Secondary ligand metal interactions are decisive in many catalytic transformations. While arene-gold interactions have repeatedly been reported as critical structural feature in many high-performance gold catalysts, we herein report that these interactions can also be replaced by Au···H-C hydrogen bonds without suffering any reduction in catalytic performance. Systematic experimental and computational studies on a series of ylide-substituted phosphines featuring either a PPh 3 ( Ph YPhos) or PCy 3 ( Cy YPhos) moiety showed that the arene-gold interaction in the aryl-substituted compounds is efficiently compensated by the formation of Au···H-C hydrogen bonds. The strongest interaction is found with the C-H moiety next to the onium center, which due to the polarization results in remarkably strong interactions with the shortest Au···H-C hydrogen bonds reported to date. Calorimetric studies on the formation of the gold complexes further confirmed that the Ph YPhos and Cy YPhos ligands form similarly stable complexes. Consequently, both ligands showed the same catalytic performance in the hydroamination, hydrophenoxylation and hydrocarboxylation of alkynes, thus demonstrating that Au···H-C hydrogen bonds are equally suited for the generation of highly effective gold catalysts than gold-arene interactions. The generality of this observation was confirmed by a comparative study between a biaryl phosphine ligand and its cyclohexyl-substituted derivative, which again showed identical catalytic performance. These observations clearly support Au···H-C hydrogen bonds as fundamental secondary interactions in gold catalysts, thus further increasing the number of design elements that can be used for future catalyst construction.
https://ift.tt/3iXfvqR
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c09832
Francesco Ibba, Gabriele Pupo, Amber L. Thompson, John M. Brown, Timothy D. W. Claridge, and Véronique Gouverneur
https://ift.tt/32w8Mgp
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c06905
https://ift.tt/2FhwkNA
Journal of the American Chemical SocietyDOI: 10.1021/jacs.9b13872
https://ift.tt/2WbMApz
Journal of the American Chemical SocietyDOI: 10.1021/jacs.1c02808
Jian Zhang, Jun Wei, Wei-Yi Ding, Shaoyu Li, Shao-Hua Xiang, and Bin Tan
https://ift.tt/3nyjkVC
An efficient bifunctional electrocatalyst toward hydrazine‐assisted H2 production was designed by constructing the Ni3N‐Co3N heterointerfaces on Ni foam (Ni3N‐Co3N PNAs/NF). The catalyst can achieve energy‐saving hydrogen production in an overall hydrazine splitting (OHzS) unit, showing its potential for practical applications.
Abstract
Electrochemical water splitting for H2 production is limited by the sluggish anode oxygen evolution reaction (OER), thus using hydrazine oxidation reaction (HzOR) to replace OER has received great attention. Here we report the hierarchical porous nanosheet arrays with abundant Ni3N‐Co3N heterointerfaces on Ni foam with superior hydrogen evolution reaction (HER) and HzOR activity, realizing working potentials of −43 and −88 mV for 10 mA cm−2, respectively, and achieving an industry‐level 1000 mA cm−2 at 200 mV for HzOR. The two‐electrode overall hydrazine splitting (OHzS) electrolyzer requires the cell voltages of 0.071 and 0.76 V for 10 and 400 mA cm−2, respectively. The H2 production powered by a direct hydrazine fuel cell (DHzFC) and a commercial solar cell are investigated to inspire future practical applications. DFT calculations decipher that heterointerfaces simultaneously optimize the hydrogen adsorption free energy (ΔGH*) and promote the hydrazine dehydrogenation kinetics. This work provides a rationale for advanced bifunctional electrocatalysts, and propels the practical energy‐saving H2 generation techniques.
https://ift.tt/3785ouE
Journal of the American Chemical SocietyDOI: 10.1021/jacs.1c01046
Shuaihua Gao, Emily J. Thompson, Samuel L. Barrow, Wenju Zhang, Anthony T. Iavarone, and Judith P. Klinman
https://ift.tt/3aapSo3
A possible way to trigger hydrogen evolution reaction (HER) activity of the basal‐plane sites and make a MoS2 monolayer a single‐atom‐layer catalyst, is through long‐range ferromagnetism order induced by magnetic cobalt ion doping. The effect of the doping promotes the hydrogen adsorption ability of basal S sites.
