N.B.! These descriptors can be only used for model development on OCHEM web site and cannot be exported.
Most of Chemaxon descriptors (also known as: Chemaxon calculators) are implemented in OCHEM platform and can be calculated for any set of molecules. Desscriptors implemented are those which return munerical or boolean results. Unimplemented descriptors are those which return results not suitable for modeling purposes such as molecules, formula, or fingerprints. Also calculators that require specific input parameters are not implemented. Example of these calculators are those that check whether certain atom is assymetric, whether 2 atoms are connected, or calculate the angle between 3 specified atoms.
The implemented descriptors are divided into 7 groups: Elemental Analysis, Charge, Geometry, Partitioning, Protonation, Isomers, and Others
| Descriptor Name | Descriptor class | Definition | Considers pH during calculation |
| atomcount | Elemental Analysis | Number of atoms in the molecule | no |
| exactmass | Elemental Analysis | Exact molecule mass calculation based on the most frequent natural isotopes of the elements | no |
| mass | Elemental Analysis | Molecule mass calculation | no |
| no | |||
| averagemolecularpolarizability | Charge | Average molecular polarizability calculation | yes |
| formalcharge | Charge | Formal charge calculation | yes |
| molecularpolarizability | Charge | Molecular polarizability calculation | yes |
| no | |||
| aliphaticatomcount | Geometry | Aliphatic atom count | no |
| aliphaticbondcount | Geometry | Aliphatic bond count | no |
| aliphaticringcount | Geometry | Aliphatic ring count | no |
| aliphaticringcountofsize | Geometry | Aliphatic ring count of size | no |
| aromaticatomcount | Geometry | Aromatic atom count | no |
| aromaticbondcount | Geometry | Aromatic bond count | no |
| aromaticringcount | Geometry | Aromatic ring count | no |
| aromaticringcountofsize | Geometry | Aromatic ring count of size | no |
| asymmetricatomcount | Geometry | The number of asymmetric atoms | no |
| balabanindex | Geometry | The Balaban index | no |
| bondcount | Geometry | Bond count | no |
| carboaliphaticringcount | Geometry | Carboaliphatic ring count | no |
| carboaromaticringcount | Geometry | Carboaromatic ring count | no |
| carboringcount | Geometry | Carbo ring count | no |
| chainatomcount | Geometry | Chain atom count | no |
| chainbondcount | Geometry | Chain bond count | no |
| chiralcentercount | Geometry | The number of tetrahedral stereogenic center atoms | no |
| dreidingenergy | Geometry | Calculates the dreiding energy of a conformer of the molecule in kcal/mol | no |
| fragmentcount | Geometry | Fragment count | no |
| fusedaliphaticringcount | Geometry | The number of fused aliphatic rings (SSSR smallest set of smallest aliphatic rings) | no |
| fusedaromaticringcount | Geometry | The number of fused aromatic rings (SSSR smallest set of smallest aromatic rings) | no |
| fusedringcount | Geometry | The number of fused rings (SSSR smallest set of smallest rings) | no |
| hararyindex | Geometry | Harary index | no |
| heteroaliphaticringcount | Geometry | Heteroaliphatic ring count | no |
| heteroaromaticringcount | Geometry | Heteroaromatic ring count | no |
| heteroringcount | Geometry | Hetero ring count | no |
| hyperwienerindex | Geometry | Hyper Wiener index | no |
| largestringsize | Geometry | Largest ring size | no |
| largestringsystemsize | Geometry | Largest ring system size | no |
| maximalprojectionarea | Geometry | Calculates the maximal projection area | no |
| maximalprojectionradius | Geometry | Calculates the maximal projection radius | no |
| maximalprojectionsize | Geometry | no | |
| minimalprojectionarea | Geometry | Calculates the minimal projection area | no |
| minimalprojectionradius | Geometry | Calculates the minimal projection radius | no |
| minimalprojectionsize | Geometry | no | |
