Highly efficient catalyst for 1,1,2-trichloroethane dehydrochlorination via BN_(3) frustrated Lewis acid-base pairs

In this study,a novel non-metallic carbon-based catalyst co-doped with boron and nitrogen(B,N)was successfully synthesized.By precisely controlling the carbonization temperature of a binary mixed ionic liquid,we selectively modified the doping site structure,ultimately constructing a B,N co-doped frustrated Lewis acid-base pair catalyst.This catalyst exhibited remarkable catalytic activity,selectivity,and stability in the dehydrochlorination reaction of 1,1,2-trichloroethane(TCE).Detailed characterization and theoretical calculations revealed that the primary active center of this catalyst was the BN_(3)configuration.Compared to conventional graphitic N structures,the BN_(3)structure had a higher p-band center,ensuring superior adsorption and activation capabilities for TCE during the reaction.Within the BN_(3)site,three negatively charged nitrogen atoms acted as Lewis bases,while positively charged boron atoms acted as Lewis acids.This synergistic interaction facilitated the specific dissociation of chlorine and hydrogen atoms from TCE,significantly enhancing the 1,1-dichloroethene selectivity.Through this research,we not only explored the active site structure and catalytic mechanism of B,N co-doped catalysts in depth but also provided an efficient,selective,and stable catalyst for the dehydrochlorination of TCE,contributing significantly to the development of non-metallic catalysts.

Efficient nitrite-to-ammonia electroreduction over Zr-Ni frustrated Lewis acid-base pairs

Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herein, we report an efficient Zr-NiO catalyst with atomically dispersed Zr-dopants incorporated in NiO lattice, delivering the exceptional NO_(2)RR performance with industriallevel current density(>0.2 A cm^(-2)). In situ spectroscopic measurements and theoretical simulations reveal the construction of ZrNi frustrated Lewis acid-base pairs(FLPs) on Zr-Ni O, which can substantially increase the number of absorbed nitrite(NO_(2)~-),promote the activation and protonation of NO_(2)~- and concurrently hamper the H coverage, boosting the activity and selectivity of Zr-NiO towards the NO_(2)RR. Remarkably, Zr-NiO exhibits the exceptional performance in a flow cell with high Faradaic efficiency for NH_(3) of 94.0% and NH_(3)yield rate of 1,394.1 μmol h^(-1)cm^(-2) at an industrial-level current density of 228.2 m A cm^(-2),placing it among the best NO_(2)RR electrocatalysts for NH_(3) production.

关于frustrated Lewis pair的中文名

frustrated Lewis pair(FLP)是一个最近出现的新名词,指分子内或混合体系中同时具有路易斯酸和路易斯碱两个位点,由于空间位阻较大而使得这两个位点不能结合形成路易斯酸碱加合物,从而具有独特的反应活性。建议译为"受阻路易斯酸碱对"。

Carboxylation of Aromatics by CO₂under “Si/Al Based Frustrated Lewis Pairs” Catalytic System

Carboxylation of aromatics by CO2 to generate corresponding carboxylic acids is recently providing a novel approach to utilize the green gas CO2, in which the activation of CO2 is the key procedure. Among the many catalytic systems employed in the carboxylation, the concept of “Frustrated Lewis Pairs” (FLPs) was scarcely mentioned, which perform excellently in activating small molecules like CO2. The FLPs are combinations of Lewis acids and Lewis bases which failed to form adducts due to their bulky steric congestion. In this paper, we first attempted various Si/Al Based FLPs to catalyze the carboxylation of aromatics through the activation of CO2, and a good yield of 62% - 97% was obtained. The reaction mechanism was proposed, involving the activation of CO2 mainly contributed by AlCl3 in cooperation with organosilane, forming an intermediate consisting of CO2, AlCl3, and R4Si, as well as the subsequent electrophilic attack to aromatics, thus to promote the carboxylation reaction.

