Ce(iii)-Containing tungstotellurate(vi) with a sandwich structure: an efficient Lewis acid–base catalyst for the condensation cyclization of 1,3-diketones with hydrazines/hydrazides or diamines

2018 ◽  
Vol 5 (10) ◽  
pp. 2472-2477 ◽  
Author(s):  
Guo-Ping Yang ◽  
Shu-Xia Shang ◽  
Bing Yu ◽  
Chang-Wen Hu
Keyword(s):  
Lewis Acid ◽  
Sandwich Structure ◽  
Condensation Reaction ◽  
Lewis Base ◽  
Base Catalyst ◽  
Acid Base

A new Ce3+ modified Dawson-like polyoxometalate cluster was synthesized, which showed good Lewis acid and Lewis base activities in the condensation reaction.

Influence of Lewis base HMPA on the properties of efficient planar MAPbI3 solar cells fabricated by one-step process assisted by Lewis acid-base adduct approach

2020 ◽  
Vol 380 ◽  
pp. 122436 ◽  
Author(s):  
Kyungeun Jung ◽  
Weon-Sik Chae ◽  
Yun Chang Park ◽  
Joosun Kim ◽  
Man-Jong Lee
Keyword(s):  
Solar Cells ◽  
Lewis Acid ◽  
Lewis Base ◽  
Acid Base ◽  
Step Process ◽  
One Step

scholarly journals Structure investigations of group 13 organometallic carboxylates

2017 ◽  
Vol 46 (3) ◽  
pp. 669-677 ◽  
Author(s):  
Iwona Justyniak ◽  
Daniel Prochowicz ◽  
Adam Tulewicz ◽  
Wojciech Bury ◽  
Piotr Goś ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Lewis Acid ◽  
Relative Magnitude ◽  
Lewis Base ◽  
Acid Base ◽  
Group 13 ◽  
Structure Investigations

The effect of both the relative magnitude of electrophilicity of metal centres and the character of a Lewis base on the molecular structure of the electron-precise [R2M(μ-O2CPh)]2-type carboxylates and their Lewis acid–base adducts [(R2M)(μ-O2CPh)(py-Me)] is reported.

Investigation of the Interaction, Rheological and Tribological Properties of Bis(pinacolato)diboron with Lithium Grease During Mechanical Aging

2021 ◽  
Author(s):  
Jia Ren ◽  
Kuiliang Gong ◽  
Gaiqing Zhao ◽  
Xinhu Wu ◽  
Xiaobo Wang
Keyword(s):  
Lewis Acid ◽  
Lewis Base ◽  
Mechanical Degradation ◽  
Fiber Structure ◽  
Acid Base ◽  
Lithium Grease ◽  
Base Complex ◽  
Structure Strength ◽  
Base Grease ◽  
Mechanical Aging

Abstract In this article, Lewis acid–base complex of lithium 12-hydroxystearate (LHS) with diboron compound is formed by the introduction of bis(pinacolato)diboron (B2Pin2) into lithium grease. The interaction between Lewis acid B2Pin2 and Lewis base RCO2− of LHS is characterized by various techniques. Moreover, the rheological and tribological behaviors of the base grease are evaluated at low and moderate temperature, and the results indicate that the addition of B2Pin2 noticeably enhanced the rheological, friction-reducing, and anti-wear (AW) properties of the base grease, which likely owing to the fact that the formation of Lewis acid–base complex is beneficial for improving the soap fiber structure strength, helping to prevent the mechanical degradation of the lithium grease during mechanical aging process.

scholarly journals Selective Chemical Conversion of Sugars in Aqueous Solutions without Alkali to Lactic Acid Over a Zn-Sn-Beta Lewis Acid-Base Catalyst

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Wenjie Dong ◽  
Zheng Shen ◽  
Boyu Peng ◽  
Minyan Gu ◽  
Xuefei Zhou ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Aqueous Solutions ◽  
Lewis Acid ◽  
Chemical Conversion ◽  
Base Catalyst ◽  
Acid Base ◽  
Selective Chemical

scholarly journals Interplay of hemilability and redox activity in models of hydrogenase active sites

2017 ◽  
Vol 114 (46) ◽  
pp. E9775-E9782 ◽  
Author(s):  
Shengda Ding ◽  
Pokhraj Ghosh ◽  
Marcetta Y. Darensbourg ◽  
Michael B. Hall
Keyword(s):  
Lewis Acid ◽  
Hydrogen Evolution Reaction ◽  
Resting State ◽  
Active Sites ◽  
Reductive Elimination ◽  
Lewis Base ◽  
Redox Activity ◽  
Production Mechanism ◽  
Acid Base ◽  
Redox Active

The hydrogen evolution reaction, as catalyzed by two electrocatalysts [M(N2S2)·Fe(NO)2]+, [Fe-Fe]+ (M = Fe(NO)) and [Ni-Fe]+ (M = Ni) was investigated by computational chemistry. As nominal models of hydrogenase active sites, these bimetallics feature two kinds of actor ligands: Hemilabile, MN2S2 ligands and redox-active, nitrosyl ligands, whose interplay guides the H2 production mechanism. The requisite base and metal open site are masked in the resting state but revealed within the catalytic cycle by cleavage of the MS–Fe(NO)2 bond from the hemilabile metallodithiolate ligand. Introducing two electrons and two protons to [Ni-Fe]+ produces H2 from coupling a hydride temporarily stored on Fe(NO)2 (Lewis acid) and a proton accommodated on the exposed sulfur of the MN2S2 thiolate (Lewis base). This Lewis acid–base pair is initiated and preserved by disrupting the dative donation through protonation on the thiolate or reduction on the thiolate-bound metal. Either manipulation modulates the electron density of the pair to prevent it from reestablishing the dative bond. The electron-buffering nitrosyl’s role is subtler as a bifunctional electron reservoir. With more nitrosyls as in [Fe-Fe]+, accumulated electronic space in the nitrosyls’ π*-orbitals makes reductions easier, but redirects the protonation and reduction to sites that postpone the actuation of the hemilability. Additionally, two electrons donated from two nitrosyl-buffered irons, along with two external electrons, reduce two protons into two hydrides, from which reductive elimination generates H2.

