Pub Date : 2016-01-02DOI: 10.1080/0144235X.2015.1132595
R. Rodríguez-Cantano, T. González-Lezana, P. Villarreal
One of the most commonly employed methods to study doped helium clusters is the path integral Monte Carlo (PIMC) approach. In this review we present results of recent investigations on a series of both atomic and diatomic dopants attached to droplets formed with up to 40 He atoms. Besides the comparison with similar studies existing in the literature, this work also gives the possibility to analyse different issues such as the role played by the He–impurity interaction in the overall geometry of the clusters, the inclusion of internal molecular degrees of freedom and the exchange permutation symmetry in the PIMC calculations. The study of the structure and energies of and at thermal equilibrium presented in this work thus covers most of the usual aspects treated for these kinds of doped systems.
{"title":"Path integral Monte Carlo investigations on doped helium clusters","authors":"R. Rodríguez-Cantano, T. González-Lezana, P. Villarreal","doi":"10.1080/0144235X.2015.1132595","DOIUrl":"https://doi.org/10.1080/0144235X.2015.1132595","url":null,"abstract":"One of the most commonly employed methods to study doped helium clusters is the path integral Monte Carlo (PIMC) approach. In this review we present results of recent investigations on a series of both atomic and diatomic dopants attached to droplets formed with up to 40 He atoms. Besides the comparison with similar studies existing in the literature, this work also gives the possibility to analyse different issues such as the role played by the He–impurity interaction in the overall geometry of the clusters, the inclusion of internal molecular degrees of freedom and the exchange permutation symmetry in the PIMC calculations. The study of the structure and energies of and at thermal equilibrium presented in this work thus covers most of the usual aspects treated for these kinds of doped systems.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77699651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-02DOI: 10.1080/0144235X.2015.1127027
Lan Yuan, Chuang Han, Min‐Quan Yang, Yi‐Jun Xu
The expected depletion of fossil fuel reserves and its serious environmental impact have emphasised the issue of sustainable development of the human society. Solar hydrogen by photocatalytic water splitting is a promising alternative to conventional fossil fuels, which is of great potential to relieve the energy and environmental issues and bring an energy revolution in a clean and sustainable manner. This review is going to make a brief introduction of the basic principles of photocatalytic water splitting and the concept of different kinds of water splitting systems. Various engineering strategies for searching higher efficiency of water splitting based on the photocatalytic processes, including light harvesting, charge carriers separation and co-catalysts loading, have been outlined and discussed with selected typical examples on some elaborately designed semiconductor-based photocatalytic systems. Moreover, recent impressive progresses and advancements for photocatalytic water splitting with some promising materials are presented. Finally, this review is concluded with a summary and perspective in this hot area of research.
{"title":"Photocatalytic water splitting for solar hydrogen generation: fundamentals and recent advancements","authors":"Lan Yuan, Chuang Han, Min‐Quan Yang, Yi‐Jun Xu","doi":"10.1080/0144235X.2015.1127027","DOIUrl":"https://doi.org/10.1080/0144235X.2015.1127027","url":null,"abstract":"The expected depletion of fossil fuel reserves and its serious environmental impact have emphasised the issue of sustainable development of the human society. Solar hydrogen by photocatalytic water splitting is a promising alternative to conventional fossil fuels, which is of great potential to relieve the energy and environmental issues and bring an energy revolution in a clean and sustainable manner. This review is going to make a brief introduction of the basic principles of photocatalytic water splitting and the concept of different kinds of water splitting systems. Various engineering strategies for searching higher efficiency of water splitting based on the photocatalytic processes, including light harvesting, charge carriers separation and co-catalysts loading, have been outlined and discussed with selected typical examples on some elaborately designed semiconductor-based photocatalytic systems. Moreover, recent impressive progresses and advancements for photocatalytic water splitting with some promising materials are presented. Finally, this review is concluded with a summary and perspective in this hot area of research.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77712844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-02DOI: 10.1080/0144235X.2016.1147816
Lai‐Sheng Wang
Photoelectron spectroscopy (PES) in combination with computational chemistry has been used systematically over the past decade to elucidate the structures and chemical bonding of size-selected boron clusters. Small boron clusters have been found to be planar or quasi-planar, consisting of a monocyclic circumference with one or more interior atoms. The propensity for planarity has been found to be a result of both σ and π electron delocalisation over the molecular plane, giving rise to concepts of σ and π multiple aromaticity. In particular, the B36 cluster has been found to possess a highly stable planar structure with a central hexagonal vacancy. This finding provides the first indirect experimental evidence that single-atom layer boron-sheets with hexagonal vacancies, dubbed ‘borophene’, are potentially viable. Another exciting discovery has been the observation and characterisation of the first all-boron fullerenes. PES revealed that the cluster consisted of two isomers with very different electron binding energies. Global minimum searches led to two nearly degenerate isomers competing for the global minimum: a quasi-planar isomer with a double hexagonal vacancy and an unprecedented cage isomer. In the neutral, the B40 cage is overwhelmingly the global minimum, which is the first all-boron fullerene to be observed and is named ‘borospherene’. Rapid progresses in our understanding of the structures and bonding of size-selected boron clusters have been made during the past decade, which will be the focus of this review. The recent findings about borophenes and borospherenes have stimulated growing interests in boron clusters and will accelerate the pace of discovery in boron chemistry and nanostructures.
