Nanotube Matrices for Flexible SnIP Nanowires

A detailed density functional theory (DFT) study on 1D-SnIP@2D-material
hybrids was conducted. Selected two-dimensional (2D) materials like
carbon nanotubes (CNTs), MoS2, phosphorus allotropes (gray
and black P), carbon nitrides, and boron nitride were tested as potential
2D hosts or matrices for a highly flexible, pseudo one-dimensional
semiconductor SnIP. For a matrix, we selected sheets of the 2D materials
rolled-up to nanotubes of 13.1 to 13.8 Å in diameter to accommodate
one enantiomeric form of double helical SnIP. SnIP, an atomic-scale
inorganic double helix compound, is composed of a racemic mixture
of M- and P-double helices that
form a pseudo-hexagonal rod packing in the bulk phase. Hybrid materials
investigated in this study were classified based on total energy,
the internal diameter of the matrix, and bonding interactions. Less-probable
and most-probable hybrids were identified. With the hybrid SnIP@C6N8 (8,4), the first example was identified, which
seems to allow separation of the M- and P-SnIP enantiomers due to significant differences in bonding interactions
and overall fit. Differential crystal orbital Hamilton population
analysis shows clear preference of M-SnIP over P-SnIP with a 31 kJ/mol stabilization in total energy for M-SnIP@C6N8. A vibrational mode analysis
of all hybrids illustrates that the length of the propagation vector
of the SnIP double helix directly correlates with a red shift of the
SnIP phosphorus modes. As a proof of principle, a core–shell
particle consisting of SnIP and hBN was successfully prepared and
investigated.