Triggering activity of catalytic rod-like supramolecular polymers

Area of Science:

• Supramolecular chemistry
• Organic catalysis
• Polymer science

Background:

• Supramolecular polymers offer tunable properties for catalysis.
• Benzene-1,3,5-tricarboxamides (BTAs) are versatile building blocks for self-assembly.
• Chiral catalysts are crucial for stereoselective synthesis.

Purpose of the Study:

• To develop highly active and stereoselective supramolecular catalysts for aldol reactions in water.
• To investigate the role of temperature and polymer conformation in catalytic activity.
• To explore the influence of proline configuration on stereoselectivity.

Main Methods:

• Synthesis of BTAs functionalized with L- or D-proline.
• Characterization of supramolecular polymer formation and conformation.
• Evaluation of catalytic activity and stereoselectivity in aldol reactions.
• Recyclability and low catalyst loading studies.

Main Results:

• BTAs functionalized with proline exhibit high catalytic activity (TOF up to 27×10⁻⁴ s⁻¹) in water.
• Excellent stereoselectivities were achieved (up to 96% de, 99% ee).
• Catalyst reusability was demonstrated at low catalyst loadings (0.1 mol%) and substrate concentrations (50 mM).
• Temperature-induced conformational changes in the supramolecular polymer correlate with high catalytic activity.

Conclusions:

• Temperature-responsive supramolecular BTAs are effective catalysts for aldol reactions.
• The helical sense of the supramolecular polymer and proline configuration dictate stereoselectivity.
• These findings open avenues for designing efficient and recyclable organocatalysts.