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Kuzkova N, Kiyan IY, Wilkinson I, Merschjann C. Ultrafast dynamics in polymeric carbon nitride thin films probed by time-resolved EUV photoemission and UV-Vis transient absorption spectroscopy. Phys Chem Chem Phys 2023; 25:27094-27113. [PMID: 37807824 DOI: 10.1039/d3cp03191h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
The ground- and excited-state electronic structures of four polymeric carbon nitride (PCN) materials have been investigated using a combination of photoemission and optical absorption spectroscopy. To establish the driving forces for photocatalytic water-splitting reactions, the ground-state data was used to produce a band diagram of the PCN materials and the triethanolamine electron scavenger, commonly implemented in water-splitting devices. The ultrafast charge-carrier dynamics of the same PCN materials were also investigated using two femtosecond-time-resolved pump-probe techniques: extreme-ultraviolet (EUV) photoemission and ultraviolet-visible (UV-Vis) transient absorption spectroscopy. The complementary combination of these surface- and bulk-sensitive methods facilitated photoinduced kinetic measurements spanning the sub-picosecond to few nanosecond time range. The results show that 400 nm (3.1 eV) excitation sequentially populates a pair of short-lived transient species, which subsequently produce two different long-lived excited states on a sub-picosecond time scale. Based on the spectro-temporal characteristics of the long-lived signals, they are assigned to singlet-exciton and charge-transfer states. The associated charge-separation efficiency was inferred to be between 65% and 78% for the different studied materials. A comparison of results from differently synthesized PCNs revealed that the early-time processes do not differ qualitatively between sample batches, but that materials of more voluminous character tend to have higher charge separation efficiencies, compared to exfoliated colloidal materials. This finding was corroborated via a series of experiments that revealed an absence of any pump-fluence dependence of the initial excited-state decay kinetics and characteristic carrier-concentration effects that emerge beyond few-picosecond timescales. The initial dynamics of the photoinduced charge carriers in the PCNs are correspondingly determined to be spatially localised in the immediate vicinity of the lattice-constituting motif, while the long-time behaviour is dominated by charge-transport and recombination processes. Suppressing the latter by confining excited species within nanoscale volumes should therefore affect the usability of PCN materials in photocatalytic devices.
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Affiliation(s)
- Nataliia Kuzkova
- Institute of Electronic Structure Dynamics, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Igor Yu Kiyan
- Institute of Electronic Structure Dynamics, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Iain Wilkinson
- Institute of Electronic Structure Dynamics, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Christoph Merschjann
- Department Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
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2
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Curtis K, King C, Odoh SO. Novel Triangulenes: Computational Investigations of Energy Thresholds for Photocatalytic Water Splitting. Chemphyschem 2023:e202300556. [PMID: 37718310 DOI: 10.1002/cphc.202300556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 09/15/2023] [Accepted: 09/17/2023] [Indexed: 09/19/2023]
Abstract
Organic materials with Inverted Singlet-Triplet (INVEST) gaps are interesting for their potential use in photocatalytic small molecule transformations such as the entirely solar-driven water splitting reaction. However, only a few INVEST emitters are thermodynamically able to split water requiring a first singlet excited dark state, S1 , above 1.27 or 1.76 eV, and absorption near solar the maximum, 2.57 eV. These requirements and the INVEST character are key for achieving a long-lived photocatalyst for water splitting. The only known INVEST emitters that conform to these criteria are large triangular boron carbon nitrides with unknown synthesis pathways. Using ADC(2), a quantum-mechanical method, we describe three triangulenes. 3 a is a cyano azacyclopenta[cd]phenalene derivative while 3 b and 3 c are cycl[3.3.3]azine derivatives. 3 b has a previously undescribed disulfide bridge. Overall, 3 a fulfills requirements for photocatalytic four-electron reduction of water while the S1 states of 3 b and 3 c are likely slightly low for the two-electron reduction process. By analyzing impacts of ligands, we find that there are guidelines describing how S1 -S5 energies and oscillator strengths, T1 energies, and ΔES1T1 gaps are affected, requiring deep-learning algorithms for which studies will be presented by us in due time. The impact of ground-state geometries, solvation effects, as well as reduced-cost ADC(2) algorithms on our findings are also discussed.
