Allosteric P═O-based receptors for dicarboxylic acids

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Host-Guest Chemistry

Background:

• Crown ethers are known for their ability to bind cations.
• Phosphorus-oxygen (P═O) containing compounds can act as receptors.
• Dicarboxylic acids present a unique binding challenge due to their two acidic groups.

Purpose of the Study:

• To synthesize novel P═O-disubstituted receptors functionalized with crown ethers.
• To investigate the binding properties of these receptors towards dicarboxylic acids.
• To explore the impact of cationic effectors on the receptor-dicarboxylic acid interaction.

Main Methods:

• Synthesis of P═O-disubstituted compounds appended with various crown ethers (4-, 5-, 6-, and 8-membered rings).
• Binding studies using techniques to quantify the affinity of receptors for oxalic and malonic acids.
• Investigation of allosteric effects by introducing cationic species (e.g., Li+) into the crown ether cavity.

Main Results:

• The synthesized receptors exhibited high binding affinities for dicarboxylic acids, specifically oxalic and malonic acids.
• The presence of different crown ether ring sizes influenced the binding strength.
• A notable positive allosteric effect was observed upon cation binding (e.g., Li+) within the crown ether, enhancing dicarboxylic acid binding by up to a relative affinity (Krel) of 7.

Conclusions:

• Novel P═O-disubstituted receptors incorporating crown ethers are effective hosts for dicarboxylic acids.
• The receptor's binding affinity can be modulated by the crown ether size and the presence of cations.
• This work demonstrates a strategy for developing allosterically regulated host-guest systems for enhanced molecular recognition.