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N. Tshilande and L. Mammino
3.3.5 HOMO-LUMO Energy Gap of the Conformers
Tables S39–S41 report the values of the HOMO-LUMO energy difference for all
the calculated conformers. The difference is mostly influenced by the presence of
O–H···π IHBs. The orientation of the BDE ring system and the orientation of the
OH ortho to CRO and not engaged in the first IHB also have significant influence.
The position of the first IHB (whether H15···O14 or H17···O14) has minor influence
and the other factors, such as the orientation of the OHs in rings B and E, have no
significant influence. Figures S9, S11 and S13 show the shapes of the HOMO and
LUMO of the calculated conformers of the three molecules having the same geometry
of R and different geometries of ABDE, and Figs. S10, S12 and S14 show the shapes
for the conformers having different geometries of R and the same geometry of ABDE.
The HOMO shapes show greater electron density concentration in the phloroglucinol
moiety and the BDE ring system for all conformers, with few exceptions for d-w,
d-r-q and s-w-u conformers, where the electron density is concentrated in the BDE
ring system only. The LUMO shapes show greater electron density concentration in
the phloroglucinol moiety.
Tables S42–S44 and Figs. S37–S39 compare the results from different calculation
methods for the HOMO-LUMO energy gap of the calculated conformers having
different geometries of R and the same geometry of ABDE. The HF and MP2 values
are very close. The DFT values are much smaller than the values obtained with
the other two methods, consistently with the known tendency of DFT to greatly
underestimate the HOMO-LUMO energy gap. The trends are similar with the three
methods.
3.4 Results in Solution
3.4.1 Results from the CPCM Calculations
CPCM calculations in solution were performed at the HF level on conformers with
in-vacuo relative energy ≤1.984 kcal/mol. Sets of tables (S45–S74) and corresponding figures (S40–S69) compare the properties in vacuo and in the three solvents
considered. Although acetonitrile has greater dipole moment than water, its effects
on the properties of the solute molecules are usually intermediate between those of
chloroform and those of water; therefore, on analysing results, the wording “as the
medium polarity increases” is meant to refer to the vacuum-chloroform-acetonitrilewater sequence and the wording “as the solvent polarity increases” is meant to refer
to the chloroform-acetonitrile-water sequence.
Tables S45–S47 and Figs. S40–S42 compare the relative energies of the conformers having the same geometry of R and different geometries of ABDE in the
different media; the values show that the relative energy decreases as the medium
polarity increases. The identification of the lowest energy conformer appears to differ
N. Tshilande and L. Mammino
3.3.5 HOMO-LUMO Energy Gap of the Conformers
Tables S39–S41 report the values of the HOMO-LUMO energy difference for all
the calculated conformers. The difference is mostly influenced by the presence of
O–H···π IHBs. The orientation of the BDE ring system and the orientation of the
OH ortho to CRO and not engaged in the first IHB also have significant influence.
The position of the first IHB (whether H15···O14 or H17···O14) has minor influence
and the other factors, such as the orientation of the OHs in rings B and E, have no
significant influence. Figures S9, S11 and S13 show the shapes of the HOMO and
LUMO of the calculated conformers of the three molecules having the same geometry
of R and different geometries of ABDE, and Figs. S10, S12 and S14 show the shapes
for the conformers having different geometries of R and the same geometry of ABDE.
The HOMO shapes show greater electron density concentration in the phloroglucinol
moiety and the BDE ring system for all conformers, with few exceptions for d-w,
d-r-q and s-w-u conformers, where the electron density is concentrated in the BDE
ring system only. The LUMO shapes show greater electron density concentration in
the phloroglucinol moiety.
Tables S42–S44 and Figs. S37–S39 compare the results from different calculation
methods for the HOMO-LUMO energy gap of the calculated conformers having
different geometries of R and the same geometry of ABDE. The HF and MP2 values
are very close. The DFT values are much smaller than the values obtained with
the other two methods, consistently with the known tendency of DFT to greatly
underestimate the HOMO-LUMO energy gap. The trends are similar with the three
methods.
3.4 Results in Solution
3.4.1 Results from the CPCM Calculations
CPCM calculations in solution were performed at the HF level on conformers with
in-vacuo relative energy ≤1.984 kcal/mol. Sets of tables (S45–S74) and corresponding figures (S40–S69) compare the properties in vacuo and in the three solvents
considered. Although acetonitrile has greater dipole moment than water, its effects
on the properties of the solute molecules are usually intermediate between those of
chloroform and those of water; therefore, on analysing results, the wording “as the
medium polarity increases” is meant to refer to the vacuum-chloroform-acetonitrilewater sequence and the wording “as the solvent polarity increases” is meant to refer
to the chloroform-acetonitrile-water sequence.
Tables S45–S47 and Figs. S40–S42 compare the relative energies of the conformers having the same geometry of R and different geometries of ABDE in the
different media; the values show that the relative energy decreases as the medium
polarity increases. The identification of the lowest energy conformer appears to differ