Understanding and Controlling Coupled Molecular Motion on Surfaces

在这个由化学部门的大分子、超分子和纳米化学项目资助的项目中，塔夫茨大学的Charles Sykes教授和他的学生正在研究如何将单分子器件耦合到能够执行更高任务的分子机器和分子大小的器件中。这项工作的最终目标是发现构建分子机器和分子大小的设备的设计原则，这些设备可以更容易地与现有技术集成。目标是更好地理解分子运动。分子运动的控制对于设计独特的新应用的新方法至关重要，包括微小的分子大小的泵，传感器和光电子学。为了让更多的人参与到这个项目中来，赛克斯的研究小组在当地的高中做了关于纳米科学的演讲，并展示了新开发的演示。制作了展示项目成果的YouTube视频。该小组在塔夫茨大学和梅德福高中之间开发了一个科学博览会，每年约有300名学生能够与研究生研究人员就他们的科学项目演示进行互动。单分子装置能够执行从机械运动到简单计算的许多功能。然而，由于相互耦合或与电极等接口耦合的困难，它们的效用受到了一定的限制。这个项目采用了一种新的方法，利用分子自组装来生产分子转子的二维晶体阵列，这些晶体阵列显示出相关旋转开关等紧急特性。该阵列由前驱体分子转子与Cu（111）表面的Ullmann反应合成，生成金属有机配合物的二维网络，其中旋转单元可以相互作用。扫描隧道显微镜能够激发单个转子群，并能够研究单个分子转子的重新定向如何影响其邻居。通过研究电压、电流和隧道间隙距离对转子运动的影响，探讨励磁机理。改变前体分子的大小和功能，可以控制转子单元在二维分子晶体中的位置，并能够研究转子间距和角度对相关旋转开关的影响。通过改变转子本身的功能，将探索空间和偶极耦合。最后，手性旋转单元将被引入，作为一种通过闪烁温度棘轮状机制诱导单向旋转的方法。

In this project funded by the Macromolecular, Supramolecular, and Nanochemistry Program of the Chemistry Division, Professor Charles Sykes and his students at Tufts University are investigating ways to couple single molecule devices, already pioneered by his research team with prior NSF funding, into molecular machines and molecular-sized devices capable of performing higher tasks. The ultimate goal of the work is the discovery of design principles for the construction of molecular machines and molecular-sized devices that can more easily integrate with existing technologies. A goal is to gain a better understanding of molecular motion. Control of molecular motion is crucial for the design of new approaches for unique new applications, including tiny molecular-sized pumps, sensors, and optoelectronics. To engage broad audiences in this project, the Sykes research team gives presentations about nanoscienceat local high schools with newly developed demonstrations. YouTube videos featuring the project results are produced. The group has developed a Science Fair between Tufts and Medford High which enables ~300 students per year to interact with graduate researchers about their science project presentations.Single molecule devices are capable of performing a number of functions from mechanical motion to simple computation. Their utility is somewhat limited, however, by difficulties associated with coupling them with either each other or with interfaces such as electrodes. This project takes a new approach using molecular self-assembly to produce 2D crystalline arrays of molecular rotors that display emergent properties like correlated rotational switching. The arrays are synthesized by the Ullmann reaction of precursor molecular rotors with a Cu (111) surface, yielding 2D networks of metal-organic complexes in which the rotary units can interact with each other. Scanning tunneling microscopy enables excitation of the individual rotor groups and the ability to study how reorientation of an individual molecular rotor affects its neighbors. By studying the effect of voltage, current, and tunneling gap distance on rotor motion, the mechanism of excitation will be explored. Altering the size and functionality of the precursor molecules enables control over the placement of the rotor units in the 2D molecular crystals and the ability to study the effect of rotor-rotor spacing and angle on correlated rotational switching. By changing the functionality of the rotor itself, both steric and dipolar coupling will be explored. Finally, chiral rotary units will be introduced as a way to induce unidirectional rotation via a flashing temperature ratchet-like mechanism.