Carbohydrate and Trivalent Iron Ion Interactions in the Gas Phase and in Aqueous Solution - Metallic Systems: A Quantum Chemist's Perspective - page 94

coordination.of.the.second.Fe 3+ .ion.is.energetically.unfavorable.with.a.BE.value.of.
+328.6.kJ.mol −1 ..The.calculated.BEs.might.be.overestimated.since.we.did.not.include.
the.basis.set.superposition.error.in.these.calculations..Overall,.these.BE.values.sup-
port. the. structural. properties. reported. above. and. indicate. that. the. coordination. of.
a.single.Fe 3+ .is.more.likely.than.the.coordination.of.two.Fe 3+ .ions.to.M.in.the.gas.
phase.
The.relative.torsional.energies.of.the.glycosidic.linkage.(φ).of.M.were.calculated.
for.M,.M-Fe 3+ ,.and.M-Fe 3+ .in.the.gas.phase.utilizing.both.CPMD.and.CMD.simu-
lations.. Changes. arising. in. PMF. as. a. function. of. the. torsional. angle. derived. from.
these.simulations.are.presented.in.Figure.3.4A..Similar.trends.for.the.conformational.

9

8

9

8

7

7

6

5

4

3

6

2

1

0

5

-200 -100 100 200

4

3

2

1

0

-200 -100 100 200

(A) Ψ (O5-C1-O1-C7)/degrees

9

8

7

6

5

4

3

2

1

0

-200 -100 100 200

(B) Ψ (O5-C1-O1-C7)/degrees

FIGURE 3.4 Calculated. torsional. energy. change. of. the. glycosidic. linkage. of. methyl-α-
mannopyranoside.(solid.line).and.its.energy.change.in.the.vicinity.of.one.(dashed.line).and.
two.Fe 3+ .ions.(dotted.line).in.the.gas.phase,.with.the.PMF.method:.(A).CPMD.simulations,.
(B). CMD. simulations.. The. inset. plot. (B). presents. the. calculated. energy. differences. of. the.
glycosidic. linkage. of. methyl-α-mannopyranoside. with. the. perturbation. and. PMF. methods.
by. CMD. simulations.. Errors. were. calculated. using. the. time-dependent. standard. deviation.
method.