Sequence- and chain-length-specific complementary double-helix formation.

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Molecular Recognition

Background:

• Artificial molecular strands offer tunable properties for self-assembly.
• Designing complementary binding sites is crucial for sequence-specific hybridization.
• Diacetylene linkers and m-terphenyl groups provide structural rigidity and defined spacing.

Purpose of the Study:

• To synthesize artificial sequential strands with specific binding sites (amidine or carboxyl).
• To investigate the sequence-specific hybridization of these strands into double-helical structures.
• To demonstrate the selective formation and isolation of specific molecular assemblies.

Main Methods:

• Stepwise synthesis of m-terphenyl based molecular strands with diacetylene linkers.
• Utilizing circular dichroism and (1)H NMR spectroscopies for structural analysis.
• Employing liquid chromatography for separation and isolation of assembled structures.

Main Results:

• Successfully synthesized dimeric and trimeric molecular strands with amidine (A) or carboxyl (C) groups.
• Demonstrated sequence-specific hybridization to form one-handed double-helical dimers (e.g., AA.CC) and trimers (e.g., AAA.CCC).
• Achieved selective formation and chromatographic isolation of specific double helices, such as AAC.CCA, from complex mixtures.
• Observed precise chain length specificity in the assembly of homo-oligomers (e.g., AAAA.CCCC).

Conclusions:

• Artificial sequential strands can self-assemble into predictable double-helical structures via complementary salt bridges.
• Sequence and chain length specificity are key features of these self-assembly processes.
• The developed methods allow for the selective synthesis and isolation of designed supramolecular architectures.