{"title":"Photoelectron spectroscopy of size-selected boron clusters: from planar structures to borophenes and borospherenes","authors":"Lai‐Sheng Wang","doi":"10.1080/0144235X.2016.1147816","DOIUrl":"https://doi.org/10.1080/0144235X.2016.1147816","url":null,"abstract":"Photoelectron spectroscopy (PES) in combination with computational chemistry has been used systematically over the past decade to elucidate the structures and chemical bonding of size-selected boron clusters. Small boron clusters have been found to be planar or quasi-planar, consisting of a monocyclic circumference with one or more interior atoms. The propensity for planarity has been found to be a result of both σ and π electron delocalisation over the molecular plane, giving rise to concepts of σ and π multiple aromaticity. In particular, the B36 cluster has been found to possess a highly stable planar structure with a central hexagonal vacancy. This finding provides the first indirect experimental evidence that single-atom layer boron-sheets with hexagonal vacancies, dubbed ‘borophene’, are potentially viable. Another exciting discovery has been the observation and characterisation of the first all-boron fullerenes. PES revealed that the cluster consisted of two isomers with very different electron binding energies. Global minimum searches led to two nearly degenerate isomers competing for the global minimum: a quasi-planar isomer with a double hexagonal vacancy and an unprecedented cage isomer. In the neutral, the B40 cage is overwhelmingly the global minimum, which is the first all-boron fullerene to be observed and is named ‘borospherene’. Rapid progresses in our understanding of the structures and bonding of size-selected boron clusters have been made during the past decade, which will be the focus of this review. The recent findings about borophenes and borospherenes have stimulated growing interests in boron clusters and will accelerate the pace of discovery in boron chemistry and nanostructures.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89070954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-10-02DOI: 10.1080/0144235X.2015.1088217
C. Janssen, N. Macías-ruvalcaba, M. Aguilar-martínez, Mark N. Kobrak
Ionic liquids (ILs) have recently emerged as an extremely promising medium for the extraction of metals from aqueous phases. ILs are salts that are liquid at room temperature, and have physical and chemical properties that make them potentially valuable replacements for organic molecular solvents. However, that same ionic character gives rise to extraction mechanisms that have no analogue in molecular liquids. While metals generally exist in hydrophobic neutral complexes in molecular liquids, charged complexes incorporating hydrophobic ligands may be highly soluble in IL phases. Further, the ionic character of ILs permits ion exchange mechanisms involving component ions of the IL, raising the possibility that the extraction process may degrade the IL and contaminate the aqueous phase. The purpose of this review is to provide a broad overview of metal extraction from aqueous to IL phase, using the extraction mechanism as a common basis for analysis of extraction phenomena that might otherwise appear quite different. The goal is to identify both the challenges and opportunities offered by the unique properties of ILs, and to provide a framework for the design of metal extraction processes based on the use of ILs.
