There are literature(Macromolecules 1995,28, 1180-1196) which claim that aromatic polyimines are electron deficient in nature. However the electron rich Nitrogen group would readily delocalise with conjugated framework to provide electrons to the framework. Then from where does the electron deficient nature arises?
Polyamine refers to a compound that consists of at least two amino groups. It is a highly charged, low molecular weight aliphatic polycation. In the atmospheric corrosion of mild steel, this compound acts as a corrosion inhibitor. Polyamines are also important chelating agents. Five compounds bearing electron-deficient pentafluorophenyl as well as electron-rich (salicylate or indole) aromatic moieties connected by amide or ester linkages were investigated by X-ray diffraction. In the crystals, various interactions (π–π, lone pair–π) between the different aromatic units are important structure controlling factors in addition to the stronger inter- or intramolecular hydrogen bonds induced by the amide and ester moieties. The hydrogen bonding leads to polymeric and macrocyclic assembly of the molecular building blocks. Aromaticity is a property associated with the extra stability of certain types of systems. Fundamentally it arises from having the maximum number of electrons in the bonding molecular orbitals. As we will see, it is not restricted to benzene, substituted benzenes, 6-membered rings or just hydrocarbons.
A versatile method for the post-modification of sulfonated polyimides by charge-transfer (CT) complex formation between electron-deficient naphthalenediimide units in polyimide and electron-rich dihydroxynaphthalene was developed. CT complex hybrid films whose physicochemical properties, such as mechanical strength, differed from those of the original polyimide films were successfully fabricated.
http://www.mhhe.com/physsci/chemistry/carey/student/olc/ch11aromaticity.html
Conference Paper Aromatic polyimides containing naphthalene rings
Article Connecting Electron‐Deficient and Electron‐Rich Aromatics to...
Dear Patnaik.
The aromatic polyimine are electrondeficient in nature. The main causes are mesomeric and inductive effects. The imine group (-C=N-) can withdraw electron
density by resonance as shown in attached ilustration. And this can withdraw electron density weakly by induction or inductive effect.
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