“Bioinspired Energy Conversion Schemes”.

MOORE, GARY F, HAMBOURGER, MICHAEL, KODIS, GERDENIS, GERVALDO, MIGUEL, LIDDELL, PAUL, GUST, DEVENS, MOORE, THOMAS A, MOORE, ANA L.

Rio Grande, Puerto Rico

Conferencia; 33rd American Society for Photobiology Meeting; 2006

American Society for Photobiology

The long-term objective of our research is the design of bioinspired schemes that couples solar energy to the oxidation of water and the subsequent use of the reducing equivalents to synthesize energy rich/reduced compounds. In an initial approach, a photoelectrochemical cell that oxidizes carbohydrates, alcohols, or other organic compounds, uses light to boost the reduction potential of the resulting electrons, and reduces hydrogen ions to hydrogen at neutral pH is being developed. The photoanode consists of a Gratzeltype nanoparticulate TiO2 electrode coated with a porphyrin sensitizer. Upon visible light excitation of the porphyrin sensitizer, electrons are injected from the S1 state of the porphyrin into the TiO2 conduction band. These electrons are then passed through the external circuit to a microporous platinum cathode where hydrogen evolution occurs. It was found that excitation of the photoanode with light absorbed only by the porphyrin results in evolution of hydrogen from the cathode with a quantum yield of ca. 5%. Glucose or other reduced carbon compounds in the anode solution are oxidized by the appropriate NAD-linked dehydrogenase enzyme reducing NAD+ to NADH. NADH is oxidized by the porphyrin radical cation, regenerating the porphyrin ground state for subsequent rounds of photo-excitation. Key to the operation of the cell is the coupling of the anode photoreactions to the oxidation of biological fuels by the NADH/ NAD+ coenzyme and NAD-linked dehydrogenase enzyme and the facile and cyclical electron donation to the oxidized sensitizer by NADH, generating NAD+, which is not reduced by charge recombination reactions at the photoanode. The design, synthesis, and electrochemical and photophysical characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described. characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described.2 electrode coated with a porphyrin sensitizer. Upon visible light excitation of the porphyrin sensitizer, electrons are injected from the S1 state of the porphyrin into the TiO2 conduction band. These electrons are then passed through the external circuit to a microporous platinum cathode where hydrogen evolution occurs. It was found that excitation of the photoanode with light absorbed only by the porphyrin results in evolution of hydrogen from the cathode with a quantum yield of ca. 5%. Glucose or other reduced carbon compounds in the anode solution are oxidized by the appropriate NAD-linked dehydrogenase enzyme reducing NAD+ to NADH. NADH is oxidized by the porphyrin radical cation, regenerating the porphyrin ground state for subsequent rounds of photo-excitation. Key to the operation of the cell is the coupling of the anode photoreactions to the oxidation of biological fuels by the NADH/ NAD+ coenzyme and NAD-linked dehydrogenase enzyme and the facile and cyclical electron donation to the oxidized sensitizer by NADH, generating NAD+, which is not reduced by charge recombination reactions at the photoanode. The design, synthesis, and electrochemical and photophysical characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described. characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described.1 state of the porphyrin into the TiO2 conduction band. These electrons are then passed through the external circuit to a microporous platinum cathode where hydrogen evolution occurs. It was found that excitation of the photoanode with light absorbed only by the porphyrin results in evolution of hydrogen from the cathode with a quantum yield of ca. 5%. Glucose or other reduced carbon compounds in the anode solution are oxidized by the appropriate NAD-linked dehydrogenase enzyme reducing NAD+ to NADH. NADH is oxidized by the porphyrin radical cation, regenerating the porphyrin ground state for subsequent rounds of photo-excitation. Key to the operation of the cell is the coupling of the anode photoreactions to the oxidation of biological fuels by the NADH/ NAD+ coenzyme and NAD-linked dehydrogenase enzyme and the facile and cyclical electron donation to the oxidized sensitizer by NADH, generating NAD+, which is not reduced by charge recombination reactions at the photoanode. The design, synthesis, and electrochemical and photophysical characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described. characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described.2 conduction band. These electrons are then passed through the external circuit to a microporous platinum cathode where hydrogen evolution occurs. It was found that excitation of the photoanode with light absorbed only by the porphyrin results in evolution of hydrogen from the cathode with a quantum yield of ca. 5%. Glucose or other reduced carbon compounds in the anode solution are oxidized by the appropriate NAD-linked dehydrogenase enzyme reducing NAD+ to NADH. NADH is oxidized by the porphyrin radical cation, regenerating the porphyrin ground state for subsequent rounds of photo-excitation. Key to the operation of the cell is the coupling of the anode photoreactions to the oxidation of biological fuels by the NADH/ NAD+ coenzyme and NAD-linked dehydrogenase enzyme and the facile and cyclical electron donation to the oxidized sensitizer by NADH, generating NAD+, which is not reduced by charge recombination reactions at the photoanode. The design, synthesis, and electrochemical and photophysical characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described. characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described.+ to NADH. NADH is oxidized by the porphyrin radical cation, regenerating the porphyrin ground state for subsequent rounds of photo-excitation. Key to the operation of the cell is the coupling of the anode photoreactions to the oxidation of biological fuels by the NADH/ NAD+ coenzyme and NAD-linked dehydrogenase enzyme and the facile and cyclical electron donation to the oxidized sensitizer by NADH, generating NAD+, which is not reduced by charge recombination reactions at the photoanode. The design, synthesis, and electrochemical and photophysical characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described. characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described.+ coenzyme and NAD-linked dehydrogenase enzyme and the facile and cyclical electron donation to the oxidized sensitizer by NADH, generating NAD+, which is not reduced by charge recombination reactions at the photoanode. The design, synthesis, and electrochemical and photophysical characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described. characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described.+, which is not reduced by charge recombination reactions at the photoanode. The design, synthesis, and electrochemical and photophysical characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described. characterization of a series of synthetic models of the donor side of PSII where a porphyrin chromophore plays the role of P680 will also be presented. In these biomimetic models, the porphyrin moiety is covalently attached to either tyrosine or to a hydrogen bonded phenol/imidazole pair. Initial experiments with these models adsorbed on the photoanode of the photoelectrochemical will be described.