Multiple photosynthetic reaction centres composed of supramolecular assemblies of zinc porphyrin dendrimers with a fullerene acceptor

Fukuzumi, Shunichi,Saito, Kenji,Ohkubo, Kei,Khoury, Tony,Kashiwagi, Yukiyasu,Absalom, Mark A.,Gadde, Suresh,D'Souza, Francis,Araki, Yasuyuki,Ito, Osamu,Crossley, Maxwell J. Royal Society of Chemistry 2011 Chemical communications Vol.47 No.28

<P>Multiple photosynthetic reaction centres have successfully been constructed using supramolecular complexes of zinc porphyrin dendrimers [D(ZnP)<SUB><I>n</I></SUB>: <I>n</I> = 4, 8, 16] with fulleropyrrolidine bearing a pyridine ligand (C<SUB>60</SUB>py). Efficient energy migration occurs completely between the ZnP units of dendrimers prior to the electron transfer with increasing the generation of dendrimers to attain an extremely long charge–separation lifetime.</P> <P>Graphic Abstract</P><P>Efficient energy migration occurs more efficiently between the ZnP units of dendrimers prior to the electron transfer with increasing the generation of dendrimers to attain an extremely long charge–separation lifetime. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cc11725d'> </P>

Fuel Production from Seawater and Fuel Cells Using Seawater

Fukuzumi, Shunichi,Lee, Yong-Min,Nam, Wonwoo Wiley (John WileySons) 2017 ChemSusChem Vol.10 No.22

<P>Seawater is the most abundant resource on our planet and fuel production from seawater has the notable advantage that it would not compete with growing demands for pure water. This Review focuses on the production of fuels from seawater and their direct use in fuel cells. Electrolysis of seawater under appropriate conditions affords hydrogen and dioxygen with 100% faradaic efficiency without oxidation of chloride. Photo-electrocatalytic production of hydrogen from seawater provides a promising way to produce hydrogen with low cost and high efficiency. Microbial solar cells (MSCs) that use biofilms produced in seawater can generate electricity from sunlight without additional fuel because the products of photosynthesis can be utilized as electrode reactants, whereas the electrode products can be utilized as photosynthetic reactants. Another important source for hydrogen is hydrogen sulfide, which is abundantly found in Black Sea deep water. Hydrogen produced by electrolysis of Black Sea deep water can also be used in hydrogen fuel cells. Production of a fuel and its direct use in a fuel cell has been made possible for the first time by a combination of photocatalytic production of hydrogen peroxide from seawater and dioxygen in the air and its direct use in one-compartment hydrogen peroxide fuel cells to obtain electric power.</P>

Catalytic activity of metal-based nanoparticles for photocatalytic water oxidation and reduction

Fukuzumi, Shunichi,Yamada, Yusuke The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.46

<P>Precious-metal catalysts, predominantly platinum (Pt), have been used to minimize the overpotentials for both the oxidation and reduction of water. This article focuses on the catalytic activity of non-Pt metal nanoparticles for the photocatalytic oxidation and reduction of water. Efficient photocatalytic hydrogen evolution was made possible by using ruthenium nanoparticles (RuNPs) instead of platinum nanoparticles (PtNPs) under basic conditions (pH 10) with 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh<SUP>+</SUP>–NA) as an organic photocatalyst and dihydronicotinamide adenine dinucleotide (NADH) as an electron source. Nickel nanoparticles (NiNPs) can also be used as a non-precious metal catalyst in the photocatalytic hydrogen evolution with QuPh<SUP>+</SUP>–NA and NADH maintaining 40% of the catalytic activity of PtNPs. On the other hand, some metal-based nanoparticles can also act as catalysts for photocatalytic water oxidation. Iridium hydroxide nanoparticles (Ir(OH)<SUB><I>x</I></SUB>NPs) formed during the thermal oxidation of water by (NH<SUB>4</SUB>)<SUB>2</SUB>[Ce<SUP>IV</SUP>(NO<SUB>3</SUB>)<SUB>6</SUB>] as an oxidant and cobalt hydroxide nanoparticles (Co(OH)<SUB><I>x</I></SUB>NPs) were produced during the photocatalytic oxidation of water with Ru(bpy)<SUB>3</SUB><SUP>2+</SUP> as a photocatalyst and persulphate as a sacrificial oxidant using Ir and Co complexes with organic ligands as precatalysts. The catalytic activity and stability of Ir(OH)<SUB><I>x</I></SUB>NPs and Co(OH)<SUB><I>x</I></SUB>NPs were improved significantly as compared with Ir and Co precatalysts.</P> <P>Graphic Abstract</P><P>This article presents water reduction by non-Pt metal nanoparticles and water oxidation by metal oxide nanoparticles prepared from metal complexes. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm32926c'> </P>

