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A Double Helix of Bent Molecular Dimers

Simple bent molecules like CB7CB shown in the image perform some seemingly miraculous tricks when packed together to make a liquid. Because the molecular ends and middles attract each other, the molecules spontaneously knit themselves together into double stranded chains many units long, like the twisted rope in the graphic. Although the chains are transient, constantly dissolving and reforming, they sense each other's presence and perform a collective dance in which they all adopt the same helical twist.   Dynamic simulations, which can carry out the dance at the molecular level on a computer, show the molecules in action, the image capturing the instantaneous arrangement of about 400 molecules. Images like these reveal the molecular chains forming,  packing together, filling space, and cooperatively reforming into a single helical structure having the same handedness everywhere.  Understanding such self-assembly is key to  creating new applications for soft materials like liquid crystals and polymers.

Broader Impacts – Simple bent molecules like CB7CB shown in the image perform some seemingly miraculous tricks when packed together to make a liquid, spontaneously knitting themselves together into double stranded chains many units long, like the twisted rope in the graphic. Understanding such self-assembly is key to  creating new applications for soft materials like liquid crystals and polymers.

This highlight and associated research was supported by NSF through the University of Colorado Materials Research Science and Engineering Center, DMR 1420736.