{"title":"Metal extraction to ionic liquids: the relationship between structure, mechanism and application","authors":"C. Janssen, N. Macías-ruvalcaba, M. Aguilar-martínez, Mark N. Kobrak","doi":"10.1080/0144235X.2015.1088217","DOIUrl":"https://doi.org/10.1080/0144235X.2015.1088217","url":null,"abstract":"Ionic liquids (ILs) have recently emerged as an extremely promising medium for the extraction of metals from aqueous phases. ILs are salts that are liquid at room temperature, and have physical and chemical properties that make them potentially valuable replacements for organic molecular solvents. However, that same ionic character gives rise to extraction mechanisms that have no analogue in molecular liquids. While metals generally exist in hydrophobic neutral complexes in molecular liquids, charged complexes incorporating hydrophobic ligands may be highly soluble in IL phases. Further, the ionic character of ILs permits ion exchange mechanisms involving component ions of the IL, raising the possibility that the extraction process may degrade the IL and contaminate the aqueous phase. The purpose of this review is to provide a broad overview of metal extraction from aqueous to IL phase, using the extraction mechanism as a common basis for analysis of extraction phenomena that might otherwise appear quite different. The goal is to identify both the challenges and opportunities offered by the unique properties of ILs, and to provide a framework for the design of metal extraction processes based on the use of ILs.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2015-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90289087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-10-02DOI: 10.1080/0144235X.2015.1075279
L. Gartzia‐Rivero, J. Bañuelos, I. López‐Arbeloa
The development of nanometrically templated artificial light harvesting antennas and energy transfer devices is a highly active area with outstanding challenges. The herein presented review deals with the design of photoactive nanomaterials and multichromophoric arrays looking towards the development of artificial antenna systems. In particular we have focused in the conditions which rule the excitation energy transfer processes in each case. To this aim, a wide variety of luminescent fluorophores encapsulated into either inorganic or organic hosts, as well as molecular systems based on scaffolding of suitable laser dyes have been deeply studied. The main goal is to design systems which harvest the light over a broad spectral region (in particular the ultraviolet-visible section of the electromagnetic spectrum) and transfer it to the target place and with a desired energy (especially in the red edge of the visible) via successive energy transfer hops. To this purpose, three different approaches have been considered to develop optical antennas: (i) hybrid materials based on LTL zeolite aluminosilicate doped with laser dyes absorbing and emitting in different regions of the visible (blue, green or red); (ii) dye-doped latex nanoparticles, in which luminescent fluorophores undergoing intermolecular energy transfer processes are encapsulated; (iii) molecular antennas based on donor and acceptor dyes covalently linked through a spacer. These luminescent antennas have been designed for photonic purposes such as tunable dye lasers, light modulators or polarity probes.
{"title":"Excitation energy transfer in artificial antennas: from photoactive materials to molecular assemblies","authors":"L. Gartzia‐Rivero, J. Bañuelos, I. López‐Arbeloa","doi":"10.1080/0144235X.2015.1075279","DOIUrl":"https://doi.org/10.1080/0144235X.2015.1075279","url":null,"abstract":"The development of nanometrically templated artificial light harvesting antennas and energy transfer devices is a highly active area with outstanding challenges. The herein presented review deals with the design of photoactive nanomaterials and multichromophoric arrays looking towards the development of artificial antenna systems. In particular we have focused in the conditions which rule the excitation energy transfer processes in each case. To this aim, a wide variety of luminescent fluorophores encapsulated into either inorganic or organic hosts, as well as molecular systems based on scaffolding of suitable laser dyes have been deeply studied. The main goal is to design systems which harvest the light over a broad spectral region (in particular the ultraviolet-visible section of the electromagnetic spectrum) and transfer it to the target place and with a desired energy (especially in the red edge of the visible) via successive energy transfer hops. To this purpose, three different approaches have been considered to develop optical antennas: (i) hybrid materials based on LTL zeolite aluminosilicate doped with laser dyes absorbing and emitting in different regions of the visible (blue, green or red); (ii) dye-doped latex nanoparticles, in which luminescent fluorophores undergoing intermolecular energy transfer processes are encapsulated; (iii) molecular antennas based on donor and acceptor dyes covalently linked through a spacer. These luminescent antennas have been designed for photonic purposes such as tunable dye lasers, light modulators or polarity probes.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2015-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86620500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-10-02DOI: 10.1080/0144235X.2015.1075280
A. Mebel, R. Kaiser
Resonance stabilised free radicals (RSFRs) play an important role in the growth of polycyclic aromatic hydrocarbons and ultimately in the production of soot and carbonaceous particles in combustion flames, in the interstellar medium, and in planetary atmospheres. This article reviews extensive experimental crossed molecular beams and theoretical ab initio/Rice–Ramsperger–Kassel–Marcus studies in the last two decades of the reactions of atomic carbon, C(3P), dicarbon, C2(X1Σg+/a3Πu), and tricarbon, C3(X1Σg+), with unsaturated hydrocarbons, from acetylene to benzene, showing that the reactions form various types of RSFR via Cn(n = 1–3)-for-H, Cn-for-CH3, and Cn-for-CxHy exchange mechanisms. The RSFRs produced in these reactions include CxH (x = 1–8), propargyl (C3H3) and its substituted analogues, 2,4-pentadiynyl-1 (i-C5H3) and 1,4-pentadiynyl-3 (n-C5H3) together with their methyl substituted counterparts, butatrienyl (i-C4H3) and its substituted analogues, and hexenediynyl, i-C6H3, as well as cyclic five-, six-, and seven-member ring radicals including aromatic phenyl, benzyl, and tolyls. The reactions of atomic carbon and dicarbon proceed by barrierless additions to double, triple, or ‘aromatic’ bonds of the unsaturated hydrocarbons, form highly exothermic products, and are fast even at very low temperatures, whereas the reactions of singlet tricarbon require high barriers to be overcome, often leading to endothermic products, and can occur only at high temperatures. The paper summarises typical reaction mechanisms for small carbon species (C, C2, and C3) with unsaturated hydrocarbons and describes implications of the considered reactions in combustion chemistry and astrochemistry.
