Influence of isomeric phthaloperinone monomers on the formation of π-dimers and σ-bonded segments in electrochemically-crosslinked products

A mixture of three constitutional isomers containing terminal reactive phthaloperinone units was obtained by the condensation of 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) with 1,8naphthalenediamine. Both terminal units underwent an addition reaction via electrochemical oxidation and subsequent reduction at the perimidine core and isoindolinone, respectively, to create a multidirectional crosslinked product. The course of electropolymerization depended significantly on the isomer used, which was related to the intermediate products formed during electrooxidation: pi-dimers formed in the precursor solution with stronger pi-pi interactions between radical cations and/or products containing pi-conjugated segments: bis-isoindolinone, bis-perimidine (bonded via 3/4 and 3 ' /4 ' positions) and protonated sigma-bonded bis-perimidine via 1/6 and 1'/3'/4'/6' positions, where hydrogen bonds stabilized these latter adducts and prevented their deprotonation. The polymers were characterized by a mixed structure, which had different effects on the long-range interactions, stability of hydrogen bonds providing a redox center located on the protonated dicationic bis-perimidine segment underwent reversible reduction to stable radical cation. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A mixture of three constitutional isomers containing terminal reactive phthaloperinone units was obtained through condensation reaction, leading to the formation of multidirectional crosslinked products. The electropolymerization process was influenced by the isomer used, which was related to the intermediate products formed during electrooxidation. The study highlighted the impact of intermediate products on the final structure and stability of the products.