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What's new
November 5, 1996
T. Wieland
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New features and future developments in MOLGEN
New features:
Hydrogen distribution
The analysis of NMR speturesctra often provides information on the degree of substitution
of a compound, i.e. on the number of H-atoms connected to carbon or hetero
atoms. This information can now be used in MOLGEN to drastically reduce the number of
isomers constructed from the given molecular formula. So the user may optionally
input the hydrogen distribution of the carbon, nitrogen and oxygen
atoms.
For example, in the previous version it was possible that a prescribed CH2
subgroup with two free valences could get another hydrogen leading to a
CH3 subgroup during the construction process.
The input dialog is
Hybridization
MOLGEN 3.5 will furthermore allow to
make use of another important result of NMR spectroscopy, i.e. to
optionally input
the hybridization states of carbon and hetero atoms,
which also considerably reduces the number of isomers that must be generated and
checked. It will again be possible to give the exact distribution
of the hybridization states or to enter just intervals. A draft of the input
window is depicted here:
The following table shows the effect of using these new
features of hydrogen distribution and hybridization:
| Restrictions | No. of Isomers | CPU-time |
|---|
| Chemical formula C6H8O6 only | 2,558,517 | 240s |
| No triple bonds | 2,434,123 | 204s |
| No O-O | 360,594 | 390s |
| Hydrogen distribution
1 CH2, 2 CH, 3 C, 4 OH | 35,058 | 10s |
| Hybridization
1 Csp3-2H, 2 Csp3-1H, 3 Csp2-0H, 1 Osp2-0H | 990 | 0.5s |
| Minimal ringsize 5 | 348 | 0.7s |
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