{"title":"Formation of resonantly stabilised free radicals via the reactions of atomic carbon, dicarbon, and tricarbon with unsaturated hydrocarbons: theory and crossed molecular beams experiments","authors":"A. Mebel, R. Kaiser","doi":"10.1080/0144235X.2015.1075280","DOIUrl":"https://doi.org/10.1080/0144235X.2015.1075280","url":null,"abstract":"Resonance stabilised free radicals (RSFRs) play an important role in the growth of polycyclic aromatic hydrocarbons and ultimately in the production of soot and carbonaceous particles in combustion flames, in the interstellar medium, and in planetary atmospheres. This article reviews extensive experimental crossed molecular beams and theoretical ab initio/Rice–Ramsperger–Kassel–Marcus studies in the last two decades of the reactions of atomic carbon, C(3P), dicarbon, C2(X1Σg+/a3Πu), and tricarbon, C3(X1Σg+), with unsaturated hydrocarbons, from acetylene to benzene, showing that the reactions form various types of RSFR via Cn(n = 1–3)-for-H, Cn-for-CH3, and Cn-for-CxHy exchange mechanisms. The RSFRs produced in these reactions include CxH (x = 1–8), propargyl (C3H3) and its substituted analogues, 2,4-pentadiynyl-1 (i-C5H3) and 1,4-pentadiynyl-3 (n-C5H3) together with their methyl substituted counterparts, butatrienyl (i-C4H3) and its substituted analogues, and hexenediynyl, i-C6H3, as well as cyclic five-, six-, and seven-member ring radicals including aromatic phenyl, benzyl, and tolyls. The reactions of atomic carbon and dicarbon proceed by barrierless additions to double, triple, or ‘aromatic’ bonds of the unsaturated hydrocarbons, form highly exothermic products, and are fast even at very low temperatures, whereas the reactions of singlet tricarbon require high barriers to be overcome, often leading to endothermic products, and can occur only at high temperatures. The paper summarises typical reaction mechanisms for small carbon species (C, C2, and C3) with unsaturated hydrocarbons and describes implications of the considered reactions in combustion chemistry and astrochemistry.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2015-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74069651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-07-03DOI: 10.1080/0144235X.2015.1072365
G. Nyman, M. Gustafsson, S. Antipov
To form a stable molecule by association of two colliding fragments, energy must be removed or else the fragments will eventually dissociate again. Energy can be removed by a third body and by emission of a photon, where the latter process is termed radiative association. Radiative association is a ubiquitous process for forming molecules, albeit not so well known as on Earth it is normally outcompeted by three body collisions. In interstellar space however, particularly in regions with little dust (few grains), it can be important. There are only few experimental studies of radiative association as the process is improbable and therefore hard to measure. We will briefly mention the experimental work but our main focus is on theoretical approaches to calculate radiative association cross sections and thermal rate constants. We limit the descriptions to the formation of diatomic molecules. We begin with an introduction to and overview of radiative association. This is followed by a brief section on how cross sections are related to the thermal rate constant. Thereafter we describe methods for obtaining radiative association cross sections, with a bias towards methods that are our own favorites. This will include quantum mechanically based perturbation theory and an optical potential approach that is also quantum mechanically based. From the optical potential method the derivation of a semi-classical method is given. We also describe a recent classical approach that is applicable to transitions within the same electronic state, which the semi-classical approach is not. The semi-classical and classical methods do not treat resonances, which are of quantal origin. We therefore describe Breit–Wigner theory for treating the resonance contribution to the cross sections. Thereafter we review the techniques that are used in the quantum dynamics calculations themselves. The methods discussed are then illustrated in three applications to the formation of diatomic molecules, viz. HF, CO and CN. We end with concluding remarks and summary. In this review we do not discuss electronic structure calculations for obtaining the potential energy and dipole curves that are used in the dynamics calculations.
