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De Kreijger S, Cauët E, Elias B, Troian-Gautier L. Synthesis of Ru(II) and Os(II) photosensitizers bearing one 9,10-diamino-1,4,5,8-tetraazaphenanthrene scaffold. Dalton Trans 2024; 53:10270-10284. [PMID: 38829264 DOI: 10.1039/d4dt01077a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
The synthesis of eight Ru(II) and Os(II) photosensitizers bearing a common 9,10-disubstituted-1,4,5,8-tetraazaphenanthrene backbone is reported. With Os(II) photosensitizers, the 9,10-diNH2-1,4,5,8-tetraazaphenanthrene could be directly chelated onto the metal center via the heteroaromatic moiety, whereas similar conditions using Ru(II) resulted in the formation of an o-quinonediimine derivative. Hence, an alternative route, proceeding via the chelation of 9-NH2-10-NO2-1,4,5,8-tetraazaphenanthrene and subsequent ligand reduction of the corresponding photosensitizers was developed. Photosensitizers chelated via the polypyridyl-type moiety exhibited classical photophysical properties whereas the o-quinonediimine chelated Ru(II) analogues exhibited red-shifted absorption (520 nm) and no photoluminescence at room temperature in acetonitrile. The most promising photosensitizers were investigated for excited-state quenching with guanosine-5'-monophosphate in aqueous buffered conditions where reductive excited-state electron transfer was observed by nanosecond transient absorption spectroscopy.
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Affiliation(s)
- Simon De Kreijger
- UCLouvain, Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1/L4.01.02, B-1348 Louvain-la-Neuve, Belgium.
| | - Emilie Cauët
- Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (CP 160/09), Université libre de Bruxelles (ULB), 50 av. F. D. Roosevelt, CP160/09, B-1050 Brussels, Belgium
| | - Benjamin Elias
- UCLouvain, Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1/L4.01.02, B-1348 Louvain-la-Neuve, Belgium.
| | - Ludovic Troian-Gautier
- UCLouvain, Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1/L4.01.02, B-1348 Louvain-la-Neuve, Belgium.
- Wel Research Institute, Avenue Pasteur 6, 1300 Wavre, Belgium
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2
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Goodwin MJ, Dickenson JC, Ripak A, Deetz AM, McCarthy JS, Meyer GJ, Troian-Gautier L. Factors that Impact Photochemical Cage Escape Yields. Chem Rev 2024; 124:7379-7464. [PMID: 38743869 DOI: 10.1021/acs.chemrev.3c00930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The utilization of visible light to mediate chemical reactions in fluid solutions has applications that range from solar fuel production to medicine and organic synthesis. These reactions are typically initiated by electron transfer between a photoexcited dye molecule (a photosensitizer) and a redox-active quencher to yield radical pairs that are intimately associated within a solvent cage. Many of these radicals undergo rapid thermodynamically favored "geminate" recombination and do not diffuse out of the solvent cage that surrounds them. Those that do escape the cage are useful reagents that may undergo subsequent reactions important to the above-mentioned applications. The cage escape process and the factors that determine the yields remain poorly understood despite decades of research motivated by their practical and fundamental importance. Herein, state-of-the-art research on light-induced electron transfer and cage escape that has appeared since the seminal 1972 review by J. P. Lorand entitled "The Cage Effect" is reviewed. This review also provides some background for those new to the field and discusses the cage escape process of both homolytic bond photodissociation and bimolecular light induced electron transfer reactions. The review concludes with some key goals and directions for future research that promise to elevate this very vibrant field to even greater heights.
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Affiliation(s)
- Matthew J Goodwin
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - John C Dickenson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Alexia Ripak
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Alexander M Deetz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jackson S McCarthy
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Ludovic Troian-Gautier
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
- Wel Research Institute, Avenue Pasteur 6, 1300 Wavre, Belgium
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3
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Maurer AB, Loague QR, Goodwin MJ, Meyer GJ. Impact of Diimine Ligand on Singlet-to-Triplet Charge Transfer Electroabsorption in Iron and Ruthenium Complexes. J Phys Chem A 2024. [PMID: 38683682 DOI: 10.1021/acs.jpca.3c08357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
The electroabsorption and absorption spectra of eight homoleptic complexes of the general form [M(LL)3]2+ where M = Ru, Fe, and LL = 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), and 4,4',-(R)2-bpy where R = -OCH3, -CF3, were quantified at 77 K in a butyronitrile glass. Intense metal-to-ligand charge transfer (MLCT) absorption bands were evident in the visible region. Electroabsorption spectra measured with applied electric fields >0.2 MV/cm were analyzed by the two-state Liptay model. Significant light-induced dipole moment changes of Δ μ ⇀ = 4-13 D were found consistent with a metal-to-ligand charge transfer (MLCT) excited state comprised an electron localized on a single diimine ligand, [MIII(LL-)(LL)2]*2+, in the initially formed Franck-Condon excited state. A low energy feature evident in the electroabsorption spectra was assigned to a direct singlet-to-triplet MLCT excited state. The identity of the diimine ligand had an unexpected and large impact on these transitions. Analysis relative to the higher energy absorption provides a comparison of spin-allowed and disallowed transitions for first- and second-row transition metal complexes. With the notable exception of [Fe(CF3bpy)3]2+, the change in dipole moment for the 3MLCT excited states was less than or equal to that of the 1MLCT excited states. The charge transfer distances for the iron complexes were generally larger than those for the Ru complexes, a behavior attributed to a smaller degree of iron-diimine coupling in the ground state. A striking result was the sensitivity of the extinction coefficient and spectral profile of the low energy electroabsorption assigned to the identity of the diimine ligand; data that suggests electronic coupling with ligand localized triplet states and high spin metal centered states must be considered when modeling the Franck-Condon excited state.
