Properly designed molecular rotors
with sizable stators and a fast-moving
rotator could provide efficient building blocks for amphidynamic crystals.
Herein, we report the synthesis of steroidal compounds
1
,
2
, and
3
and their deuterated analogues
1D
,
2D
, and
3D
envisioned to work
as molecular rotors. The obtained compounds were characterized by
attenuated total reflection-infrared, Raman, and circular dichroism
(CD) spectroscopy measurements. The interpretation of spectra was
supported by theoretical calculations using density functional theory
methods. The analysis of the most characteristic bands confirmed different
molecular dynamics of the rotors investigated. Angle-dependent polarized
Raman spectra showed the crystallinity of some samples. Electronic
CD (ECD) spectra of compounds
1–3
and their relevant
deuterated analogues
1D–3D
are identical. The
increase of the band intensity with lowering the temperature shows
that the equilibrium is shifted to the thermodynamically most stable
conformer. ECD spectra simulated at the TDFFT level of theory for
compound
3
were compared with experimental results. It
was proved that conformer
3a
, with a torsion angle of
+50°, exhibits the best agreement with the experimental results.
Simulated vibrational CD and IR spectra for conformer
3a
and its deuterated analogue
3Da
also display good agreement
with experimental results. In light of our comprehensive investigations,
we evidenced that steroidal compounds
1
,
2
, and
3
can work as molecular rotors.
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