Abstract The use of hydrogen as a fuel requires both safe and robust technologies for its storage transportation. Formic acid (FA) produced by the catalytic hydrogenation CO 2 is recognized potential intermediate H carrier. Herein, we present development formate‐based system that employs Ru PNP‐pincer catalyst. high stability this allows cyclic operation with an exceptionally fast loading liberation . Kinetic studies highlight crucial role base promoter, which controls rate‐determining step...

Abstract Any catalyst should be efficient and stable to implemented in practice. This requirement is particularly valid for manganese hydrogenation catalysts. While representing a more sustainable alternative conventional noble metal-based systems, catalysts are prone degrade under catalytic conditions once operation temperatures high. Herein, we report highly Mn(I)-CNP pre-catalyst which gives rise the excellent productivity (TOF° up 41 000 h −1 ) stability (TON 200 000) catalysis. system...

A recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) bears the promise for efficient and selective synthesis of hydrocarbons carboxylic acids. CvFAP, however, exhibits a clear preference long-chain fatty acids thereby limiting its broad applicability. In this contribution, we demonstrate that decoy molecule approach enables conversion range by filling up vacant substrate access channel photodecarboxylase. These results not only practical application unique,...

The metal–ligand cooperative activation of CO2 with pyridine-based ruthenium PNP pincer catalysts leads to pronounced inhibition the activity in catalytic hydrogenation formic acid. addition water restores performance by activating alternative reaction pathways and unprecedented Ru-catalyzed activity. mechanism underlying chemical transformations is proposed on basis DFT calculations, kinetic experiments, NMR reactivity studies.

The reaction mechanism of CO2 hydrogenation by pyridine-based Ru-PNP catalyst in the presence DBU base promoter was studied means density functional theory calculations. Three alternative channels promoted complexes potentially present under conditions, namely dearomatized complex 2 and products cooperative (3) H2 (4) addition, were analysed. It is shown that bis-hydrido 4 provides unique lowest-energy path involving a direct effectively barrierless hydrogenolysis polarized 5*. rate this...

Lutidine-derived bis-N-heterocyclic carbene (NHC) ruthenium CNC–pincer complexes (Ru-CNC's) were prepared. Depending on the synthetic procedure, normal (1, 2) or mixed normal/abnormal NHC-complexes (3) are formed. In presence of phosphazene base, Ru-CNC activate nitriles to give ketimino compounds 4–6. Nitrile adduct 4 shows reactivity toward strong bases yield dearomatized complex 7, which heterolytically activates H2 form bis-hydrido 8. Finally, these Ru-CNC's active in catalytic...

Metal–ligand cooperative properties of a bis-N-heterocyclic carbene ruthenium CNC pincer catalyst and its activity in CO2 hydrogenation to formates were studied by DFT calculations complemented NMR spectroscopy kinetic measurements. The dearomatized Ru–CNC* (1*) is significantly more reactive toward metal–ligand activation H2 than the structurally related phosphine-based Ru–PNP complex. enhanced reactivity stems from combination electronic this system reduced geometric constraints imposed...

Bis-N-heterocyclic carbene (NHC) aminopincer ligands were successfully applied for the first time in catalytic hydrogenation of esters. We have isolated and characterized a well-defined catalyst precursor as dimeric [Ru2(L)2Cl3]PF6 complex studied its reactivity performance. Remarkable initial activities up to 283,000 h(-1) achieved ethyl hexanoate at only 12.5 ppm Ru loading. A wide range aliphatic aromatic esters can be converted with this corresponding alcohols near quantitative yields....

Abstract A series of faujasite zeolites was modified by extraframework Al (Al EF ) with the goal to investigate influence such species on intrinsic Brønsted acidity and catalytic activity towards paraffin cracking. The chemical state zeolite were investigated 27 MAS NMR CO ads IR spectroscopy, H/D exchange reaction, propane Strongly acidic defect‐free Y obtained substitution framework Si (NH 4 2 SiF 6 . In accordance next‐nearest‐neighbor model, protons increased decreasing density. This...

Homogeneously catalyzed reactions often make use of additives and promotors that affect reactivity patterns improve catalytic performance. While the role reaction is discussed in view their chemical reactivity, we demonstrate they can be involved catalysis indirectly. In particular, adjust thermodynamics key transformations homogeneous hydrogenation enable would unfavorable otherwise. We identified this phenomenon a set well-established new Mn pincer catalysts suffer from persistent product...

