Homodiselenacalix[4]arenes: Molecules with Unique Channelled Crystal Structures

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Crystal Engineering

Background:

• Calixarenes are versatile macrocyclic hosts with tunable properties.
• Dynamic covalent chemistry offers efficient routes to complex molecular architectures.
• Selenium-containing macrocycles are of interest for host-guest chemistry and materials science.

Purpose of the Study:

• To develop a synthetic strategy for homodiselenacalix[4]arene macrocycles.
• To investigate the structural and supramolecular properties of these novel compounds.
• To explore the dynamic behavior and conformational flexibility of the synthesized macrocycles.

Main Methods:

• Dynamic covalent chemistry utilizing diselenide linkages.
• Synthesis and characterization of homodiselenacalix[4]arene derivatives.
• Single-crystal X-ray diffraction analysis.
• Molecular modeling for conformational and energetic studies.

Main Results:

• Successful synthesis of homodiselenacalix[4]arene macrocycles with alkoxy or tert-butyl ester groups.
• X-ray analysis revealed structural similarities and supramolecular differences in THF solvates.
• Distinct solvent channel characteristics were observed in different crystal structures.
• A single-crystal-to-single-crystal transformation from 1,3-alternate to 1,2-alternate conformation was documented.

Conclusions:

• Homodiselenacalix[4]arenes can be synthesized via dynamic covalent chemistry.
• The macrocycles exhibit interesting structural and supramolecular features, including solvent channels.
• Conformational flexibility and dynamic transformations are key characteristics of these selenium macrocycles.