Ion molecule reactions in the HBr + CH system: a combined experimental and theoretical study.

Reactions in the system HBr + CH have been investigated inside a guided ion-beam apparatus under single-collision conditions. The HBr is vibrational and rotational state selected in the electronic XΠ state created by (2+1)-REMPI. Due to the exitation scheme employed different rotational states of the HBr are accessible.

Atomistic Insight into the Lipid Nanodomains of Synaptic Vesicles.

Membrane curvature, once regarded as a passive consequence of membrane composition and cellular architecture, has been shown to actively modulate various properties of the cellular membrane. These changes could also lead to segregation of the constituents of the membrane, generating nanodomains with precise biological properties. Proteins often linked with neurodegeneration (e.

Hypergolic ionic liquids: to be or not to be?

Hypergolic ionic liquids (HIL) - ionic liquids which ignite spontaneously upon contact with an oxidizer - emerged as green space propellants. Exploiting the previously marked hypergolic [EMIM][CBH] - WFNA (1-ethyl-3-methylimidazolium cyanoborohydride - white fuming nitric acid) system as a benchmark, through the utilization of a novel chirped-pulse droplet-merging technique in an ultrasonic levitation environment and electronic structure calculations, this work deeply questions the hypergolicity of the [EMIM][CBH]-WFNA system. Molecular oxygen is critically required for the [EMIM][CBH]-WFNA system to ignite spontaneously.

Unraveling the initial steps of the ignition chemistry of the hypergolic ionic liquid 1-ethyl-3-methylimidazolium cyanoborohydride ([EMIM][CBH]) with nitric acid (HNO) exploiting chirped pulse triggered droplet merging.

The composition of the products and the mechanistic routes for the reaction of the hypergolic ionic liquid (HIL) 1-ethyl-3-methylimidazolium cyanoborohydride ([EMIM][CBH]) and nitric acid (HNO) at various concentrations from 10% to 70% were explored using a contactless single droplet merging within an ultrasonic levitation setup in an inert atmosphere of argon to reveal the initial steps that cause hypergolicity. The reactions were initiated through controlled droplet-merging manipulation triggered by a frequency chirp pulse amplitude modulation. Utilizing the high-speed optical and infrared cameras surrounding the levitation process chamber, intriguing visual images were unveiled: (i) extensive gas release and (ii) temperature rises of up to 435 K in the merged droplets.

Ion-molecule reactions in the HBr + HCl (DCl) system: a combined experimental and theoretical study.

Reactions in the system HBr + HCl (DCl) were investigated inside a guided ion-beam apparatus under single-collision conditions. In the HBr + HCl system, the proton transfer (PT) and charge transfer (CT) are observable. In the HBr + DCl system, proton transfer (PT) and deuterium abstraction (DA) are accessible.

Unsupervised Reaction Pathways Search for the Oxidation of Hypergolic Ionic Liquids: 1-Ethyl-3-methylimidazolium Cyanoborohydride (EMIM/CBH) as a Case Study.

Hypergolic ionic liquids have come under increased study for having several desirable properties as a fuel source. One particular ionic liquid, 1-ethyl-3-methylimidazolium/cyanoborohydride (EMIM/CBH), and oxidant, nitric acid (HNO), has been reported to be hypergolic experimentally, but its mechanism is not well-understood at a mechanistic level. In this computational study, the reaction is first probed with molecular dynamics simulations to confirm that anion-oxidant interactions likely are the first step in the mechanism.

Directed gas phase preparation of ethynylallene (HCCCHCCH; XA') the crossed molecular beam reaction of the methylidyne radical (CH; XΠ) with vinylacetylene (HCCHCCH; XA').

The gas-phase bimolecular reaction of the methylidyne (CH; XΠ) radical with vinylacetylene (HCCHCCH; XA') was conducted at a collision energy of 20.3 kJ mol under single collision conditions exploiting the crossed molecular beam experimental results merged with electronic structure calculations and molecular dynamics (AIMD) simulations. The laboratory data reveal that the bimolecular reaction proceeds barrierlessly indirect scattering dynamics through long-lived CH reaction intermediate(s) ultimately dissociating to CH isomers along with atomic hydrogen with the latter predominantly originating from the vinylacetylene reactant as confirmed by the isotopic substitution experiments in the D1-methylidyne-vinylacetylene reaction.

The Potential Energy Profile of the HBr + HCl Bimolecular Collision.

Recently, the HBr + HCl bimolecular reaction has been exploited by guided ion beam studies to probe the effect of rotational excitations and collision energies on the dynamics of the ion-molecule reactions. The current manuscript employs high-level calculations and reports the potential energy of pathways leading to various products, including HBr + HCl, HCl + Br, HBr + Cl, and H + BrCl. The study shows that the intermediates involved in this reaction are connected by low-lying transition states, thus frequent isomerizations and diverse products are expected.

A chemical dynamics study of the reaction of the methylidyne radical (CH, XΠ) with dimethylacetylene (CHCCCH, XA).

The gas-phase reaction of the methylidyne (CH; XΠ) radical with dimethylacetylene (CHCCCH; XA) was studied at a collision energy of 20.6 kJ mol under single collision conditions with experimental results merged with calculations of the potential energy surface (PES) and molecule dynamics (AIMD) simulations. The crossed molecular beam experiment reveals that the reaction proceeds barrierless indirect scattering dynamics through long-lived CH reaction intermediate(s) ultimately dissociating to CH isomers along with atomic hydrogen with atomic hydrogen predominantly released from the methyl groups as verified by replacing the methylidyne with the D1-methylidyne reactant.

Assessing the Intestinal Permeability of Small Molecule Drugs via Diffusion Motion on a Multidimensional Free Energy Surface.

A protocol that accurately assesses the intestinal permeability of small molecule compounds plays an essential role in decreasing the cost and time in inventing a new drug. This manuscript presents a novel computational method to study the passive permeation of small molecule drugs based on the inhomogeneous solubility-diffusion model. The multidimensional free energy surface of the drug transiting through a lipid bilayer is computed with transition-tempered metadynamics that accurately captures the mechanisms of passive permeation.

Theoretical Study of the Dynamics of the HBr + CO → HOCO + Br Reaction.

The dynamics of the HBr + CO → HOCO + Br reaction was recently investigated with guided ion beam experiments under various excitations (collision energy of the reactants, rotational and spin-orbital states of HBr, etc.), and their impacts were probed through the change of the cross section of the reaction. The potential energy profile of this reaction has also been accurately characterized by high-level methods such as CCSD(T)/CBS, and the UMP2/cc-pVDZ/lanl08d has been identified as an ideal method to study its dynamics.