A quasi-planar member of the so-called 'Wankel motor' family, B18(2-), is found. This boron cluster an electronically stable dianion and a concentric doubly σ- π-aromatic system. The inner B6 unit in B18(2-) undergoes quasi-free rotation inside perimeter B12 ring. absence any localized σ-bond between ring peripheral atoms makes system fluxional.

Although aromaticity is a concept in chemistry, the last years, special efforts have been carried out order to propose theoretical strategies quantify it as property of molecular rings. Among them, perhaps computation nucleus independent chemical shifts (NICSs) most commonly used, since possible calculate an easy and fast way with used quantum chemistry software. However, contradicting assignments by NICS other methods reported literature, especially studies concerning inorganic chemistry....

Several of the lowest energy structures small and medium sized boron clusters are two-dimensional systems made up a pair concentric rings. In some cases, barriers to rotation one those rings relative other remarkably low. We find that combination electronic geometrical factors, including apparently sizes symmetries inner outer rings, decisive for diminished in-plane in these two dimensional clusters. A sufficiently large ring is important; instance, expansion by single atom may reduce...

B₁₂ is a rigid cluster with high inner ring rotational energy barrier. However, doping it Ir lowers the barrier significantly, transforming IrB₁₂⁻ in Wankel motor.

Viable planar pentacoordinate carbon (ppC) systems with a ppC bonded to transition metal and embedded in metallocene framework are reported. Our detailed global minima search shows that CAl4MX2 (M = Zr Hf; X F-I C5H5) clusters ppCs appropriate candidates for experimental realization the gas phase. The fulfillment of 18 electron rule delocalization is found be crucial stabilization these arrangements.

It was recently shown that, when tested in cellular systems, quercetin oxidized products (Qox) have significantly better antioxidant activity than (Q) itself. The main Qox identified the experiments are either 2,5,7,3′,4′-pentahydroxy-3,4-flavandione (Fl) or its tautomer, 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (Bf). We now performed a theoretical evaluation of different physicochemical properties using density functional theory (DFT) calculations on Q and species. most...

We performed global minimum searches for the B(n) H(n+2) (n=2-5) series and found that classical structures composed of 2c-2e B-H B-B bonds become progressively less stable along series. Relative energies increase from 2.9 kcal mol(-1) in B(2) H(4) to 62.3 B(5) H(7). believe this occurs because boron atoms studied molecules are trying avoid sp(2) hybridization trigonal structure at atoms, as case one 2p-AO is empty, which highly unfavorable. This affinity have some electron density on all...

The potential energy surfaces (PES) of a series gold–boron clusters with formula Au n B ( = 1–8) and m 2 1–7) have been explored using modified stochastic search algorithm. Despite the complexity PES these clusters, there are well‐defined growth patterns. bonding is analyzed adaptive natural density partitioning orbital analyses. Reactivity studied in terms molecular electrostatic potential. © 2014 Wiley Periodicals, Inc.

The potential energy surfaces of a series clusters with the formula CAl₃E (E = P, As, Sb, Bi) are systematically explored using density functional theory and high level <italic>ab initio</italic> calculations.

The most stable forms of E(5)Li(7)(+) (E = Ge, Sn, and Pb) have been explored by means a stochastic search their potential-energy surfaces using the gradient embedded genetic algorithm (GEGA). preferred isomer Ge(5)Li(7)(+) ion is slightly distorted analogue D(5h) three-dimensional seven-pointed starlike structure adopted lighter C(5)Li(7)(+) Si(5)Li(7)(+) clusters. In contrast, structures for Sn(5)Li(7)(+) Pb(5)Li(7)(+) are quite different. By starting from arrangement, corresponding...

A new approach to stabilize compounds containing a planar tetracoordinate carbon (ptC), embedded in aromatic hydrocarbons, is presented herein.

This article details the synthesis, full characterization, optical properties, theoretical analysis, evaluation of nonlinear properties (NLO), and determination hemolytic capacity quinoline-1,3-benzodioxole chalcone(5).

In this article, we employed the induced magnetic field method to show that Al2X6 (X = F, Cl, Br, I) clusters cannot be classified as aromatic systems. Interestingly, even nucleus independent chemical shift (NICS) reveals same conclusion when analyzed in greater detail, showing a superficial analysis of index can easily lead incorrect interpretations. view fact NICS is extensively used by computational and theoretically oriented experimental chemists, an important warning against analyses,...

The B19− anion and other boron species have been dubbed 'Wankel motors' for the almost barrierless rotation of inner outer concentric rings relative to each in these compounds. A single substitution is shown shut down well-established fluxionality anion. carbon atom substituted structure give a neutral CB18 computationally enforce bond localization.

Amaryllidaceae plants are the commercial source of galanthamine, an alkaloid approved for clinical treatment Alzheimer’s disease. The chemistry and bioactivity Chilean representatives Rhodophiala genus from family have not been widely studied so far. Ten collections five different were analyzed in vitro activity against enzymes such as acetylcholinesterase (AChE) butyrylcholinesterase (BuChE) well their composition by GC-MS. To obtain insight into potential AChE BuChE inhibitory alkaloids...

Therapeutic strategies for Alzheimer’s disease (AD) often involve inhibiting acetylcholinesterase (AChE), underscoring the need novel inhibitors with high selectivity and minimal side effects. A detailed analysis of protein-ligand pharmacophore dynamics can facilitate this. In this study, we developed employed dyphAI , an innovative approach integrating machine learning models, ligand-based complex-based models into a model ensemble. This ensemble captures key interactions, including...

Can relativistic effects modify the NICS and B(ind) values? In this manuscript we evaluate corrections incorporated via zeroth-order regular approximation to calculations of nucleus-independent chemical shifts induced magnetic field (B(ind)) in E12(2-) spherenes (E = Ge, Sn, Pb). We found that both electron delocalization descriptors are strongly affected by corrections. For instance, for plumbaspherene, difference values from nonrelativistic relativity-included calculation is almost 40 ppm!...

A simple and chemically intuitive approach is used to design ptC-containing E–C clusters (E = Si–Pb).

The antioxidant activity of nine lichen substances, including methylatrarate (1), methyl haematommate (2), lobaric acid (3), fumarprotocetraric (4), sphaerophorin (5), subsphaeric (6), diffractaic (7), barbatolic (8) and salazinic (9) has been determined through cyclic voltammetry. compounds 1-4 presented slopes close to the Nernst constant 0.059 V, indicating a 2H+/2e- relation between protons electrons, as long 5, 6, 7, 8, 9 present 0.037 V 0.032 1H+/2e- electrons. These results show high...

The increase in and concern about neurodegenerative diseases continue to grow an increasingly long-lived world population.

Alkaline earth metals (Ca, Sr, and Ba) can form inverted sandwich compounds with C₆H₆, C₇H₇⁺, C₈H₈²⁺ of <italic>D</italic>_nh symmetry holding planar 10-π-electron aromatic cores.

MNgCN (M = Cu, Ag, Au; Ng Xe, Rn) molecules are metastable in nature with respect to possible dissociation. The M–Ng bonds and the Ng–C AuNgCN can be represented as an electron-shared covalent bond.

Cocoa beans contain antioxidant molecules with the potential to inhibit type 2 coronavirus (SARS-CoV-2), which causes a severe acute respiratory syndrome (COVID-19). In particular, protease. Therefore, using in silico tests, 30 obtained from cocoa were evaluated. Using molecular docking and quantum mechanics calculations, chemical properties binding efficiency of each ligand was evaluated, allowed selection 5 compounds this series. The ability amentoflavone, isorhoifolin, nicotiflorin,...