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Affiliation(s)
- Kevin Curtis
- Department of Chemistry, University of Nevada Reno, 1664 N. Virginia Street, Reno, NV, 89557-0216, USA
| | - Corban King
- Department of Chemistry, University of Nevada Reno, 1664 N. Virginia Street, Reno, NV, 89557-0216, USA
| | - Samuel O Odoh
- Department of Chemistry, University of Nevada Reno, 1664 N. Virginia Street, Reno, NV, 89557-0216, USA
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3
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Ponzi A, Rosa M, Kladnik G, Unger I, Ciavardini A, Di Nardi L, Viola E, Nicolas C, Došlić N, Goldoni A, Lanzilotto V. Inequivalent Solvation Effects on the N 1s Levels of Self-Associated Melamine Molecules in Aqueous Solution. J Phys Chem B 2023; 127:3016-3025. [PMID: 36972466 PMCID: PMC10084451 DOI: 10.1021/acs.jpcb.3c00327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
This work shows how the N 1s photoemission (PE) spectrum of self-associated melamine molecules in aqueous solution has been successfully rationalized using an integrated computational approach encompassing classical metadynamics simulations and quantum calculations based on density functional theory (DFT). The first approach allowed us to describe interacting melamine molecules in explicit waters and to identify dimeric configurations based on π-π and/or H-bonding interactions. Then, N 1s binding energies (BEs) and PE spectra were computed at the DFT level for all structures both in the gas phase and in an implicit solvent. While pure π-stacked dimers show gas-phase PE spectra almost identical to that of the monomer, those of the H-bonded dimers are sensibly affected by NH···NH or NH···NC interactions. Interestingly, the solvation suppresses all of the non-equivalences due to the H-bonds yielding similar PE spectra for all dimers, matching very well our measurements.
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Affiliation(s)
- Aurora Ponzi
- Division of Physical Chemistry, Ruđer Bošković Institute, 10000 Zagreb, Croatia
| | - Marta Rosa
- Department of Chemical Sciences, University of Padova, 35122 Padova, Italy
| | - Gregor Kladnik
- Department of Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
- IOM-CNR, Laboratorio TASC, Basovizza SS-14, Km 163.5, 34149 Trieste, Italy
| | - Isaak Unger
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | | | - Lorys Di Nardi
- Department of Chemistry, Sapienza University of Rome, 00185 Roma, Italy
| | - Elisa Viola
- Department of Chemistry, Sapienza University of Rome, 00185 Roma, Italy
| | | | - Nađa Došlić
- Division of Physical Chemistry, Ruđer Bošković Institute, 10000 Zagreb, Croatia
| | - Andrea Goldoni
- Elettra Synchrotron, Micro & Nano Carbon Laboratory, 34149 Trieste, Italy
| | - Valeria Lanzilotto
- IOM-CNR, Laboratorio TASC, Basovizza SS-14, Km 163.5, 34149 Trieste, Italy
- Department of Chemistry, Sapienza University of Rome, 00185 Roma, Italy
- Elettra Synchrotron, Micro & Nano Carbon Laboratory, 34149 Trieste, Italy
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4
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Ullah N, Chen S, Zhang R. Excited‐state nonadiabatic dynamics simulations on the heptazine and adenine in a water environment: A mini review. J CHIN CHEM SOC-TAIP 2023. [DOI: 10.1002/jccs.202200445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Naeem Ullah
- Department of Physics City University of Hong Kong Kowloon Hong Kong SAR China
- Department of Physics Government Degree College Dara Adam Khel, Higher Education Department Khyber Pakhtunkhwah Pakistan
| | - Shunwei Chen
- Department of Physics City University of Hong Kong Kowloon Hong Kong SAR China
- School of Materials Science and Engineering Qilu University of Technology (Shandong Academy of Sciences) Jinan China
| | - Ruiqin Zhang
- Department of Physics City University of Hong Kong Kowloon Hong Kong SAR China
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5
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Guo RT, Wang J, Bi ZX, Chen X, Hu X, Pan WG. Recent advances and perspectives of g-C 3N 4-based materials for photocatalytic dyes degradation. CHEMOSPHERE 2022; 295:133834. [PMID: 35124079 DOI: 10.1016/j.chemosphere.2022.133834] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/21/2022] [Accepted: 01/31/2022] [Indexed: 06/14/2023]
Abstract
Photocatalytic degradation technology is regarded as a promising technology for dye-contained wastewater treatment due to its superior efficiency and recycling. The key to the implementation of photocatalytic degradation technology is the selection of sunlight-active photocatalyst. Graphitic carbon nitride (g-C3N4) photocatalyst has been put into a lot of research in the field of organic pollutant degradation because of its low cost, suitable electronic structure and high chemical stability. In this perspective review, we comprehensively discuss the recent advance of photocatalytic dyes degradation over g-C3N4-based materials. The properties, structure and preparation methods of g-C3N4 are briefly introduced. Furthermore, the progress in improving the degradation efficiency of g-C3N4-based photocatalyst is highlighted in the article. The possible pathways and different active species for dyes decomposition are also summarized. We expect this review can provide instructive application of g-C3N4-based catalysts for environmental remediation.