Disproportionation of Dipyrrolylquinoxaline Radical Anions via the Internal Protons of the Pyrrole Moieties

Fukuzumi, Shunichi,Mase, Kentaro,Ohkubo, Kei,Fu, Zhen,Karnas, Elizabeth,Sessler, Jonathan L.,Kadish, Karl M. American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.19

<P>Disproportionation of dipyrrolylquinoxaline radical anions occurs via hydrogen atom transfer from the pyrrole moiety to the quinoxaline moiety to produce monodeprotonated dipyrrolylquinoxaline anions and monohydrodipyrrolylquinoxaline anions. In contrast, simple quinoxaline radical anions without pyrrole moieties are stable, and disproportionation occurs only in the presence of external protons.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-19/ja200925e/production/images/medium/ja-2011-00925e_0002.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja200925e'>ACS Electronic Supporting Info</A></P>

Assemblies of artificial photosynthetic reaction centres

Fukuzumi, Shunichi,Ohkubo, Kei The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.11

<P>Nature harnesses solar energy for photosynthesis in which one reaction centre is associated with a number of light harvesting units. The reaction centre and light-harvesting units are assembled by non-covalent interactions such as hydrogen bonding and π–π interactions. This article presents various strategies to assemble artificial photosynthetic reaction centres composed of multiple light harvesting units and charge-separation units, which are connected by non-covalent bonding as well as covalent bonding. First light-harvesting units are assembled on alkanethiolate-monolayer-protected metal nanoparticles (MNPs), which are connected with electron acceptors by non-covalent bonding. Light-harvesting units can also be assembled using dendrimers and oligopeptides to combine with electron acceptors by π–π interactions. The cup-shaped nanocarbons generated by the electron-transfer reduction of cup-stacked carbon nanotubes have been functionalized with a number of porphyrins acting as light-harvesting units as well as electron donors. In each case, the photodynamics of assemblies of artificial photosynthetic reaction centres have revealed efficient energy transfer and electron transfer to afford long-lived charge-separated states.</P> <P>Graphic Abstract</P><P>This article presents various strategies to assemble artificial photosynthetic reaction centres composed of multiple light harvesting units and charge-separation units, which are connected by non-covalent bonding as well as covalent bonding. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm15585k'> </P>

Mimicry and functions of photosynthetic reaction centers

Fukuzumi, Shunichi,Lee, Yong-Min,Nam, Wonwoo Biochemical Society 2018 Biochemical Society transactions Vol.46 No.5

<P>The structure and function of photosynthetic reaction centers (PRCs) have been modeled by designing and synthesizing electron donor-acceptor ensembles including electron mediators, which can mimic multi-step photoinduced charge separation occurring in PRCs to obtain long-lived charge-separated states. PRCs in photosystem I (PSI) or/and photosystem II (PSII) have been utilized as components of solar cells to convert solar energy to electric energy. Biohybrid photoelectrochemical cells composed of PSII have also been developed for solar-driven water splitting into H-2 and O-2. Such a strategy to bridge natural photosynthesis with artificial photosynthesis is discussed in this minireview.</P>

Crystal structure of a metal ion-bound oxoiron(IV) complex and implications for biological electron transfer

Fukuzumi, Shunichi,Morimoto, Yuma,Kotani, Hiroaki,Naumov, Pan?e,Lee, Yong-Min,Nam, Wonwoo Nature Publishing Group, a division of Macmillan P 2010 Nature chemistry Vol.2 No.9

