Introduction

Jannes, G.; Dubois, Vincent

doi:10.1007/978-1-4615-1909-6_1

Cited by 22 publications

(23 citation statements)

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“…Since the pioneering work by Stephan and co-workers in 2006 who reported the reversible, metal-free hydrogen activation catalyzed by sterically encumbered Lewis acid and Lewis base combinations, termed as “frustrated Lewis pairs (FLPs)”, FLPs have aroused considerable academic attention. − In the past decade, the reactivity of FLPs has evolved to a broad range of other small molecules including olefins, alkynes, heteroarenes, CO 2 , SO 2 , NH 3 , and so forth, showing a promising future of FLPs in catalysis, organic synthesis, and materials chemistry. − However, as the concept of FLPs is mainly limited in homogeneous molecular-based chemistry and catalysis, further utilization of FLP catalysts in industrial applications is hindered by problematic and costly catalyst recycling . Therefore, developing heterogeneous FLP catalysts using the knowledge of homogeneous molecular-based FLPs is of great promise.…”

Section: Introductionmentioning

confidence: 99%

Understanding All-Solid Frustrated-Lewis-Pair Sites on CeO₂ from Theoretical Perspectives

et al. 2017

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The development of heterogeneous frustrated-Lewis-pair (FLP) catalysts from homogeneous FLP conception is of great promise in practical applications. While our recent discovery has shown that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation ( Zhang Zhang Nat. Commun.2017815266), a sound understanding of the intrinsic property and reactivity of the solid FLPs is still expected. Here we present a comprehensive theoretical study on the FLPs (Ce···O) constructed on CeO2(110) and (100) surfaces by using density functional theory calculations. We find that the creation of surface oxygen vacancy can enhance both the acidity of FLP-acid site and the basicity of FLP-base site. The enhanced acidity and basicity of Lewis sites together with the elongated distance of Lewis pairs (Ce···O) contribute to the high activity of solid FLPs. The dissociative activation of H2 on FLPs experiences a heterolytic pathway (H2 → Hδ+ + Hδ−) with a low activation energy of 0.07 eV on CeO2(110) and 0.08 eV on CeO2(100). Unlike the phenomenon on stoichiometric CeO2 surfaces that the dissociated hydride (Hδ−) adsorbed at Ce sites is prone to transfer to more stable O sites, the hydride on FLPs can be stabilized at Ce sites and thus benefits the hydrogenation of acetylene via an easier pathway. The rate-determining barriers of acetylene hydrogenation on FLP-CeO2(110) and FLP-CeO2(100) are calculated to be 0.58 and 0.88 eV, respectively. These results could help to understand the nature of solid FLPs and pave the way for rational design of heterogeneous FLP catalysts.

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Section: Introductionmentioning

confidence: 99%

Understanding All-Solid Frustrated-Lewis-Pair Sites on CeO₂ from Theoretical Perspectives

et al. 2017

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“…Frustrated Lewis pairs (FLPs), constituted by sterically encumbered Lewis acid and Lewis base combinations, have aroused increasing attention since the pioneering work by Stephan and co-workers in the past decade. − The applications of FLPs have also evolved from the primary stoichiometric reactions to catalytic processes, in particular in the domain of homogeneous catalysis. However, the problematic and costly recycling of homogeneous catalyst hinders the large-scale application of soluble FLPs, and thus, developing heterogeneous FLP catalysts becomes more attractive. Currently, the heterogeneous FLPs can be classified into two categories: semisolid FLPs − and all-solid FLPs. − The former require appropriate solid substrates and matched molecular components and thus are always difficult to control.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Frustrated Lewis Pairs on Ceria for Direct Nonoxidative Coupling of Methane

