Apr 8, 2016
Xing Jiang
Graduate student Xing Jiang (Garcia-Garibay group) (pictured) is the lead author of the paper featured in Chemical and Engineering News (C&EN).
The paper titled “Crystal Fluidity Reflected by Fast Rotational Motion at the Core, Branches, and Peripheral Aromatic Groups of a Dendrimeric Molecular Rotor” was published in the March 14, 2016 issue of the Journal of the American Chemical Society (J.A.C.S.).
The co-authors include Prof. Miguel Garcia-Garibay and several of his other current and former group members:  Dr. Zachary J. O’Brien (Ph.D. ’12 Chemistry), graduate student Lan Huong Lai, Jeffrey Buenaflor (B.S. ’10), and Colleen Tan (B.S. ’10).  Prof. Kendall Houk and his graduate student Song Yang (Houk group), and Dr. Saeed Khan, MIC X-Ray Diffraction Staff Scientist, were also co-authors on the paper.
From Chemical and Engineering News (C&EN) (by Jyllian Kemsley):
Molecule spins in its crystal
Phenyl rings of dendrimeric species rapidly rotate in fluidlike crystal, could have applications in molecular machines
Envision a crystalline material and you might think of atoms holding static positions within a regular molecular lattice. A new dendrimeric molecular rotor represents another extreme: In crystalline form, the molecule’s aliphatic framework stays stationary, but its 25 phenyl rings rapidly rotate (J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.6b01398). A team led by Xing Jiang, Miguel A. Garcia-Garibay, and Kendall N. Houk of UCLA constructed the molecule (shown), which has a phenylene core connected on each end to a triphenylpropynyl group. Each of those six phenyl rings in turn connects to another triphenylpropynyl group. The molecule consequently has three types of phenyl rings: one core phenylene, six branch phenylenes, and 18 peripheral phenyls. X-ray, NMR, and molecular dynamics data show that crystals of the compound are loosely packed and each of the three kinds of phenyl rings may rotate independently of the others. Within a particular set of phenyl rings, however, the motion may be coordinated. In a set of three branch phenylenes, for example, one ring may rotate while the other two oscillate, or all three rings may rotate synchronously. The molecule could find use in molecular machines.
To learn more about their research visit the Garcia-Garibay group website and the Houk group website.