Comparison of Various Theoretical Measures of Aromaticity within Monosubstituted Benzene

Molecules, Год журнала: 2024, Номер 29(10), С. 2260 - 2260

Опубликована: Май 11, 2024

The effects of monosubstitution on the aromaticity benzene are assessed using a number different quantitative schemes. ability mobile π-electrons to respond an external magnetic field is evaluated several variants NICS scheme which calculate shielding points along axis perpendicular molecule. Another class measures related drive toward uniformity C-C bond lengths and strengths. Several energetic quantities devised approximate aromatic stabilization energy tendency molecule maintain planarity. There lack consistency in that various lead differing conclusions as substituents ring.

Язык: Английский

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Aromaticity and Antiaromaticity

Опубликована: Май 17, 2024

During the last decades, concept of aromaticity has evolved and broadened to incorporate new types such as σ-, δ-, ϕ-aromaticity, all-metal aromaticity, spherical three-dimensional hyperaromaticity, open-shell systems, excited state Möbius aromaticity. Not only have appeared but also aromatic species species, heteroderivatives metallabenzenes, metallabenzynes, many others. The study this complex variety different aromaticities required development methods for its detection that are usually based on fact molecules or most these properties: (i) a continuous electron delocalization, (ii) more stability than one would expect, (iii) bond length equalization, (iv) particular chemical reactivity, (v) differencial spectroscopic properties, (vi) special response in presence magnetic fields. Although been known nearly two centuries, there is no way measure it experimentally. To gain insight into exact nature, examine several abovementioned characteristics, namely, geometrical, electronic, magnetic, thermodynamic, reactivity properties. In years, we seen advances evaluated. chapter discusses, first, second, examines measures third, reviews rules and, finally reports series metallabenzenes related compounds.

Язык: Английский

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Cyclo[n]carbons and catenanes from different perspectives: disentangling the molecular thread

Physical Chemistry Chemical Physics, Год журнала: 2023, Номер 25(43), С. 29386 - 29403

Опубликована: Янв. 1, 2023

All-carbon atomic rings, cyclo[ n ]carbons, have recently attracted vivid attention of experimentalists and theoreticians.

Язык: Английский

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Harmonic oscillator model of aromaticity (HOMA) in conjugated radicals and cations

Computational and Theoretical Chemistry, Год журнала: 2023, Номер 1230, С. 114370 - 114370

Опубликована: Окт. 14, 2023

Язык: Английский

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py.Aroma: An Intuitive Graphical User Interface for Diverse Aromaticity Analyses

Chemistry, Год журнала: 2024, Номер 6(6), С. 1692 - 1703

Опубликована: Дек. 23, 2024

The nucleus-independent chemical shift (NICS) criterion plays a significant role in evaluating (anti-)aromaticity. While being readily accessible even for non-computational chemists, adding ghost atoms multi-points NICS evaluations poses challenge. In this article, I introduce py.Aroma 4, freely available and open-source Python package designed specifically analyzing Through its user-friendly graphical interface, simplifies enhances aromaticity analyses by offering key features such as HOMA/HOMER index computation, Gaussian-type input file generation diverse calculations corresponding output processing, NMR spectra plotting, computational supporting information (SI) scientific manuscripts. Additionally, NICS⊥ is suggested (anti-)aromaticity non-planar or tilted rings. Pre-compiled executables macOS Windows are online. Facilitate accessibility users lacking programming experience time constraints.

Язык: Английский

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Stability and Reactivity of the Phenalene and Olympicene Isomers

The Journal of Physical Chemistry A, Год журнала: 2023, Номер 127(45), С. 9430 - 9441

Опубликована: Ноя. 3, 2023

The phenalene (triangulene) and olympicene molecules belong to the polycyclic aromatic hydrocarbon class, which have attracted substantial technological interest due their unique electronic properties. Electronic structure calculations serve as a valuable tool in investigating stability reactivity of these molecular systems. In present work, multireference calculations, namely, complete active space second-order perturbation theory averaged quadratic coupled cluster (MR-AQCC), were employed study isomers, well modified structures where sp3-carbon at borders removed. harmonic oscillator model aromaticity (HOMA) nucleus-independent chemical shift geometric magnetic indexes calculated with density functional utilized assess studied molecules. These compared properties such excitation energy natural orbitals occupation. analyzed using HOMA index combined MR-AQCC revealed radical character certain weakening aromaticity. Moreover, results suggest that removal atoms addition hydrogen did not alter π network energies

Язык: Английский

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Harmonic Oscillator Model of Aromaticity for Organometallics Containing the Os–C Bond

Organometallics, Год журнала: 2023, Номер 42(17), С. 2369 - 2377

Опубликована: Авг. 30, 2023

Aromaticity is an important concept in chemistry with multidimensional properties, attracting considerable attention from both experimental and computational chemists. Among various aromaticity indices, the harmonic oscillator model of (HOMA) a reliable criterion negligible cost based on geometry (bond distance). However, HOMA parameters for organometallic aromatics are not available. Here, we develop Os–C bond parameter by theoretical calculations. Its reliability evaluating supported its good correlation against other including electron density delocalized electrons order difference, R2 values ranging 0.74 to 0.77. Our finding might be particularly helpful chemists evaluate organometallics their geometries.

Язык: Английский

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Aromaticity in the Electronic Ground and Lowest Triplet States of Molecules with Fused Thiophene Rings

Chemistry - A European Journal, Год журнала: 2023, Номер 30(20)

Опубликована: Дек. 1, 2023

Analysis of the variations off-nucleus isotropic magnetic shielding, σ

Язык: Английский

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Increased matrix stiffness promotes fibrogenesis of hepatic stellate cells through AP-1-induced chromatin priming

Research Square (Research Square), Год журнала: 2024, Номер unknown

Опубликована: Окт. 16, 2024

Matrix stiffness can have significant effects on cell behavior, regulating processes such as proliferation, differentiation, migration, and extracellular matrix production; however, less is known regarding the epigenomic transcriptional regulation underling effect of phenotypic shifts. In present study, we utilized an in vitro system to assess shifts hepatic stellate cells (HSCs) following changes in stiffness, addition integrating multi-omics with imaging biochemical assays investigate mechanism underlying mechanical stimuli fibrosis. We show that cultured a stiff display more accessible chromatin sites, which consist primed regions become prior upregulation nearby genes. These are enriched fibrosis-associated genes function cytoskeletal organization response stimuli. Mechanistically, demonstrate activation AP-1 transcription factor family responsible for priming, among activated p-JUN critical promotion fibrogenic The identified accessibility-dependent cellular may be various fibrotic diseases provide insight into intervening approaches.

Язык: Английский

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What did aromaticity ever do for us? A user’s guide to aromatic and antiaromatic molecules

Advances in physical organic chemistry, Год журнала: 2024, Номер unknown

Опубликована: Янв. 1, 2024

Язык: Английский

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