et al. 2019

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While the regulation of surface oxygen vacancy (VO) of ceria is an effective methodology to construct solid frustrated Lewis pairs (FLPs), the intrinsic properties and potential applications of solid FLPs are not well-demonstrated. Herein, we present a theoretical study on the formation rules and dynamic behaviors of FLPs on CeO2(110) and their performance on nonoxidative conversion of methane. The density functional theory studies show that the formation of solid FLPs on CeO2(110) is dependent on the number of oxygen vacancies (VOs). The FLPs constructed by three or more VOs are stable in thermodynamics, whereas the FLPs containing few VOs (i.e., VO monomer and VO dimer) are less stable but can be dynamically formed via thermal fluctuation and reactant-adsorption, as observed by ab initio molecular dynamics simulations. Hence, the general existence of FLPs on reduced CeO2(110) surface under reaction conditions is revealed. Calculations on methane activation show that FLPs are active for C–H bond breaking with an activation energy as low as 0.63 eV, attributed to the enhanced acidity and basicity of FLPs. Because of the structure of FLPs, the subsequent dissociation of a second methane and the C–C coupling of CH3 to form C2H6 is relatively prevailing at FLP sites, different from the popular gas-phase coupling mechanism. Ethane can be further dehydrogenated at FLP sites to form more valuable ethylene. On the basis of these findings, our study provides insights into the formation and dynamic behaviors of solid FLPs on CeO2 and more importantly predicts a promising strategy for nonoxidative coupling of methane into more valuable chemicals on abundant oxide-based catalysts.

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“…Because natural resources are limited and the demand for enantiomerically pure compounds was further increasing, great efforts were made in the field of enantioselective catalysis to synthesize such compounds chemically. Until recently, research concentrated on homogeneous asymmetric catalysts, which are already used in industrial applications. , The heterogeneous counterpart holds intrinsic advantages over homogeneous ones, but only a few examples are known at present . One basic approach for the design of such a catalyst is the usage of a common achiral heterogeneous catalyst, which is then asymmetrized.…”

Section: Introductionmentioning

confidence: 99%

Tunable Induced Circular Dichroism in Thin Organic Films

et al. 2019

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In this work, we study the induced optical activity (OA) of spin-coated molecular films made of a pristine optically inactive laser dye (Rhodamine 110) in the visible range. The OA is brought about by a “transparent” chiral modifier (1,1′-Bi-2-naphthol). For the first time, it was experimentally shown how two separate mechanisms yield induced circular dichroism (ICD) in such a film and how they are describable through a model. In one, ICD occurs via a direct interaction between dye and modifier molecules. In the other, ICD takes place in optical transitions of present dye aggregates. It is proposed that this is caused by a chiral bias through an enantiomeric excess in inherently chiral and optically active dye aggregates promoted by the chiral modifier in a sergeant-soldier manner. Further, the strength of ICD strongly depends on the ratio between the modifier and the dye as well as on the preparation conditions. The resulting high tunability of the OA paired with a straightforward film preparation opens up a route for fabrication of homogeneous thin films with customized OA.

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Introduction

Cited by 22 publications

References 0 publications

Understanding All-Solid Frustrated-Lewis-Pair Sites on CeO₂ from Theoretical Perspectives

Understanding All-Solid Frustrated-Lewis-Pair Sites on CeO₂ from Theoretical Perspectives

Dynamic Frustrated Lewis Pairs on Ceria for Direct Nonoxidative Coupling of Methane

Tunable Induced Circular Dichroism in Thin Organic Films

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Introduction

Cited by 22 publications

References 0 publications

Understanding All-Solid Frustrated-Lewis-Pair Sites on CeO2 from Theoretical Perspectives

Understanding All-Solid Frustrated-Lewis-Pair Sites on CeO2 from Theoretical Perspectives

Dynamic Frustrated Lewis Pairs on Ceria for Direct Nonoxidative Coupling of Methane

Tunable Induced Circular Dichroism in Thin Organic Films

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Understanding All-Solid Frustrated-Lewis-Pair Sites on CeO₂ from Theoretical Perspectives

Understanding All-Solid Frustrated-Lewis-Pair Sites on CeO₂ from Theoretical Perspectives