Sequence-Modification in Copoly(ester-Imide)s: A Catalytic/supramolecular Approach to Writing/reading Copolymer Sequence-Information

Catalytic ester-interchange reactions, analogous to mutation and recombination, allow new sequence-information to be written, statistically, into NDI-based poly(ester-imide) chains. Thus, insertion of the cyclic ester cyclopentadecanolide ("exaltolide") into an NDI-based homopolymer, and quantitative sequence-exchange between two different homopoly(ester-imide)s, are catalysed by di-n-butyl tin(IV) oxide. Emerging sequences are identified at the triplet and quintet levels by ¹H NMR analysis, using supramolecular complexation of pyrene-d₁₀ at the NDI residues to amplify the separation of resonances associated with different sequences. In such systems, pyrene is able to act as a "reader-molecule" by generating different levels of ring-current shielding from the different patterns of supramolecular binding to all the NDI-centred sequences of a given length.