Differences

This shows you the differences between two versions of the page.

--- structurelevels [2012/10/15 12:29] – sanmark
+++ structurelevels [2012/10/15 12:50] – sanmark
@@ Line 3: / Line 3: @@
 In the mcule database chemical structures can be described in three structure specification levels: conformers, structures and compounds.
-//**Conformers**// have a fully specified 3D structure including the position of all hydrogens. They are in a fixed tautomeric and protonation state, and they have a known absolute [[stereonotations|stereo configuration]] (as reflected in the geometry).
+//**Conformers**// have a fully specified 3D structure including the position of all hydrogens. They are in a fixed [[http://en.wikipedia.org/wiki/Tautomer|tautomeric]] and protonation state, and they have a known absolute [[stereonotations|stereo configuration]] (as reflected in the geometry).
 //**Structures**// refer to molecular structures representing a fixed tautomeric and protonation state as reflected by the 2D structural formula. They can have a fully defined or a partially or fully unknown/undefined [[stereonotations|stereo configuration]].
 //**Compounds**// refer to chemical compounds that can be represented by multiple molecular structures, i.e. with multiple tautomeric and protonation forms. Their [[stereonotations|stereo configuration]] can be well-defined as well as fully or partially unknown / undefined, similarly to the case of //structures//.
+^Structure specification level ^Identical                                           ^Different ^
+|Compound                      |Mesomers, tautomers, protonation states, conformers | Stereoisomers |
+|Structure                     |Mesomers, conformers                                | Stereoisomers, tautomers, protonation states |
+|Conformer                     |Mesomers                                            |Stereoisomers, tautomers, protonation states, conformers |
 Chemical structures with different stereo configurations are distinguished at all specification levels. Depending on the stereo configuration type, they represent a single isomer or a set of potential isomers and/or mixtures of isomers. (figure) Their stereo configurations are treated identical if and only if the represented isomers / set of isomers are identical. If the configuration differs, the chemical structures are treated as different database entries.
 //Compounds// can have more symmetries than //structures//. In //compounds// neither the number of hydrogens nor the position of some hydrogens are fixed. A //compound// can represent all realistic tautomeric and protonation states (//structures//). Therefore those asymmetry centers that are present only in one potential //structure// (tautomer and protonation state) are not treated as stereogenic at the //compound level//. Similarly, some cis-trans bonds found a //structure// might be missing from the corresponding //compound//.