Non-Globular Organic Ionic Plastic Crystal Containing a Crown-Ether Moiety - Tuning Its Behaviour Using Sodium Salts

Area of Science:

• Materials Science
• Crystallography
• Solid-State Chemistry

Background:

• Organic ionic plastic crystals (OIPCs) exhibit positional order and orientational freedom, leading to plasticity, non-flammability, and high ionic conductivity.
• OIPC behavior is common in simple globular molecules but less understood in complex, non-globular structures.

Purpose of the Study:

• To investigate the interactions governing OIPC phase formation in complex non-globular molecules.
• To synthesize and characterize novel non-globular OIPCs incorporating a 15-crown-5 ether moiety.

Main Methods:

• Synthesis of a new family of non-globular OIPCs.
• Characterization of molecular structure and properties.
• Complexation of crown-ether moieties with sodium salts.

Main Results:

• The synthesized 15C5BA molecule did not exhibit OIPC behavior due to its non-globular shape and strong hydrogen bonds restricting motion.
• Complexation with sodium salts and chaotropic anions successfully induced OIPC behavior.
• Anion complexation weakened intermolecular interactions, promoting molecular rotational freedom.

Conclusions:

• Molecular design and specific salt complexation are crucial for achieving OIPC behavior in non-globular molecules.
• Chaotropic anions play a key role in tuning OIPC properties by facilitating molecular motion.
• This study advances the understanding of OIPC formation in complex molecular systems.