Abstract
Single‐atom‐layer catalysts with fully activated basal‐atoms will provide a solution to the low loading‐density bottleneck of single‐atom catalysts. Herein, we activate the majority of the basal sites of monolayer MoS2, by doping Co ions to induce long‐range ferromagnetic order. This strategy, as revealed by in situ synchrotron radiation microscopic infrared spectroscopy and electrochemical measurements, could activate more than 50 % of the originally inert basal‐plane S atoms in the ferromagnetic monolayer for the hydrogen evolution reaction (HER). Consequently, on a single monolayer of ferromagnetic MoS2 measured by on‐chip micro‐cell, a current density of 10 mA cm−2 could be achieved at the overpotential of 137 mV, corresponding to a mass activity of 28, 571 Ag−1, which is two orders of magnitude higher than the multilayer counterpart. Its exchange current density of 75 μA cm−2 also surpasses most other MoS2‐based catalysts. Experimental results and theoretical calculations show the activation of basal plane S atoms arises from an increase of electronic density around the Fermi level, promoting the H adsorption ability of basal‐plane S atoms.
https://ift.tt/3rWOW8Z
Molybdenum sulfide based materials are known as efficient hydrogen evolution reaction (HER) catalysts. As the binding site for H atoms on molybdenum sulfide for the catalytic process is under debate, [HMo 3 S 13 ] – is an interesting molecular model system to address this question. Herein, we probe the [HMo 3 S 13 ] – cluster in the gas phase by coupling Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR MS) with infrared multiple photon dissociation (IRMPD) spectroscopy. Our investigations show one distinct S‐H stretching vibration at 2450 cm –1 . Thermochemical arguments based on DFT calculations strongly suggest a terminal disulfide unit as the H adsorption site.
https://ift.tt/37t9EoY
Journal of the American Chemical SocietyDOI: 10.1021/jacs.1c04482
Benyu Zhou and François P. Gabbaï
https://ift.tt/3ge0QpU
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c11787
Mao Cai, Kaini Xu, Yuze Li, Zongxiu Nie, Long Zhang, and Sanzhong Luo
https://ift.tt/38j5Kz6
A simple gold nanoparticle catalyzes the oxidative coupling of benzylamine to form imine in presence of visible light. Photoexcitation of Au NP generates an electron–hole pair that activates adsorbates (reactants) at Au NP surface to form a strong oxidant–reductant pair (benzylamine radical cation and superoxide radical), which is conducive for the reaction at a low temperature, with high product yield and selectivity.
Abstract
Here, we demonstrate the simultaneous utilization of both the hot carriers (electrons and holes) in the photocatalytic transformation of benzylamine to N‐benzylidenebenzylamine and the scope of reaction has also been successfully demonstrated with catalytic oxidation of 4‐methoxybenzylamine. The wavelength‐dependent excitation of AuNP allows us to tune the potential energy of charge carriers relative to the redox potential of the reactants which leads to energetically favorable product formation on the nanoparticle surface. We capture the formation of reaction intermediates and products by using in situ Raman spectroscopy, complemented by NMR spectroscopy and GC‐MS. Based on the experimental substantiations, a plausible reaction mechanism has been proposed.
https://ift.tt/38SXxle
“Like an enzyme” best describes the supramolecular catalyst reported by Rafael Gramage-Doria et al. in their Research Article (DOI: 10.1002/anie.202101997). The remotely-located Zn…N interactions within an iridium borylating catalyst are responsible for the unique selectivity and reactivity patterns observed for pyridine C−H bond functionalization. The pyridine approaches the substrate recognition pocket like a Perseid shooting star. Artwork: Romain Baloche.
https://ift.tt/3d1O3Gq
"OH! We didn't know this was supposed to be a joke." Came the reply.
A simplified pressurized gas‐assisted process, provides the first non‐metal single‐atom phosphorus with atomic‐level dispersion on unique single‐crystal Mo2C hexagonal nanosheet arrays supported by a carbon sheet. This single‐atom catalyst system is structurally stable and has exceptional electrocatalytic activity for the hydrogen evolution reaction (HER).
Abstract
Non‐metal‐based single‐atom catalysts (SACs) offer low cost, simple synthesis methods, and effective regulation for substrates. Herein, we developed a simplified pressurized gas‐assisted process, and report the first non‐metal single‐atom phosphorus with atomic‐level dispersion on unique single‐crystal Mo2C hexagonal nanosheet arrays with a (001) plane supported by carbon sheet (SAP‐Mo2C‐CS). The SAP‐Mo2C‐CS is structurally stable and shows exceptional electrocatalytic activity for the hydrogen evolution reaction (HER). A so‐called high‐active “window” based on the active sites of P atoms and their adjacent Mo atoms gives a ΔGH* close to zero for hydrogen evolution, which is the most ideal ΔGH* reported so far. Meanwhile, the moderate d‐band center value of SAP‐Mo2C‐CS can be also used as an ideal standard value to evaluate the HER performance in non‐metal‐based SACs.
https://ift.tt/3chuVCD
An iridium‐based supramolecular catalyst has been designed to selectively recognize pyridine‐like derivatives via secondary Zn⋅⋅⋅N interactions. Owing to the distance between the substrate binding site and the active site as well as the geometrically constraints, meta‐selective borylation reactions were accomplished displaying catalytic behaviors typically encountered in enzymes.
