1
|
Martínez SR, Odella E, Ibarra LE, Sosa Lochedino A, Wendel AB, Durantini AM, Chesta CA, Palacios RE. Conjugated polymer nanoparticles as sonosensitizers in sono-inactivation of a broad spectrum of pathogens. Ultrasonics 2024; 137:107180. [PMID: 37847942 DOI: 10.1016/j.ultras.2023.107180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/23/2023] [Accepted: 10/07/2023] [Indexed: 10/19/2023]
Abstract
Sonodynamic inactivation (SDI) of pathogens has an important advantage when compared to optical excitation-based protocols due to the deeper penetration of ultrasound (US) excitation in biological media or animal tissue. Sonosensitizers (SS) are compounds or systems that upon US stimulation in the therapeutic window (frequency = 0.8-3 MHz and intensity < 3 W/cm2) can induce damage to vital components of pathogenic microorganisms. Herein, we report the synthesis and application of conjugated polymer nanoparticles (CPNs) as an efficient SS in SDI of methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae and Candida tropicalis. A frequent problem in the design and testing of new SS for SDI is the lack of proper sonoreactor characterization which leads to reproducibility concerns. To address this issue, we performed dosimetry experiments in our setup. This enables the validation of our results by other researchers and facilitates meaningful comparisons with different SDI systems in future studies. On a different note, it is generally accepted that the mechanisms of action underlying SS-mediated SDI involve the production of reactive oxygen species (ROS). In an attempt to establish the nature of the cytotoxic species involved in our CPNs-based SDI protocol, we demonstrated that singlet oxygen (1O2) does not play a major role in the observed sonoinduced killing effect. SDI experiments in planktonic cultures of optimally growing pathogens using CPNs result in a germicide effect on the studied pathogenic microorganisms. The implementation of SDI protocols using CPNs was further tested in mature biofilms of a MRSA resulting in ∼40 % reduction of biomass and ∼70 % reduction of cellular viability. Overall, these results highlight the unique and unexplored capacity of CPNs to act as sonosensitizers opening new possibilities in the design and application of novel inactivation protocols against morbific microbes.
Collapse
Affiliation(s)
- Sol R Martínez
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina
| | - Emmanuel Odella
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina
| | - Luis E Ibarra
- Instituto de Biotecnología Ambiental y Salud (INBIAS), UNRC y CONICET, Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina
| | - Arianna Sosa Lochedino
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina
| | - Ana B Wendel
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Física, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina
| | - Andrés M Durantini
- Departamento de Química. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina; Instituto para el Desarrollo Agroindustrial y de la Salud (IDAS), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina
| | - Carlos A Chesta
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina.
| | - Rodrigo E Palacios
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina.
| |
Collapse
|
2
|
Ponzio RA, Ibarra LE, Achilli EE, Odella E, Chesta CA, Martínez SR, Palacios RE. Sweet light o' mine: Photothermal and photodynamic inactivation of tenacious pathogens using conjugated polymers. J Photochem Photobiol B 2022; 234:112510. [PMID: 36049287 DOI: 10.1016/j.jphotobiol.2022.112510] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 06/20/2022] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
Each year a rising number of infections can not be successfully treated owing to the increasing pandemic of antibiotic resistant pathogens. The global shortage of innovative antibiotics fuels the emergence and spread of drug resistant microbes. Basic research, development, and applications of alternative therapies are urgently needed. Since the 90´s, light-mediated therapies have promised to be the next frontier combating multidrug-resistance microbes. These platforms have demonstrated to be a reliable, rapid, and efficient alternative to eliminate tenacious pathogens while avoiding the emergence of resistance mechanisms. Among the materials showing antimicrobial activity triggered by light, conjugated polymers (CPs) have risen as the most promising option to tackle this complex situation. These materials present outstanding characteristics such as high absorption coefficients, great photostability, easy processability, low cytotoxicity, among others, turning them into a powerful class of photosensitizer (PS)/photothermal agent (PTA) materials. Herein, we summarize and discuss the advances in the field of CPs with applications in photodynamic inactivation and photothermal therapy towards bacteria elimination. Additionally, a section of current challenges and needs in terms of well-defined benchmark experiments and conditions to evaluate the efficiency of phototherapies is presented.