Critical biological electron-transfer processes involving high-valent oxometal chemistry occur widely, for example in haem proteins [oxoiron(IV); Fe<SUP>IV</SUP>(O)] and in photosystem II. Photosystem II involves Ca<SUP>2+</SUP> as well as high-valent oxomanganese cluster species. However, there is no example of an interaction between metal ions and oxoiron(IV) complexes. Here, we report new findings concerning the binding of the redox-inactive metal ions Ca<SUP>2+</SUP> and Sc<SUP>3+</SUP> to a non-haem oxoiron(IV) complex, [(TMC)Fe<SUP>IV</SUP>(O)]<SUP>2+</SUP> (TMC?=?1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). As determined by X-ray diffraction analysis, an oxo-Sc<SUP>3+</SUP> interaction leads to a structural distortion of the oxoiron(IV) moiety. More importantly, this interaction facilitates a two-electron reduction by ferrocene, whereas only a one-electron reduction process occurs without the metal ions. This control of redox behaviour provides valuable mechanistic insights into oxometal redox chemistry, and suggests a possible key role that an auxiliary Lewis acid metal ion could play in nature, as in photosystem II.

Mononuclear Copper Complex-Catalyzed Four-Electron Reduction of Oxygen

Fukuzumi, Shunichi,Kotani, Hiroaki,Lucas, Heather R.,Doi, Kaoru,Suenobu, Tomoyoshi,Peterson, Ryan L.,Karlin, Kenneth D. American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.20

<P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-20/ja100538x/production/images/medium/ja-2010-00538x_0002.gif'> <P>A mononuclear Cu<SUP>II</SUP> complex acts as an efficient catalyst for four-electron reduction of O<SUB>2</SUB> to H<SUB>2</SUB>O. Its reduction by a ferrocene derivative (Fc*) and reaction with O<SUB>2</SUB> leads to the formation of a peroxodicopper(II) complex; this is subsequently reduced by Fc* in the presence of protons to regenerate the Cu<SUP>II</SUP> complex.</P></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja100538x'>ACS Electronic Supporting Info</A></P>

Synthesis and Photodynamics of 9-Mesitylacridinium Ion-Modified Gold Nanoclusters

Fukuzumi, Shunichi,Hanazaki, Ryo,Kotani, Hiroaki,Ohkubo, Kei American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.32

<P>Photoexcitation of gold nanoclusters covalently functionalized with 9-mesityl-10-methylacridinium ion (Mes-Acr<SUP>+</SUP>) resulted in the formation of the electron-transfer state (Mes<SUP>•+</SUP>-Acr<SUP>•</SUP>), which forms a π-dimer radical cation with the neighboring Mes-Acr<SUP>+</SUP> via an intramolecular π−π interaction.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-32/ja105314x/production/images/medium/ja-2010-05314x_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja105314x'>ACS Electronic Supporting Info</A></P>

Unusually Large Tunneling Effect on Highly Efficient Generation of Hydrogen and Hydrogen Isotopes in pH-Selective Decomposition of Formic Acid Catalyzed by a Heterodinuclear Iridium−Ruthenium Complex in Water

Fukuzumi, Shunichi,Kobayashi, Takeshi,Suenobu, Tomoyoshi American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.5

<P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-5/ja910349w/production/images/medium/ja-2009-10349w_0005.gif'> <P>A heterodinuclear iridium−ruthenium complex [Ir<SUP>III</SUP>(Cp*)(H<SUB>2</SUB>O)(bpm)Ru<SUP>II</SUP>(bpy)<SUB>2</SUB>](SO<SUB>4</SUB>)<SUB>2</SUB> {<B>1</B>(SO<SUB>4</SUB>)<SUB>2</SUB>, Cp* = η<SUP>5</SUP>-pentamethylcyclopentadienyl, bpm = 2,2′-bipyrimidine, bpy = 2,2′-bipyridine} acts as the most effective catalyst for selective production of hydrogen from formic acid in an aqueous solution at ambient temperature among catalysts reported so far. An unusually large tunneling effect was observed for the first time for the catalytic hydrogen production in H<SUB>2</SUB>O vs D<SUB>2</SUB>O.</P></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja910349w'>ACS Electronic Supporting Info</A></P>