Abstract
The use of secondary interactions between substrates and catalysts is a promising strategy to discover selective transition metal catalysts for atom‐economy C−H bond functionalization. The most powerful catalysts are found via trial‐and‐error screening due to the low association constants between the substrate and the catalyst in which small stereo‐electronic modifications within them can lead to very different reactivities. To circumvent these limitations and to increase the level of reactivity prediction in these important reactions, we report herein a supramolecular catalyst harnessing Zn⋅⋅⋅N interactions that binds to pyridine‐like substrates as tight as it can be found in some enzymes. The distance and spatial geometry between the active site and the substrate binding site is ideal to target unprecedented meta‐selective iridium‐catalyzed C−H bond borylations with enzymatic Michaelis–Menten kinetics, besides unique substrate selectivity and dormant reactivity patterns.
https://ift.tt/30FD4fj
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c10409
L. Anders Hammarback, Benjamin J. Aucott, Joshua T. W. Bray, Ian P. Clark, Michael Towrie, Alan Robinson, Ian J. S. Fairlamb, and Jason M. Lynam
https://ift.tt/39oppwV
A genie zaps the universe and now hydrogen bonds are just impossible. No other particles/other kinds of bonds are affected, just hydrogen bonds specifically.
I have been pondering this question for a few hours but on a test I took there was a question asking about highest boiling point and the two answers i got stuck on was HF and CH3CH2OH. I ended up picking the latter because my logic was since they both have hydrogen bonds but ethanol is a longer chain (more spread out). Does that actually make sense or did I screw up 🥲
Journal of the American Chemical SocietyDOI: 10.1021/jacs.1c11100
Soon-Hyeok Hwang, Hongsik Kim, Hanseul Ryu, Illia E. Serdiuk, Dongwhan Lee, and Tae-Lim Choi
https://ift.tt/34f9xOJ
Oligosilanes are of great interest in the fields of organic photonics and electronics. In this communication, a highly efficient visible‐light‐mediated hydrosilylation of electron‐deficient alkenes through cleavage of a trimethylsilyl‐polysilanyl Si−Si bond is explored. These reactions smoothly occur on readily available organo(tristrimethylsilyl)silanes and other oligosilanes in the presence of an Ir III ‐based photo‐redox catalyst under visible light irradiation. Silyl radicals are generated through single electron oxidation of the oligosilane assisted by the solvent. The introduced method exhibits broad substrate scope and high functional group tolerance with respect to the organo(tristrimethylsilyl)silane and alkene components, enabling the construction of functionalized trisilanes. In addition, this catalytic system can be also applied to highly strained bicyclo[1.1.0]butanes as silyl radical acceptors.
https://ift.tt/2E0DsgA
Metal‐ligand cooperativity (MLC) had a remarkable impact on transition metal chemistry and catalysis. By use of the calix[4]pyrrolato aluminate, [1] ‐ , which features a square‐planar Al(III), we transfer this concept into the p‐block and fully elucidate its mechanisms by experiment and theory. Complementary to transition metal‐based MLC (aromatization upon substrate binding), substrate binding in [1] ‐ occurs by dearomatization of the ligand. The aluminate trapps carbonyls by the formation of C‐C and Al‐O bonds, but the products maintain full reversibility and outstanding dynamic exchange rates. Remarkably, the C‐C bonds can be formed or cleaved by the addition or removal of lithium cations, permitting unprecedented control over the system's constitutional state. Moreover, the metal‐ligand cooperative substrate interaction allows to twist the kinetics of catalytic hydroboration reactions in a unique sense. Ultimately, this work describes the evolution of an anti‐van't Hoff/Le Bel species from their being as a structural curiosity to their application as a reagent and catalyst.
https://ift.tt/2zXOJME
Water is essential to life as it is main constituent of cell in living organism. All biological macromolecules are almost inactive in its structural stability and functioning in absenc.
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c05131
https://ift.tt/3fAkaeG
The cluster compound [Mo3S13]2− is an interesting model system for hydrogen evolution catalysis. Herein, we probe the protonation site of the cluster by coupling mass spectrometry with infrared action spectroscopy. One distinct band at 2450 cm−1 together with DFT calculations and IRMPD kinetics reveals the nature of this S−H stretching vibration.