Collapse
Affiliation(s)
- Rodrigo A Ponzio
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Física, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina
| | - Luis E Ibarra
- Instituto de Biotecnología Ambiental y Salud (INBIAS), UNRC y CONICET, Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina
| | - Estefanía E Achilli
- Laboratorio de Materiales Biotecnológicos (LaMaBio), Universidad Nacional de Quilmes-IMBICE (CONICET), Bernal B1876BXD, Argentina
| | - Emmanuel Odella
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina
| | - Carlos A Chesta
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina.
| | - Sol R Martínez
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina.
| | - Rodrigo E Palacios
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto (UNRC), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Río Cuarto X5804BYA, Córdoba, Argentina; Departamento de Química, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, UNRC, Río Cuarto X5804BYA, Córdoba, Argentina.
| |
Collapse
|
3
|
Odella E, Secor M, Reyes Cruz EA, Guerra WD, Urrutia MN, Liddell PA, Moore TA, Moore GF, Hammes-Schiffer S, Moore AL. Managing the Redox Potential of PCET in Grotthuss-Type Proton Wires. J Am Chem Soc 2022; 144:15672-15679. [PMID: 35993888 DOI: 10.1021/jacs.2c05820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Expanding proton-coupled electron transfer to multiproton translocations (MPCET) provides a bioinspired mechanism to transport protons away from the redox site. This expansion has been accomplished by separating the initial phenolic proton donor from the pyridine-based terminal proton acceptor by a Grotthuss-type proton wire made up of concatenated benzimidazoles that form a hydrogen-bonded network. However, it was found that the midpoint potential of the phenol oxidation that launched the Grotthuss-type proton translocations is a function of the number of benzimidazoles in the hydrogen-bonded network; it becomes less positive (i.e., a weaker oxidant) as the number of bridging benzimidazoles increases. Herein, we report a strategy to maintain the high redox potential necessary for oxidative processes relevant to artificial photosynthesis, e.g., water oxidation and long-range MPCET processes for managing protons. The integrated structural and functional roles of the benzimidazole-based bridge provide sites for substitution of the benzimidazoles with electron-withdrawing groups (e.g., trifluoromethyl groups). Such substitution increases the midpoint potential of the phenoxyl radical/phenol couple so that proton translocations over ∼11 Å become thermodynamically comparable to that of an unsubstituted system where one proton is transferred over ∼2.5 Å. The extended, substituted system maintains the hydrogen-bonded network; infrared spectroelectrochemistry confirms reversible proton translocations from the phenol to the pyridyl terminal proton acceptor upon oxidation and reduction. Theory supports the change in driving force with added electron-withdrawing groups and provides insight into the role of electron density and electrostatic potential in MPCET processes associated with these Grotthuss-type proton translocations.
Collapse
Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Maxim Secor
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Edgar A Reyes Cruz
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Walter D Guerra
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - María N Urrutia
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Paul A Liddell
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gary F Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Ana L Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| |
Collapse
|
4
|
Arsenault EA, Guerra WD, Shee J, Reyes Cruz EA, Yoneda Y, Wadsworth BL, Odella E, Urrutia MN, Kodis G, Moore GF, Head-Gordon M, Moore AL, Moore TA, Fleming GR. Concerted Electron-Nuclear Motion in Proton-Coupled Electron Transfer-Driven Grotthuss-Type Proton Translocation. J Phys Chem Lett 2022; 13:4479-4485. [PMID: 35575065 PMCID: PMC9150097 DOI: 10.1021/acs.jpclett.2c00585] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/02/2022] [Indexed: 06/15/2023]
Abstract
Photoinduced proton-coupled electron transfer and long-range two-proton transport via a Grotthuss-type mechanism are investigated in a biomimetic construct. The ultrafast, nonequilibrium dynamics are assessed via two-dimensional electronic vibrational spectroscopy, in concert with electrochemical and computational techniques. A low-frequency mode is identified experimentally and found to promote double proton and electron transfer, supported by recent theoretical simulations of a similar but abbreviated (non-photoactive) system. Excitation frequency peak evolution and center line slope dynamics show direct evidence of strongly coupled nuclear and electronic degrees of freedom, from which we can conclude that the double proton and electron transfer processes are concerted (up to an uncertainty of 24 fs). The nonequilibrium pathway from the photoexcited Franck-Condon region to the E2PT state is characterized by an ∼110 fs time scale. This study and the tools presented herein constitute a new window into hot charge transfer processes involving an electron and multiple protons.