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Affiliation(s)
- Andrew B Maurer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Quentin R Loague
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Matthew J Goodwin
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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4
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Kessler BJO, Mansoor IF, Wozniak DI, Emge TJ, Lipke MC. Controlling Intramolecular and Intermolecular Electronic Coupling of Radical Ligands in a Series of Cobaltoviologen Complexes. J Am Chem Soc 2023; 145:15924-15935. [PMID: 37460450 DOI: 10.1021/jacs.3c03725] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Controlling electronic coupling between multiple redox sites is of interest for tuning the electronic properties of molecules and materials. While classic mixed-valence (MV) systems are highly tunable, e.g., via the organic bridges connecting the redox sites, metal-bridged MV systems are difficult to control because the electronics of the metal cannot usually be altered independently of redox-active moieties embedded in its ligands. Herein, this limitation was overcome by varying the donor strengths of ancillary ligands in a series of cobalt complexes without directly perturbing the electronics of viologen-like redox sites bridged by the cobalt ions. The cobaltoviologens [1X-Co]n+ feature four 4-X-pyridyl donor groups (X = CO2Me, Cl, H, Me, OMe, NMe2) that provide gradual electronic tuning of the bridging CoII centers, while a related complex [2-Co]n+ with NHC donors supports exclusively CoIII states even upon reduction of the viologen units. Electrochemistry and IVCT band analysis indicate that the MV states of these complexes have electronic structures ranging from fully localized ([2-Co]4+; Robin-Day Class I) to fully delocalized ([1CO2Me-Co]3+; Class III) descriptions, demonstrating unprecedented control over electronic coupling without changing the identity of the redox sites or bridging metal. Additionally, single-crystal XRD characterization of the homovalent complexes [1H-Co]2+ and [1H-Zn]2+ revealed radical-pairing interactions between the viologen ligands of adjacent complexes, representing a type of through-space electronic coupling commonly observed for organic viologen radicals but never before seen in metalloviologens. The extended solid-state packing of these complexes produces 3D networks of radical π-stacking interactions that impart unexpected mechanical flexibility to these crystals.
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Affiliation(s)
- Brice J O Kessler
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 123 Bevier Road, Piscataway, New Jersey 08854, United States
| | - Iram F Mansoor
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 123 Bevier Road, Piscataway, New Jersey 08854, United States
| | - Derek I Wozniak
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 123 Bevier Road, Piscataway, New Jersey 08854, United States
| | - Thomas J Emge
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 123 Bevier Road, Piscataway, New Jersey 08854, United States
| | - Mark C Lipke
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 123 Bevier Road, Piscataway, New Jersey 08854, United States
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5
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Cotic A, Cerfontaine S, Slep LD, Elias B, Troian-Gautier L, Cadranel A. Anti-Dissipative Strategies toward More Efficient Solar Energy Conversion. J Am Chem Soc 2023; 145:5163-5173. [PMID: 36790737 DOI: 10.1021/jacs.2c11593] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
In natural and artificial photosynthesis, light absorption and catalysis are separate processes linked together by exergonic electron transfer. This leads to free energy losses between the initial excited state, formed after light absorption, and the active catalyst formed after the electron transfer cascade. Additional deleterious processes, such as internal conversion (IC) and vibrational relaxation (VR), also dissipate as much as 20-30% of the absorbed photon energy. Minimization of these energy losses, a holy grail in solar energy conversion and solar fuel production, is a challenging task because excited states are usually strongly coupled which results in negligible kinetic barriers and very fast dissipation. Here, we show that topological control of oligomeric {Ru(bpy)3} chromophores resulted in small excited-state electronic couplings, leading to activation barriers for IC by means of inter-ligand electron transfer of around 2000 cm-1 and effectively slowing down dissipation. Two types of excited states are populated upon visible light excitation, that is, a bridging-ligand centered metal-to-ligand charge transfer [MLCT(Lm)], and a 2,2'-bipyridine-centered MLCT [MLCT(bpy)], which lies 800-1400 cm-1 higher in energy. As a proof-of-concept, bimolecular electron transfer with tri-tolylamine (TTA) as electron donor was performed, which mimics catalyst activation by sacrificial electron donors in typical photocatalytic schemes. Both excited states were efficiently quenched by TTA. Hence, this novel strategy allows to trap higher energy excited states before IC and VR set in, saving between 100 and 170 meV. Furthermore, transient absorption spectroscopy suggests that electron transfer reactions with TTA produced the corresponding Lm•--centered and bpy•--centered reduced photosensitizers, which involve different reducing abilities, that is, -0.79 and -0.93 V versus NHE for Lm•- and bpy•-, respectively. Thus, this approach probably leads in fine to a 140 meV more potent reductant for energy conversion schemes and solar fuel production. These results lay the first stone for anti-dissipative energy conversion schemes which, in bimolecular electron transfer reactions, harness the excess energy saved by controlling dissipative conversion pathways.