Abstract
Materials based on molybdenum sulfide are known as efficient hydrogen evolution reaction (HER) catalysts. As the binding site for H atoms on molybdenum sulfides for the catalytic process is under debate, [HMo3S13]− is an interesting molecular model system to address this question. Herein, we probe the [HMo3S13]− cluster in the gas phase by coupling Fourier‐transform ion‐cyclotron‐resonance mass spectrometry (FT‐ICR MS) with infrared multiple photon dissociation (IRMPD) spectroscopy. Our investigations show one distinct S−H stretching vibration at 2450 cm−1. Thermochemical arguments based on DFT calculations strongly suggest a terminal disulfide unit as the H adsorption site.
https://ift.tt/39jNN4f
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c07866
Shuaihua Gao, Emily J. Thompson, Samuel L. Barrow, Wenju Zhang, Anthony T. Iavarone, and Judith P. Klinman
https://ift.tt/2UoIaJO
A simple gold nanoparticle catalyzes the oxidative coupling of benzylamine to form imine in presence of visible light. Photoexcitation of Au NP generates an electron–hole pair that activates adsorbates (reactants) at Au NP surface to form a strong oxidant–reductant pair (benzylamine radical cation and superoxide radical), which is conducive for the reaction at a low temperature, with high product yield and selectivity.
Abstract
Here, we demonstrate the simultaneous utilization of both the hot carriers (electrons and holes) in the photocatalytic transformation of benzylamine to N‐benzylidenebenzylamine and the scope of reaction has also been successfully demonstrated with catalytic oxidation of 4‐methoxybenzylamine. The wavelength‐dependent excitation of AuNP allows us to tune the potential energy of charge carriers relative to the redox potential of the reactants which leads to energetically favorable product formation on the nanoparticle surface. We capture the formation of reaction intermediates and products by using in situ Raman spectroscopy, complemented by NMR spectroscopy and GC‐MS. Based on the experimental substantiations, a plausible reaction mechanism has been proposed.
https://ift.tt/38SXxle
Non‐metal‐based single‐atom catalysts (SACs) feature low cost, simple synthesis methods and effective regulation for substrates, while there are few studies on this aspect. Herein, we developed a simplified pressurized gas‐assisted process, and first reported a non‐metal single‐atom phosphorus with atomic‐level dispersion on unique single‐crystal Mo 2 C hexagonal nanosheet arrays with (001) plane exposure supported by carbon sheet (SAP‐Mo 2 C‐CS). The SAP‐Mo 2 C‐CS is structurally stable and shows exceptional electrocatalytic activity for the hydrogen evolution reaction (HER). Because of the bidirectional regulation of single P atoms, P bonds with the surrounding Mo atoms to form a localized electronic state. A so‐called high‐active “window” based on the active sites of P atoms and their adjacent Mo atoms shows the ΔG H* close to zero for hydrogen evolution, which is the most ideal ΔG H* reported so far. Meanwhile, the moderate d‐band center value of SAP‐Mo 2 C‐CS can be also used as an ideal standard value to evaluate the HER performance in non‐metal‐based SACs. Our work is investigation of the origin of the HER electrocatalytic activity based on non‐metal‐based SACs, and also provides an efficient strategy to achieve the synthesis and application of non‐metal SACs.
https://ift.tt/3chuVCD
The use of secondary interactions between substrates and catalysts is a promising strategy to discover selective transition metal catalysts for atom‐ economy C‐H bond functionalizations. Unfortunately, the most powerful catalysts are still found via trial‐and‐error screening due to the low association constants between the substrate and the catalyst in which small stereo‐electronic modifications in the catalyst (and/or the substrate) can lead to completely different reactivity patterns. In order to circumvent these limitations and to increase the level of reactivity prediction in this type of important reactions, we report herein a supramolecular catalyst harnessing Zn…N interactions that bind to pyridine‐like substrates as tight as it could be found in some enzymes. Furthermore, the distance and spatial geometry between the catalytically active site and the substrate binding site is ideal to target unprecedented meta ‐selective iridium‐catalyzed C‐H bond borylations with enzymatic Michaelis‐Menten kinetics, besides unique substrate‐selectivity and dormant reactivity patterns.
https://ift.tt/30FD4fj
Strong light‐matter interaction driven chemical transformations on plasmonic metal nanostructures offers selective reaction pathways that cannot be accessed in temperature‐driven catalysis. Utilization of the nonequilibrium energetic carriers, generated by the optical excitation of plasmon‐supporting metal nanostructures, is the key to activate adsorbates and trigger chemical reactions. Here, we demonstrate the simultaneous utilization of both the hot carriers (electrons and holes) in the photocatalytic transformation of benzylamine to N‐benzylidenebenzylamine and the scope of reaction has also been successfully demonstrated with catalytic oxidation of 4‐ methoxybenzylamine. The wavelength‐dependent excitation of Au nanoparticle allows us to tune the potential energy of charge carriers relative to the redox potential of the reactants which leads to energetically favourable product formation on the nanoparticle surface. We capture the formation of reaction intermediates and products by using in situ Raman spectroscopy, complemented by NMR spectroscopy and GC‐MS. Based on the experimental substantiations, a plausible reaction mechanism has been proposed.
https://ift.tt/38SXxle
