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.

“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。

Lewis酸碱位点共存的MOFs在CO_(2)环加成反应中的催化应用

二氧化碳(CO_(2))是一种温室气体,同时也是丰富、无毒、不燃的可再生碳一资源,其转化和利用具有重要意义,CO_(2)与环氧化物环加成反应制备环状碳酸酯就是其中一种具有研究价值的途径。金属有机骨架材料(MOFs)由于具有可设计的模块化结构,在催化等领域一直以来都是研究热点。通过选择合适的有机配体与金属中心组装可以得到同时含有Lewis酸、碱位点的MOFs材料,能够在无助催化剂无溶剂条件下催化CO_(2)环加成反应。本文将以MOFs材料中Lewis酸、碱位点的类型为出发点来介绍含Lewis酸-碱对MOFs材料催化CO_(2)环加成的相关工作。

Regulating Lewis Acid-Base Sites over Fenton System for Enhancing Degradation of Pollutants in Saline and Buffered Wastewater

The saline and buffered environment in actual wastewater imposes higher demands on Fenton and Fenton-like catalytic systems.This study developed a MoS_(2)co-catalytic Fe_(2)O_(3)Fenton-like system with controllable Lewis acid-base sites,achieving efficient treatment of various model pollutants and actual industrial wastewater under neutral buffered environment.The acidic microenvironment structured by the edge S sites(Lewis basic sites)in the MoS_(2)/Fe_(2)O_(3)catalyst is susceptible to the influence of Lewis acidic sites constructed by Mo and Fe element,affecting catalytic performance.Optimizing the ratio of precursor amounts ensures the stable presence of the acidic microenvironment on the surface of catalyst,enabling the beneficial co-catalytic effect of Mo sites to be realized.Furthermore,it transcends the rigid constraints imposed by the Fenton reaction on reaction environments,thereby expanding the applicability of commonplace oxides such as Fe_(2)O_(3)in actual industrial water remediation.

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.

Living/controlled polymerization of vinylpyridines into sequence-regulated copolymers by Lewis pair

The poly(vinylpyridine)(PVP) based(co)polymers are of particular interest in materials science, due to their multifunctionality and diverse applications. So far, there is no report on the sequence-regulated copolymerization of vinylpyridines(VPs) and methacrylate monomer in one-step manner yet. Here we designed and synthesized a series of guanidine phosphines as Lewis base(LB), which is combined with bulky organoaluminium to construct Lewis pairs(LPs) for polymerization of VPs. The living/controlled polymerization of 4-vinylpyridine(4-VP) or 2-vinylpyridine(2-VP) can be accomplished with remarkable efficiency by such Lewis pair polymerization(LPP), furnishing polymers with high molecular weight(up to 288 kg/mol) and narrow molecular weight distribution(as low as 1.17). Mechanistic studies reveal the interaction of LPs and formation of zwitterionic intermediates, providing solid evidences to support the proposed polymerization mechanism. More importantly, by simply adjusting the LA dosage, this LPP strategy realizes the unprecedented control over the sequence regulation of 2-VP-based copolymers from gradient to block in one-step manner, regardless of the monomer ratio, which greatly expands the versatility of the LPP.

Synergistic Lewis acid-base sites of ultrathin porous Co_(3)O_(4)nanosheets with enhanced peroxidase-like activity

Surface Lewis acid-base sites in crystal structure may influence the physicochemical properties and the catalytic performances in nanozymes.Understanding the synergistic effect mechanism of Co_(3)O_(4)nanozymes towards substances(3,3’,5,5’-tetramethylbenzidine(TMB)and hydrogen peroxide(H2O2))induced by surface Lewis acid-base sites is important to enhance the efficiency for peroxidase-like reaction.Herein,ultrathin porous Co_(3)O_(4)nanosheets with abundant Lewis acid-base sites were prepared by sodium borohydride(NaBH4)reduction treatment,which exhibited high-efficiency peroxidase-like activity compared with original Co_(3)O_(4)nanosheets.The Lewis acid-base sites for ultrathin porous Co_(3)O_(4)nanosheets nanozyme were owing to the coordination unsaturation of Co ions and the formation of defect structure.Ultrathin porous Co_(3)O_(4)nanosheets had 18.26-fold higher catalytic efficiency(1.27×10^(-2)s^(-1)·mM^(-1))than that of original Co_(3)O_(4)(6.95×10^(-4)s^(-1)·mM^(-1))in oxidizing TMB substrate.The synergistic effect of surface acid and base sites can enhance the interfacial electron transfer process of Co_(3)O_(4)nanosheets,which can be a favor of absorption substrates and the generation of reactive intermediates such as radicals.Furthermore,the limit of detection of hydroquinol was 0.58μM for ultrathin porous Co_(3)O_(4)nanosheets,965-fold lower than original Co_(3)O_(4)(560μM).Besides,the linear range of ultrathin porous Co_(3)O_(4)nanosheets was widely with the concentration of 5.0-1,000μM.Colorimetric detection of hydroquinol by agarose-based hydrogel membrane was provided based on excellent peroxidase-like properties.This study provided insights into designing high-performance nanozymes for peroxidase-like catalysis via a strategy of solid surface acid-base sites engineering.

