Bendy Crystals Are Back: Watch Two More Surprising Examples in Action

Earlier this year, we took a look at molecular crystals that could bend without breaking. If you thought that was unusual behavior for a crystal, we have two more studies that offer examples of how dynamic crystalline materials can challenge our expectations. One of these crystals appears to slither like a snake as it transforms from one form to another, and the other bends so far that its ends can nearly touch while remaining intact!

The ACS Headline Science team gets up close and personal with both crystals’ bendy behavior in this video:

A crystal that moves like a snake during a phase transition

Crystals may look static, but some can undergo dramatic structural changes. In a study published in the Journal of the American Chemical Society, researchers investigated a molecular crystal that transitions between two crystal forms when heated. As the molecules rearrange into a different packing pattern, the crystal deforms in a striking snakelike motion that can be observed under a microscope.

To better understand how this transformation occurs, the researchers captured crystals in a partially transformed state and examined the boundary between the two crystal phases. Their results provide a detailed look at how a single-crystal-to-single-crystal transition progresses through a dynamic crystal, helping to explain the mechanism behind its unusual motion.

This crystal bends so far it acts like a molecular spring

Most crystals crack when bent. But researchers reporting in Crystal Growth & Design created a series of coordination polymer crystals that do something very different: they flex and then return to their original shape. One crystal achieved an elastic bending strain of 4.27%, among the highest reported for this class of material. The team traced that flexibility to the architecture of the polymer chain itself, which contains interconnected eight-membered ring structures that can accommodate mechanical stress more effectively than related designs. The findings highlight how the architecture of a crystal can influence its mechanical properties and may help inform the design of future flexible coordination polymer crystals.

Watch more Headline Science on YouTube!

The video above is brought to you by the ACS Science Communications team. To watch more exciting videos and shorts covering some of the latest research in ACS journals, visit the Headline Science page on YouTube.

Video credits:
Written and produced by Anne Hylden
Editing and animations by Janali Thompson
Narrated and hosted by Anne Hylden
Series produced by Vangie Koonce, Anne Hylden, Andrew Sobey, Janali Thompson, Darren Weaver, and Jefferson Beck
Executive produced by Matthew Radcliff
Research videos by Shu-wen An, Ph.D., Durga Prasad Karothu, Ph.D., Emmanuele Parisi, Ph.D., and Roberto Centore, Ph.D.

Explore related articles from ACS journals:

The Hidden Rules of Bendable Crystals: Quantifying the Energetics of Plastic Deformation at the Molecular Level
Aleksandr S. Dubok and Denis A. Rychkov*
DOI: 10.1021/acs.cgd.5c01744

Flexible Organic Single Crystals with Unconventional Negative Photoconductivity for Intelligent Security Systems
Prodipta Samadder, Charanjeet Singh, Romy Garg, Abhilasha Rani Goel, Subash Chandra Sahoo, Kaushik Parida*, and Prakash P. Neelakandan*
DOI: 10.1021/jacs.6c08011

Photoswitchable Flexible-Brittle Transition with Reversible Cracking and Healing in a Photochromic Crystal
Ryo Nishimura*, Jun Fukuchi, Yuichi Hirai, Takahito Ohmura, Haruki Sugiyama, and Masakazu Morimoto
DOI: 10.1021/jacs.6c01187

Comprehensive Structure–Property Mapping of Tuned Mechanical Flexibility in Organic Cocrystals
Saikat Mondal*, Swayam Prakash, Birte Riechers, Robert Maaß, Franziska Emmerling*, and Biswajit Bhattacharya*
DOI: 10.1021/acs.cgd.5c01550

Superflexible Fluorescent π-Conjugated Organic Crystals: Synergistic Mechanical-Optical Properties and Molecular Engineering Insights
Chunyan Zhang, Jiayao Li, Feiqiang He, Zhi Gao, Yijing Xiang, Limin Zhou, Li Xu, Jerry. Y. Y. Heng, Yifu Chen, Shichao Du, and Jinbo Ouyang*
DOI: 10.1021/acs.cgd.5c01167