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Affiliation(s)
- Rui-Tang Guo
- College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai, China; Shanghai Engineering Research Center of Power Generation Environment Protection, Shanghai, China.
| | - Juan Wang
- College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai, China
| | - Zhe-Xu Bi
- College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai, China
| | - Xin Chen
- College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai, China
| | - Xing Hu
- College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai, China
| | - Wei-Guo Pan
- College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai, China; Shanghai Engineering Research Center of Power Generation Environment Protection, Shanghai, China
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6
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Huang X, Domcke W. Ab Initio Nonadiabatic Surface-Hopping Trajectory Simulations of Photocatalytic Water Oxidation and Hydrogen Evolution with the Heptazine Chromophore. J Phys Chem A 2021; 125:9917-9931. [PMID: 34748705 DOI: 10.1021/acs.jpca.1c08291] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the past decade, polymeric carbon nitrides consisting of heptazine (Hz) building blocks emerged as highly promising materials for photocatalytic hydrogen evolution from water or sacrificial electron donors with near-ultraviolet light. However, the complexity of these materials and their poor characterization at the atomic level are detrimental to the unraveling of the detailed mechanisms of the reactions leading to hydrogen evolution. Recently, it has been shown that a derivative of the Hz molecule, trianisole-heptazine (TAHz), is a potent photobase, which readily oxidizes various derivatives of phenol and even water by an excited-state proton-coupled electron-transfer (PCET) reaction. Energy profiles along minimum-energy reaction paths and relaxed PCET potential-energy surfaces, which previously were computed with ab initio electronic-structure methods for complexes of Hz and TAHz with protic substrates, led to qualitative insights. To obtain more quantitative insight, reaction dynamics simulations are required. In the present work, the time scales of the electron and proton transfer processes and the branching ratios of competing channels were explored with ab initio on-the-fly quasiclassical surface-hopping trajectory simulations for the hydrogen-bonded Hz-H2O complex. By the analysis of representative trajectories, detailed insight into the interplay of various nonadiabatic electronic transitions, electron transfer, proton transfer, and vibrational energy relaxation is obtained. The HzH radicals which are formed by the photoreduction of Hz can disproportionate to Hz and HzH2 in an exothermic reaction with a low reaction barrier. The time scales and branching ratios of competing channels in H-atom photodetachment from the HzH2 molecule also were explored with ab initio surface-hopping simulations. These results delineate for the first time a quantitatively supported scenario of water oxidation and hydrogen evolution with a molecular carbon nitride photocatalyst.