The preconditions of reversible hydrogenation–dehydrogenation of B/N and B/P frustrated Lewis Pairs

Boron-nitrogen-hydrogen compounds have been investigated and developed very fast in last decades caused by its excellent hydrogen-storage performances. The bottleneck problem hindering its application is the irreversibility after its dehydrogenation. However, the traditional B-N(or B-P) bond can be hindered by connecting with large steric hindrances, which results in the possible reversible hydrogenationdehydrogenation properties. In this research, we analyse the structural characters based on the experiments to obtain the required electronic structure properties for realizing the reversibility of FLPs in the hydrogenation(or dehydrogenation).

Reaction mechanism of hydrogen activation by frustrated Lewis pairs

Typically, a Lewis acid and a Lewis base can react with each other and form a classical Lewis adduct. The neutralization reaction can however be prevented by ligating the acid and base with bulky substituents and the resulting complex is known as a "frustrated Lewis pair"(FLP). Since the Lewis acid and base reactivity remains in the formed complex, FLPs can display interesting chemical activities, with promising applications in catalysis. For example, FLPs were shown to function as the first metal-free catalyst for molecular hydrogen activation. This, and other recent applications of FLPs, have opened a new thriving research field. In this short-review, we recapitulate the computational and experimental studies of the H_2 activation by FLPs. We discuss the thus-far uncovered mechanistic aspects, including pre-organization of FLPs,the reaction paths for the activation, the polarization of He H bond and other factors affecting the reactivity. We aim to provide a rather complete mechanistic picture of the H_2 activation by FLPs, which has been under debate for decades since the first discovery of FLPs. This review is meant as a starting point for future studies and a guideline for industrial applications.

Role of surface frustrated Lewis pairs on reduced CeO2(110)in direct conversion of syngas

Direct syngas conversion to light olefins on bifunctional oxide-zeolite(OX-ZEO)catalysts is of great interest to both academia and industry,but the role of oxygen vacancy(Vo)in metal oxides and whether the key intermediate in the reaction mechanism is ketene or methanol are still not well-understood.To address these two issues,we carry out a theoretical study of the syngas conversion on the typical reducible metal oxide,CeO2,using density functional theory calculations.Our results demonstrate that by forming frustrated Lewis pairs(FLPs),the VOs in CeO2 play a key role in the activation of H2 and CO.The activation of H2 on FLPs undergoes a heterolytic dissociative pathway with a tiny barrier of 0.01 eV,while CO is activated on FLPs by combining with the basic site(O atom)of FLPs to form CO2^2-.Four pathways for the conversion of syngas were explored on FLPs,two of which are prone to form ketene and the other two are inclined to produce methanol suggesting a compromise to resolve the debate about the key intermediates(ketene or methanol)in the experiments.Rate constant calculations showed that the route initiating with the coupling of two CO*into OCCO*and ending with the formation of ketene is the dominant pathway,with the neighboring FLPs playing an important role in this pathway.Overall,our study reveals the function of the surface FLPs in the activation of H2 and CO and the reaction mechanism for the production of ketene and methanol for the first time,providing novel insights into syngas conversion over OX-ZEO catalysts.

Asymmetric Partial Hydrosilylation of 2,2-Difluoro-1,3-diketones with Chiral Frustrated Lewis Pairs

Comprehensive Summary,The asymmetric partial reduction of 1,3-diketones stands as a straightforward pathway to access optically active β-hydroxyketones. In this paper, an asymmetric Piers-type hydrosilylation of 2,2-difluoro-1,3-diketones was successfully realized by using a frustrated Lewis pair of chiral borane and tricyclohexylphosphine as a catalyst, delivering a variety of α,α-difluoro-β-hydroxyketones in high yields with up to 99% ee. Significantly, no over-reduced diol products were observed even with an excess amount of silanes. The product can be conveniently converted to α,α-difluoro-β-hydroxyester or 1,3-anti-diol via an oxidation with m-CPBA or a reduction with DIBAL-H without obvious loss of ee.