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Affiliation(s)
- Agustina Cotic
- Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, C1428EHA Buenos Aires, Argentina.,Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, CONICET─Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina
| | - Simon Cerfontaine
- Molecular Chemistry, Materials and Catalysis (MOST), Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Leonardo D Slep
- Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, C1428EHA Buenos Aires, Argentina.,Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, CONICET─Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina
| | - Benjamin Elias
- Molecular Chemistry, Materials and Catalysis (MOST), Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Ludovic Troian-Gautier
- Molecular Chemistry, Materials and Catalysis (MOST), Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Alejandro Cadranel
- Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, C1428EHA Buenos Aires, Argentina.,Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, CONICET─Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina.,Physical Chemistry I, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058 Erlangen, Germany.,Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058 Erlangen, Germany
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6
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Ramírez‐Wierzbicki I, Cotic A, Cadranel A. Photoinduced Intervalence Charge Transfers: Spectroscopic Tools to Study Fundamental Phenomena and Applications. Chemphyschem 2022; 23:e202200384. [PMID: 35785464 PMCID: PMC9805035 DOI: 10.1002/cphc.202200384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/01/2022] [Indexed: 01/09/2023]
Abstract
The exploitation of excited state chemistry for solar energy conversion or photocatalysis has been continuously increasing, and the needs of a transition to a sustainable human development indicate this trend will continue. In this scenario, the study of mixed valence systems in the excited state offers a unique opportunity to explore excited state electron transfer reactivity, and, in a broader sense, excited state chemistry. This Concept article analyzes recent contributions in the field of photoinduced mixed valence systems, i. e. those where the mixed valence core is absent in the ground state but created upon light absorption. The focus is on the utilization of photoinduced intervalence charge transfer bands, detected via transient absorption spectroscopy, as key tools to study fundamental phenomena like donor/acceptor inversion, hole delocalization, coexistence of excited states and excited state nature, together with applications in molecular electronics.
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Affiliation(s)
- Ivana Ramírez‐Wierzbicki
- Instituto de Química Física de MaterialesMedio Ambiente y Energía (INQUIMAE)CONICET – Universidad de Buenos AiresPabellón 2, Ciudad UniversitariaC1428EHABuenos AiresArgentina
- Departamento de Química InorgánicaAnalítica y Química FísicaUniversidad de Buenos AiresFacultad de Ciencias Exactas y NaturalesPabellón 2, Ciudad UniversitariaC1428EHABuenos AiresArgentina
| | - Agustina Cotic
- Instituto de Química Física de MaterialesMedio Ambiente y Energía (INQUIMAE)CONICET – Universidad de Buenos AiresPabellón 2, Ciudad UniversitariaC1428EHABuenos AiresArgentina
- Departamento de Química InorgánicaAnalítica y Química FísicaUniversidad de Buenos AiresFacultad de Ciencias Exactas y NaturalesPabellón 2, Ciudad UniversitariaC1428EHABuenos AiresArgentina
| | - Alejandro Cadranel
- Instituto de Química Física de MaterialesMedio Ambiente y Energía (INQUIMAE)CONICET – Universidad de Buenos AiresPabellón 2, Ciudad UniversitariaC1428EHABuenos AiresArgentina
- Departamento de Química InorgánicaAnalítica y Química FísicaUniversidad de Buenos AiresFacultad de Ciencias Exactas y NaturalesPabellón 2, Ciudad UniversitariaC1428EHABuenos AiresArgentina
- Department Chemie und PharmaziePhysikalische ChemieFriedrich-Alexander-Universität Erlangen-NürnbergEgerlandstraße 391058ErlangenGermany
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7
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Heidari M, Loague Q, Bangle RE, Galoppini E, Meyer GJ. Reorganization Energies for Interfacial Electron Transfer across Phenylene Ethynylene Rigid-Rod Bridges. ACS APPLIED MATERIALS & INTERFACES 2022; 14:35205-35214. [PMID: 35862637 DOI: 10.1021/acsami.2c07151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A family of three ruthenium bipyridyl rigid-rod compounds of the general form [Ru(bpy)2(LL)](PF6)2 were anchored to mesoporous thin films of tin-doped indium oxide (ITO) nanocrystals. Here, LL is a 4-substituted 2,2-bipyridine (bpy) ligand with varying numbers of conjugated phenylenethynylene bridge units between the bipyridine ring and anchoring group consisting of a bis-carboxylated isophthalic group. The visible absorption spectra and the formal potentials, Eo(RuIII/II), of the surface anchored rigid-rods were insensitive to the presence of the phenylene ethynylene bridge units in 0.1 M tetrabutyl ammonium perchlorate acetonitrile solutions (TBAClO4/CH3CN). The conductive nature of the ITO enabled potentiostatic control of the Fermi level and hence a means to tune