three moieties were considered for the lowest-energy IHB pattern, only some of
them were considered—with a representative role—for the other IHB patterns. It is
important to note that the conformers which may be responsible for the biological
activity are those with comparatively low relative energy (a sufficiently cautious
threshold value considering those with relative energy ≤3.5 kcal/mol). Conformers
Table 2 Relative energies of the calculated conformers of muchimangin B from the results of
different calculation methods in vacuo, and from PCM DFT/B3LYP/6-31+G(d,p) results in
solution
Conformer Relative energy (kcal/mol)
Results in vacuo
Results in solution
HF /6-31G(d,p) MP2/6-31 G(d,p)/
HF 6-31G(d,p)
DFT/B3LYP/
6-31+G(d,p)
Single point PCM DFT/B3LYP/
6-31+G(d,p)
In chloroform In acetonitrile In water
1-a
0.0000
0.5982
0.0000
0.0000
0.0000
0.0000
1-b
0.3343
0.0000
0.2140
0.2789
0.3582
0.5897
1-c
2.4190
1.7529
2.5401
2.5649
2.6450
2.6953
1-d
2.4558
1.7070
2.5747
2.5973
2.6781
2.5461
1-e
2.4874
1.8227
2.6084
2.5971
2.5151
2.5647
1-f
3.0172
1.4935
2.7248
3.1242
3.3410
3.3195
2-a
3.3325
4.1170
3.2298
2.3954
2.1274
2.5658
1-g
4.1060
4.5032
3.9878
3.9250
3.9809
3.1990
1-h
3.4252
2.6130
4.1677
4.4261
4.5547
4.7132
1-i
4.8767
6.2248
4.3222
–
a
4.6177
4.4089
2-b
3.4452
3.2651
4.4005
3.6109
3.3168
2.2662
3-a
4.8394
6.3072
5.5822
4.1419
3.2705
1.1222
3-b
5.2861
5.6544
6.1847
5.4740
5.1303
4.0781
3-c
7.2460
7.4161
8.1035
6.7170
6.0750
3.8554
4
10.0476
8.8642
10.7170
8.8718
8.2724
6.7211
5-a
9.8454
10.7076
11.9078
9.7970
8.9512
6.4816
5-b
10.4446
10.3351
12.4754
10.3284
9.5053
7.1355
6-b
10.4990
10.2458
12.5153
10.3284
9.5053
7.1355
6-a
10.4921
11.2258
12.6213
10.3306
9.4168
6.9981
5-c
12.6057
12.2092
14.7312
12.5653
11.7334
9.3089
6-c
12.7889
12.2429
15.0566
12.9609
12.2222
9.7075
7
15.0441
14.6959
16.4368
12.9303
11.5555
7.8820
8
13.7769
13.8853
16.7844
13.6567
12.4045
9.0351
9-a
15.4831
17.1122
18.2963
14.4347
12.7259
8.2238
9-b
16.2296
16.6169
18.7053
15.7674
14.4449
11.2084
9-c
17.7476
18.0487
20.7192
17.1660
15.8641
10.9043
10
21.9005
22.6201
25.5025
20.9490
19.1335
15.7362
11-a
22.0281
23.1336
27.0336
22.3711
20.5083
15.4427
11-b
22.5293
22.3876
27.1816
22.6862
20.9011
15.9954
11-c
24.6747
24.4410
29.7708
25.2173
23.4325
18.3900
The conformers are listed in order of increasing energy referred to the DFT/B3LYP/6-31+G(d,p) results in vacuo. The
DFT/B3LYP/6-31+G(d,p) results in vacuo are reported in the third column to facilitate comparisons with the results in
solution, that appear in the subsequent columns
a The calculation in chloroform solution does not converge for this conformer
Ab-Initio and DFT Study of the Muchimangin-B Molecule
97
them were considered—with a representative role—for the other IHB patterns. It is
important to note that the conformers which may be responsible for the biological
activity are those with comparatively low relative energy (a sufficiently cautious
threshold value considering those with relative energy ≤3.5 kcal/mol). Conformers
Table 2 Relative energies of the calculated conformers of muchimangin B from the results of
different calculation methods in vacuo, and from PCM DFT/B3LYP/6-31+G(d,p) results in
solution
Conformer Relative energy (kcal/mol)
Results in vacuo
Results in solution
HF /6-31G(d,p) MP2/6-31 G(d,p)/
HF 6-31G(d,p)
DFT/B3LYP/
6-31+G(d,p)
Single point PCM DFT/B3LYP/
6-31+G(d,p)
In chloroform In acetonitrile In water
1-a
0.0000
0.5982
0.0000
0.0000
0.0000
0.0000
1-b
0.3343
0.0000
0.2140
0.2789
0.3582
0.5897
1-c
2.4190
1.7529
2.5401
2.5649
2.6450
2.6953
1-d
2.4558
1.7070
2.5747
2.5973
2.6781
2.5461
1-e
2.4874
1.8227
2.6084
2.5971
2.5151
2.5647
1-f
3.0172
1.4935
2.7248
3.1242
3.3410
3.3195
2-a
3.3325
4.1170
3.2298
2.3954
2.1274
2.5658
1-g
4.1060
4.5032
3.9878
3.9250
3.9809
3.1990
1-h
3.4252
2.6130
4.1677
4.4261
4.5547
4.7132
1-i
4.8767
6.2248
4.3222
–
a
4.6177
4.4089
2-b
3.4452
3.2651
4.4005
3.6109
3.3168
2.2662
3-a
4.8394
6.3072
5.5822
4.1419
3.2705
1.1222
3-b
5.2861
5.6544
6.1847
5.4740
5.1303
4.0781
3-c
7.2460
7.4161
8.1035
6.7170
6.0750
3.8554
4
10.0476
8.8642
10.7170
8.8718
8.2724
6.7211
5-a
9.8454
10.7076
11.9078
9.7970
8.9512
6.4816
5-b
10.4446
10.3351
12.4754
10.3284
9.5053
7.1355
6-b
10.4990
10.2458
12.5153
10.3284
9.5053
7.1355
6-a
10.4921
11.2258
12.6213
10.3306
9.4168
6.9981
5-c
12.6057
12.2092
14.7312
12.5653
11.7334
9.3089
6-c
12.7889
12.2429
15.0566
12.9609
12.2222
9.7075
7
15.0441
14.6959
16.4368
12.9303
11.5555
7.8820
8
13.7769
13.8853
16.7844
13.6567
12.4045
9.0351
9-a
15.4831
17.1122
18.2963
14.4347
12.7259
8.2238
9-b
16.2296
16.6169
18.7053
15.7674
14.4449
11.2084
9-c
17.7476
18.0487
20.7192
17.1660
15.8641
10.9043
10
21.9005
22.6201
25.5025
20.9490
19.1335
15.7362
11-a
22.0281
23.1336
27.0336
22.3711
20.5083
15.4427
11-b
22.5293
22.3876
27.1816
22.6862
20.9011
15.9954
11-c
24.6747
24.4410
29.7708
25.2173
23.4325
18.3900
The conformers are listed in order of increasing energy referred to the DFT/B3LYP/6-31+G(d,p) results in vacuo. The
DFT/B3LYP/6-31+G(d,p) results in vacuo are reported in the third column to facilitate comparisons with the results in
solution, that appear in the subsequent columns
a The calculation in chloroform solution does not converge for this conformer
Ab-Initio and DFT Study of the Muchimangin-B Molecule
97