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Single-Site Binding of Pyrene to Poly(ester-Imide)s Incorporating Long Spacer Units: Prediction of NMR Resonance-Patterns from a Fractal Model

revised on 09.07.2020, 14:07 and posted on 10.07.2020, 05:38 by Marcus Knappert, Tianqi Jin, Scott D. Midgley, Guanglu Wu, Oren Scherman, Ricardo Grau-crespo, Howard Colquhoun
Co-polycondensation of the diimide-based diols N,N'-bis(2-hydroxyethyl)hexafluoro-isopropylidene-diphthalimide, (HFDI), and N,N'-bis(2-hydroxy-ethyl)naphthalene-1,4,5,8-tetracarboxylic-diimide, (NDI), with aliphatic diacyl chlorides ClOC(CH2)xCOCl (x = 5 to 8) affords linear copoly(ester-imide)s. Such copolymers interact with pyrene via supramolecular binding of the polycyclic aromatic molecule at NDI residues. This results in upfield complexation shifts and sequence-related splittings of the NDI 1H NMR resonances, but gives a very different resonance-pattern from the corresponding copolymer where x = 2. Computational modelling of the polymer with x = 5 suggests that, in this system, each pyrene molecule binds to just a single NDI residue rather than to an adjacent pair of NDI's in a tight chain-fold ("dual-site" binding) as found for x = 2. The new single-site binding model enables the pattern of 1H NMR resonances for copolymers with longer spacers (x = 5 to 8) to be reproduced and assigned by simulation from sequence-specific shielding factors based on the fractal known as the fourth-quarter Cantor set. As this set also enables an understanding of dual-site binding systems, it evidently provides a general numerical framework for supramolecular sequence-analysis in binary copolymers.


EU Marie Sklodowska-Curie ITN, Euro-Sequences, grant number 642083

Leverhulme Trust, Emeritus Fellowship, grant number EM-2018-0161/4

ERC Consolidator Grant, CAM-RIG, 726470

EPSRC programme grant, number EP/L027151/1


Email Address of Submitting Author


University of Reading



ORCID For Submitting Author


Declaration of Conflict of Interest

There are no conflicts of interest to declare.

Version Notes

Email address added to MS and ESI