the Gibbs free energy change, -ΔG°, for electron transfer from the ITO to the rigid-rods. Pseudo-rate constants for this electron transfer reaction increased as the number of bridge units decreased at a fixed -ΔG°. With the assumption that the reorganization energy, λ, and the electronic coupling matrix element, Hab, were independent of the applied potential, rate constants measured as a function of -ΔG° and analyzed through Marcus-Gerischer theory provided estimates of Hab and λ. In rough accordance with the dielectric continuum theory, λ was found to increase from 0.61 to 0.80 eV as the number of bridge units was increased. In contrast, Hab decreased markedly with distance from 0.54 to 0.11 cm-1, consistent with non-adiabatic electron transfer. Comparative analysis with previously published studies of bridges with an sp3-hybridized carbon indicated that the phenylene ethynylene bridge does not enhance electronic coupling between the oxide and the rigid-rod acceptor. The implications of these findings for practical applications in solar energy conversion are specifically discussed.
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Affiliation(s)
- Marzieh Heidari
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Quentin Loague
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Rachel E Bangle
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Elena Galoppini
- Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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8
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Cotic A, Cerfontaine S, Slep LD, Elias B, Troian-Gautier L, Cadranel A. A photoinduced mixed valence photoswitch. Phys Chem Chem Phys 2022; 24:15121-15128. [PMID: 35699139 DOI: 10.1039/d2cp01791a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ground state and photoinduced mixed valence states (GSMV and PIMV, respectively) of a dinuclear (Dp4+) ruthenium(II) complex bearing 2,2'-bipyridine ancillary ligands and a 2,2':4',4'':2'',2'''-quaterpyridine (Lp) bridging ligand were investigated using femtosecond and nanosecond transient absorption spectroscopy, electrochemistry and density functional theory. It was shown that the electronic coupling between the transiently light-generated Ru(II) and Ru(III) centers is HDA ∼ 450 cm-1 in the PIMV state, whereas the electrochemically generated GSMV state showed HDA ∼ 0 cm-1, despite virtually identical Ru-Ru distances. This stemmed from the changes in dihedral angles between the two bpy moieties of Lp, estimated at 30° and 4° for the GSMV and PIMV states, respectively, consistent with a through-bond rather than a through-space mechanism. Electronic coupling can be turned on by using visible light excitation, making Dp4+ a competitive candidate for photoswitching applications. A novel strategy to design photoinduced charge transfer molecular switches is proposed.
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Affiliation(s)
- Agustina Cotic
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. .,CONICET - Universidad de Buenos Aires, Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Simon Cerfontaine
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium.
| | - Leonardo D Slep
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. .,CONICET - Universidad de Buenos Aires, Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Benjamin Elias
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium.
| | - Ludovic Troian-Gautier
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium.
| | - Alejandro Cadranel
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. .,CONICET - Universidad de Buenos Aires, Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Physical Chemistry I, Egerlandstr. 3, 91058, Erlangen, Germany.,Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Interdisciplinary Center for Molecular Materials, Egerlandstr. 3, 91058, Erlangen, Germany
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9
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Li S, Pershin A, Thiering G, Udvarhelyi P, Gali A. Ultraviolet Quantum Emitters in Hexagonal Boron Nitride from Carbon Clusters. J Phys Chem Lett 2022; 13:3150-3157. [PMID: 35362989 PMCID: PMC9014460 DOI: 10.1021/acs.jpclett.2c00665] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 03/30/2022] [Indexed: 05/30/2023]
Abstract
Ultraviolet (UV) quantum emitters in hexagonal boron nitride (hBN) have generated considerable interest due to their outstanding optical response. Recent experiments have identified a carbon impurity as a possible source of UV single-photon emission. Here, on the basis of first-principles calculations, we systematically evaluate the ability of substitutional carbon defects to develop the UV color centers in hBN. Of 17 defect configurations under consideration, we particularly emphasize the carbon ring defect (6C), for which the calculated zero-phonon line agrees well the experimental 4.1 eV emission signal. We also compare the optical properties of 6C with those of other relevant defects, thereby outlining the key differences in the emission mechanism. Our findings provide new insights into the strong response of this color center to external perturbations and pave the way to a robust identification of the particular carbon substitutional defects by spectroscopic methods.
