Photochemically driven shape changes of crystalline organic nanorods
Photochemically driven shape changes of crystalline organic nanorods
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DOI：
10.1021/ja064535p
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发表时间：
2006-12-20
影响因子：
15
通讯作者：
Bardeen, Christopher J.
中科院分区：
文献类型：
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作者：
Al-Kaysi, Rabih O.;Mueller, Astrid M.;Bardeen, Christopher J.
以Al_2O_3为模板剂，采用溶剂退火法合成了9-叔丁基罗丹酸酯(9-TBAE)纳米棒。棒由微米级的晶区组成，紫外光诱导[4+4]光二聚，导致棒轴线上均匀15%的膨胀。这与随机的9-TBAE晶体形成对比，后者在相同的条件下解体。透射电子显微镜、原子力显微镜以及单体和光二聚体的X射线晶体结构的比较都为基于晶体到晶体的光反应导致分子体积增加的机制提供了证据。很可能是纳米棒中的高表面体积比提供了较大晶体中所没有的应变缓解途径。使用较短波长的光来光解二聚体来逆转反应的初步尝试只取得了部分成功。这些结果表明，晶态有机纳米结构可能提供了一种在纳米尺度上将光化学能转化为机械运动的有效途径。
Nanorods composed of 9-tert-butylanthroate (9-TBAE) are synthesized using an Al2O3template and solvent annealing. The rods consist of micron-scale crystalline domains, and UV light induces a [4 + 4] photodimerization that results in a uniform 15% expansion along the rod axis. This is in contrast to random 9-TBAE crystals, which disintegrate under the same conditions. Transmission electron microscopy, atomic force microscopy, and comparison of the X-ray crystal structures of the monomer and photodimer all provide evidence for a mechanism based on a crystal-to-crystal photoreaction leading to an increase in molecular volume. It is likely that the high surface-to-volume ratio in the nanorods provides a strain relief pathway that is absent in larger crystals. Preliminary attempts to reverse the reaction using shorter wavelength light to photodissociate the dimers were only partly successful. These results suggest that crystalline organic nanostructures may provide an efficient way to transform photochemical energy into mechanical motion on the nanometer scale.