Limited option for the drawing of non-determined _relative_ stereochemistry

[MichelML]

Is your feature request related to a problem? Please describe. Limited option for the drawing of non-determined relative stereochemistry

Describe the solution you'd like In addition to the 'up" and "down" wedged bonds to define absolute stereochemistry (second and forth in the picture), it would be nice to have the bold and dashed "bar bonds" for the drawing of non-determined relative stereochemistry (first and third in the picture):

Additional context Suggested by my computational chemist colleague @Fransu86

[AlexanderSavelyev]

Is it correct that such stereo are used to specify the "boat" like structures? Ketcher supports the MDL (CTfile) format stereochemistry. And I'm not able to find the appropriate type for the bonds inside the CTfile specification. @MichelML please inform if it is ok to keep such bond types only for ket format - it means one will not be able to copy it to other editors?

[Fransu86]

Hi @AlexanderSavelyev, The tick bar bonds are used to refer to relative configuration whereas wedged bonds refers to absolute stereochemistry. For example, you may have two substituents on a ring in a cis conformation but as a mixture of enantiomers. In that case the two substitutions would be written using the tick bar bonds. This type of depiction is purely graphical and, as you mention, it does not have a proper stereochemical meaning and it is usually not compatible with any molecular format. For example, in other sketchers you may draw a molecule with those bonds, but when the drawing is exported, let's say, in MOL format, the sketcher automatically converts the tick bar bonds into simple bonds. This type of representation is more useful when presenting data (e.g. powerpoint, technical report) so it would be nice to have the option to be able to draw a molecule with these bonds format, even if they will be "removed" when exporting the molecule in other formats.

[MichelML]

Thanks for the clarifications @Fransu86 :pray:

Maybe to recap in a nutshell:

• minimally support the requested bond depiction while drawing
• support these bond types in the ket format
• for formats not supporting them, follow this conversion convention (potentially with a warning right before saving ):
  • bold bond --> simple bond
  • bold dashed bond --> simple bond

The conversion convention is what ChemDraw does apparently (according to @Fransu86 ) .

Would that make sense @AlexanderSavelyev @Fransu86 @evgeniiFrolov1 ?