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Affiliation(s)
- Song Li
- Wigner
Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary
| | - Anton Pershin
- Wigner
Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary
| | - Gergő Thiering
- Wigner
Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary
| | - Péter Udvarhelyi
- Wigner
Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary
| | - Adam Gali
- Wigner
Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary
- Department
of Atomic Physics, Institute of Physics, Budapest University of Technology and Economics, Müegyetem rakpart 3, H-1111 Budapest, Hungary
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Roh DH, Park JH, Han HG, Kim YJ, Motoyoshi D, Hwang E, Kim WH, Mapley JI, Gordon KC, Mori S, Kwon OH, Kwon TH. Molecular design strategy for realizing vectorial electron transfer in photoelectrodes. Chem 2022. [DOI: 10.1016/j.chempr.2022.01.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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11
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Muñoz-García AB, Benesperi I, Boschloo G, Concepcion JJ, Delcamp JH, Gibson EA, Meyer GJ, Pavone M, Pettersson H, Hagfeldt A, Freitag M. Dye-sensitized solar cells strike back. Chem Soc Rev 2021; 50:12450-12550. [PMID: 34590638 PMCID: PMC8591630 DOI: 10.1039/d0cs01336f] [Citation(s) in RCA: 109] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Indexed: 12/28/2022]
Abstract
Dye-sensitized solar cells (DSCs) are celebrating their 30th birthday and they are attracting a wealth of research efforts aimed at unleashing their full potential. In recent years, DSCs and dye-sensitized photoelectrochemical cells (DSPECs) have experienced a renaissance as the best technology for several niche applications that take advantage of DSCs' unique combination of properties: at low cost, they are composed of non-toxic materials, are colorful, transparent, and very efficient in low light conditions. This review summarizes the advancements in the field over the last decade, encompassing all aspects of the DSC technology: theoretical studies, characterization techniques, materials, applications as solar cells and as drivers for the synthesis of solar fuels, and commercialization efforts from various companies.
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Affiliation(s)
- Ana Belén Muñoz-García
- Department of Physics "Ettore Pancini", University of Naples Federico II, 80126 Naples, Italy
| | - Iacopo Benesperi
- School of Natural and Environmental Science, Newcastle University, Bedson Building, NE1 7RU Newcastle upon Tyne, UK.
| | - Gerrit Boschloo
- Department of Chemistry, Ångström Laboratory, Uppsala University, P.O. Box 523, 751 20 Uppsala, Sweden.
| | - Javier J Concepcion
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Jared H Delcamp
- Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677, USA
| | - Elizabeth A Gibson
- School of Natural and Environmental Science, Newcastle University, Bedson Building, NE1 7RU Newcastle upon Tyne, UK.
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Michele Pavone
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy
| | | | - Anders Hagfeldt
- Department of Chemistry, Ångström Laboratory, Uppsala University, P.O. Box 523, 751 20 Uppsala, Sweden.
- University Management and Management Council, Vice Chancellor, Uppsala University, Segerstedthuset, 752 37 Uppsala, Sweden
| | - Marina Freitag
- School of Natural and Environmental Science, Newcastle University, Bedson Building, NE1 7RU Newcastle upon Tyne, UK.
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12
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Deetz AM, Troian-Gautier L, Wehlin SAM, Piechota EJ, Meyer GJ. On the Determination of Halogen Atom Reduction Potentials with Photoredox Catalysts. J Phys Chem A 2021; 125:9355-9367. [PMID: 34665634 DOI: 10.1021/acs.jpca.1c06772] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The standard one-electron reduction potentials of halogen atoms, E°'(X•/-), and many other radical or unstable species, are not accessible through standard electrochemical methods. Here, we report the use of two Ir(III) photoredox catalysts to initiate chloride, bromide, and iodide oxidation in organic solvents. The kinetic rate constants were critically analyzed through a derived diffusional model with Marcus theory to estimate E°'(X•/-) in propylene carbonate, acetonitrile, butyronitrile, and dichloromethane. The approximations commonly used to determine diffusional rate constants in water gave rise to serious disagreements with the experiment, particularly in high-ionic-strength dichloromethane solutions, indicating the need to utilize the exact Debye expression. The Fuoss equation was adequate for determining photocatalyst-halide association constants with photocatalysts that possessed +2, +1, and 0 ionic charges. Similarly, the work term contribution in the classical Rehm-Weller expression, necessary for E°'(X•/-) determination, accounted remarkably well for the stabilization of the charged reactants as the solution ionic strength was increased. While a sensitivity analysis indicated that the extracted reduction potentials were all within experimental error the same, use of fixed parameters established for aqueous solution provided the periodic trend expected, E°'(I•/-) <E°'(Br•/-) <E°'(Cl•/-), in all of the organic solvents investigated; however, the potentials were more closely spaced than what would have been predicted based on gas-phase electron affinities or aqueous reduction potentials. The origin(s) of such behavior are discussed that provide new directions for future research.
