Building blocks for recognition-encoded oligoesters that form H-bonded duplexes

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Polymer Science

Background:

• Designing synthetic oligomers for sequence-selective intermolecular duplex formation is challenging due to intramolecular folding.
• Rigid backbones can hinder duplex formation, while flexible backbones require specific recognition units.

Purpose of the Study:

• To develop a novel long-short base-pairing scheme to prevent intramolecular folding in synthetic oligomers.
• To synthesize and characterize monomer building blocks and short oligomers (dimers) with this new design.
• To evaluate the self-assembly properties and sequence-selectivity of the synthesized compounds.

Main Methods:

• Synthesis of monomer building blocks with phenol (D, long donor) and phosphine oxide (A, short acceptor) recognition units.
• Preparation of homo- and hetero-sequence dimers (AA, DD, AD) using ester coupling.
• Characterization of assembly properties in toluene solution using 19F and 31P Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

• AA and DD dimers formed stable, doubly hydrogen-bonded duplexes.
• AD dimers exhibited similar duplex stability.
• No evidence of intramolecular folding was observed in the monomeric state, confirming the effectiveness of the long-short base-pairing scheme.

Conclusions:

• The long-short base-pairing strategy effectively prevents intramolecular folding in synthetic oligomers.
• The developed ester coupling chemistry is suitable for synthesizing longer oligomers.
• This molecular architecture holds promise for creating longer, mixed-sequence oligomers with high-fidelity sequence-selective duplex formation.