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.

Lewis Pairs催化环酯开环聚合与环酐/环氧化物开环交替共聚

近年来,路易斯酸碱对(Lewis pairs)催化聚合已成为高分子化学领域的研究热点之一,受到人们的广泛关注.利用Lewis pairs催化环酯开环聚合以及环酐/环氧化物开环交替共聚,为合成新型聚酯材料以及聚酯的化学改性提供了简便快捷方法.Lewis酸和Lewis碱的协同作用不仅提高了催化活性,同时亦可提高单体选择性和开环反应的立体选择性.本专论总结了近几年课题组在利用Lewis pairs催化合成环境友好高分子材料方面的研究进展,分析了Lewis pairs催化环酯开环聚合和环酐/环氧化合物开环交替共聚的聚合机理,论述了Lewis pairs结构—催化活性—单体选择性/开环立体化学之间的关系,阐述了混合单体“自切换”聚合制备序列可控脂肪族或半芳香族聚酯材料的新方法,深入讨论了Lewis pairs催化开环聚合的发展前景.

Lewis pairs polymerization of polar vinyl monomers

The globally increasing demands for polymer materials stimulate the significantly intense attention focused on the Lewis pair polymerization(LPP) of various polar vinyl monomers catalyzed by Lewis pairs(LPs) composed of Lewis acid(LA) and Lewis base(LB). According to the degree of interaction between LA and LB, LPs could be divided into classical Lewis adduct(CLA), interacting Lewis pair(ILP) and frustrated Lewis pair(FLP). Regulation of the Lewis basicity, Lewis acidity, and steric effects of these LPs has a significant impact on the polymer chain initiation, propagation and termination as well as chain transfer reaction during polymerization. Compared with other polymerization strategies, LPP has shown several unique advantages towards the polymerization of polar vinyl monomers such as high activity, control or livingness, mild conditions, and complete chemo-or regioselectivity. We will comprehensively review the recent advances achieved in the LPP of polar vinyl monomers according to the classification of the employed LPs based on different LAs, by highlighting the key polymerization results, polymerization mechanisms as well as the currently unmet challenges and the future research directions of LPP chemistry.

Isospecific Polymerization of Methyl Methacrylate by Intramolecular Rare-Earth Metal Based Lewis Pairs

A series of cationic rare-earth aryloxide complexes,ie,,[LREOAr^(1)]^(+)[B(C_(6)F_(5))_(4)]^(-)(L=CH_(3)C(NAr)CHC(CH_(3))(NCH(R)CH_(2)PPh_(2));RE=Y,Lu;Ar'=2,6-tBU_(2)-C_(6)H_(3),2,6-(PhCMe_(2))_(2)-4-Me-C_(6)H_(2);Ar=2,6-iPr_(2)-C_(6)H_(3),2,6-(Ph_(2)CH)_(2)-4-iPr-C_(6)H_(2);R=H,CH_(3),iPr,Ph),were prepared and ap-plied to the Lewis pair polymerization of methyl methacrylate(MMA).The stereoregularity of the resulting PMMA was significantly affected by the R substituent on the pendant arm of the tridentate NNP ligand,and was found to increase with increase in the steric hindrance of R.

Manipulating micro-electric field and coordination-saturated site configuration boosted activity and safety of frustrated single-atom Cu/O Lewis pair for acetylene hydrochlorination

Simultaneously boosting acetylene hydrochlorination activity and avoiding formation of explosive copper acetylide over Cu-based catalyst,which represented a promising alternative to Hg-based and noble metal catalysts,remained challenging.Herein,we fabricated a frustrated single-atom Cu/O Lewis pair catalyst(Cu/O-FLP)by coupling epoxide group(C-O-C)with atomdispersed Cu-cis-N_(2)C_(2)Cl center to address this challenge.The basic epoxy site modulated the electron-deficient state of Lewisacidic Cu center and paired with the Cu-cis-N_(2)C_(2)Cl moiety to preferentially break HCl into different electronegative Cu-Clδ-and C-O-H^(δ+)intermediates,which further induced both an extra localized electric field to polarize acetylene and a upshift of the dband center of catalyst,thereby promoting adsorption and enrichment of acetylene by enhancing the dipolar interaction between acetylene and active intermediates.Moreover,the generated Cu-Clδ-and C-O-H^(δ+)drastically reduced the energy barrier of ratelimiting step and made vinyl chloride easier to desorb from the Lewis-basic oxygen-atom site rather than traditional Lewis-acidic Cu center.These superiorities ensured a higher activity of Cu/O-FLP compared with its counterparts.Meanwhile,preferential dissociation of HCl endowed single-atom Cu with the coordination-saturated configuration,which impeded formation of explosive copper acetylide by avoiding the direct interaction between Cu and acetylene,ensuring the intrinsic safety during catalysis.