Supported Recyclable Metal-free Frustrated Lewis Pair Catalyst for Catalytic Hydrogenation of Substituted Pyridines to Piperidines

The construction of heterogeneous frustrated Lewis pairs(FLPs)catalysts is crucial for realizing highly efficient and recyclable pyridines catalytic hydrogenation.In this work,we prepared a recyclable heterogenous FLPs catalyst CMP-BF with conjugated microporous polymer CMP-ethynyl as the support via self-catalyzed 1,1-carboboration reaction with commercial Lewis acid B(C_(6)F_(5))_(3).The as-synthesized CMP-BF demonstrates superior heterogenous catalytic hydrogenation performance(conversion>99%),and considerable stability(84%conversion after three cycles)in recyclable hydrogenation of 2,6-phenylpyridine.This work provides insights into the fabrication and catalytic application of recyclable heterogenous FLP catalysts.

“受阻Lewis酸碱对”化学的研究进展

受阻Lewis酸碱对(Frustrated Lewis Pairs,FLPs)是一类具有特殊反应活性的Lewis酸碱对。自发现以来,FLPs受到了广泛关注并在许多领域崭露头角。本文对FLPs在不对称氢化、高分子聚合、CO_2催化还原等应用领域取得的突破进行了介绍;同时对过渡金属FLPs和FLPs配位的过渡金属催化体系进行了综述;最后对FLPs领域未来的发展前景进行了展望。

二氧化铈表面构建固体“受阻”Lewis酸碱对用于小分子活化

近年来,固体"受阻"Lewis酸碱对(FLP)在小分子活化领域受到了广泛的关注和研究。但是,在纳米材料表面构建FLP活性位仍然是一个挑战,并且因此限制了其广泛的应用。作为一种常见的催化剂或者功能性载体,二氧化铈(CeO2)表面同时具有Lewis酸和碱性位点,以及大量容易调控的表面缺陷。当CeO2表面的Lewis酸和碱性位点相互独立时,就有望形成类似于均相FLP活性位点。因此,具有丰富表面性质的纳米CeO2展现极大的可能性去构建固体FLP活性位点。本论文综述了一种通过表面缺陷调控,在CeO2(110)表面成功构建固体FLP的策略。在具有表面氧缺陷团簇的CeO2表面能够成功构建一种由两个相连的Ce3+组成的Lewis酸性位点;该酸性位点与氧缺陷团簇相邻的Lewis碱性的O原子,可以构建成一种新颖的FLP位点。该固体FLP活性位点可以实现H2活化用于不饱和烷烃的加氢反应,也可以用于实现CO2的活化,并且转化为环状碳酸脂。此外,该活性位点理论上可实现CH4分子的活化。最后,该综述还总结了固体FLP发展中的挑战及前景。

Photo-induced surface frustrated Lewis pairs for promoted photocatalytic decomposition of perfluorooctanoic acid

Heterogeneous photocatalysis has gained substantial research interest in treating per-and polyfluoroalkyl substances(PFAS)-contaminated water.However,sluggish degradation kinetics and low defluorination efficiency compromise their practical applications.Here,we report a superior photocatalyst,defected Bi_(3)O(OH)(PO_(4))_(2),which could effectively degrade typical PFAS,perfluorooctanoic acid(PFOA),with high defluorination efficiency.The UV light irradiation could in situ generate oxygen vacancies on Bi_(3)O(OH)(PO_(4))_(2) through oxidation of the lattice hydroxyls,which further promotes the formation of Lewis acidic coordinately unsaturated bismuth sites.Then,the Lewis acidic sites couple with the proximal surface hydroxyls to constitute the surface frustrated Lewis pairs(SFLPs).With the in-depth spectroscopic analysis,we revealed that the photo-induced SFLPs act as collection centers to effectively adsorb PFOA and endow accessible pathways to transfer photogenerated holes to PFOA rapidly.Consequently,activation of the terminal carboxyl,a ratelimiting step for PFOA decomposition,could be easily achieved over the defected Bi_(3)O(OH)(PO_(4))_(2) photocatalyst.These results suggest that SFLPs exhibit great potential in developing highly efficient photocatalysts to degrade persistent organic pollutants.