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Affiliation(s)
- Xiang Huang
- Department of Chemistry, Technical University of Munich, Garching D-85747, Germany
| | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, Garching D-85747, Germany
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7
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Hwang D, Schlenker CW. Photochemistry of carbon nitrides and heptazine derivatives. Chem Commun (Camb) 2021; 57:9330-9353. [PMID: 34528956 DOI: 10.1039/d1cc02745j] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We explore the photochemistry of polymeric carbon nitride (C3N4), an archetypal organic photocatalyst, and derivatives of its structural monomer unit, heptazine (Hz). Through spectroscopic studies and computational analysis, we have observed that Hz derivatives can engage in non-innocent hydrogen bonding interactions with hydroxylic species. The photochemistry of these complexes is influenced by intermolecular nπ*/ππ* mixing of non-bonding orbitals of each component and the relative energy of intermolecular charge-transfer (CT) states. Coupling of the former to the latter appears to facilitate proton-coupled electron transfer (PCET), resulting in biradical products. We have also observed that Hz derivatives exhibit an extremely rare inverted singlet/triplet energy splitting (ΔEST). In violation of Hund's multiplicity rules, the lowest energy singlet (S1) is stabilized relative to the lowest triplet (T1) electronic excited state. Exploiting this unique inverted ΔEST character has obvious implications for transformational discoveries in solid-state OLED lighting and photovoltaics. Harnessing this inverted ΔEST, paired with light-driven intermolecular PCET reactions, may enable molecular transformations relevant for applications ranging from solar energy storage to new classes of non-triplet photoredox catalysts for pharmaceutical development. To this end, we have explored the possibility of optically controlling the photochemistry of Hz derivatives using ultrafast pump-push-probe spectroscopy. In this case, the excited state branching ratios among locally excited states of the chromophore and the reactive intermolecular CT state can be manipulated with an appropriate secondary "push" excitation pulse. These results indicate that we can predictively redirect chemical reactivity with light in this system, which is an avidly sought achievement in the field of photochemistry. Looking forward, we anticipate future opportunities for controlling heptazine photochemistry, including manipulating PCET reactivity with a diverse array of substrates and optically delivering reducing equivalents with, for example, water as a partial source of electrons and protons. Furthermore, we wholly expect that, over the next decade, materials such as Hz derivatives, that exhibit inverted ΔEST character, will spawn a significant new research effort in the field of thin-film optoelectronics, where controlling recombination via triplet excitonic states can play a critical role in determining device performance.
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Affiliation(s)
- Doyk Hwang
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Cody W Schlenker
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA.,Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195-1652, USA.,Clean Energy Institute, University of Washington, Seattle, Washington 98195-1653, USA.
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8
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Sobolewski AL, Domcke W. Are Heptazine-Based Organic Light-Emitting Diode Chromophores Thermally Activated Delayed Fluorescence or Inverted Singlet-Triplet Systems? J Phys Chem Lett 2021; 12:6852-6860. [PMID: 34279950 DOI: 10.1021/acs.jpclett.1c01926] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two chromophores derived from heptazine, HAP-3MF and HAP-3TPA, were synthesized and tested as emitters in light-emitting diodes (OLEDs) by Adachi and co-workers. Both emitters were shown to exhibit quantum efficiencies which exceed the theoretical maximum of conventional fluorescent OLEDs. The enhanced emission efficiency was explained by the mechanism of thermally activated delayed fluorescence (TADF). In the present work, the electronic excitation energies and essential features of the topography of the excited-state potential-energy surfaces of HAP-3MF and HAP-3TPA have been investigated with a wave function-based ab initio method (ADC(2)). It is found that HAP-3MF is an inverted singlet-triplet (IST) system; that is, the energies of the S1 and T1 states are robustly inverted in violation of Hund's multiplicity rule. Notably, HAP-3MF presumably is the first IST emitter which was implemented in an OLED device. In HAP-3TPA, on the other hand, the vertical excitation energies of the S1 and T1 states are essentially degenerate. The excited states exhibit vibrational stabilization energies of similar magnitude along different relaxation coordinates, resulting in adiabatic excitation energies which also are nearly degenerate. HAP-3TPA is found to be a chromophore at the borderline of TADF and IST systems. The spectroscopic data reported by Adachi and co-workers for HAP-3MF and HAP-3TPA are analyzed in light of these computational results.
