moments. The same phenomenon was observed in the previous study of naphthylisoquinoline alkaloids with antimalarial activity [16] and in the study of
michellamine A [12]. The mutual orientation of the moieties also has considerable
influence on the dipole moment. Different orientations of the S and S′ units may
cause 1−4 D difference in the dipole moments, and different orientations of the
isoquinoline and naphthalene moieties within each unit may cause 1−2 D difference
in the dipole moments. This trend is reversed with respect to what was observed for
the conformers of michellamine A [12], where the orientation of the units caused a
1−2 D difference and the different orientation of the isoquinoline and naphthalene
moieties within each unit caused a 1−4 D difference. When two conformers of JZM
differ both by the orientation of the S and S′ units and by the orientations of the
isoquinoline and naphthalene moieties, the dipole moment difference is ≈2 D.
Conformers of S/S′ symmetric pairs have the same dipole moment.
Table 7 reports the HOMO-LUMO energy gap for the conformers listed in
Table 2. The gap is influenced by the IHB patterns. Conformers with only one
O−H⋯O IHB and other types of IHBs interactions (O−H⋯π and C−H⋯O), such
as
conformers
JZM-b-c-e-g-p-v-x,
JZM-c-f-h-q-t-x,
JZM-a-d-e-g-p-t-x,
JZM-a-d-e-g-q-v-y, have the smallest HOMO-LUMO energy gap. The gap is
slightly greater for conformers with the two O−H⋯O IHBs and other IHB-type
interactions and highest for conformers with only O−H⋯π interactions (which are
accompanied by C−H⋯O interactions if they involve the two moieties within the
same unit). The presence of the C−H⋯O interactions in a conformer slightly
decreases the HOMO-LUMO energy gap with respect to a corresponding conformer where it is absent; for instance, the gap in JZM-c-d-f-h-p-v-x is ≈1 kcal/mol
less than in JZM-c-d-p-v-x. Conformers of S/S′ have the same HOMO-LUMO
energy.
The estimation of the HOMO-LUMO energy gap shows marked difference
between HF and DFT values. This is a known phenomenon, as DFT substantially
Table 5 Relative energy (ΔE correct , kcal/mol) corrected for ZPE and ZPE corrections (kcal/mol)
for conformers of jozimine A 2 selected among those reported in Table 2. Results from HF/6-31G
(d,p) frequency calculations
Conformer
ΔE correct
ZPE
correction
Conformer
ΔE correct
ZPE
correction
a-b-e-f-g-h-p-v-x
0.000
572.602
a-b-e-g-p-t-x
6.100
572.150
a-b-e-f-g-h-q-v-x
0.644
572.503
c-d-e-f-g-h-p-v-x
11.036
572.011
a-b-e-f-g-h-q-t-x
0.688
572.497
a-d-e-g-p-t-x
11.053
571.973
a-b-e-f-g-h-q-v-y
1.268
572.407
a-b-q-v-y
11.089
571.791
a-b-e-f-g-h-p-t-x
1.294
572.430
a-b-p-t-x
11.313
571.819
a-d-e-f-g-h-q-v-x
5.545
572.289
c-d-f-h-p-v-x
14.776
571.846
b-c-e-f-g-h-q-t-x
5.616
572.284
c-d-f-h-q-v-x
14.866
571.781
a-b-e-g-q-t-x
5.575
572.215
b-c-q-v-y
15.280
571.621
b-c-e-f-g-h-p-v-x
5.871
572.264
c-d-q-v-y
19.007
571.572
a-d-e-f-g-h-p-v-x
5.872
572.264
c-d-p-t-x
19.433
571.603
318
M. K. Bilonda and L. Mammino
michellamine A [12]. The mutual orientation of the moieties also has considerable
influence on the dipole moment. Different orientations of the S and S′ units may
cause 1−4 D difference in the dipole moments, and different orientations of the
isoquinoline and naphthalene moieties within each unit may cause 1−2 D difference
in the dipole moments. This trend is reversed with respect to what was observed for
the conformers of michellamine A [12], where the orientation of the units caused a
1−2 D difference and the different orientation of the isoquinoline and naphthalene
moieties within each unit caused a 1−4 D difference. When two conformers of JZM
differ both by the orientation of the S and S′ units and by the orientations of the
isoquinoline and naphthalene moieties, the dipole moment difference is ≈2 D.
Conformers of S/S′ symmetric pairs have the same dipole moment.
Table 7 reports the HOMO-LUMO energy gap for the conformers listed in
Table 2. The gap is influenced by the IHB patterns. Conformers with only one
O−H⋯O IHB and other types of IHBs interactions (O−H⋯π and C−H⋯O), such
as
conformers
JZM-b-c-e-g-p-v-x,
JZM-c-f-h-q-t-x,
JZM-a-d-e-g-p-t-x,
JZM-a-d-e-g-q-v-y, have the smallest HOMO-LUMO energy gap. The gap is
slightly greater for conformers with the two O−H⋯O IHBs and other IHB-type
interactions and highest for conformers with only O−H⋯π interactions (which are
accompanied by C−H⋯O interactions if they involve the two moieties within the
same unit). The presence of the C−H⋯O interactions in a conformer slightly
decreases the HOMO-LUMO energy gap with respect to a corresponding conformer where it is absent; for instance, the gap in JZM-c-d-f-h-p-v-x is ≈1 kcal/mol
less than in JZM-c-d-p-v-x. Conformers of S/S′ have the same HOMO-LUMO
energy.
The estimation of the HOMO-LUMO energy gap shows marked difference
between HF and DFT values. This is a known phenomenon, as DFT substantially
Table 5 Relative energy (ΔE correct , kcal/mol) corrected for ZPE and ZPE corrections (kcal/mol)
for conformers of jozimine A 2 selected among those reported in Table 2. Results from HF/6-31G
(d,p) frequency calculations
Conformer
ΔE correct
ZPE
correction
Conformer
ΔE correct
ZPE
correction
a-b-e-f-g-h-p-v-x
0.000
572.602
a-b-e-g-p-t-x
6.100
572.150
a-b-e-f-g-h-q-v-x
0.644
572.503
c-d-e-f-g-h-p-v-x
11.036
572.011
a-b-e-f-g-h-q-t-x
0.688
572.497
a-d-e-g-p-t-x
11.053
571.973
a-b-e-f-g-h-q-v-y
1.268
572.407
a-b-q-v-y
11.089
571.791
a-b-e-f-g-h-p-t-x
1.294
572.430
a-b-p-t-x
11.313
571.819
a-d-e-f-g-h-q-v-x
5.545
572.289
c-d-f-h-p-v-x
14.776
571.846
b-c-e-f-g-h-q-t-x
5.616
572.284
c-d-f-h-q-v-x
14.866
571.781
a-b-e-g-q-t-x
5.575
572.215
b-c-q-v-y
15.280
571.621
b-c-e-f-g-h-p-v-x
5.871
572.264
c-d-q-v-y
19.007
571.572
a-d-e-f-g-h-p-v-x
5.872
572.264
c-d-p-t-x
19.433
571.603
318
M. K. Bilonda and L. Mammino