Collapse
Affiliation(s)
- Eric A. Arsenault
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli
Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, United States
| | - Walter D. Guerra
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - James Shee
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Edgar A. Reyes Cruz
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- The Biodesign
Institute Center for Applied Structural Discovery (CASD), Tempe, Arizona 85287, United States
| | - Yusuke Yoneda
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli
Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, United States
| | - Brian L. Wadsworth
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- The Biodesign
Institute Center for Applied Structural Discovery (CASD), Tempe, Arizona 85287, United States
| | - Emmanuel Odella
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Maria N. Urrutia
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Gerdenis Kodis
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- The Biodesign
Institute Center for Applied Structural Discovery (CASD), Tempe, Arizona 85287, United States
| | - Gary F. Moore
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- The Biodesign
Institute Center for Applied Structural Discovery (CASD), Tempe, Arizona 85287, United States
| | - Martin Head-Gordon
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Ana L. Moore
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Thomas A. Moore
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Graham R. Fleming
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli
Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, United States
| |
Collapse
|
5
|
Odella E, Moore TA, Moore AL. Tuning the redox potential of tyrosine-histidine bioinspired assemblies. Photosynth Res 2022; 151:185-193. [PMID: 33432530 DOI: 10.1007/s11120-020-00815-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
Photosynthesis powers our planet and is a source of inspiration for developing artificial constructs mimicking many aspects of the natural energy transducing process. In the complex machinery of photosystem II (PSII), the redox activity of the tyrosine Z (Tyrz) hydrogen-bonded to histidine 190 (His190) is essential for its functions. For example, the Tyrz-His190 pair provides a proton-coupled electron transfer (PCET) pathway that effectively competes against the back-electron transfer reaction and tunes the redox potential of the phenoxyl radical/phenol redox couple ensuring a high net quantum yield of photoinduced charge separation in PSII. Herein, artificial assemblies mimicking both the structural and redox properties of the Tyrz-His190 pair are described. The bioinspired constructs contain a phenol (Tyrz model) covalently linked to a benzimidazole (His190 model) featuring an intramolecular hydrogen bond which closely emulates the one observed in the natural counterpart. Incorporation of electron-withdrawing groups in the benzimidazole moiety systematically changes the intramolecular hydrogen bond strength and modifies the potential of the phenoxyl radical/phenol redox couple over a range of ~ 250 mV. Infrared spectroelectrochemistry (IRSEC) demonstrates the associated one-electron, one-proton transfer (E1PT) process upon electrochemical oxidation of the phenol. The present contribution provides insight regarding the factors controlling the redox potential of the phenol and highlights strategies for the design of futures constructs capable of transporting protons across longer distances while maintaining a high potential of the phenoxyl radical/phenol redox couple.
Collapse
Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA.
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA
| | - Ana L Moore
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA.
| |
Collapse
|
6
|
Odella E, Secor M, Elliott M, Groy TL, Moore TA, Hammes-Schiffer S, Moore AL. Multi PCET in symmetrically substituted benzimidazoles. Chem Sci 2021; 12:12667-12675. [PMID: 34703552 PMCID: PMC8494046 DOI: 10.1039/d1sc03782j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 08/21/2021] [Indexed: 12/02/2022] Open
Abstract
Proton-coupled electron transfer (PCET) reactions depend on the hydrogen-bond connectivity between sites of proton donors and acceptors. The 2-(2′-hydroxyphenyl) benzimidazole (BIP) based systems, which mimic the natural TyrZ-His190 pair of Photosystem II, have been useful for understanding the associated PCET process triggered by one-electron oxidation of the phenol. Substitution of the benzimidazole by an appropriate terminal proton acceptor (TPA) group allows for two-proton translocations. However, the prototropic properties of substituted benzimidazole rings and rotation around the bond linking the phenol and the benzimidazole can lead to isomers that interrupt the intramolecular hydrogen-bonded network and thereby prevent a second proton translocation. Herein, a strategic symmetrization of a benzimidazole based system with two identical TPAs yields an uninterrupted network of intramolecular hydrogen bonds regardless of the