The Study Of Molecular Recognition Of Arylene Ethynylene Macrocycles At Solid/Liquid Interface

Scanning tunneling microscopy （STM） has atomic resolution and goodenvironment adaptability, thus became one of the important tools for nano science andtechnology, surface chemistry and surface physics research since its invention.Supramolecular self-assembled structures at the solid/liquid interface especially thosewith nanosize pores has attracted much attention due to its potential applications suchas nanotemplate and nanoreactors.Recognition and selection are of fundamental importance for the hierarchicalassembly of supramolecular systems. By introducing functional groups into themolecules functionalization of the networks can also be achieved, which havepotential application for the surface modification of material and the production ofhigh-performance materials. Nanostructures of high complexity at surfaces can befabricated using appropriately designed building blocks, under ultrahigh vacuumconditions （UHV）, in ambient conditions or at liquid-solid interfaces, by tuning thehierarchical intermolecular interactions. So self-recognition and self-selectionbetween building blocks is very important for the self-assembly of hierarchicalsupramolecular system. The recognition and selection events enable efficient errorcorrection and healing in redundant mixtures.In this thesis we have studied the recognition of AEMs with the DBA-OC₁₂andbisDBA-Cn molecules at interface. The DBA-OC₁₂molecule has identical alkoxysubstituents as the AEMs. The two kinds of molecules were mixed in certain ratio （1:1）and applied on the HOPG surface. Using STM we studied the assembling behavior ofbinary mixtures of DBA-OC₁₂/AEM-B and DBA-OC₁₂/AEM-N andbisDBA-Cn/AEM-B and bisDBA-Cn/AEM-N under different concentration. Wefound that the DBA-OC₁₂/AEM-B and DBA-OC₁₂/AEM-N show a very efficientrecognition behavior at the TCB/graphite interface, and the recognition efficiencyincreases with the reduction of solution concentration. Steric hindrance showed noobvious effects on the molecular recognition behavior between DBA-OC₁₂and AEMs.The molecular recognition behavior is based on the intermolecular interactionbetween alkoxy chain. The DBA-OC₁₂interact through the2+2interact betweenalkoxy chains and AEM-B and AEM-N in a1+1style. The interaction betweenDBA-OC₁₂and AEM-B or AEM-N is2+1style. So the efficient recognition betweenDBA-OC₁₂with AEM-B and AEM-N indicates that2+1is more favorable incompare with2+2and1+1. To test this hypothesis we also studied the assemblingbehavior of binary mixtures of bisDBA-Cn/AEM-B and bisDBA-Cn/AEM-N. ForbisDBA the alkyl chain can interact either in a form of1+1,2+2, or2+1, so weexpect that the recognition efficiency should be lower than that for DBA-OC₁₂. Theexperimental results are consistent with our hypothesis.