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Affiliation(s)
- Alexander M Deetz
- Department of Chemistry, University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, United States
| | - Ludovic Troian-Gautier
- Department of Chemistry, University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, United States
| | - Sara A M Wehlin
- Department of Chemistry, University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, United States
| | - Eric J Piechota
- Department of Chemistry, University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, United States
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13
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Panetti GB, Carroll PJ, Gau MR, Manor BC, Schelter EJ, Walsh PJ. Synthesis of an elusive, stable 2-azaallyl radical guided by electrochemical and reactivity studies of 2-azaallyl anions. Chem Sci 2021; 12:4405-4410. [PMID: 34163704 PMCID: PMC8179533 DOI: 10.1039/d0sc04822d] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 02/01/2021] [Indexed: 12/31/2022] Open
Abstract
The super electron donor (SED) ability of 2-azaallyl anions has recently been discovered and applied to diverse reactivity, including transition metal-free cross-coupling and dehydrogenative cross-coupling processes. Surprisingly, the redox properties of 2-azaallyl anions and radicals have been rarely studied. Understanding the chemistry of elusive species is the key to further development. Electrochemical analysis of phenyl substituted 2-azaallyl anions revealed an oxidation wave at E 1/2 or E pa = -1.6 V versus Fc/Fc+, which is ∼800 mV less than the reduction potential predicted (E pa = -2.4 V vs. Fc/Fc+) based on reactivity studies. Investigation of the kinetics of electron transfer revealed reorganization energies an order of magnitude lower than commonly employed SEDs. The electrochemical study enabled the synthetic design of the first stable, acyclic 2-azaallyl radical. These results indicate that the reorganization energy should be an important design consideration for the development of more potent organic reductants.
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Affiliation(s)
- Grace B Panetti
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Patrick J Carroll
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Michael R Gau
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Brian C Manor
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Eric J Schelter
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
| | - Patrick J Walsh
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia PA USA
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14
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Hu K, Sampaio RN, Schneider J, Troian-Gautier L, Meyer GJ. Perspectives on Dye Sensitization of Nanocrystalline Mesoporous Thin Films. J Am Chem Soc 2020; 142:16099-16116. [DOI: 10.1021/jacs.0c04886] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Ke Hu
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Renato N. Sampaio
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Jenny Schneider
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Ludovic Troian-Gautier
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Gerald J. Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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15
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Al-Faouri T, Buguis FL, Azizi Soldouz S, Sarycheva OV, Hussein BA, Mahmood R, Koivisto BD. Exploring Structure-Property Relationships in a Bio-Inspired Family of Bipodal and Electronically-Coupled Bistriphenylamine Dyes for Dye-Sensitized Solar Cell Applications. Molecules 2020; 25:E2260. [PMID: 32403290 PMCID: PMC7248778 DOI: 10.3390/molecules25092260] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/06/2020] [Accepted: 05/09/2020] [Indexed: 11/26/2022] Open
Abstract
A bio-inspired family of organic dyes with bichromic-bipodal architectures were synthesized and tested in dye-sensitized solar cells (DSSC). These dyes are comprised of a D-π-D-A motif with two triphenylamine (TPA) units acting as donors (D) and two cyanoacetic acid acceptors (A) capable of binding to a titania semiconductor. The role of the thiophene π-spacer bridging the two TPA units was examined and the distal TPA (relative to TiO2) was modified with various substituents (-H, -OMe, -SMe, -OHex, -3-thienyl) and contrasted against benchmark L1. It was found that the two TPA donor units could be tuned independently, where π-spacers can tune the proximal TPA and R-substituents can tune the distal TPA. The highest performing DSSCs were those with -SMe, 3-thienyl, and -H substituents, and those with one spacer or no spacers. The donating abilities of R-substituents was important, but their interactions with the electrolyte was more significant in producing high performing DSSCs. The introduction of one π-spacer provided favourable electronic communication within the dye, but more than one was not advantageous.
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Affiliation(s)
| | | | | | | | | | | | - Bryan D. Koivisto
- Department of Chemistry and Biology, Ryerson University, 350 Victoria St, Toronto, ON M5B 2K3, Canada; (T.A.-F.); (F.L.B.); (S.A.S.); (O.V.S.); (B.A.H.); (R.M.)