| molecularsurfacearea | Geometry | Molecular Surface Area calculation (3D) | yes |
| plattindex | Geometry | The Platt index | no |
| randicindex | Geometry | The Randic index | no |
| polarsurfacearea | Geometry | Topological Polar Surface Area calculation (2D) | yes |
| ringatomcount | Geometry | Ring atom count | no |
| ringbondcount | Geometry | Ring bond count | no |
| ringcount | Geometry | Ring count | no |
| ringcountofsize | Geometry | Ring count of size | no |
| ringsystemcount | Geometry | The number of ring systems | no |
| ringsystemcountofsize | Geometry | Ring system count of size | no |
| rotatablebondcount | Geometry | Rotatable bond count | no |
| smallestringsize | Geometry | Size of smallest ring | no |
| smallestringsystemsize | Geometry | Smallest ring system size | no |
| stereodoublebondcount | Geometry | The number of stereo double bonds | no |
| szegedindex | Geometry | Szeged index | no |
| volume | Geometry | Calculate the van der Waals volume of the molecule | no |
| wienerindex | Geometry | Wiener index | no |
| wienerpolarity | Geometry | Wiener polarity | no |
| vdwsa | Geometry | Van der Waals Surface Area calculation | yes |
| no | |||
| logp | Partitioning | logP calculation: logP of uncharged species, or, in the case of zwitterions, logD at pI | no |
| logd | Partitioning | logD calculation | yes |
| no | |||
| isoelectricpoint | protonationDescriptors | Isoelectric point calculation | no |
| no | |||
| doublebondstereoisomercount | Isomers | The number of double-bond stereoisomers of the molecule | no |
| stereoisomercount | Isomers | The number of stereoisomers of the molecule | no |
| tautomercount | Isomers | The number of tautomers | no |
| tetrahedralstereoisomercount | Isomers | The number of tetrahedral stereoisomers of the molecule | no |
| no | |||
| acceptorcount | Others | Hydrogen bond acceptor atom count in molecule | yes |
| acceptorsitecount | Others | Hydrogen bond acceptor multiplicity in molecule | no |
| donorcount | Others | Hydrogen bond donor atom count in molecule | yes |
| donorsitecount | Others | Hydrogen bond donor multiplicity in molecule | yes |
| hmopienergy | Others | HMO Pi energy | yes |
| pienergy * | Others | Pi energy | yes |
| msacc | Others | Hydrogen bond acceptor average multiplicity over microspecies by pH | no |
| msdon | Others | Hydrogen bond donor average multiplicity over microspecies by pH | no |
| resonantcount | Others | The number of resonant structures | no |
- - Descriptors that will not be supported in in future versions.
pH descriptors
Calculation of some descriptors require consideration of pH value. User is allowed 3 options for pH:
- All: This calculates the value of the descriptor over the pH range from 0 to 14 taking 1 pH unit increments at a time. Additionally, the descriptor value at pH 7.4 is calculated.
- Specific value: calculates the value of the descriptor at the speicifed pH.
- Specific range: calculates the value of the descriptor over the pH range specified between "from" until "to" taking pH unit increments equal to the value specifid in "step". Additionally, the descriptor value at pH 7.4 is calculated.
Descriptors which consider pH value during their calculation are: veragemolecularpolarizability, formalcharge, molecularpolarizability, molecularsurfacearea, polarsurfacearea, vdwsa, logd, acceptorcount, acceptorsitecount, donorcount, donorsitecount, hmopienergy, pienergy
Ring size
The following descriptors measure the ring size: aliphaticringcountofsize, aromaticringcountofsize, ringcountofsize, ringsystemcountofsize They are calculated for 3-, 4-, 5-, 6-, 7-, and 8-membered rings.
The following calculators are unable to handle molecules with multiple fragments, instead OCHEM platform replaces it with a "missing descriptor value". Currently this value is set to 0. We plan to allow the user to specify such value in the future or even skip the whole molecule altogether from the dataset.