Solid materials have traditionally been seen as rigid and immovable. However, scientists are challenging this notion by exploring the incorporation of moving parts into solids. This groundbreaking research opens up possibilities for the development of innovative materials, such as amphidynamic crystals. These crystals combine both rigid and mobile components, allowing for control over their properties by manipulating molecular rotation within the material.
One of the major challenges in achieving motion in crystals, and solids in general, is the densely packed nature of their structure. This hampers dynamic motion, especially for molecules of larger sizes. However, a team of researchers led by Associate Professor Mingoo Jin from the Institute for Chemical Reaction Design and Discovery (WPI-ICReDD) at Hokkaido University has successfully tackled this obstacle.
In a groundbreaking study published in the journal Angewandte Chemie International Edition, the team achieved a size record for dynamic motion in crystals. They demonstrated the largest molecular rotor ever functional in the solid-state. This notable achievement was made possible by utilizing the molecule pentiptycene, which boasts a diameter nearly 40% larger than previous rotors in the solid-state.
Enabling the rotation of such a large molecule required the creation of sufficient free space within the solid. To accomplish this, the researchers synthesized concave, umbrella-like metal complexes, designed to protect the rotor molecule from unwanted interactions with other molecules within the crystal. By attaching a bulky molecule to the metal atom of the stator, they were able to generate enough space to accommodate the giant rotor.
Inspired by Nature
The concept of encapsulating the rotator space using bulky concave-shaped stators was inspired by the observation of an egg. Much like an egg creates ample space and protects its contents with a circular hardcover, the researchers aimed to replicate this feature within a molecule. This ingenuity allowed them to successfully overcome the size limitation barriers in molecular rotation within solids.
The study’s findings expand the realm of what is possible for molecular motion in the solid-state. This breakthrough presents a blueprint for further exploration in the development of amphidynamic crystals. The ability to manipulate molecular rotation opens up opportunities to create new functional materials with unique properties. Associate Professor Mingoo Jin explains, “The pentiptycene rotators utilized in this work have several pocket sites”. These pocket sites hold the potential for a wide range of applications in various industries.
The quest to introduce motion in solid materials has led to a significant breakthrough in the field of molecular rotation. By demonstrating the operational capabilities of the largest molecular rotor in the solid-state, scientists have unlocked new possibilities for the development of advanced materials. The synthesis of amphidynamic crystals and the manipulation of molecular rotation offer potential for the creation of innovative functional materials. This research paves the way for future advancements and opens exciting avenues for exploration in the world of solid materials.
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