Molecular Rotors Built in Porous Materials

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Nanotechnology

Background:

• Molecules and materials with dynamic structures, particularly those exhibiting rotary motion, are defined as molecular rotors.
• Molecular rotors offer unique properties compared to static counterparts, with potential applications in modulating dielectric response and forming molecular motors.
• Integrating ordered rotary elements into solids is crucial for aligning rotors and fine-tuning interactions, with crystal surfaces and bulk crystals being suitable for 2D or 3D arrangements.

Purpose of the Study:

• To explore the integration of molecular rotors into porous materials for advanced applications.
• To investigate the dynamic behavior and responsive properties of molecular rotors within porous architectures.
• To develop novel materials with tunable dielectric properties and potential for molecular machinery.

Main Methods:

• Incorporation of molecular rotors as structural components (struts) in porous covalent and supramolecular architectures.
• Fabrication of both hybrid and fully organic materials containing molecular rotors.
• Characterization of rotor dynamics, including fast nanosecond motion at low temperatures (below 240 K).
• Investigation of rotor interactions with diffusing chemical species (liquids, vapors, gases) within nanoporous materials.
• Engineering of rotors with strong, noncentrosymmetric dipoles to achieve specific dielectric responses.

Main Results:

• Porous materials with integrated molecular rotors exhibit large free volumes that facilitate rotor motion.
• Molecular rotors can be arranged in various geometries within robust frameworks (stable up to 850 K) and self-assembled materials.
• Fast rotor dynamics (nanosecond regime) are achievable at temperatures below 240 K, enabling solid-state operation at low temperatures.
• Rotor speed can be modulated by guest molecules, leading to the development of guest-sensitive materials.
• Materials with dielectric properties responsive to electric fields have been fabricated, demonstrating potential for altering ferroelectric or antiferroelectric states through dipole reorientation.

Conclusions:

• Porous materials offer a promising platform for incorporating and controlling molecular rotors.
• The dynamic and responsive nature of these rotor-containing materials opens avenues for novel sensors, actuators, and data storage devices.
• Further research into rotor design and integration can lead to advanced materials with tailored dielectric and mechanical functions.