The synthesis of NHC-PdCl(2)-3-chloropyridine (NHC=N-heterocyclic carbene) complexes from readily available starting materials in air is described. The 2,6-diisopropylphenyl derivative was found to be highly catalytically active in alkyl-alkyl Suzuki and Negishi cross-coupling reactions. The synthesis, ease-of-use, and activity of this complex are substantial improvements over in situ catalyst generation and all current Pd-NHC complexes. The utilization of complex 4 led to the development of a reliable, easily employed Suzuki-Miyama protocol. Employing various reaction conditions allowed a large array of hindered biaryl and drug-like heteroaromatic compounds to be synthesized without difficulty.

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The issue of the influence of the side chain/backbone interaction on the local conformational preferences of a phenylalanine residue in a peptide chain is addressed. A synergetic approach is used, which combines gas-phase UV spectroscopy as well as gas-phase IR/UV double-resonance experiments with DFT and post Hartree-Fock calculations. N-Acetyl-Phe-amide was chosen as a model system for which three different conformers were observed. The most stable conformer has been identified as an extended L conformation of the peptide backbone. It is stabilized by a weak but significant NH-π interaction bridging the aromatic ring on the residue (i) with the NH group on residue (i+1), with the aromatic side chain being in an anti conformation. This stable conformation corresponds to the common NH(i+1)-aromatic(i) interaction encountered in proteins for the three aromatic residues (phenylalanine, tyrosine, and tryptophan), which illustrates the relevance of gas-phase investigations to structural biology issues. The two other less abundant conformers have been assigned to two γ-folded backbone conformations that differ by the orientation of the side chain. In all cases, the IR data provided spectroscopic fingerprints of these interactions. Finally, the strong conformational dependence of the fluorescence yield found for N-acetyl-Phe-amide illustrates the role of the environment on the excited-state dynamics of these species, which is often exploited by biochemists to monitor protein structural changes from tryptophan lifetime measurements.

those being implemented in solving global challenges remain accompanied by an energy reliance on non-renewable fossil fuels. The accelerated depletion of stocks of these energy sources, together with their associated pollution drives the need to expedite establishment of robust renewable alternatives. Often termed "renewables" or "clean energy," these power sources have a perennial temporalavailability and thus have greater need for energy repositories than non-renewables. Hence, prompt optimization of energy storage-delivery devices is crucial to the sustainable development, scaling, commercial delivery, and global establishment of reliable clean energy. [1,2] Batteries and electrochemical devices have most often filled the majority of power-storage and are ubiquitous as energy mediation devices, capable of harnessing large amount of energy for various applications including the aerospace, travel and transport, and electronics industries, among others. [3][4][5][6] The future of batteries lies with devices produced from ever-more sustainable components that can offer improved safety, transportability, extended battery life, have short recharge times as well as low production costs and Interfacial dynamics within chemical systems such as electron and ion transport processes have relevance in the rational optimization of electrochemical energy storage materials and devices. Evolving the understanding of fundamental electrochemistry at interfaces would also help in the understanding of relevant phenomena in biological, microbial, pharmaceutical, electronic, and photonic systems. In lithium-ion batteries, the electrochemical instability of the electrolyte and its ensuing reactive decomposition proceeds at the anode surface within the Helmholtz double layer resulting in a buildup of the reductive products, forming the solid electrolyte interphase (SEI). This review summarizes relevant aspects of the SEI including formation, composition, dynamic structure, and reaction mechanisms, focusing primarily on the graphite anode with insights into the lithium metal anode. Furthermore, the influence of the electrolyte and electrode materials on SEI structure and properties is discussed. An update is also presented on state-of-theart approaches to quantitatively characterize the structure and changing properties of the SEI. Lastly, a framework evaluating the standing problems and future research directions including feasible computational, machine learning, and experimental approaches are outlined.

The amide bond may be considered as one of the most important chemical building blocks, playing an important role not only in living organisms but in organic chemistry as well. The exact description and precise quantification of the amide bond strength is difficult, requiring a particular type of theoretical investigation. The present paper suggests a novel, yet simple, method toward quantifying amide bond strength on a linear scale, defined as the "amidity scale". This is achieved using the computed enthalpy of hydrogenation (DeltaHH2) of the compound examined. In the present conceptual work, the DeltaHH2 value for dimethylacetamide is used to define perfect amidic character (amidity=+100%), while azaadamantane-2-on represents complete absence of amidic character (amidity=0%). The component DeltaHH2 values were computed at differing levels of theory, providing a computational and quasi-"method-independent" measure of amidity. A total of 29 well-known amides were examined to demonstrate the "scoring" accuracy of this methodology. For the compounds examined, a correlation has been made between the computed amidity percentage and their common COSNAR resonance energy values, proton affinities, and reactivity in a nucleophilic addition reaction. Selected chemical reactions were also studied. It has been shown that the change of the amidity value, during acyl transfer reactions, represents a thermodynamic driving force for the reaction.

This review concentrates on the results obtained thus far in cross-coupling reactions utilising Pd-PEPPSI-IPr (pre)catalyst. Results from computational studies expose possible factors behind the high reactivity of this complex, as well as mechanistic details for the IPr-Pd-mediated alkyl-alkyl Negishi cross-coupling.

Although essential in medicinal and industrial chemistry, transamidation reactions are still poorly understood mechanistically and in particular in terms of the extreme nature for their proceeding either very smoothly or not occurring at all. As yet, there exists no qualitative rule to predict the outcome of an amide interacting with an amine, with quantitative evaluations far from being established. In this paper we aim to clarify the thermodynamic selection rule and driving force of transamidation reactions based on amidicity value, measuring numerically the amide bond strength, toward providing a relatively simple protocol for practicing organic chemists to predict the outcome of an experiment. The change of amidicity over the course of a reaction made it possible to see that the process is favorable or unfavorable. This recently evaluated driving force of amidicity behaves analogously to the driving force of aromaticity in other organic reactions. This paper presents a successful comparison between empirical synthetic results and relevant computational characterizations, for a variety of transamidation reactions, all toward a synergy between experiments and theory. In this paper, we are re-examining experimentally and theoretically earlier experimental findings in relation to transamidation reactions and interpreting them from the aspect of amidicity change and stabilization enthalpies.

Bioactive glass ionomer cements (GICs) have been in widespread use for ∼40 years in dentistry and medicine. However, these composites fall short of the toughness needed for permanent implants. Significant impediment to improvement has been the requisite use of conventional destructive mechanical testing, which is necessarily retrospective. Here we show quantitatively, through the novel use of calorimetry, terahertz (THz) spectroscopy and neutron scattering, how GIC's developing fracture toughness during setting is related to interfacial THz dynamics, changing atomic cohesion and fluctuating interfacial configurations. Contrary to convention, we find setting is non-monotonic, characterized by abrupt features not previously detected, including a glass–polymer coupling point, an early setting point, where decreasing toughness unexpectedly recovers, followed by stress-induced weakening of interfaces. Subsequently, toughness declines asymptotically to long-term fracture test values. We expect the insight afforded by these in situ non-destructive techniques will assist in raising understanding of the setting mechanisms and associated dynamics of cementitious materials.