ABSTRACT
Spherical fullerenes offer noteworthy structures usually involving six‐ and five‐membered faces, with application in technological issues. In this sense, cavernous spherical‐like structures ...bearing larger holes provide interesting examples for further understanding of structure‐properties relationship. Here, we explored the magnetic response of a proposed cavernous nitride fullerene, C
24
N
24
, which has a
O
h
‐symmetry with six N
4
‐macrocyclic and eight 1,3,5‐triazine faces displaying 48‐π electrons. C
24
N
24
exhibits a local aromatic behavior owing to the contrasting antiaromatic response of the N
4
‐macrocyclic faces and the aromatic character of the 1,3,5‐triazine faces. Thus, the overall structure is ascribed as a local aromatic species, where the triazine faces exhibit the characteristic shielding cone for aromatic rings. Furthermore, the constructive combination of local shielding cones in C
24
N
24
delivers a related shielding‐cone response, as expected for a perfect aromatic cage. Hence, the local aromatic/nonaromatic/antiaromatic sections exhibit an additive or subtractive interaction, leading to a characteristic response inherent to the nature of the spherical cage. We expect that further study of the interplay between different aromatic and antiaromatic faces in fullerene‐like cages can deliver interesting pseudo‐aromatic or pseudo‐antiaromatic spherical species.
Inclusion of heteroatoms into a ring skeleton obtained unique electronic features, which differ from the respective isoelectronic organic counterparts, increasing the versatility of aromatic ...molecules. Herein, we evaluate the role of heteroatoms on the electronic and magnetic properties in a number of inorganic 10π-electron eight-member aromatic rings involving the isoelectronic (EH)
2
S
2
N
4
q
(E = C, P, B, Si, Al) series using density functional methods. The inclusion of different heteroatoms with increasing electronegativity increased the aromatic behavior in relation to the representative 10π-electron C
8
H
8
2−
organic ring. A deeper analysis on the magnetic response to an applied magnetic field, in terms of individual π-orbitals contributions, revealed that the differentiation in aromaticity originates from orbitals with major contributions from p
z
of heteroatom E, whereas the diatropic contributions that arise from the S
2
N
4
core remained similar throughout the series. Therefore, the effect of including a certain type of heteroatom can be addressed in terms of the variation and contribution of each individual π-orbital, starting from the respective organic counterpart, which appears to be a convenient approach. The similar π-aromatic character observed suggests the proposed hypothetical rings are feasible structures to explore synthetically. The less aromatic counterpart given by the Al counterpart should lead to a less stable ring in this series.
Heteroatoms with increasing electronegativity increased the aromatic behavior in a representative 10π-electron C
8
H
8
2−
organic ring.
Inclusion of heteroatoms into a ring skeleton obtained unique electronic features, which differ from the respective isoelectronic organic counterparts, increasing the versatility of aromatic ...molecules. Herein, we evaluate the role of heteroatoms on the electronic and magnetic properties in a number of inorganic 10π-electron eight-member aromatic rings involving the isoelectronic (EH) 2 S 2 N 4 q (E = C, P, B, Si, Al) series using density functional methods. The inclusion of different heteroatoms with increasing electronegativity increased the aromatic behavior in relation to the representative 10π-electron C 8 H 8 2− organic ring. A deeper analysis on the magnetic response to an applied magnetic field, in terms of individual π-orbitals contributions, revealed that the differentiation in aromaticity originates from orbitals with major contributions from p z of heteroatom E, whereas the diatropic contributions that arise from the S 2 N 4 core remained similar throughout the series. Therefore, the effect of including a certain type of heteroatom can be addressed in terms of the variation and contribution of each individual π-orbital, starting from the respective organic counterpart, which appears to be a convenient approach. The similar π-aromatic character observed suggests the proposed hypothetical rings are feasible structures to explore synthetically. The less aromatic counterpart given by the Al counterpart should lead to a less stable ring in this series.
The induced magnetic field of fullerenes is strongly dependent on the charge state, where C60 is depicted as a nonaromatic species, in contrast to C60 10+ which exhibits a strong spherical aromatic ...character. Here, we account for the response of relevant charged stable building blocks for novel extended networks with variable applications, as observed in A12C60 and A6C60 phases (A = alkali metal), given by, Li12C60 and Na6C60, as well as four different charge states of C60 q (q = +10, 0, −6, −12), to an external magnetic field is studied in detail, focusing on the contributions from the π and σ systems to the induced magnetic field. C60, C60 6–, and C60 12– accounts for the variation of their isolated species upon addition of charge, whereas C60 10+ is a hypothetical highly aromatic counterpart. Our results show that each spherical shell and each canonical molecular orbital exhibit characteristic patterns, revealing the direct dependence of the magnetic response, and therefore of spherical aromatic character, with regard to electron configuration. In particular, low-lying S, P, D, and F π-type shells exhibit identical strong and long-range shielding character among the four charge states. The G shell exhibits a weak shielding response, precluding the strong deshielding contribution from high-lying H and I shells. A similar analysis is given for σ-type orbitals. Thus, the aromatic, nonaromatic, and antiaromatic character of C60 among the different charge states is ruled by the population of the high-lying π-shells, which is explained in terms of π → π* excitations of high-lying canonical molecular orbitals. Hence, in spherical aromatic fullerenes, the formation of a shielding cone is given mainly by the π-type shells, extending characteristic features from planar aromatics to three-dimensional structures, which is useful for further rationalization and characterization of spherical/nonaromatic and antiaromatic spherical structures.
3D Normal Modes is a Web application for interactive visualization and three-dimensional perception of the normal modes of molecular vibration, suitable for undergraduate students in chemistry.
3DNormalModes Sigalas, Michael P; Charistos, Nickolas D; Teberekidis, Vasilios I ...
Journal of chemical education,
10/2003, Letnik:
80, Številka:
10
Journal Article
Recenzirano
Odprti dostop
3DNormalModes enables one to choose from 28 different molecules, orient it appropriately on the screen, choose any of its normal vibrational modes, and animate molecular vibrations in 3D.
In this paper the design and development of 3DNormalModes, an educational tool for interactive visualization and three dimensional perception of vibrational spectra data of molecules is presented. ...The details of the architecture of the tool and its functionality are described. Means of application in chemical education at university level are discussed. A pilot study summarizes the strengths, the educational value and the possible extensions of the system.PUBLICATION ABSTRACT
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