Temat: aromaticity - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Calculation of the HOMA model parameters for the carbon-boron bond
Autorzy:: Proniewicz, Leonard
Alkorta, Ibon
Zborowski, Krzysztof
Elguero, Jose
Opis:: An extension of the harmonic oscillator model of aromaticity (HOMA) model to systems with carbon– boron bonds is presented. Model parameters were esti- mated using experimental and theoretical bond lengths. It is shown that both approaches produce very similar HOMA models. In the second part of the article, the aromaticity levels of several model compounds containing carbon– boron bonds are calculated using the previously obtained parameters. The results of these calculations are compared with those provided by other aromaticity indices. The aromaticity of boron-containing compounds is also com- pared with the aromaticity of analogous compounds con- taining carbon and nitrogen.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 2.

Tytuł:: Pyridine‐fused bis(azacorrole)s : easily accessible NIR III absorbing cation radicals and biradicaloids of antiaromatic ground state
Autorzy:: Szydełko, Kinga
Zhang, Shaowei
Li, Sha
Chmielewski, Piotr J.
Smaga, Oskar
Li, Xiaofang
Pawlicki, Miłosz
Opis:: A family of pyridine-fused bis(porphyrinoids) is obtained, including constitutionally isomeric bis(azacorrole)s, azacorrole-oxacorrole, as well as azacorrole-norcorrole heterodimers by two distinct synthetic approaches. Spectroscopic characteristics, corroborated by Density Functional Theory (DFT) calculations, indicate aromaticity of the bis(azacorrole) as well as azacorrole-oxacorrole products, while for the azacorrole-norcorrole heterodimers, the presence of both dia- and paratropic currents is detected. Electrochemical analyses indicate facile chemical access to cation radicals and dicationic species that have been characterized by electronic and electron spin resonance spectroscopy as well as by DFT calculations. Monocations give rise to the relatively strong absorption bands in the near infra red (NIR) region between 2400 and 3200 nm, while dications are characterized by a series of absorptions between 1000 and 2200 nm. Electron spin resonance (ESR) experiments indicate the presence of singlet-triplet spin equilibria for the dications. For the dication of bis(azacorrole) of the most planar structure, the singlet ground state is established, and low temperature nuclear magnetic resonance (NMR) as well as gauge-independent atomic orbital NMR calculations indicate its antiaromatic character.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 3.

Tytuł:: HOMA parameters for the boron–boron bond : how the introduction of a BB bond influences the aromaticity of selected hydrocarbons
Autorzy:: Proniewicz, Leonard
Akorta, Ibon
Zborowski, Krzysztof
Elguero, Jose
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 4.

Tytuł:: Molecular properties of selenomaltols : new interesting ligands for bioactive metal complexes
Autorzy:: Tejchman, Waldemar
Zborowski, Krzysztof
Proniewicz, Leonard
Opis:: Properties of numerous selenium derivatives of maltol (3-hydroxy-2-methyl-4H-pyran-4-one), which is an important ligand in medicinal chemistry, were studied. Selenium derivatives were obtained using consecutive in silico replacements of maltol oxygen atoms, which produced three mono-substituted, three di-substituted and one tri-substituted derivatives. The geometry optimisations for these compounds in neutral, anionic and cationic forms were performed at the B1LYP/6-311++G** level of theory. The aromatic properties of the considered selenium compounds were studied in their heterocyclic rings using several indices of aromaticity: harmonic oscillator model of aromaticity, nucleus independent chemical shift(0), nucleus independent chemical shift(1), aromatic stabilisation energy, H index, para delocalisation index and multicentre index. The methods cover all of the main types of aromaticity indices: geometric, magnetic, energetic and electronic. The calculated data show the identical aromaticity order (cation > neutral molecule > anion) for maltol and its thio and seleno derivatives. The predicted aromaticity levels of selenomaltols were compared with the previously studied maltol and various thiomaltols.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego