The Simulation of Solvent Polarizabilities and Dipolarities with Polarizable Continuum Model.

The ability of polarizable continuum models (PCM) to simulate nonspecific solvent effects (dipolarity and polarizability) was evaluated by calculating the transition energies of 1,1,10,10-tetrabutyldecanonaene (ttbp9) and 2-,-dimethylamino-7-nitrofluorene (DMANF), basis of Catalán's polarizability () and dipolarity () solvent scales, respectively. Time-dependent density-functional theory (TD-DFT) calculations were performed at different levels of theory, employing four basis sets in 10 different solvents, covering the full range of the normalized and scales. Transition energies were calculated using linear response (LR) and corrected linear response (cLR) schemes.

Deafness causing neuroplastin missense variants fail to promote plasma membrane Ca-ATPase levels and Ca transient regulation in brain neurons.

Hearing, the ability to sense sounds, and the processing of auditory information are important for perception of the world. Mice lacking expression of neuroplastin (Np), a type-1 transmembrane glycoprotein, display deafness, multiple cognitive deficiencies, and reduced expression of plasma membrane calcium (Ca) ATPases (PMCAs) in cochlear hair cells and brain neurons. In this study, we transferred the deafness causing missense mutations pitch (C315S) and audio-1 (I122N) into human Np (hNp) constructs and investigated their effects at the molecular and cellular levels.

Photophysical Analysis of Aggregation-Induced Emission (AIE) Luminogens Based on Triphenylamine and Thiophene: Insights into Emission Behavior in Solution and PMMA Films.

Aggregation-Induced Emission (AIE) luminogens have garnered significant interest due to their distinctive applications in different applications. Among the diverse molecular architectures, those based on triphenylamine and thiophene hold prominence. However, a comprehensive understanding of the deactivation mechanism both in solution and films remains lacking.

On the role of water in the hydrogen bond network in DESs: an molecular dynamics and quantum mechanical study on the urea-betaine system.

We herein report an ab initio molecular dynamics study on a natural DES composed of urea and betaine in a 3 : 2 ratio, as a test case for evaluating the water effect. The article deals with a theoretical study using both ab initio molecular dynamics and quantum chemistry computations in order to unravel the role of water in the nanostructure of a urea-betaine mixture. Preliminary molecular dynamics outcomes (both radial and spatial distribution functions) suggest that water promotes the association between urea and betaine by increasing the hydrogen bond network and precluding the aggregation of urea molecules.

Unraveling the Selectivity Patterns in Phosphine-Catalyzed Annulations of Azomethine Imines and Allenoates.

The mechanism and selectivity of phosphine-catalyzed [3 + 2] and [3 + 3] annulations of azomethine imines and allenoates have been computationally studied. Exploration of the potential energy surface reveals that the cyclization step is a key step controlling the selectivity of the process. This contrasts with previous studies on related transformations where the initial nucleophilic addition involving the activated allenoate was found to exclusively control the regioselectivity of the transformation.

Meisenheimer complexes as hidden intermediates in the aza-SAr mechanism.

In this work we report a computational study about the aza-SNAr mechanism in fluorine- and chlorine-containing azines with the aim to unravel the physical factors that determine the reactivity patterns in these heterocycles towards propylamine. The nature of the reaction intermediate was analyzed in terms of its electronic structure based on a topological analysis framework in some non-stationary points along the reaction coordinate. The mechanistic dichotomy of a concerted or a stepwise pathway is interpreted in terms of the qualitative Diabatic Model of Intermediate Stabilization (DMIS) approach, providing a general mechanistic picture for the SNAr process involving both activated benzenes and nitrogen-containing heterocycles.

Theoretical insights into the E1cB/E2 mechanistic dichotomy of elimination reactions.

E1cB and E2 eliminations have been described as competing mechanisms that can even share a common pathway when the E1cB/E2 borderline mechanism operates. A suitable case study evincing such a mechanistic dichotomy corresponds to the elimination reaction of β-phenylmercaptoethyl phenolate, since its mechanism has been thought to be an E2 elimination. Nonetheless, according to the computational assessment of the substituents on the leaving group, we demonstrate that the reaction proceeds via a borderline E1cB mechanism.

How Meaningful Is the Halogen Bonding in 1-Ethyl-3-methyl Imidazolium-Based Ionic Liquids for CO Capture?

We report on several parameters that can be used to describe the 1-ethyl-3-methyl-4,5-(X)imidazolium cations (where X = H, Br, and I) within the Canongia-Lopez and Padua Force Field (CL&P) framework. Geometrical parameters like intramolecular distances and radial distribution functions are close to the experimental structure. Density values obtained with our force field are within the expected ones from CL&P calculations in related systems.

Lewis Acidity/Basicity Changes in Imidazolium Based Ionic Liquids Brought About by Impurities.

We herein report on the effect that water molecules, present as impurities, in the vicinity of an ionic liquid model structure, may induce on the Lewis acidity/basicity patterns normally observed in these materials. Depending on the position and orientation of water, the Lewis acidity/basicity pattern changes from "normal distribution" (i.e.

Regional electrophilic and nucleophilic Fukui functions efficiently highlight the Lewis acidic/basic regions in ionic liquids.

The origin of catalysis and selectivity induced by room temperature ionic liquids in several organic reactions has putatively been associated with the concept of cation effect (hydrogen bond donor ability of the ionic liquids) or anion effect (hydrogen bond accepting ability of the ionic liquids). We show that there may be cases where this a priori classification may not be correctly assigned. Cations may concentrate both Lewis acidity and basicity functions in one fragment of the ionic liquid: an effect we tentatively call bifunctional distribution of the molecular Lewis acidity/basicity.

Hydrogen bond contribution to preferential solvation in S(N)Ar reactions.

Preferential solvation in aromatic nucleophilic substitution reactions is discussed using a kinetic study complemented with quantum chemical calculations. The model system is the reaction of a series of secondary alicyclic amines toward phenyl 2,4,6-trinitrophenyl ether in aqueous ethanol mixtures of different compositions. From solvent effect studies, it is found that only piperidine is sensitive to solvation effects, a result that may be traced to the polarity of the solvent composition in the ethanol/water mixture, which points to a specific electrophilic solvation in the aqueous phase.

Specific nucleophile-electrophile interactions in nucleophilic aromatic substitutions.

We herein report results obtained from an integrated experimental and theoretical study on aromatic nucleophilic substitution (S(N)Ar) reactions of a series of amines towards 1-fluoro-2,4-dinitrobenzene in water. Specific nucleophile-electrophile interactions in the title reactions have been kinetically evaluated. The whole series undergoes S(N)Ar reactions where the formation of the Meisenheimer complex is rate determining.

Reactivity indices profile: a companion tool of the potential energy surface for the analysis of reaction mechanisms. Nucleophilic aromatic substitution reactions as test case.

We herein report on the usefulness of the reactivity indices profiles along a reaction coordinate. The model is tested to fully describe the reaction mechanism of the title reactions. Group nucleophilicity and electrophilicity profiles help describe the bond-breaking/bond-formation processes and the intramolecular electron density reorganization.

Are electrophilicity and electrofugality related concepts? A density functional theory study.

It is proposed that the electrofugality of a fragment within a molecule is determined by its group nucleophilicity. The variation of electrofugality should be tightly related to the electron releasing ability of the substituent attached to the electrofuge moiety. This contribution closes the set of relationships between philicity and fugality quantities: while nucleofugality appears related to the group electrophilicity of the leaving group, electrofugality is related to the group nucleophilicity of the permanent group.