Head-to-Head Linked Double Calix[4]arenes: Convenient Synthesis and Complexation Properties

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Analytical Chemistry

Background:

• Calixarenes are versatile macrocyclic compounds with tunable properties.
• Developing selective receptors for metal ions is crucial for sensing and separation technologies.
• Functionalization of calixarene scaffolds enables the creation of complex molecular architectures.

Purpose of the Study:

• To synthesize and characterize novel "head-to-head" linked double calix[4]arenes.
• To investigate the complexation behavior of these new receptors with silver(I) ions.
• To evaluate the selectivity of the synthesized receptors for silver(I) ions.

Main Methods:

• Synthesis of double calix[4]arenes via functionalization at specific positions.
• X-ray crystallography for structural elucidation of the modified double calix[4]arene.
• Spectroscopic methods (e.g., NMR) to confirm structure and binding.
• Determination of complexation constants (K(ass)) using solution-phase methods.
• Supported liquid membrane (SLM) transport experiments for selectivity studies.
• Chemically modified field-effect transistor (ChemFET) measurements for ion sensing.

Main Results:

• Nearly quantitative yield achieved for the synthesis of "head-to-head" linked double calix[4]arenes.
• X-ray structure confirmed the expected molecular architecture.
• High binding affinity for silver(I) ions demonstrated (K(ass) = 9.5 x 10(5) M(-)(1) in CDCl(3)).
• Selective complexation of silver(I) ions was confirmed through SLM transport and ChemFET measurements.

Conclusions:

• The novel "head-to-head" linked double calix[4]arenes are readily synthesized and possess a well-defined structure.
• These macrocyclic receptors exhibit strong and selective binding towards silver(I) ions.
• The findings suggest potential applications in silver ion sensing and separation technologies.