Cleaving DNA-model phosphodiester with Lewis acid–base catalytic sites in bifunctional Zr–MOFs

2019 ◽  
Vol 48 (23) ◽  
pp. 8044-8048 ◽  
Author(s):  
Ying-Hua Zhou ◽  
Zhiyan Zhang ◽  
Margaret Patrick ◽  
Fan Yang ◽  
Rangling Wei ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Active Sites ◽  
Lewis Base ◽  
Zinc Hydroxide ◽  
Acid Base ◽  
Enhanced Activity ◽  
Nitrophenyl Phosphate ◽  
Catalytic Sites ◽  
Catalytic Active Sites ◽  
Hydrolysis Of

UiO-67-bpydc-Zn with isolated multi-catalytic active sites was fabricated as a catalyst for the hydrolysis of bis(p-nitrophenyl) phosphate as a DNA model. The enhanced activity may likely be attributed to the cooperation effects between the Lewis acid from the zirconium center at the node and the zinc hydroxide Lewis base in the linkers.

Site and chirality selective chemical modifications of boron nitride nanotubes (BNNTs) via Lewis acid–base interactions

2015 ◽  
Vol 17 (5) ◽  
pp. 3850-3866 ◽  
Author(s):  
Rajashabala Sundaram ◽  
Steve Scheiner ◽  
Ajit K. Roy ◽  
Tapas Kar
Keyword(s):  
Boron Nitride ◽  
Lewis Acid ◽  
Boron Nitride Nanotubes ◽  
Lewis Base ◽  
Chemical Modifications ◽  
Acid Base ◽  
Selective Chemical

The pristine BNNTs contain both Lewis acid (boron) and Lewis base (nitrogen) centers at their surface.

Cycloaddition Reactions of Dienes on the SI(100)-2 × 1 Surface

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1205-1210 ◽  
Author(s):  
Cheol Ho Choi ◽  
Mark S. Gordon
Keyword(s):  
Lewis Acid ◽  
Potential Energy Surfaces ◽  
Surface Reaction ◽  
Lewis Base ◽  
Acid Base ◽  
Activation Barriers ◽  
Type Complex ◽  
Mechanical Methods ◽  
Energy Surfaces ◽  
Base Substrate

Quantum mechanical methods were adopted to study the surface reaction mechanisms of 1, 3-cyclohexadiene and acrylonitrile on the Si(100)-2x1 surface. According to the computed potential energy surfaces, both ⌊4+2⌋ and ⌊2+2⌋ cycloaddition products resulting from the reactions of surface dimers are possible due to the negligible activation barriers at the surface. Isomerization reactions among the surface products are very unlikely due to the predicted large activation barriers preventing thermal redistributions of the surface products. As a result, the distribution of the final surface products is kinetically controlled leading to a reinterpretation of recent experiments. An intermediate Lewis acid-base type complex appears in both the ⌊4+2⌋ and ⌊2+2⌋ cycloadditions of acrylonitrile entrance channels, indicating that the surface may act as an electrophile/Lewis acid towards a strong Lewis base substrate.

Amine functionalized K10 montmorillonite: a solid acid–base catalyst for the Knoevenagel condensation reaction

2013 ◽  
Vol 42 (14) ◽  
pp. 5122 ◽  
Author(s):  
G. Bishwa Bidita Varadwaj ◽  
Surjyakanta Rana ◽  
K. M. Parida
Keyword(s):  
Solid Acid ◽  
Knoevenagel Condensation ◽  
Condensation Reaction ◽  
Base Catalyst ◽  
Acid Base ◽  
Amine Functionalized ◽  
Knoevenagel Condensation Reaction

scholarly journals Investigation of the Interaction, Rheological and Tribological Properties of Bis(pinacolato)diboron with Lithium Grease

2021 ◽  
Vol 69 (4) ◽  
Author(s):  
J. Ren ◽  
K. L. Gong ◽  
G. Q. Zhao ◽  
X. H. Wu ◽  
X. B. Wang
Keyword(s):  
Lewis Acid ◽  
Tribological Properties ◽  
Mechanical Stability ◽  
Lewis Base ◽  
Acid Base ◽  
Tribochemical Reaction ◽  
Lithium Grease ◽  
Base Complex ◽  
Lubrication Film ◽  
Base Grease

AbstractIn this article, Lewis acid–base complex of lithium 12-hydroxystearate (LHS) with diboron compound is formed by the introduction of bis(pinacolato)diboron (B2Pin2) into lithium grease. The interaction between Lewis acid B2Pin2 and Lewis base RCO2− of LHS is characterized by various techniques. Moreover, the rheological and tribological behaviors of the base grease are evaluated at low and moderate temperature. The results indicate that the addition of B2Pin2 can noticeably enhance the rheological property of the base grease because the formation of Lewis acid–base complex is beneficial for improving the soap fiber structure strength, and B2Pin2 could also help reduce the friction and wear of the grease during the sliding process, which likely owing to the boundary lubrication film generated by B2Pin2 adsorption on the rubbing surface and tribochemical reaction between borate esters and steel surfaces. The improvement of mechanical stability and tribological properties is beneficial to increasing the grease service life. Graphical Abstract

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