Thermodynamics, Kinetics, and Optical Properties of Rotaxane: A First-Principles Molecular Dynamics Study

Through molecular mechanics using the force field along
with the
quantum dynamical aspect of mechanically interlocked compounds, rotaxanes
(defined as macromolecular rings that are threaded on a dumbbell-shaped
axle molecule) are investigated with advanced quantum mechanical methods,
including the atom-centered density matrix propagation simulation
technique, at different temperatures like 300, 500, 700, 900, 2000,
and 2500 K for 1.2 ps. Ab initio molecular dynamics
simulation is carried out. In addition to, we investigate the noncovalent
interaction present in the rotaxane compound 2R-D-2PF6 with
the help of reduced density gradient, average reduced density gradient,
density overlap region indicator, and interaction region indicator
as well as Hirshfeld surface analyses. Furthermore, the stability
of 2R-D-2PF6 at room temperature and higher temperatures
is elucidated by analyzing the thermal fluctuation index through a
dynamic process. In order to check the optical behavior of our selected
rotaxane compound, an evaluation of the electronic dipole moment,
static and frequency-dependent average polarizability, and first-
and second-order hyperpolarizability is carried out. The rotaxane
compound shows very promising linear and nonlinear optical responses,
which indicates its utility as a very good optical material. The calculation
of the time-dependent density-functional theory highlights the broad
absorption band of rotaxane spanning the UV–visible domain.
Therefore, we also unravel that this can tap into solar radiation
or harnessing of solar energy.