{"title":"Computational methods to study the formation of small molecules by radiative association","authors":"G. Nyman, M. Gustafsson, S. Antipov","doi":"10.1080/0144235X.2015.1072365","DOIUrl":"https://doi.org/10.1080/0144235X.2015.1072365","url":null,"abstract":"To form a stable molecule by association of two colliding fragments, energy must be removed or else the fragments will eventually dissociate again. Energy can be removed by a third body and by emission of a photon, where the latter process is termed radiative association. Radiative association is a ubiquitous process for forming molecules, albeit not so well known as on Earth it is normally outcompeted by three body collisions. In interstellar space however, particularly in regions with little dust (few grains), it can be important. There are only few experimental studies of radiative association as the process is improbable and therefore hard to measure. We will briefly mention the experimental work but our main focus is on theoretical approaches to calculate radiative association cross sections and thermal rate constants. We limit the descriptions to the formation of diatomic molecules. We begin with an introduction to and overview of radiative association. This is followed by a brief section on how cross sections are related to the thermal rate constant. Thereafter we describe methods for obtaining radiative association cross sections, with a bias towards methods that are our own favorites. This will include quantum mechanically based perturbation theory and an optical potential approach that is also quantum mechanically based. From the optical potential method the derivation of a semi-classical method is given. We also describe a recent classical approach that is applicable to transitions within the same electronic state, which the semi-classical approach is not. The semi-classical and classical methods do not treat resonances, which are of quantal origin. We therefore describe Breit–Wigner theory for treating the resonance contribution to the cross sections. Thereafter we review the techniques that are used in the quantum dynamics calculations themselves. The methods discussed are then illustrated in three applications to the formation of diatomic molecules, viz. HF, CO and CN. We end with concluding remarks and summary. In this review we do not discuss electronic structure calculations for obtaining the potential energy and dipole curves that are used in the dynamics calculations.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2015-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82926433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-07-03DOI: 10.1080/0144235X.2015.1055676
D. Osborn, C. Taatjes
Carbonyl oxides, also known as Criegee intermediates, are key intermediates in both gas phase ozonolysis of unsaturated hydrocarbons in the troposphere and solution phase organic synthesis via ozonolysis. Although the study of Criegee intermediates in both arenas has a long history, direct studies in the gas phase have only recently become possible through new methods of generating stabilised Criegee intermediates in sufficient quantities. This advance has catalysed a large number of new experimental and theoretical investigations of Criegee intermediate chemistry. In this article we review the physical chemistry of Criegee intermediates, focusing on their molecular structure, spectroscopy, unimolecular and bimolecular reactions. These recent results have overturned conclusions from some previous studies, while confirming others, and have clarified areas of investigation that will be critical targets for future studies. In addition to expanding our fundamental understanding of Criegee intermediates, the rapidly expanding knowledge base will support increasingly predictive models of their impacts on society.