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Affiliation(s)
| | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, Garching, Germany
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9
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Pios S, Huang X, Sobolewski AL, Domcke W. Triangular boron carbon nitrides: an unexplored family of chromophores with unique properties for photocatalysis and optoelectronics. Phys Chem Chem Phys 2021; 23:12968-12975. [PMID: 34059871 DOI: 10.1039/d1cp02026a] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
It has recently been shown that cycl[3.3.3]azine and heptazine (1,3,4,6,7,9,9b-heptaazaphenalene) as well as related azaphenalenes exhibit inverted singlet and triplet states, that is, the energy of the lowest singlet excited state (S1) is below the energy of the lowest triplet excited state (T1). This feature is unique among all known aromatic chromophores and is of outstanding relevance for applications in photocatalysis and organic optoelectronics. Heptazine is the building block of the polymeric material graphitic carbon nitride which is an extensively explored photocatalyst in hydrogen evolution photocatalysis. Derivatives of heptazine have also been identified as efficient emitters in organic light emitting diodes (OLEDs). In both areas, the inverted singlet-triplet gap of heptazine is a highly beneficial feature. In photocatalysis, the absence of a long-lived triplet state eliminates the activation of atmospheric oxygen, which is favourable for long-term operational stability. In optoelectronics, singlet-triplet inversion implies the possibility of 100% fluorescence efficiency of electron-hole recombination. However, the absorption and luminescence wavelengths of heptazine and the S1-S0 transition dipole moment are difficult to tune for optimal functionality. In this work, we employed high-level ab initio electronic structure theory to devise and characterize a large family of novel heteroaromatic chromophores, the triangular boron carbon nitrides. These novel heterocycles inherit essential spectroscopic features from heptazine, in particular the inverted singlet-triplet gap, while their absorption and luminescence spectra and transition dipole moments are widely tuneable. For applications in photocatalysis, the wavelength of the absorption maximum can be tuned to improve the overlap with the solar spectrum at the surface of earth. For applications in OLEDs, the colour of emission can be adjusted and the fluorescence yield can be enhanced.
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Affiliation(s)
- Sebastian Pios
- Department of Chemistry, Technical University of Munich, 85747 Garching, Germany.
| | - Xiang Huang
- Department of Chemistry, Technical University of Munich, 85747 Garching, Germany.
| | | | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, 85747 Garching, Germany.
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10
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Lanzilotto V, Grazioli C, Stredansky M, Zhang T, Schio L, Goldoni A, Floreano L, Motta A, Cossaro A, Puglia C. Tailoring surface-supported water-melamine complexes by cooperative H-bonding interactions. NANOSCALE ADVANCES 2021; 3:2359-2365. [PMID: 36133766 PMCID: PMC9419257 DOI: 10.1039/d0na01034k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/23/2021] [Indexed: 06/15/2023]
Abstract
The water-splitting photo-catalysis by carbon nitride heterocycles has been the subject of recent theoretical investigations, revealing a proton-coupled electron transfer (PCET) reaction from the H-bonded water molecule to the CN-heterocycle. In this context, a detailed characterization of the water-catalyst binding configuration becomes mandatory in order to validate and possibly improve the theoretical modeling. To this aim, we built a well-defined surface-supported water/catalyst interface by adsorbing water under ultra-high vacuum (UHV) conditions on a monolayer of melamine grown on the Cu(111) surface. By combining X-ray photoemission (XPS) and absorption (NEXAFS) spectroscopy we observed that melamine adsorbed onto copper is strongly tilted off the surface, with one amino group dangling to the vacuum side. The binding energy (BE) of the corresponding N 1s component is significantly higher compared to other N 1s contributions and displays a clear shift to lower BE as water is adsorbed. This finding along with density functional theory (DFT) results reveals that two adjacent melamine molecules concurrently work for stabilizing the H-bonded water-catalyst complex: one melamine acting as a H-donor via the amino-N (NH⋯OHH) and another one as a H-acceptor via the triazine-N (C[double bond, length as m-dash]N⋯HOH).
