AUTHOR=Jaynes Tyler J. , Sharafi Mona , Campbell Joseph P. , Bocanegra Jessica , McKay Kyle T. , Little Kassondra , Osadchey Brown Reilly , Gray Danielle L. , Woods Toby J. , Li Jianing , Schneebeli Severin T. 

TITLE=Iterative Exponential Growth of Oxygen-Linked Aromatic Polymers Driven by Nucleophilic Aromatic Substitution Reactions

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2021.620017

DOI=10.3389/fchem.2021.620017

ISSN=2296-2646

ABSTRACT=This work presents the first transition metal-free synthesis of oxygen-linked aromatic polymers by integrating iterative exponential polymer growth (IEG) with nucleophilic aromatic substitution (SNAr) reactions. Our approach applies methyl sulfones as the leaving groups, which eliminates the need for a transition-metal catalyst, while also providing flexibility in functionality and configuration of the building blocks used. As indicated by (i) 1H-1H NOESY NMR spectroscopy, (ii) single crystal X-ray crystallography, and (iii) density functional theory (DFT) calculations, the unimolecular polymers obtained are folded by non-classical hydrogen bonds formed between the oxygens of the electron rich aromatic rings and the positively-polarized C–H bonds of the electron poor pyrimidine functions. Our results not only introduce a transition metal-free synthetic methodology to access precision polymers, but also demonstrate how interactions between relatively small, neutral aromatic units in the polymers can be utilized as a new supramolecular interaction pairs to control the folding of precision macromolecules.