Folding and duplex formation in mixed sequence recognition-encoded m-phenylene ethynylene polymers. Issue 30 (6th July 2021)

• Record Type: Journal Article
• Authors: Iadevaia, Giulia; Swain, Jonathan A.; Núñez-Villanueva, Diego; Bond, Andrew D.; Hunter, Christopher A.
• Is Part Of: Chemical science. Volume 12:Issue 30(2021)
• Page Start: 10218
• Page End: 10226
• Publication Date: 2021-07-06
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d1sc02288a
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : One pot oligomerisation reactions give access to families of oligomers that allow facile analysis of folding propensity and assessment of suitability for sequence-selective duplex formation. Abstract : Oligomers equipped with complementary recognition units have the potential to encode and express chemical information in the same way as nucleic acids. The supramolecular assembly properties of m -phenylene ethynylene polymers equipped with H-bond donor (D = phenol) and H-bond acceptor (A = phosphine oxide) side chains have been investigated in chloroform solution. Polymerisation of a bifunctional monomer in the presence of a monofunctional chain stopper was used for the one pot synthesis of families of m -phenylene ethynylene polymers with sequences AD n A or DA n D ( n = 1–5), which were separated by chromatography. All of the oligomers self-associate due to intermolecular H-bonding interactions, but intramolecular folding of the monomeric single strands can be studied in dilute solution. NMR and fluorescence spectroscopy show that the 3-mers ADA and DAD do not fold, but there are intramolecular H-bonding interactions for all of the longer sequences. Nevertheless, 1 : 1 mixtures of sequence complementary oligomers all form stable duplexes. Duplex stability was quantified using DMSO denaturation experiments, which show that the association constant for duplex formation increases by an order of magnitude for every base-pairing interaction added to the chain, from 10 3 M −1 for ADA·DAD to 10 5 M −1 for ADDDA·DAAAD . Intramolecular folding is the major pathway that competes with duplex formation between recognition-encoded oligomers and limits the fidelity of sequence-selective assembly. The experimental approach described here provides a practical strategy for rapid evaluation of suitability for the development of programmable synthetic polymers.