isomeric form. NMR data confirms the presence of a single isomeric form in the disubstituted system but not in the monosubstituted system in certain solvents. Infrared spectroelectrochemistry demonstrates a two-proton transfer process associated with the oxidation of the phenol occurring at a lower redox potential in the disubstituted system relative to its monosubstituted analogue. Computational studies support these findings and show that the disubstituted system stabilizes the oxidized two-proton transfer product through the formation of a bifurcated hydrogen bond. Considering the prototropic properties of the benzimidazole heterocycle in the context of multiple PCET will improve the next generation of novel, bioinspired constructs built by concatenated units of benzimidazoles, thus allowing proton translocations at nanoscale length. Proton-coupled electron transfer (PCET) reactions depend on the hydrogen-bond connectivity between sites of proton donors and acceptors.![]()
Collapse
Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Maxim Secor
- Department of Chemistry, Yale University New Haven Connecticut 06520-8107 USA
| | - Mackenna Elliott
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Thomas L Groy
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | | | - Ana L Moore
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| |
Collapse
|
7
|
Sayre H, Ripberger HH, Odella E, Zieleniewska A, Heredia DA, Rumbles G, Scholes GD, Moore TA, Moore AL, Knowles RR. PCET-Based Ligand Limits Charge Recombination with an Ir(III) Photoredox Catalyst. J Am Chem Soc 2021; 143:13034-13043. [PMID: 34378919 DOI: 10.1021/jacs.1c01701] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Upon photoinitiated electron transfer, charge recombination limits the quantum yield of photoredox reactions for which the rates for the forward reaction and back electron transfer are competitive. Taking inspiration from a proton-coupled electron transfer (PCET) process in Photosystem II, a benzimidazole-phenol (BIP) has been covalently attached to the 2,2'-bipyridyl ligand of [Ir(dF(CF3)ppy)2(bpy)][PF6] (dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridine; bpy = 2,2'-bipyridyl). Excitation of the [Ir(dF(CF3)ppy)2(BIP-bpy)][PF6] photocatalyst results in intramolecular PCET to form a charge-separated state with oxidized BIP. Subsequent reduction of methyl viologen dication (MV2+), a substrate surrogate, by the reducing moiety of the charge separated species demonstrates that the inclusion of BIP significantly slows the charge recombination rate. The effect of ∼24-fold slower charge recombination in a photocatalytic phthalimide ester reduction resulted in a greater than 2-fold increase in reaction quantum efficiency.
Collapse
Affiliation(s)
- Hannah Sayre
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Hunter H Ripberger
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Anna Zieleniewska
- National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Daniel A Heredia
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Garry Rumbles
- National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Ana L Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Robert R Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| |
Collapse
|
8
|
Guerra WD, Odella E, Urrutia MN, Liddell PA, Moore TA, Moore AL. Models to study photoinduced multiple proton coupled electron transfer processes. J PORPHYR PHTHALOCYA 2021. [DOI: 10.1142/s1088424621500577] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In water-oxidizing photosynthetic organisms, excitation of the reaction-center chlorophylls (P680) triggers a cascade of electron and proton transfer reactions that establish charge separation across the membrane and proton-motive force. An early oxidation step in this process involves proton-coupled electron transfer (PCET) via a tyrosine-histidine redox relay (Yz-H190). Herein, we report the synthesis and structural characterization of two isomeric dyads designed to model this PCET process. Both are based on the same high potential fluorinated porphyrin (model for P680), linked to isomeric pyridylbenzimidazole-phenols (models for Yz-H190). The two isomeric dyads have different hydrogen bond frameworks, which is expected to change the PCET photooxidation mechanism. In these dyads, 1H NMR evidence indicates that in one dyad the hydrogen bond network would support a Grotthuss-type proton transfer process, whereas in the other the hydrogen bond network is interrupted. Photoinduced one-electron, two-proton transfer is expected to occur in the fully hydrogen-bonded dyad upon oxidation of the phenol by the excited state of the porphyrin. In contrast for the isomer with the interrupted hydrogen bond network, an ultrafast photoinduced one-electron one-proton transfer process is anticipated, followed by a much slower proton transfer to the terminal proton acceptor. Understanding the nature of photoinduced PCET mechanisms in these biomimetic models will provide insights into the design of future generations of artificial constructs involved in energy conversion schemes.