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Affiliation(s)
- Valeria Lanzilotto
- Department of Physics and Astronomy, Uppsala University P.O. Box 516 751 20 Uppsala Sweden
- Department of Chemistry, Sapienza University of Rome P.le Aldo Moro 8 00185 Roma Italy
- IOM-CNR, Istituto Officina dei Materiali Basovizza SS-14, Km 163.5 34149 Trieste Italy
| | - Cesare Grazioli
- IOM-CNR, Istituto Officina dei Materiali Basovizza SS-14, Km 163.5 34149 Trieste Italy
| | - Matus Stredansky
- IOM-CNR, Istituto Officina dei Materiali Basovizza SS-14, Km 163.5 34149 Trieste Italy
- Department of Physics, University of Trieste Via A. Valerio 2 34127 Trieste Italy
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology (BIT) 100081 Beijing China
| | - Teng Zhang
- Department of Physics and Astronomy, Uppsala University P.O. Box 516 751 20 Uppsala Sweden
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology (BIT) 100081 Beijing China
| | - Luca Schio
- IOM-CNR, Istituto Officina dei Materiali Basovizza SS-14, Km 163.5 34149 Trieste Italy
| | - Andrea Goldoni
- Elettra-Sincrotrone Trieste S.C.p.A. Basovizza SS-14, Km 163.5 34149 Trieste Italy
| | - Luca Floreano
- IOM-CNR, Istituto Officina dei Materiali Basovizza SS-14, Km 163.5 34149 Trieste Italy
| | - Alessandro Motta
- Consortium INSTM Via G. Giusti 9 50121 Firenze Italy
- Department of Chemistry, Sapienza University of Rome P.le Aldo Moro 8 00185 Roma Italy
| | - Albano Cossaro
- IOM-CNR, Istituto Officina dei Materiali Basovizza SS-14, Km 163.5 34149 Trieste Italy
- Department of Chemical and Pharmaceutical Sciences, University of Trieste Via Giorgieri 1 34127 Trieste Italy
| | - Carla Puglia
- Department of Physics and Astronomy, Uppsala University P.O. Box 516 751 20 Uppsala Sweden
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Wu Y, Du J, Hao W, Jiang B. Synthesis of Fused Pyridines via Microwave-Assisted [3+3] Cyclization. CHINESE J ORG CHEM 2021. [DOI: 10.6023/cjoc202102018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Domcke W, Sobolewski AL, Schlenker CW. Photooxidation of water with heptazine-based molecular photocatalysts: Insights from spectroscopy and computational chemistry. J Chem Phys 2020; 153:100902. [PMID: 32933269 DOI: 10.1063/5.0019984] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a conspectus of recent joint spectroscopic and computational studies that provided novel insight into the photochemistry of hydrogen-bonded complexes of the heptazine (Hz) chromophore with hydroxylic substrate molecules (water and phenol). It was found that a functionalized derivative of Hz, tri-anisole-heptazine (TAHz), can photooxidize water and phenol in a homogeneous photochemical reaction. This allows the exploration of the basic mechanisms of the proton-coupled electron-transfer (PCET) process involved in the water photooxidation reaction in well-defined complexes of chemically tunable molecular chromophores with chemically tunable substrate molecules. The unique properties of the excited electronic states of the Hz molecule and derivatives thereof are highlighted. The potential energy landscape relevant for the PCET reaction has been characterized by judicious computational studies. These data provided the basis for the demonstration of rational laser control of PCET reactions in TAHz-phenol complexes by pump-push-probe spectroscopy, which sheds light on the branching mechanisms occurring by the interaction of nonreactive locally excited states of the chromophore with reactive intermolecular charge-transfer states. Extrapolating from these results, we propose a general scenario that unravels the complex photoinduced water-splitting reaction into simple sequential light-driven one-electron redox reactions followed by simple dark radical-radical recombination reactions.