Catalytic reductions of carbonyl-containing compounds are highly important for the safe, sustainable, and economical production alcohols. Herein, we report on efficient transfer hydrogenation ketones catalyzed by a potent Mn(I)-NHC complex. Mn-NHC 1 is practical at metal concentrations as low 75 ppm, thus approaching loadings more conventionally reserved noble based systems. With these Mn concentrations, catalyst deactivation found to be temperature dependent becomes especially prominent...

Dynamic phosphorescent copper complex incorporated into the main chain of polyurethanes produces a facile and reversible response to tensile stress. In contrast common deformation sensors, applied stress does not lead bond scission, or alters phosphor structure. The suppression dynamics responsible for nonradiative relaxation is found be major pathway governing response. As result, dynamic described in this work specific. Compared initial unloaded state, nearly twofold increase...

A simple amphiphilic surfactant containing a mono-quaternary ammonium head group (N-methylpiperidine) is effective in imparting substantial mesoporosity during synthesis of SSZ-13 and ZSM-5 zeolites. Highly mesoporous prepared this manner shows greatly improved catalytic performance the methanol-to-olefins reaction compared to bulk SSZ-13.

The catalytic asymmetric transfer hydrogenation (ATH) of ketones is a powerful methodology for the practical and efficient installation chiral centers. Herein, we describe synthesis, characterization, application series manganese complexes bearing simple diamine ligands. We performed an extensive experimental computational mechanistic study present first detailed kinetic Mn-catalyzed ATH. demonstrate that conventional approaches toward catalyst optimization fail how apparently different...

The reaction mechanism of ester hydrogenation catalyzed by a bidentate aminophosphine ligated manganese catalyst was studied DFT calculations. Particular emphasize placed on the role alkoxide base additives. presence such basic promoters as KOtBu can improve activity lowering activation barriers H2 dissociation well step. promoting effect is much stronger than that tert-butoxides with other alkali metals, which crucial for regeneration from deactivated Mn-alkoxide species in resting state.

Structural heterogeneity defines the properties of many functional polymers and it is often crucial for their performance ability to withstand mechanical impact. Such heterogeneity, however, poses a tremendous challenge characterization these materials limits our design them rationally. Herein we present practical methodology capable resolving complex behavior tracking impact in discrete phases segmented polyurethane-a typical example structurally polymer. Using direct optical imaging...

Aromatization of furan and substituted furans over zeolite catalysts is a promising reaction to convert cellulose-derived compounds into valuable aromatic hydrocarbons light olefins. A lack understanding the mechanism however hinders further development this process. Here, we propose mechanism, underlying chemistry methanol co-aromatization HZSM-5 catalyst. Applying 13C isotope labeling in combination with NMR spectroscopy high temporal resolution gas chromatography-mass spectrometry...

Photoluminescent compounds can undergo various structural changes upon interaction with light. When these manifest themselves in the excited state, resulting emitters obtain a sensory function. In this work, we designed coordination that vary their emission color response to thermal and mechanical stimuli. embedded polymer matrix, Cu-NHC sensors act as mechanophores, color-based readily describe stress phase transition phenomena. A strong practical advantage of new mechanophores over...

While Mn-catalyzed (de)hydrogenation of carbonyl derivatives has been well established, the reactivity Mn hydrides with olefins remains very rare. Herein, we report a Mn(I) pincer complex that effectively promotes site-controlled transposition olefins. This is shown to emerge once N-H functionality within Mn/NH bifunctional suppressed by alkylation. detrimental for (de)hydrogenation, such masking cooperative allows highly efficient conversion wide range allylarenes higher-value...

Mechanophores are powerful molecular tools used to track bond rupture and characterize mechanical damage in polymers. The majority of mechanophores known respond external stresses, we report this study the first precedent a mechanochemical response internal, residual stresses that accumulate during polymer vitrification. While internal stress is intrinsic polymers can form solids, demonstrate it dramatically affect mechanochemistry spiropyran probes alter their intramolecular isomerization...

In applying a multi-scale spectroscopic and computational approach, we demonstrate that the synthesis of stacked zeolite silicalite-1 nanosheets, in presence long-tail diquaternary ammonium salt surfactant, proceeds through pre-organised phase condensed state. situ small-angle X-ray scattering, coupled to paracrystalline theory, backed by electron microscopy, shows this establishes its meso-scale order within first five hours hydrothermal synthesis. Quasi vibrational solid-state NMR...