Frustrated Lewis pairs in situ formation in B-based porous aromatic frameworks for efficient o-phenylenediamine cyclization

Benzimidazoles are very important chemical materials in the pharmaceutical industry,and the most common synthetic route is cyclization of o-phenylenediamine with carbon sources,in which utilization of inexpensive and abundant CO_(2)as C1 source is very impressive.Porous aromatic frameworks(PAFs)with highly desired skeletons have attracted great attentions in gas capture and catalysis.Herein,B-based PAF-165 and PAF-166 are designed and synthesized via Friedel-Crafts alkylation reaction,which present high surface areas as well as high stability.Benefiting from the abundant electron-deficient B centers,both PAFs exhibit excellent selective CO_(2)adsorption abilities.The presence of sterically hindered B units in PAFs can act as Lewis acid active sites for the frustrated Lewis pairs(FLPs)in situ formation with ophenylenediamine,thus promoting the synthesis of benzimidazole.The optimal reaction conditions for o-phenylenediamine cyclization with PAF catalysts are explored,and the reaction mechanism is also proposed.This work provides feasible ideas for incorporating FLPs within porous materials as reusable heterogeneous catalysts for CO_(2)capture and conversion.

In Situ Formation of Frustrated Lewis Pairs in a Zirconium Metal-Organic Cage for Sustainable CO_(2)Chemical Fixation

Sustainable CO_(2)fixation represents a facile and promising approach to constructing various valueadded chemicals.Herein,we contribute a robust metal-organic cage(MOC),denoted as TCPB-1,comprising a bulky Lewis acid functionalized linker,which can in situ form frustrated Lewis pairs(FLPs)upon the addition of Lewis basic substrates to efficiently drive CO_(2)transformation.Significantly,the incorporation of Lewis acidic boron sites within TCPB-1 promotes the efficient CO_(2)conversion to potentially medicinal benzimidazole derivatives via an FLPmediated pathway,and boosts the stability/durability of the FLP catalyst.In addition,the underlying catalysis mechanism has been established by combined experimental and molecular simulation studies.This work not only advances FLP/MOC as a new type of highly efficient catalyst for CO_(2)chemical fixation,but also opens a new avenue to design heterogeneous FLP-based catalysts for small molecule activation and beyond.

Organic Synthesis through Radical Innovation:Frustrated Radical Pairs

Frustrated Lewis Pairs(FLPs)represent a unique class of interactions in Lewis acid-base chemistry,driven by spatial hindrance or incongruent orbital energy levels that hinder the formation of effective coordination bonds.FLPs have received significant attention for their application in activating small molecules and facilitating organic synthesis reactions.Recent developments have led to the emergence of Frustrated Radical Pairs(FRPs)as an extension of the radical family.FRPs are formed from FLPs through Single Electron Transfer(SET)and exhibit the ability to activate a variety of chemical bonds.While research on FLPs is well-established,investigations into FRPs in organic reactions remain limited.This review highlights the current state of FRPs in organic synthesis,delves into mechanistic insights,explores their potential,and underscores the challenges in this emerging field.

Recent advances in selective C–C bond coupling for ethanol upgrading over balanced Lewis acid-base catalysts

Ethanol is a considerable platform molecule in biomass conversion,which could be acquired in quantity through acetone-butanol-ethanol(ABE)fermentation.People have been working on the upgrading of ethanol to value added chemicals for decades.In the meantime,1-butanol and a series of value added products have been selectively generated through C–C bond coupling.In this mini-review,we focus on the recent advances in selective C–C bond formation over balanced Lewis acid-base catalysts such as modified metal oxide,mixed metal oxide,hydroxyapatite and zeolite confined transition metal oxide catalysts.Among them,Pd-MgAlO_x and Sr-based hydroxyapatite exhibit>70%1-butanol selectivity,while Zn——xZr_yO_z and Ta-Si BEA zeolite achieve>80%of isobutene and butadiene selectivity respectively.The mechanism and reaction pathway of C–C bond formation in each reaction system are described in detail.The correlation between C–C bond coupling and the acidity/basicity of the Lewis acid-base pairs from the surface of the catalysts are also discussed.