{"title":"The physical chemistry of Criegee intermediates in the gas phase","authors":"D. Osborn, C. Taatjes","doi":"10.1080/0144235X.2015.1055676","DOIUrl":"https://doi.org/10.1080/0144235X.2015.1055676","url":null,"abstract":"Carbonyl oxides, also known as Criegee intermediates, are key intermediates in both gas phase ozonolysis of unsaturated hydrocarbons in the troposphere and solution phase organic synthesis via ozonolysis. Although the study of Criegee intermediates in both arenas has a long history, direct studies in the gas phase have only recently become possible through new methods of generating stabilised Criegee intermediates in sufficient quantities. This advance has catalysed a large number of new experimental and theoretical investigations of Criegee intermediate chemistry. In this article we review the physical chemistry of Criegee intermediates, focusing on their molecular structure, spectroscopy, unimolecular and bimolecular reactions. These recent results have overturned conclusions from some previous studies, while confirming others, and have clarified areas of investigation that will be critical targets for future studies. In addition to expanding our fundamental understanding of Criegee intermediates, the rapidly expanding knowledge base will support increasingly predictive models of their impacts on society.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2015-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75127019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-07-03DOI: 10.1080/0144235X.2015.1061793
N. Simpson, N. T. Hunt
Applications of ultrafast two-dimensional infrared (2D-IR) spectroscopy to study the structural dynamics of haem-containing proteins are reviewed. The 2D-IR experiments discussed exploit diatomic ligands bound to the haem as reporters on the dynamic protein environment in the electronic ground-state. This is possible because fluctuations of the protein give rise to inhomogeneous broadening of the ligand stretching vibrational mode that is manifest as spectral diffusion in a time-resolved 2D-IR measurement. Methods for measuring and quantifying spectral diffusion data are introduced, prior to a discussion of recent results focussing on the influence of protein structure, water ingress into the haem pocket and substrate binding on the measured dynamics. Particular emphasis will be placed on proteins featuring the ferric oxidation state of the haem ligated by a nitric oxide molecule, though comparisons with other haem systems will be drawn throughout.
{"title":"Ultrafast 2D-IR spectroscopy of haemoproteins","authors":"N. Simpson, N. T. Hunt","doi":"10.1080/0144235X.2015.1061793","DOIUrl":"https://doi.org/10.1080/0144235X.2015.1061793","url":null,"abstract":"Applications of ultrafast two-dimensional infrared (2D-IR) spectroscopy to study the structural dynamics of haem-containing proteins are reviewed. The 2D-IR experiments discussed exploit diatomic ligands bound to the haem as reporters on the dynamic protein environment in the electronic ground-state. This is possible because fluctuations of the protein give rise to inhomogeneous broadening of the ligand stretching vibrational mode that is manifest as spectral diffusion in a time-resolved 2D-IR measurement. Methods for measuring and quantifying spectral diffusion data are introduced, prior to a discussion of recent results focussing on the influence of protein structure, water ingress into the haem pocket and substrate binding on the measured dynamics. Particular emphasis will be placed on proteins featuring the ferric oxidation state of the haem ligated by a nitric oxide molecule, though comparisons with other haem systems will be drawn throughout.","PeriodicalId":54932,"journal":{"name":"International Reviews in Physical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2015-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87146906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-07-03DOI: 10.1080/0144235X.2015.1072364
Hyun Sik You, Songhee Han, Jungki Yoon, Jeong Sik Lim, Jeongmook Lee, Soyeun Kim, Doo-Sik Ahn, J. Lim, Sang Kyu Kim
Conical intersection as a dynamic funnel in nonadiabatic transition dictates many important chemical reaction outputs such as reaction rates, yields, and energy disposals especially for chemical reactions taking place on electronically excited states. Therefore, the energetics and topology of conical intersections have been subjected to intensive theoretical and experimental studies for decades as these things are the keys to understanding and controlling nonadiabatic transitions which are ubiquitous in nature. In this article, we focus on πσ*-mediated photodissociation reactions of thiophenols and thioanisoles. Interestingly, for these chemical systems, the nonadiabatic transition probability can be precisely measured as a function of the excitation energy, giving a great opportunity for spectroscopic characterization of the multi-dimensional conical intersection seam that governs the nonadiabatic transition dynamics of polyatomic molecules. The passage of the reactive flux in the proximity of the conical intersection gives rise to dynamic resonances corresponding to dramatic state-specific increases of the nonadiabatic transition probability. Accordingly, it is found that the electronic and nuclear configurations of the reactive flux and their evolution, coupled to the conical intersection seam, are critical in nonadiabatic transition dynamics. Nonadiabaticity is found to be extremely sensitive to the conformational molecular structure, and this has been demonstrated in the photodissociation dynamics of the chemical derivatives of thiophenol. Intramolecular vibrational redistribution, which is nontrivial in surmounting the reaction barrier, is found to wash out state-specific dynamic resonances, implying the importance of the dynamic interplay between vibrational energy flow and nonadiabatic transition. The experimental results on conical intersection dynamics presented in this review provide many interesting and important issues to be pursued in the near future by both theoreticians and experimentalists.
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