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16
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Vibronic coherence contributes to photocurrent generation in organic semiconductor heterojunction diodes. Nat Commun 2020; 11:617. [PMID: 32001688 PMCID: PMC6992633 DOI: 10.1038/s41467-020-14476-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 01/09/2020] [Indexed: 11/24/2022] Open
Abstract
Charge separation dynamics after the absorption of a photon is a fundamental process relevant both for photosynthetic reaction centers and artificial solar conversion devices. It has been proposed that quantum coherence plays a role in the formation of charge carriers in organic photovoltaics, but experimental proofs have been lacking. Here we report experimental evidence of coherence in the charge separation process in organic donor/acceptor heterojunctions, in the form of low frequency oscillatory signature in the kinetics of the transient absorption and nonlinear two-dimensional photocurrent spectroscopy. The coherence plays a decisive role in the initial ~200 femtoseconds as we observe distinct experimental signatures of coherent photocurrent generation. This coherent process breaks the energy barrier limitation for charge formation, thus competing with excitation energy transfer. The physics may inspire the design of new photovoltaic materials with high device performance, which explore the quantum effects in the next-generation optoelectronic applications. Although coherent vibrational motion in donor-acceptor blends may contribute to photogeneration generation in organic solar cells (OSCs), proof of a direct correlation is still lacking. Here, the authors report the role of vibrational coherence on photocurrent generation in ternary OSC blends.
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17
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Maurer AB, Piechota EJ, Meyer GJ. Excited-State Dipole Moments of Homoleptic [Ru(bpy′)3]2+ Complexes Measured by Stark Spectroscopy. J Phys Chem A 2019; 123:8745-8754. [DOI: 10.1021/acs.jpca.9b05874] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Andrew B. Maurer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Eric J. Piechota
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gerald J. Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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18
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Wang D, Sampaio RN, Troian-Gautier L, Marquard SL, Farnum BH, Sherman BD, Sheridan MV, Dares CJ, Meyer GJ, Meyer TJ. Molecular Photoelectrode for Water Oxidation Inspired by Photosystem II. J Am Chem Soc 2019; 141:7926-7933. [DOI: 10.1021/jacs.9b02548] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Degao Wang
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Renato N. Sampaio
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Ludovic Troian-Gautier
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Seth L. Marquard
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Byron H. Farnum
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Benjamin D. Sherman
- Department of Chemistry, Texas Christian University, Fort Worth, Texas 76129, United States
| | - Matthew V. Sheridan
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Christopher J. Dares
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, Florida 33199, United States
| | - Gerald J. Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Thomas J. Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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19
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Troian-Gautier L, Turlington MD, Wehlin SAM, Maurer AB, Brady MD, Swords WB, Meyer GJ. Halide Photoredox Chemistry. Chem Rev 2019; 119:4628-4683. [PMID: 30854847 DOI: 10.1021/acs.chemrev.8b00732] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Halide photoredox chemistry is of both practical and fundamental interest. Practical applications have largely focused on solar energy conversion with hydrogen gas, through HX splitting, and electrical power generation, in regenerative photoelectrochemical and photovoltaic cells. On a more fundamental level, halide photoredox chemistry provides a unique means to generate and characterize one electron transfer chemistry that is intimately coupled with X-X bond-breaking and -forming reactivity. This review aims to deliver a background on the solution chemistry of I, Br, and Cl that enables readers to understand and utilize the most recent advances in halide photoredox chemistry research. These include reactions initiated through outer-sphere, halide-to-metal, and metal-to-ligand charge-transfer excited states. Kosower's salt, 1-methylpyridinium iodide, provides an early outer-sphere charge-transfer excited state that reports on solvent polarity. A plethora of new inner-sphere complexes based on transition and main group metal halide complexes that show promise for HX splitting are described. Long-lived charge-transfer excited states that undergo redox reactions with one or more halogen species are detailed. The review concludes with some key goals for future research that promise to direct the field of halide photoredox chemistry to even greater heights.