Collapse
Affiliation(s)
- Walter D. Guerra
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - María N. Urrutia
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Paul A. Liddell
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| |
Collapse
|
9
|
Guerra WD, Odella E, Secor M, Goings JJ, Urrutia MN, Wadsworth BL, Gervaldo M, Sereno LE, Moore TA, Moore GF, Hammes-Schiffer S, Moore AL. Role of Intact Hydrogen-Bond Networks in Multiproton-Coupled Electron Transfer. J Am Chem Soc 2020; 142:21842-21851. [DOI: 10.1021/jacs.0c10474] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Walter D. Guerra
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Maxim Secor
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Joshua J. Goings
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - María N. Urrutia
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Brian L. Wadsworth
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Miguel Gervaldo
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Leónides E. Sereno
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gary F. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| |
Collapse
|
10
|
Mardis KL, Niklas J, Omodayo H, Odella E, Moore TA, Moore AL, Poluektov OG. One Electron Multiple Proton Transfer in Model Organic Donor-Acceptor Systems: Implications for High Frequency EPR. Appl Magn Reson 2020; 51:977-991. [PMID: 34764625 PMCID: PMC8579843 DOI: 10.1007/s00723-020-01252-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/03/2020] [Indexed: 06/12/2023]
Abstract
EPR spectroscopy is an important spectroscopic method for identification and characterization of radical species involved in many biological reactions. The tyrosyl radical is one of the most studied amino acid radical intermediates in biology. Often in conjunction with histidine residues, it is involved in many fundamental biological electron and proton transfer processes, such as in the water oxidation in photosystem II. As biological processes are typically extremely complicated and hard to control, molecular bio-mimetic model complexes are often used to clarify the mechanisms of the biological reactions. Here we present theoretical calculations to investigate the sensitivity of magnetic resonance parameters to proton-coupled electron transfer events, as well as conformational substates of the molecular constructs which mimic the tyrosine-histidine (Tyr-His) pairs found in a large variety of proteins. Upon oxidation of the phenol, the Tyr analogue, these complexes can perform not only one-electron one-proton transfer (EPT), but also one-electron two-proton transfers (E2PT). It is shown that in aprotic environment the gX-components of the electronic g-tensor are extremely sensitive to the first proton transfer from the phenoxyl oxygen to the imidazole nitrogen (EPT product), leading to a significant increase of the gX-value of up to 0.003, but are not sensitive to the second proton transfer (E2PT product). In the latter case the change of the gX-value is much smaller (ca. 0.0001), which is too small to be distinguished even by high frequency EPR. The 14N hyperfine values are also too similar to allow differentiation between the different protonation states in EPT and E2PT. The magnetic resonance parameters were also calculated as a function of the rotation angles around single bonds. It was demonstrated that rotation of the phenoxyl group results in large positive changes (>0.001) in the gX-values. Analysis of the data reveals that the main source of these changes is related to the strength of the H-bond between phenoxyl oxygen and the proton(s) on N1 and N2 positions of the imidazole.
Collapse
Affiliation(s)
- Kristy L Mardis
- Department of Chemistry, Physics, and Engineering Studies, Chicago State University, Chicago, Illinois 60628, USA
| | - Jens Niklas
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Harriet Omodayo
- Department of Chemistry, Physics, and Engineering Studies, Chicago State University, Chicago, Illinois 60628, USA
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, 85287, USA
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, 85287, USA
| | - Ana L Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, 85287, USA
| | - Oleg G Poluektov
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| |
Collapse
|
11
|
