| Bardeen Research Group
Department of Chemistry | University of California @ Riverside | 501 Big Springs Road | 127-131 CS-1
|UC Energy Institute|
|University of California|
Our main activities are
Education: Since 2000, we've graduated 8 Ph.D., 3 M.S., 18 B.S. students, and continued in the training of 6 post-docs. Our people get great jobs in both academics and industry-read more about them here.
Outreach: In collaboration with Professor Greg Beran and a group of motivated UCR undergrads, we have developed a program that brings chemistry demonstrations to RUSD schools. We've tailored the program to meet the California State Science Requirements for States of Matter, The Water Cycle, and Electricity & Magnetism.
A novel anthracene-9-(1,3-butadiene) derivative, dimethyl-2(3-(anthracen-9-yl)allylidene)malonate (DMAAM) has been synthesized. We have studied its solid-state structure and reactivity and show that a pulse of visible light can induce a dramatic curling motion in crystalline nanowires.
Considerable effort has been devoted to making static coiled nanowires, usually by changing extrinsic factors like the nanowire’s surface chemistry or solvent environment. The coiling observed in this paper is qualitatively different, since it relies on intrinsic chemical changes taking place inside the wire itself, namely the E↔Z photoisomerization. This motion occurs under uniform illumination conditions and illustrates how a molecular crystal nanostructure can undergo a nontrivial and possibly useful geometry change after photoexcitation.
The photoinduced motion is observed for nanowires composed of either (E)- or (Z)-DMAAM and may involve interactions between crystalline reactant and amorphous product phases.
Snapshots showing coiling of an (E)-DMAAM nanowire after ~1 second of light exposure at time 0 s. Scale bars: 10 µm.
This heterometry mechanism, arising from a solid-state unimolecular photochemical reaction, could provide a way to design novel photoresponsive structures that rapidly change their extent in response to visible light.
For more information, check out our paper
Photo-induced Curling of Organic Molecular Crystal Nanowires.
Taehyung Kim et al.
Angewandte Chemie, in press May 2013