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Affiliation(s)
- Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, D-85747 Garching, Germany
| | | | - Cody W Schlenker
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
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13
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Wierzchowski J, Smyk B. Excited-State Proton Transfer in 8-Azapurines I: A Kinetic Analysis of 8-Azaxanthine Fluorescence. Molecules 2020; 25:molecules25122740. [PMID: 32545696 PMCID: PMC7356501 DOI: 10.3390/molecules25122740] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/08/2020] [Accepted: 06/09/2020] [Indexed: 01/30/2023] Open
Abstract
A super-continuum white laser with a half-pulse width of ~75 ps was used to observe the kinetics of a postulated excited-state proton transfer in 8-azaxanthine and its 8-methyl derivative. Both compounds exhibited dual emissions in weakly acidified alcoholic media, but only one band was present in aqueous solutions, exhibiting an abnormal Stokes shift (>12,000 cm−1). It was shown that long-wavelength emissions were delayed relative to the excitation pulse within alcoholic media. The rise time was calculated to be 0.4–0.5 ns in both methanol and deuterated methanol. This is equal to the main component of the fluorescence decay in the short-wavelength band (340 nm). Time-resolved emission spectra (TRES) indicated a two-state photo-transformation model in both compounds. Global analysis of the time dependence revealed three exponential components in each compound, one of which had an identical rise-time, with the second attributed to a long-wavelength band decay (6.4 ns for aza-xanthine and 8.3 ns for its 8-methyl derivative). The origin of the third, intermediate decay time (1.41 ns for aza-xanthine and 0.87 ns for 8-methyl-azaxanthine) is uncertain, but decay-associated spectra (DAS) containing both bands suggest the participation of a contact ion pair. These results confirm the model of phototautomerism proposed earlier, but the question of the anomalous isotope effect remains unsolved.
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Huang X, Aranguren JP, Ehrmaier J, Noble JA, Xie W, Sobolewski AL, Dedonder-Lardeux C, Jouvet C, Domcke W. Photoinduced water oxidation in pyrimidine-water clusters: a combined experimental and theoretical study. Phys Chem Chem Phys 2020; 22:12502-12514. [PMID: 32452507 DOI: 10.1039/d0cp01562h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photocatalytic oxidation of water with molecular or polymeric N-heterocyclic chromophores is a topic of high current interest in the context of artificial photosynthesis, that is, the conversion of solar energy to clean fuels. Hydrogen-bonded clusters of N-heterocycles with water molecules in a molecular beam are simple model systems for which the basic mechanisms of photochemical water oxidation can be studied under well-defined conditions. In this work, we explored the photoinduced H-atom transfer reaction in pyrimidine-water clusters yielding pyrimidinyl and hydroxyl radicals with laser spectroscopy, mass spectrometry and trajectory-based ab initio molecular dynamics simulations. The oxidation of water by photoexcited pyrimidine is unequivocally confirmed by the detection of the pyrimidinyl radical. The dynamics simulations provide information on the time scales and branching ratios of the reaction. While relaxation to local minima of the S1 potential-energy surface is the dominant reaction channel, the H-atom transfer reaction occurs on ultrafast time scales (faster than about 100 fs) with a branching ratio of a few percent.
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Affiliation(s)
- Xiang Huang
- Department of Chemistry, Technical University of Munich, Garching, Germany.
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15
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Ehrmaier J, Huang X, Rabe EJ, Corp KL, Schlenker CW, Sobolewski AL, Domcke W. Molecular Design of Heptazine-Based Photocatalysts: Effect of Substituents on Photocatalytic Efficiency and Photostability. J Phys Chem A 2020; 124:3698-3710. [DOI: 10.1021/acs.jpca.0c00488] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Johannes Ehrmaier
- Department of Chemistry, Technical University of Munich, Garching D-85747, Germany
| | - Xiang Huang
- Department of Chemistry, Technical University of Munich, Garching D-85747, Germany
| | - Emily J. Rabe
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Kathryn L. Corp
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Cody W. Schlenker
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | | | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, Garching D-85747, Germany
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16
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Recent Strategies for Hydrogen Peroxide Production by Metal-Free Carbon Nitride Photocatalysts. Catalysts 2019. [DOI: 10.3390/catal9120990] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Hydrogen peroxide (H2O2) is a chemical which has gained wide importance in several industrial and research fields. Its mass production is mostly performed by the anthraquinone (AQ) oxidation reaction, leading to high energy consumption and significant generation of wastes. Other methods of synthesis found in the literature include the direct synthesis from oxygen and hydrogen. However, this H2O2 production process is prone to explosion hazard or undesirable by‑product generation. With the growing demand of H2O2, the development of cleaner and economically viable processes has been under intense investigation. Heterogeneous photocatalysis for H2O2 production has appeared as a promising alternative since it requires only an optical semiconductor, water, oxygen, and ideally solar light irradiation. Moreover, employing a metal-free semiconductor minimizes possible toxicity consequences and reinforces the sustainability of the process. The most studied metal‑free catalyst employed for H2O2 production is polymeric carbon nitride (CN). Several chemical and physical modifications over CN have been investigated together with the assessment of different sacrificial agents and light sources. This review shows the recent developments on CN materials design for enhancing the synthesis of H2O2, along with the proposed mechanisms of H2O2 production. Finally, the direct in situ generation of H2O2, when dealing with the photocatalytic synthesis of added-value organic compounds and water treatment, is discussed.
