Study On The Interface Assembling Of Arylene Ethynylene Macrocycles

STM is a powerful tool for the study of supramolecular structure on the surfaceand at the interface. Using STM as a main method, the effect of molecular symmetry,substitution, substrate and various factors on suface assembling was investigated. Wecan obtain many aspects of information, such as molecular arrangement in theassembling monolayer, orientation and the registration between supramolecular layerand substrate lattice, furthermore we can also obtain information on the dynamicssuch as the rearrangement of molecular domains and so on. Though abundant STMresearches on two-dimensional assembling of functional organic molecules werecarried out, a large number of such works are focused on one-dimensional oligomers.Only in recent years assembling of more complicated olygomers are reported. In thisthesis we chose to study the interfacial assembling of a series of AEM molecules toclarify the effect of steric hindance on the π-conjugated core on molecularassembling structure and study the mechanism of molecular recognition at thesolid/liquid interface.We have designed and synthetized a series of arylene–ethynylenemacrocycles(AEM) with benzene，naphthalene and anthracene as substitutents at the center of thethree edges of the triangular AEM core. These molecules have exactly identicalperiphery alkyl substituents. Nevertheless, because the difference of molecular corestructure, these molecules show different assembly behavior at the TCB/graphiteinterface. Our experiments show that AEM-B and AEM-N form three differentpatterns, respectively, while AEM-A only forms one type of packing. Due to the sterichindrance AEM-N forms significantly different assembling patterns in compare withAEM-B. However, since the effect of steric hindrance created by the naphthalene andanthracene substitutents on the interdigitation of alkyl chains are nearly the same, theassembling structure formed by AEM-A is identical to one of the three patterns ofAEM-N. We have also discovered concentration dependence of the assemblingbehavior of AEMs. However, the packing density of the different patterns of AEM-Band AEM-N are nearly identical, so we can not explain the concentration dependencewith difference in packing density. This is different from that reported previously andneeds to be investigated further.We believe our results will benefit the understanding of mechanism governingthe self-assembling and recognition of molecules at the interface.