Two-Dimensional Crystal Engineering Of Alkynyl Modified Perylene Imide Derivatives At Solid-Liquid Interface

Crystal engineering of organic semiconductors at the interface have been attracting much attention since their potential applications in nanoelectronics and devices.Scanning tunneling microscopy（STM）opens up the possibility of studying two-dimensional crystals with atomic scale resolution.In addition,the chirality of single molecules,the chirality of two-dimensional nanopatterns,and the interlaminar chirality with respect to solid substrates can be observed in real time using STM technology.One of the most challengeable problems is how to finely control the twodimensional chirality of molecules at the solid substrate level,and how to realize the tunable crystal growth from two-dimensional to three-dimensional is also a great challenge in crystal growth research.Here,the interfacial assembly of three bulky stereoscopic perylene bisimide（PBI）derivatives composed of two PBI units connected by alkynyl group,namely PEP,PBP and PHP,at the 1-phenyloctane-highly oriented pyrolytic graphite（HOPG）interface was investigated.The assembled structure was characterized by scanning tunneling microscope under ambient conditions.It was found that two totally different kinds of ordered dense packing patterns on HOPG was revealed by STM image among these molecules with the same PBI nucleus and different length of alkynyl group chains.At the same time,the molecular chirality at the two-dimensional interface including the nanopattern chirality and monolayer chirality was also investigated in detail.The pattern packing and the two-dimensional chirality depends on the linker number of alkynyl groups.Elongated alkynyl linker group could contribute to the generation of threedimensional layer growth on HOPG.The ordered arrangement mechanism of molecules at two-dimensional interfaces was explained by molecular mechanics and dynamics.By exploring the relationship between the molecular structure,the structure of two-dimensional nanocrystals and chirality at the two-dimensional interface,we provide a theoretical basis for the preparation of molecular electronics,sensing,optoelectronics and other nano-devices,and also provided a promising strategy for the development of nanoelectronics and other nano-devices based on multilayer growth on solid substrate.