Hello dear, the unique interaction type is trough hydrogen bond, because this group is not reactive.

Dear Shu,

Isoindigo is an electron-deficient acceptor and can undergo polymirization when reacted with 3,4-ethylenedioxythiophene as the electron-rich donor. However, the polymirization reaction occurs on its phenyl ring and there is no direct role to the amide carbonyl group in the polymirization,

For more information, please use the following links:

http://pubs.acs.org/doi/abs/10.1021/ja206610u

http://pubs.acs.org/doi/abs/10.1021/cm300117x

http://onlinelibrary.wiley.com/doi/10.1002/pola.27328/abstract

http://onlinelibrary.wiley.com/doi/10.1002/adma.201304945/abstract

http://pubs.rsc.org/en/Content/ArticleLanding/2013/PY/c3py00341h#!divAbstract

Hoping this will be helpful,

Rafik

Thank you very much for solving my doubt. TQ