creating custom atom groups

I understand it is quite a though question to pose :

several times I draw structures where chains are involved, for instance :

I see the end group CF3 is supported, but I would like to have  groups -CF2- also like it is for -CH2- for instance, so the structure looks cleaner.

 

so the same way it could look like this :

 this is a drawing to help you understand (not real marvinsketch)

How can I implement such a feature ? 

I tried to define group , but I did not succeed,

Can you suggest something for me to try ? a method to follow , a procedure ?

Thank you very much, for you help.

Hi,

unfortunatelly, the images are not appended correctly to your post so I can not see them.

But I can tell you some words about user defined abbreviated groups.

They are described in the documentation here at the bottom of the page.

The easiest way to create a user.abbrevgroup file that is mentioned, is to draw the s-group in MarvinSketch, and open the Edit->Source dialog. Switch the format in the View menu of the dialog to SMILES->Chemaxon SMILES Abrreviated group, and copy the text.

Create, of open the user.abbrevgroup file in the chemaxon folder in the user home directory, and paste the copied text into the file, Save it, and restart MarvinSketch, now you can access the s-group by typing its name, you have specified.

In the linked document, there is a description about the file format, so if you feel confident, you can create or edit the file with a simple text editor also.

Marvin will use the user.abbrevgroup file in precedence, so you are able to overwrite also the built in groups in this file if you wish.

I hope this helps, if you have further questions, please do not hesitate to ask.

Regards,
Istvan