production Using Carbon Quantum Dots and a Molecular Nickel Catalyst. J. Am. Chem. Soc. 2015, 137, 6018-6025. (42) Bird, C. L.; Kuhn, A. T. Electrochemistry of the Viologens. Chem. Soc. Rev. 1981, 10, 49.


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(43) Jeon, W. S.; Kim, H.; Leeb C.; Kim, K. Control of the Stoichiometry in Host–guest Complexation by Redox Chemistry of Guests: Inclusion of Methylviologen in Cucurbit[8]uril. Chem. Commun. 2002, 17, 1828-1829.


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Efficient Conjugated PolymerâMethyl Viologen Electron Transfer

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