Study On Host-guest Interactions In Supramolecular Systems Based On Three Kinds Of Hydrogen Bonds On HOPG Surfaces

In this work,the solid/liquid two-dimensional surface assembled structure constructed by hydrogen bonding is emphatically studied.The adsorption of various organic optoelectronic functional molecules on the HOPG surface is studied by scanning tunneling microscopy（STM）and density functional theory（DFT）calculations.Using guest molecules regulate the assembly of host molecules in order to form a host-guest structure.Then we combine the results to summarize the characteristics and mechanism of molecular assembly on the surface.There are mainly three kinds of hydrogen bonds in this experiment,O-H···O,N-H···O and C-H···N hydrogen bonds.The large-scale ordered arrangement of molecules is obtained,which will facilitate the optimized and controllable assembly of molecular device performance and the development of new nanomaterials.（1）The self-assembly behavior of a porphyrin derivative,5,15-bis（4-carboxy-phenyl）porphyrin（H₂DCPp）,is investigated.There are three pyridine derivative molecules regulate the self-assembled structure formed by the molecule H₂DCPp with in-situ titration method.The addition of the bipyridine derivative Bis Py and the tripyridine derivative TPYB molecule can form a co-assembled structure with H₂DCPp through hydrogen bonds.Another bipyridine derivative molecule BP can form two kinds of co-assembly with H₂DCPp.These co-assembly referred above are constructed by hydrogen bonds and other intermolecular forces that act synergistically to generate a stable structure.（2）Achiral molecule 5’-（4,5-bis（4-carboxyphenyl）-2,5-dihydro-1H-imidazol-2-yl）–（1,1’:3’,1’’-terphenyl）-4,4’’-dicarboxylic acid（BCDTDA）is studied in part 2,which has an imidazole group as the center.Using coronene and three bipyridine molecules regulate the self-assembly of BCDTDA.They are COR,BP,PEBP-C4 and PEBP-C8,respectively.Two kinds of self-assembled structures of BCDTDA molecules in the form of dimers are obtained which result by concentration effects.At lower concentrations,less stable honeycomb structures could be obtained.On the contrary,regular nano-nets are formed at higher concentrations.The addition of COR and BP cannot destroy the dimeric form of hydrogen bonding,but the addition of PEBP-C4 and PEBP-C8 both destroy the dimeric form of BCDTDA.In co-assembly structure of BCDTDA/COR the coronene joins the small cavity formed by the dimer.BP molecules exist between the dimers.PEBP-C4 and BCDTDA form a relay-type co-assembly structure and PEBP-C8form three different assembled structures with the host molecule.And we try three components which contain BCDTDA,COR and BP,but we fail to find a stable co-assembly.（3）The third part of this work we study the self-assembly of two kinds of tripyridine derivative molecules.TPYB molecules can form an assembled structure stably on the HOPG surface.However,PBQD molecules can form two kinds of self-assembly,one is a closely staggered double-folded type,and the other is a relatively scattered self-assembly structure.The number of benzene rings influences the self-assembly behavior of the tripyridine derivatives.The zcy-2-19 molecule effects on their structure is added to the self-assembled structure formed by the two molecules,and form long-range ordered co-assembled structures.zcy-2-19 and TPYB molecules form a hexagonal staggered structure,but zcy-2-19 enters the cavity in the first structure of PBQD in the form of dimer.36 Figurers,9 tables,and 95 references.