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Affiliation(s)
- Ludovic Troian-Gautier
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Michael D Turlington
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Sara A M Wehlin
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Andrew B Maurer
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Matthew D Brady
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Wesley B Swords
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Gerald J Meyer
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
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20
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Troian-Gautier L, Sampaio RN, Piechota EJ, Brady MD, Meyer GJ. Barriers for interfacial back-electron transfer: A comparison between TiO2 and SnO2/TiO2 core/shell structures. J Chem Phys 2019; 150:041719. [DOI: 10.1063/1.5054604] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Ludovic Troian-Gautier
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Renato N. Sampaio
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Eric J. Piechota
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Matthew D. Brady
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Gerald J. Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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21
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Abstract
Iodide redox chemistry is intimately coupled with the formation and breaking of chemical bonds that are relevant to emerging solar energy technologies. In this Account, recent advances in dye-sensitized iodide oxidation chemistry in organic solutions are described. Here RuII sensitizers with high cationic charge, tuned reduction potentials, and specific iodide receptor site(s) are shown to self-assemble in organic solvents and yield structures that rapidly oxidize iodide and generate I-I bonds when illuminated with visible light. These studies provided new insights into the fascinating behavior of our most polarizable and easily oxidized monatomic anion. Sensitized iodide photo-oxidation in CH3CN solutions consists of two mechanistic steps. In the first step, an excited-state sensitizer oxidizes iodide (I-) to an iodine atom (I•) through diffusional encounters. The second step involves the reaction of I• with I- to form the I-I bond of diiodide, I2•-. The overall reaction converts a green photon into about 1.64 eV of free energy in the form of I2•- and the reduced sensitizer. The free energy is only transiently available, as back-electron transfer to yield ground-state products is quantitative. Interestingly, when the free energy change is near zero, iodide photo-oxidation occurs rapidly with rate constants near the diffusion limit, i.e., >1010 M-1 s-1. Such rapid reactivity is in line with anecdotal knowledge that iodide is an outstanding electron donor and is indicative of adiabatic electron transfer through an inner-sphere mechanism. In low-dielectric-constant solvents, dicationic RuII sensitizers were found to form tight ion pairs with iodide. Diimine ligands with additional cationic charge, or "binding pockets" that recognize halides, have been utilized to position one or more halides at specific locations about the sensitizer before light absorption. Diverse photochemical reactions observed with these supramolecular assemblies range from the photorelease of halides to the formation of I-I bonds where both iodides present in the ground-state assembly react. Natural population analysis through density functional theory calculations accurately predicts the site(s) of iodide ion-pairing and provides information on the associated free energy change. The ability to direct light-driven bond formation in these ionic assemblies is extended to chloride and bromide ions. The structure-property relationships identified, and those that continue to emerge, may one day allow for the rational design of molecules and materials that drive desired halide transformations when illuminated with light.
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Affiliation(s)
- Ludovic Troian-Gautier
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Wesley B. Swords
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gerald J. Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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22
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Luo Y, Tran JH, Wächtler M, Schulz M, Barthelmes K, Winter A, Rau S, Schubert US, Dietzek B. Remote control of electronic coupling – modification of excited-state electron-transfer rates in Ru(tpy)2-based donor–acceptor systems by remote ligand design. Chem Commun (Camb) 2019; 55:2273-2276. [DOI: 10.1039/c8cc10075f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Electronic coupling (HDA) underlying the electron transfer (ET) can be tuned by the remote substituents R.
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Affiliation(s)
- Yusen Luo
- Institute of Physical Chemistry and Abbe Center of Photonics
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
- Department Functional Interfaces
| | - Jens H. Tran
- Institute of Physical Chemistry and Abbe Center of Photonics
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
| | - Maria Wächtler
- Institute of Physical Chemistry and Abbe Center of Photonics
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
- Department Functional Interfaces
| | - Martin Schulz
- Institute of Physical Chemistry and Abbe Center of Photonics
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
| | - Kevin Barthelmes
- Laboratory of Organic and Macromolecular Chemistry (IOMC)
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena)
| | - Andreas Winter
- Laboratory of Organic and Macromolecular Chemistry (IOMC)
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena)
| | - Sven Rau
- Institute for Inorganic Chemistry I
- Ulm University
- 89081 Ulm
- Germany
| | - Ulrich S. Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC)
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena)
| | - Benjamin Dietzek
- Institute of Physical Chemistry and Abbe Center of Photonics
- Friedrich Schiller University Jena
- 07743 Jena
- Germany
- Department Functional Interfaces
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23
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Sampaio RN, Troian‐Gautier L, Meyer GJ. A Charge‐Separated State that Lives for Almost a Second at a Conductive Metal Oxide Interface. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201807627] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Renato N. Sampaio
- Department of Chemistry University of North Carolina at Chapel Hill Murray Hall 2202B, 123 South Road 27599-3290 North Carolina USA
| | - Ludovic Troian‐Gautier
- Department of Chemistry University of North Carolina at Chapel Hill Murray Hall 2202B, 123 South Road 27599-3290 North Carolina USA
| | - Gerald J. Meyer
- Department of Chemistry University of North Carolina at Chapel Hill Murray Hall 2202B, 123 South Road 27599-3290 North Carolina USA
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24
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A Charge‐Separated State that Lives for Almost a Second at a Conductive Metal Oxide Interface. Angew Chem Int Ed Engl 2018; 57:15390-15394. [DOI: 10.1002/anie.201807627] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 07/25/2018] [Indexed: 11/07/2022]
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