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A Thorough Systematic Conformational Study of an Experimentally Known Lantern‐Like Superphane.

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Title: A Thorough Systematic Conformational Study of an Experimentally Known Lantern‐Like Superphane.
Authors: Eilmes, Andrzej1 (AUTHOR), Jabłoński, Mirosław2 (AUTHOR) teojab@chem.umk.pl
Source: Journal of Computational Chemistry. 2/15/2026, Vol. 47 Issue 5, p1-19. 19p.
Subjects: Conformational analysis, Nitrogen, Density functionals, Molecular structure, Cyclophanes, Dispersive interactions, Molecular dynamics
Abstract: The results of a thorough, systematic conformational study of the experimentally known lantern‐like superphane, SP, are presented. It is shown that in SP, the relative energies of the lowest‐energy conformers within a given type increase with the number of imine nitrogen atoms pointing inward the SP cage (Nin$$ {N}_{\mathrm{in}} $$). Thus, the conformer with all outward‐pointing N atoms is the most energetically stable. The most energetically stable conformers of the types with Nin≤2$$ {N}_{\mathrm{in}}\le 2 $$ have a pinwheel structure, whereas those of types with Nin≥6$$ {N}_{\mathrm{in}}\ge 6 $$, on the contrary, feature rosette‐like structures. Both DFT‐based and GFN2‐xTB‐based minima searches are performed. Both these methods locate the same minima, and the energies correlate fairly well. The latter method, however, gives smaller energetic differences between conformers, and dispersion effects are more pronounced. Molecular dynamics (MD) simulations show that periods of low potential energy are related mainly to conformers with low Nin$$ {N}_{\mathrm{in}} $$, close to 4. Structures with 3≤Nin≤5$$ 3\le {N}_{\mathrm{in}}\le 5 $$ are more abundant than those with Nin<2$$ {N}_{\mathrm{in}}<2 $$. The influence of dispersion, electrostatic interactions, and angular stresses on the structural motifs of SP conformers and their energies is also investigated. The stabilizing effect due to dispersion decreases with increasing Nin$$ {N}_{\mathrm{in}} $$, and rosettes are more stabilized than pinwheels. The high relative energies of the Nin=12$$ {N}_{\mathrm{in}}=12 $$ conformers result from the unfavorable barrel‐shaped structure, which leads to high angular stresses. We propose several possibilities for the experimental (based on IR spectra) determination of the conformational type of the SP superphane (i.e., determination of the putative number Nin$$ {N}_{\mathrm{in}} $$). [ABSTRACT FROM AUTHOR]
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Abstract:The results of a thorough, systematic conformational study of the experimentally known lantern‐like superphane, SP, are presented. It is shown that in SP, the relative energies of the lowest‐energy conformers within a given type increase with the number of imine nitrogen atoms pointing inward the SP cage (Nin$$ {N}_{\mathrm{in}} $$). Thus, the conformer with all outward‐pointing N atoms is the most energetically stable. The most energetically stable conformers of the types with Nin≤2$$ {N}_{\mathrm{in}}\le 2 $$ have a pinwheel structure, whereas those of types with Nin≥6$$ {N}_{\mathrm{in}}\ge 6 $$, on the contrary, feature rosette‐like structures. Both DFT‐based and GFN2‐xTB‐based minima searches are performed. Both these methods locate the same minima, and the energies correlate fairly well. The latter method, however, gives smaller energetic differences between conformers, and dispersion effects are more pronounced. Molecular dynamics (MD) simulations show that periods of low potential energy are related mainly to conformers with low Nin$$ {N}_{\mathrm{in}} $$, close to 4. Structures with 3≤Nin≤5$$ 3\le {N}_{\mathrm{in}}\le 5 $$ are more abundant than those with Nin<2$$ {N}_{\mathrm{in}}<2 $$. The influence of dispersion, electrostatic interactions, and angular stresses on the structural motifs of SP conformers and their energies is also investigated. The stabilizing effect due to dispersion decreases with increasing Nin$$ {N}_{\mathrm{in}} $$, and rosettes are more stabilized than pinwheels. The high relative energies of the Nin=12$$ {N}_{\mathrm{in}}=12 $$ conformers result from the unfavorable barrel‐shaped structure, which leads to high angular stresses. We propose several possibilities for the experimental (based on IR spectra) determination of the conformational type of the SP superphane (i.e., determination of the putative number Nin$$ {N}_{\mathrm{in}} $$). [ABSTRACT FROM AUTHOR]
ISSN:01928651
DOI:10.1002/jcc.70326