Self-assembly Of Carbon Atoms Line

This paper reports the self-assembling of carbon atom wires (CAWs). CAW-thiols produced were characterized by FTIR and RAMAN; the self-assembling process was investigated in situ by scanning tunneling microscopy (STM), electrochemical quartz crystal microbalance (EQCM), and electrochemical approaches; properties and potential applications of the orderly assembled film were studied by use of cyclic voltammetry (CV), high resolution transmission microscopy (HRTEM), Raman spectroscopy, electron energy loss spectroscopy (EELS), and the contact angle measurements.Thiol-carbon-atom-wires were synthesized by use of condensation between the carboxylic acid group at the ends of CAWs, treated by concentrated nitric acid, and the amino-group in 2-aminoethyl mercaptan. The reaction progress and some reaction conditions concerned, such as reaction time, reaction temperature and the amount of triethyl amine added, were investigated by FT infrared (FT-IR) and RAMAN spectroscopy. No change in the characteristic carbon chains of CAWs was detected during the condensation process.By use of STM in situ, we clearly observed that, at the beginning of assembling, the thiol-CAWs lied on Hie electrode surface due to the presence of much unoccupied position; and, as more and more thiol-CAWs assembled, the molecules were forced to stand up on the electrode surface. In addition, the electrochemical probe species Fe(CN)₆^3- was applied and the change of differential capacitance of self-assembled monolayer was measured to establish the kinetic assembling steps: firstly, the quick self-assembling at the beginning, and, secondly, slow self-modification for the orderly oriented structure in the subsequent time of self-assembling.With the help of EQCM, the effect of electrode potential on the self-assembling was investigated as well. The fact that more positive electrode potential could speed up the progress of self-assembling implies the high density of electron cloud around the sulfur atom in CAW-thiol molecules. By calculation with the Sauerbrey's equation, the mass of CAW-thiols assembled on gold at the open-circuit potential is 621 ng·cm^-2.The features of integration, steadiness and close packing of the self-assembled CAW-thiol film were revealed by the electrochemical measurements and the HRTEM images.By use of the self-assembly approach reported in the paper, CAWs can be, not only orderly oriented, but also enriched and purified from its pristine pyrolytic product, as hinted from the experimental results of Raman and electron energy loss spectroscopy. The measurements of electrochemistry and contact angle showed that the ends of carbon-chains of CAWs could be linked to various functional groups, and thus the self-assembled films with different surface properties could be obtained, offering possibilities in many potential applications for CAWs.