Extraordinary deformation capacity of smallest carbohelicene springs

Abstract

The extraordinary deformation and loading capacity of nine different [∞]carbohelicene springs under uniaxial tension up to their fracture were computed using the density functional theory. The simulations comprised either the experimentally synthetized springs of hexagonal rings or the hypothetical ones that contained irregularities (defects) as, for example, pentagons replacing the hexagons. The results revealed that the presence of such defects can significantly improve mechanical properties. The maximum reversible strain varied from 78% to 222%, the maximum tensile force varied in the range of 5 nN to 7 nN and, moreover, the replacement of hexagonal rings by pentagons or heptagons significantly changed the location of double bonds in the helicenes. The fracture analysis revealed two different fracture mechanisms that could be related to the configurations of double and single bonds located at the internal atomic chain. Simulations performed with and without van der Waals interactions between intramolecular atoms showed that these interactions played an important role only in the first deformation stage.

Dihydrogen contacts observed by through-space indirect NMR coupling

“… 62 It is worth noting that such soft-spring behaviour of helicenes has also been described, or predicted, by other theoretical and experimental studies. 19 , 22 , 63 – 66 Fast molecular dynamics may lead to the observation of an averaged TSC value.…”

Current State of Computational Modeling of Nanohelicenes

“…It can be assumed that the difference is due to a more accurate calculation method, which was carried out within the DFT (B3LYP functional) in the TZVP basis set, taking into account the solvent and dispersion corrections. A further theoretical study of the influence of the axial deformations of [∞]helicene and its non-hexagonal modifications on mechanical stability, deformability, and fracture processes was carried out in [ 37 ] at the PBE/PAW level of theory. It was found that the presence of pentagons or heptagons instead of hexagons had a significant influence on the mechanical properties, and some helicenes could achieve very large reversible tensile strains (more than 200%).…”

Magnetic Properties of Zig-Zag-Edged Hexagonal Nanohelicenes: A Quantum Chemical Study

“…Among such works, we note the study of the mechanical properties of NHs by the methods of molecular dynamics [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. The electronic structure of NHs of various types was studied by semi-empirical DFTB methods [ 29 , 30 , 31 ] and non-empirical DFT methods [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. It has been shown that various families of NHs are possible, including diamagnetic semiconductors, antiferromagnetic semiconductors, ferromagnets, and metals.…”