Odella E, Mora SJ, Wadsworth BL, Goings JJ, Gervaldo MA, Sereno LE, Groy TL, Gust D, Moore TA, Moore GF, Hammes-Schiffer S, Moore AL. Proton-coupled electron transfer across benzimidazole bridges in bioinspired proton wires. Chem Sci 2020; 11:3820-3828. [PMID: 34122850 PMCID: PMC8152432 DOI: 10.1039/c9sc06010c] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Designing molecular platforms for controlling proton and electron movement in artificial photosynthetic systems is crucial to efficient catalysis and solar energy conversion. The transfer of both protons and electrons during a reaction is known as proton-coupled electron transfer (PCET) and is used by nature in myriad ways to provide low overpotential pathways for redox reactions and redox leveling, as well as to generate bioenergetic proton currents. Herein, we describe theoretical and electrochemical studies of a series of bioinspired benzimidazole-phenol (BIP) derivatives and a series of dibenzimidazole-phenol (BI2P) analogs with each series bearing the same set of terminal proton-accepting (TPA) groups. The set of TPAs spans more than 6 pKa units. These compounds have been designed to explore the role of the bridging benzimidazole(s) in a one-electron oxidation process coupled to intramolecular proton translocation across either two (the BIP series) or three (the BI2P series) acid/base sites. These molecular constructs feature an electrochemically active phenol connected to the TPA group through a benzimidazole-based bridge, which together with the phenol and TPA group form a covalent framework supporting a Grotthuss-type hydrogen-bonded network. Infrared spectroelectrochemistry demonstrates that upon oxidation of the phenol, protons translocate across this well-defined hydrogen-bonded network to a TPA group. The experimental data show the benzimidazole bridges are non-innocent participants in the PCET process in that the addition of each benzimidazole unit lowers the redox potential of the phenoxyl radical/phenol couple by 60 mV, regardless of the nature of the TPA group. Using a series of hypothetical thermodynamic steps, density functional theory calculations correctly predicted the dependence of the redox potential of the phenoxyl radical/phenol couple on the nature of the final protonated species and provided insight into the thermodynamic role of dibenzimidazole units in the PCET process. This information is crucial for developing molecular “dry proton wires” with these moieties, which can transfer protons via a Grotthuss-type mechanism over long distances without the intervention of water molecules. Experimental and theoretical methods characterize the thermodynamics of electrochemically driven proton-coupled electron transfer processes in bioinspired constructs involving multiple proton translocations over Grotthus-type proton wires.![]()
Collapse
Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - S Jimena Mora
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Brian L Wadsworth
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Joshua J Goings
- Department of Chemistry, Yale University New Haven Connecticut 06520-8107 USA
| | - Miguel A Gervaldo
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto Agencia Postal No 3 5800 Río Cuarto Córdoba Argentina
| | - Leonides E Sereno
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto Agencia Postal No 3 5800 Río Cuarto Córdoba Argentina
| | - Thomas L Groy
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Devens Gust
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Gary F Moore
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | | | - Ana L Moore
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| |
Collapse
|
12
|
Mora SJ, Heredia DA, Odella E, Vrudhula U, Gust D, Moore TA, Moore AL. Design and synthesis of benzimidazole phenol-porphyrin dyads for the study of bioinspired photoinduced proton-coupled electron transfer. J PORPHYR PHTHALOCYA 2020. [DOI: 10.1142/s1088424619501189] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Benzimidazole phenol-porphyrin dyads have been synthesized to study proton-coupled electron transfer (PCET) reactions induced by photoexcitation. High-potential porphyrins have been chosen to model P680, the photoactive chlorophyll cluster of photosynthetic photosystem II (PSII). They have either two or three pentafluorophenyl groups at the meso positions to impart the high redox potential. The benzimidazole phenol (BIP) moiety models the Tyr[Formula: see text]-His190 pair of PSII, which is a redox mediator that shuttles electrons from the water oxidation catalyst to P680[Formula: see text]. The dyads consisting of a porphyrin and an unsubstituted BIP are designed to study one-electron one-proton transfer (E1PT) processes upon excitation of the porphyrin. When the BIP moiety is substituted with proton-accepting groups such as imines, one-electron two-proton transfer (E2PT) processes are expected to take place upon oxidation of the phenol by the excited state of the porphyrin. The bis-pentafluorophenyl porphyrins linked to BIPs provide platforms for introducing a variety of electron-accepting moieties and/or anchoring groups to attach semiconductor nanoparticles to the macrocycle. The triads thus formed will serve to study the PCET process involving the BIPs when the oxidation of the phenol is achieved by the photochemically produced radical cation of the porphyrin.