Research progress in the living/controlled polymerization of(meth)acrylate monomers by Lewis pair

Lewis pair polymerization(LPP)has demonstrated its unique advantages,such as high activity,high stability,and adjustable variability,towards the polymerization of(meth)acrylate monomers in comparison with the other polymerization techniques.The combination of Lewis acid(LA)and Lewis base(LB)to construct Lewis pairs(LPs)with appropriate Lewis basicity,Lewis acidity,and steric effects would significantly impact the polymerization process,including chain initiation,propagation,termination and chain transfer reaction,as well as polymerization manner of monomers.In this feature article,we briefly review recent progress made by our research group towards the living/controlled polymerization of(meth)acrylate monomers,which were accomplished by a series of newly designed LPs,including monofunctional LPs,dual-initiating LPs and intramolecular tethered trifunctional LP.This article is divided into three parts:(1)the development of monofunctional living/controlled LP polymerization system;(2)the design and preparation of dual-initiating LPs in synthesizing thermoplastic elastomers;(3)the application of intramolecular trifunctional LP to the synthesis of cyclic polymers.These developed LPPs have demonstrated their powerful capability in precise control over the molecular weight,molecular weight distribution,and monomer sequence as well as the topology of polymers.This review will serve as a good resource or guideline for researchers currently working in the area of LPP and for those who are interested in synthesizing new materials by LPP.

Stable Radical Ion Pairs Induced by Single Electron Transfer:Frustrated Versus Nonfrustrated

Single electron transition reactions between amines(Lewis base)and B(C_(6)F_(5))_(3)(Lewis acid)in cooperation with benzoquinones gave rise to a frustrated radical pair 3 and a nonfrustrated radical pair 4.Both of them were isolated as stable crystals and studied by single-crystal X-ray diffraction,superconducting quantum interference device measurements,electron paramagnetic resonance,nuclear magnetic resonance,and UV–vis spectroscopy.Antiferromagnetic exchange coupling was observed among both 3 and 4.Radical anion and cation are basically separated in 3,while 4 featured a relatively strong anion-cationπ–πstacking interaction.This work demonstrated that the Lewis acid coupled electron transfer is an efficient way to prepare stable radical ion pairs.

失配的Lewis对:非金属催化氢化的新策略

"失配的Lewis对"(Frustrated Lewis Pairs,FLPs)作为有机化学领域的新概念,在非金属活化H2,CO2和NH3等小分子方面的研究和应用格外引人注目.以"失配的Lewis对"为催化剂,直接以氢气作为氢源,非金属催化氢化还原醛、烯胺、亚胺、腈和二氧化碳等获得了很好的结果.手性"失配的Lewis对"(Chiral Frustrated Lewis Pairs,Chiral FLPs)在不对称催化氢化还原亚胺的反应中也呈现出较高的光学选择性,产物胺的对映体过量最高达83%ee.综述了近几年"失配的Lewis对"在非金属催化氢化研究领域的进展情况.

胺基化聚苯乙烯负载B(C_(6)F_(5))_(3)催化醛酮的去氧化还原

以胺基改性聚苯乙烯高分子材料作为载体,负载大位阻路易斯酸三(五氟苯基)硼烷(B(C_(6)F_(5))_(3)),研究了以硅烷为还原剂,负载B(C_(6)F_(5))_(3)催化剂对醛酮的催化去氧化还原反应活性及负载催化剂的耐受性。研究结果表明,胺基改性聚苯乙烯负载的催化剂B(C_(6)F_(5))_(3)在对醛酮催化去氧化还原时,其反应活性不仅与均相条件相当,甚至在反应的选择性上有时会表现出不同于均相反应的特征。而且负载后的B(C_(6)F_(5))_(3)催化剂在催化醛酮还原时,循环使用8次以上时仍能保持较高的反应活性。