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Chen T, Wang H, Chu Y, Boyer C, Liu J, Xu J. Photo‐Induced Depolymerisation: Recent Advances and Future Challenges. CHEMPHOTOCHEM 2019. [DOI: 10.1002/cptc.201900166] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Tao Chen
- College of Materials Science and Engineering Institute for Graphene Applied Technology Innovation Collaborative Innovation Center for Marine Biomass Fibers Materials and Textiles of Shandong Province Qingdao University Qingdao 266071 China
- Centre for Advanced Macromolecular Design and Australian Centre for Nanomedicine School of Chemical Engineering UNSW Sydney NSW 2052 Australia
| | - Huining Wang
- College of Materials Science and Engineering Institute for Graphene Applied Technology Innovation Collaborative Innovation Center for Marine Biomass Fibers Materials and Textiles of Shandong Province Qingdao University Qingdao 266071 China
| | - Yingying Chu
- Centre for Advanced Macromolecular Design and Australian Centre for Nanomedicine School of Chemical Engineering UNSW Sydney NSW 2052 Australia
| | - Cyrille Boyer
- Centre for Advanced Macromolecular Design and Australian Centre for Nanomedicine School of Chemical Engineering UNSW Sydney NSW 2052 Australia
| | - Jingquan Liu
- College of Materials Science and Engineering Institute for Graphene Applied Technology Innovation Collaborative Innovation Center for Marine Biomass Fibers Materials and Textiles of Shandong Province Qingdao University Qingdao 266071 China
| | - Jiangtao Xu
- Centre for Advanced Macromolecular Design and Australian Centre for Nanomedicine School of Chemical Engineering UNSW Sydney NSW 2052 Australia
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18
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Ehrmaier J, Rabe EJ, Pristash SR, Corp KL, Schlenker CW, Sobolewski AL, Domcke W. Singlet–Triplet Inversion in Heptazine and in Polymeric Carbon Nitrides. J Phys Chem A 2019; 123:8099-8108. [DOI: 10.1021/acs.jpca.9b06215] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Johannes Ehrmaier
- Department of Chemistry, Technical University of Munich, D-85747 Garching, Germany
| | - Emily J. Rabe
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Sarah R. Pristash
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Kathryn L. Corp
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Cody W. Schlenker
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | | | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, D-85747 Garching, Germany
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19
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Pang X, Jiang C, Xie W, Domcke W. Photoinduced electron-driven proton transfer from water to an N-heterocyclic chromophore: nonadiabatic dynamics studies for pyridine–water clusters. Phys Chem Chem Phys 2019; 21:14073-14079. [DOI: 10.1039/c8cp07015f] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We performed the excited-state dynamics simulations for pyridine–water clusters and found the more water molecules involved in the cluster, the higher efficiency the water-splitting reaction has, which is qualitatively in consistent with a recent gas-phase experimental observations.
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Affiliation(s)
- Xiaojuan Pang
- Key Laboratory for Quantum Information and Quantum Optoelectronic Devices
- China
- Department of Applied Physics
- Xi’an Jiaotong University
- Xi’an 710049
| | - Chenwei Jiang
- Key Laboratory for Quantum Information and Quantum Optoelectronic Devices
- China
- Department of Applied Physics
- Xi’an Jiaotong University
- Xi’an 710049
| | - Weiwei Xie
- Department of Chemistry
- Technical University of Munich
- D-85747 Garching
- Germany
- Institute of Physical Chemistry
| | - Wolfgang Domcke
- Department of Chemistry
- Technical University of Munich
- D-85747 Garching
- Germany
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