Collapse
Affiliation(s)
- S. Jimena Mora
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Daniel A. Heredia
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal Nro 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Uma Vrudhula
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Devens Gust
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| |
Collapse
|
13
|
Odella E, Wadsworth BL, Mora SJ, Goings JJ, Huynh MT, Gust D, Moore TA, Moore GF, Hammes-Schiffer S, Moore AL. Proton-Coupled Electron Transfer Drives Long-Range Proton Translocation in Bioinspired Systems. J Am Chem Soc 2019; 141:14057-14061. [DOI: 10.1021/jacs.9b06978] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Brian L. Wadsworth
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - S. Jimena Mora
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Joshua J. Goings
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Mioy T. Huynh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Devens Gust
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gary F. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| |
Collapse
|
14
|
Odella E, Mora SJ, Wadsworth BL, Huynh MT, Goings JJ, Liddell PA, Groy TL, Gervaldo M, Sereno LE, Gust D, Moore TA, Moore GF, Hammes-Schiffer S, Moore AL. Controlling Proton-Coupled Electron Transfer in Bioinspired Artificial Photosynthetic Relays. J Am Chem Soc 2018; 140:15450-15460. [DOI: 10.1021/jacs.8b09724] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - S. Jimena Mora
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Brian L. Wadsworth
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Mioy T. Huynh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Joshua J. Goings
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Paul A. Liddell
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas L. Groy
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Miguel Gervaldo
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Leónides E. Sereno
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Devens Gust
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gary F. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| |
Collapse
|
15
|
Odella E, Falcone RD, Ceolín M, Silber JJ, Correa NM. Structural Characterization of Biocompatible Reverse Micelles Using Small-Angle X-ray Scattering, 31P Nuclear Magnetic Resonance, and Fluorescence Spectroscopy. J Phys Chem B 2018; 122:4366-4375. [PMID: 29589933 DOI: 10.1021/acs.jpcb.7b11395] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The most critical problem regarding the use of reverse micelles (RMs) in several fields is the toxicity of their partial components. In this sense, many efforts have been made to characterize nontoxic RM formulations on the basis of biological amphiphiles and/or different oils. In this contribution, the microstructure of biocompatible mixed RMs formulated by sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) and tri- n-octylphosphine oxide (TOPO) surfactants dispersed in the friendly solvent methyl laurate was studied by using SAXS and 31P NMR and by following the solvatochromic behavior of the molecular probe 4-aminophthalimide (4-AP). The results indicated the presence of RM aggregates upon TOPO incorporation with a droplet size reduction and an increase in the interfacial fluidity in comparison with pure AOT RMs. When confined inside the mixed systems, 4-AP showed a red-edge excitation shift and confirmed the increment of interfacial fluidity upon TOPO addition. Also, the partition between the external nonpolar solvent and the RM interface and an increase in both the local micropolarity and the capability to form a hydrogen bond interaction between 4-AP and a mixed interface were observed. The findings have been explained in terms of the nonionic surfactant structure and its complexing nature expressed at the interfacial level. Notably, we show how two different approaches, i.e., SAXS and the solvatochromism of the probe 4-AP, can be used in a complementary way to enhance our understanding of the interfacial fluidity of RMs, a parameter that is difficult to measure directly.
Collapse
Affiliation(s)
- Emmanuel Odella
- Departamento de Química , Universidad Nacional de Río Cuarto , Agencia Postal # 3 , C.P. X5804BYA , Río Cuarto , Argentina
| | - R Darío Falcone
- Departamento de Química , Universidad Nacional de Río Cuarto , Agencia Postal # 3 , C.P. X5804BYA , Río Cuarto , Argentina
| | - Marcelo Ceolín
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas , UNLP-CONICET (CCT-La Plata) , Diagonal 113 y 64 , C.P. B1906ZAA , La Plata , Argentina
| | - Juana J Silber
- Departamento de Química , Universidad Nacional de Río Cuarto , Agencia Postal # 3 , C.P. X5804BYA , Río Cuarto , Argentina
| | - N Mariano Correa
- Departamento de Química , Universidad Nacional de Río Cuarto , Agencia Postal # 3 , C.P. X5804BYA , Río Cuarto , Argentina
| |
Collapse
|
16
|
Abstract
