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Polybenzene multitori

100%
Szefler B., Diudea M.
Open Chemistry
|
2012
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vol. 10
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issue 6
1779-1785
EN
Polybenzene unit BT_48 can dimerize either by identification of 8-membered rings to provide a diamond-like fcc net or by identifying the opening 12-membered rings to form intercalated dendrimer-dimers which can further grow and rather quickly superimpose over the diamond-like network. The third hypothetical moiety we consider here is an eclipsed isomer, that can form multitori as negatively curved structures of various complexity. Multitori can evolve spherically or show a linear periodicity, as in rods. The polybenzene (“armchair”) multitori BTA are compared to the (“zig-zag”) BTZ ones, proposed earlier by us. A graph-theoretical study related the structure of multitori to the genus of their embedding surface and established the lower and upper bound values of genus. The total energy per carbon atom, HOMO-LUMO gap and strain energy of BTA and BTZ multitori have been computed and the results obtained point to BTZ multitori to be at least as stable as C60 what suggests BTZ multitori can be eventually synthesized in laboratory. [...]
2
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Molecular dynamics simulation study of the diamond D5 substructures

100%
Kyani A., Diudea M.
Open Chemistry
|
2012
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vol. 10
|
issue 4
1028-1033
EN
Diamond D5 is the name proposed by Diudea for hyper-diamonds having their rings mostly pentagonal. Within D5, in crystallographic terms: the mtn structure, known in clathrates of type II, several substructures can be defined. In the present work, the structural stability of such intermediates/fragments appearing in the construction/destruction of D5 net was investigated using molecular dynamics simulation. Calculations were performed using an empirical many-body potential energy function for hydrocarbons. It has been found that, at normal temperature, the hexagonal hyper-rings are more stable while at higher temperature, the pentagonal ones are relatively more resistant against heat treatment. [...]
3
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Fullerenes patched by flowers with octagonal core

71%
Pop R., Medeleanu M., Diudea M., Szefler B., Cioslowski J.
Open Chemistry
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2014
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vol. 12
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issue 1
90-97
EN
The aromatic character of three different flowers of general formula [n:(p i,p j)n/2], namely [8:(5,7)4], [8:(6,6)4] and [8:(5,6)4], has been evaluated by means of geometric (HOMA index), energetic (heats of formation) and magnetic criteria (NICS index, exaltation of magnetic susceptibility). Also, the reactivity descriptors within the DFT approach -absolute hardness, electrophilicity, Fukui functions - have been computed. All the different methods used for estimating the aromaticity led to a unitary conclusion. Two fullerene structures, patched by the most stable 8-Sumanene flower, have been designed and evaluated by means of ab initio computations [...]
4
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Fullerenes patched by flowers

71%
Pop R., Medeleanu M., Diudea M., Szefler B., Cioslowski J.
Open Chemistry
|
2013
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vol. 11
|
issue 4
527-534
EN
Stability measures, such as the total energy and the HOMO-LUMO gap, calculated at the Hartree-Fock and DFT levels of theory, and the aromatic character of five circulenes/flowers with a hexagonal core and petals consisting of 5-, 6- and 7-membered rings are investigated. Geometric (HOMA) and magnetic (NICS) criteria are used to estimate the local aromatic character of every ring of the investigated circulenes. The local aromaticity of the coronene and sumanene patches in two tetrahedrally spanned fullerenes were calculated and compared with the HOMA and NICS values of the corresponding isolated circulenes. [...]
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