The Uσ-space distortion set
{Cσ,Fσ,Aσ} as a
molecular similarity measure
We created Sa and Ra stereoisomers of
glycine by applying an electric (E) -field to induce
symmetry-breaking changes to the length of the C-H bonds attached to the
alpha carbon (C1) atom, see Table 3(a-b) and Figure 2 .
We found that reversal of the E -field caused a reversal of the
chirality Cσ of the Sa stereoisomer fromSσ to Rσ , except for
the high E -field = +200×10-4 a.u., which
distorted the structure to the extent of inducing an intramolecular
hydrogen bond. The corresponding reversal of the chirality
Cσ also occurred for the Rastereoisomer. The E -field amplification EAσ is
found to increase with the application of a non-structurally distortingE -field, demonstrating that control of the chirality
Cσ of glycine is possible in the case of negligible
structural distortion.
The largest magnitudes of bond-flexing Fσ occur for both
the Sa and Ra stereoisomers atE = -100×10-4 a.u. (Fσ ≈ 1.0)
and are approximately three times greater than for the absence of theE -field (Fσ ≈ 0.33), see Table 2(b) .
The lowest magnitudes of the bond-flexing Fσ occur atE = +100×10-4 a.u. (Fσ ≈ 0.1)
for both the Sa and Ra stereoisomers and
are approximately a third of those in the absence of theE -field (Fσ ≈ 0.33). This indicates that atE = -100×10-4 a.u. and E =
+100×10-4 a.u., the Sa and
Ra stereoisomers experience the least and greatest
degree of torsional C1-N7 BCP bond-strain, respectively.
Table 3(a). The maximum stress tensor projections{ bond-twist max, bond-flexingmax, bond-anharmonicitymax}, of the
dominant torsional C1-N7 BCP for the electric field induced
Sa and Ra stereoisomers of glycine are
presented; all entries have been multiplied by 103,
also see the caption of Table 1(a).
{ bond-twistmax,
bond-flexingmax, bond-anharmonicitymax}
Sa Ra