Artificial photosynthetic constructs can in principle operate more efficiently than natural photosynthesis because they can be rationally designed to optimize solar energy conversion for meeting human demands rather than the multiple needs of an organism competing for growth and reproduction in a complex ecosystem. The artificial photosynthetic constructs described in this Account consist primarily of covalently linked synthetic chromophores, electron donors and acceptors, and proton donors and acceptors that carry out the light absorption, electron transfer, and proton-coupled electron transfer (PCET) processes characteristic of photosynthetic cells. PCET is the movement of an electron from one site to another accompanied by proton transfer. PCET and the transport of protons over tens of angstroms are important in all living cells because they are a fundamental link between redox processes and the establishment of transmembrane gradients of proton electrochemical potential, known as proton-motive force (PMF), which is the unifying concept in bioenergetics. We have chosen a benzimidazole phenol (BIP) system as a platform for the study of PCET because with appropriate substitutions it is possible to design assemblies in which one or multiple proton transfers can accompany oxidation of the phenol. In BIP, oxidation of the phenol increases its acidity by more than ten pKa units; thus, electrochemical oxidation of the phenol is associated with a proton transfer to the imidazole. This is an example of a PCET process involving transfer of one electron and one proton, known as electron-proton transfer (EPT). When the benzimidazole moiety of BIP is substituted at the 4-position with good proton acceptor groups such as aliphatic amines, experimental and theoretical results indicate that two proton transfers occur upon one-electron oxidation of the phenol. This phenomenon is described as a one-electron-two-proton transfer (E2PT) process and results in translocation of protons over ∼7 Å via a Grotthuss-type mechanism, where the protons traverse a network of internally H-bonded sites. In the case of the E2TP process involving BIP analogues with amino group substituents, the thermodynamic price paid in redox potential to move a proton to the final proton acceptor is ∼300 mV. In this example, the decrease in redox potential limits the oxidizing power of the resulting phenoxyl radical. Thus, unlike the biological counterpart, the artificial construct is thermodynamically incapable of effectively advancing the redox state of a water oxidation catalyst. The design of systems where multiple proton transfer events are coupled to an oxidation reaction while a relatively high redox potential is maintained remains an outstanding challenge. The ability to control proton transfer and activity at defined distances and times is key to achieving proton management in the vicinity of catalysts operating at low overpotential in myriad biochemically important processes. Artificial photosynthetic constructs with well-defined structures, such as the ones described in this Account, can provide the means for discovering design principles upon which efficient redox catalysts for electrolysis and fuel cells can be based.
Collapse
Affiliation(s)
- S. Jimena Mora
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Gary F. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Devens Gust
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| |
Collapse
|
17
|
Odella E, Falcone RD, Silber JJ, Correa NM. Nanoscale Control Over Interfacial Properties in Mixed Reverse Micelles Formulated by Using Sodium 1,4-bis-2-ethylhexylsulfosuccinate and Tri-n-octyl Phosphine Oxide Surfactants. Chemphyschem 2016; 17:2407-14. [PMID: 27128745 DOI: 10.1002/cphc.201600216] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Indexed: 11/11/2022]
Abstract
The interfacial properties of pure reverse micelles (RMs) are a consequence of the magnitude and nature of noncovalent interactions between confined water and the surfactant polar head. Addition of a second surfactant to form mixed RMs is expected to influence these interactions and thus affect these properties at the nanoscale level. Herein, pure and mixed RMs stabilized by sodium 1,4-bis-2-ethylhexylsulfosuccinate and tri-n-octyl phosphine oxide (TOPO) surfactants in n-heptane were formulated and studied by varying both the water content and the TOPO mole fraction. The microenvironment generated was sensed by following the solvatochromic behavior of the 1-methyl-8-oxyquinolinium betaine probe and (31) P NMR spectroscopy. The results reveal unique properties of mixed RMs and we give experimental evidence that free water can be detected in the polar core of the mixed RMs at very low water content. We anticipate that these findings will have an impact on the use of such media as nanoreactors for many types of chemical reactions, such as enzymatic reactions and nanoparticle synthesis.
Collapse
Affiliation(s)
- Emmanuel Odella
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia Postal # 3. C.P., X5804BYA, Río Cuarto, Argentinia
| | - R Darío Falcone
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia Postal # 3. C.P., X5804BYA, Río Cuarto, Argentinia
| | - Juana J Silber
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia Postal # 3. C.P., X5804BYA, Río Cuarto, Argentinia
| | - N Mariano Correa
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia Postal # 3. C.P., X5804BYA, Río Cuarto, Argentinia.
| |
Collapse
|
18
|
Odella E, Falcone RD, Silber JJ, Correa NM. How TOPO affects the interface of the novel mixed water/AOT:TOPO/n-heptane reverse micelles: dynamic light scattering and Fourier transform infrared spectroscopy studies. Phys Chem Chem Phys 2014; 16:15457-68. [DOI: 10.1039/c4cp01026d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The proportion of TOPO in water/AOT:TOPO/n-heptane reverse micelles produces dramatic changes in the water structure, droplet size and composition of the interface.
Collapse
Affiliation(s)
- Emmanuel Odella
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto, Argentina
| | - R. Darío Falcone
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto, Argentina
| | - Juana J. Silber
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto, Argentina
| | - N. Mariano Correa
- Departamento de Química
- Universidad Nacional de Río Cuarto
- C.P. X5804BYA Río Cuarto, Argentina
| |
Collapse
|