Controllable Self-assembly Nanostructure Of Molecular Template With STM Technique

ABSTRACT:With the continuous minimization of electronic devices, molecular templates could regulate nanostructure with high selectivity-responsive. It is important significance for the construction of nanodevices. In this thesis, we have investigated controllable self-assembly of two-dimensional (2D) supramolecular network by scanning tunneling microscopy (STM) and density functional theory calculation. The main results of the thesis are as follows:(1) The molecular template greatly facilitates the efficiency of photochemical reaction on surface. The molar ratio of trans-1,2-bis(4-pyridyl)ethylene (4,4’-bpe) to iso-phthalic acid (iso-pa) was1:1. We constructed the TCDB/2(4,4’-bpe)-2(iso-pa) host-guest system, ultilizing the2D flexible networks of TCDB.4,4’-Bpe molecules first undergo photoisomerization followed by photodimerization on surface with UV irradiation for an appropriate time. However, the4,4’-bpe-iso-pa binary structure was observed only several products of photodimeirzation after irradiation,indicating a much less efficiency of the photodimerization reaction without nanotemplate. The STM results revral that the highly efficiency of photodimerization reaction is attributed to the formation of the "(?)" shaped2(4,4’-bpe)-2(iso-pa) complex in the molecular template. That is to say, this result provides a new approach to studying the photochemical reaction.(2) The molecular template could entrap guest molecules with high selectivity-responsive. Firstly, we fabricated the binary network formed by the tetraacidic azobenzene (NN4A) and trans-1,2-bis(4-pyridyl)ethylene (DPE) on surface. The coronene (COR) as guest molecule is added into these systems, the binary networks collapse and the reconstruction structures of NN4A/COR host-guest systems are subsequently formed. The STM results, as well as DFT calculations revealed that the NN4A/COR system is the energeticaly favourable structure. Secondly, we report that the bipyridine (Bpy) molecule was choosen to regulate the assembling characteristics of silicon phthalocyanines (SiPcs) derivatives. Owning to the special structure of the SiPcs derivative, the aggregation of this molecule can be manipulated by the addition of coordinating axial ligands, forming the "edge-on" oriented assemblies on surface. Thirdly, based on the regid cavities formed by the amine modified hex/oct-atomic ring, several kinds of nanosrrys were fabricated by fulleren co-adsorption on surface.