§Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany.
ACS Nano. 2015 May 26;9(5):5544-50. doi: 10.1021/acsnano.5b01658. Epub 2015 Apr 15.
We use the electric field in a scanning tunneling microscope to manipulate the transition between open and close packed 2D supramolecular networks of neutral molecules in nonpolar media. We found that while the magnitude of the applied field is not decisive, it is the sign of the polarization that needs to be maintained to select one particular polymorph. Moreover, the switching is independent of the solvent used and fully reversible. We propose that the orientation of the surface dipole determined by the electric field might favor different conformation-depended charge transfer mechanisms of the adsorbates to the surface, inducing open (closed) structures for negative (positive) potentials. Our results show the use of local fields to select the polymorphic outcome of supramolecular assemblies at the solid/liquid interface. The effect has potential to locally control the capture and release of analytes in host-guest systems and the 2D morphology in multicomponent layers.
我们利用扫描隧道显微镜中的电场来操纵非极性介质中中性分子的开放和关闭二维超分子网络之间的转变。我们发现，虽然所施加电场的大小不是决定性的，但需要保持极化的符号来选择一种特定的多晶型物。此外，这种转变不依赖于所使用的溶剂，而且是完全可逆的。我们提出，电场决定的表面偶极子的取向可能有利于吸附剂到表面的不同构象依赖性电荷转移机制，从而诱导对负（正）电势的开放（闭合）结构。我们的结果表明，可以使用局部场来选择固态/液态界面上超分子组装的多晶型结果。该效应有可能在主体-客体系统中局部控制分析物的捕获和释放，以及多组分层中的二维形态。
