The Assembly And Regulation Of Porphyrins Containing Carboxylic Groups

Porphyrin is a conjugated large ring with 18πelectrons and has special photoelectric effect.The conductivity and semiconducting properties of porphyrin molecules make them suitable for solar cells,molecular sensors,photoelectric devices,etc.The structures,properties and dynamic changes of nanomaterials at the surface and interface are the fundamental factors that determine the performance of molecular devices.Therefore,the self-assembly of porphyrin molecules at the solid/liquid interface has attracted extensive research in recent years.We will focus on the assembly and regulation of porphyrins containing carboxylic groups at the solid/liquid interface in the paper.Scanning tunneling microscope（STM）was used to observe the assembly of porphyrin molecules in real time and in situ,and density functional theory（DFT）was used for theoretical calculation.The main research contents are as follows:（1）The self-assembly of 1,3-isophthalic acid-5-ether-4-tetraphenyl porphyrin（IPETPP）at the 1-heptanoic acid（HA）/highly oriented pyrolytic graphite（HOPG）interface was investigated by STM.The self-assembly of IPETPP was affected by the concentration effect according to the experiments.At a higher concentration,the self-assembly of the porphyrin molecule presents regular rhombus-shaped structure.However,the self-assembly of the molecule appears two kinds of self-assembled patterns at a lower concentration,one is regular flower-like structure,the other is a rectangular cavity structure with short range order.Further investigation by DFT showed that HA did not participate in the self-assembly of the porphyrin molecule.Therefore,concentration effect plays an important role in the self-assembly of IPETPP.（2）Since the self-assembly of IPETPP molecule presents porous network patterns,it has been further explored the host-guest co-assembly with coronene（COR）and C₆₀.On the basis of the rhombus-shaped structure of IPETPP molecule,guest molecule COR with a higher concentration was deposited on the system,the rhombus-shaped structure did not change,and several COR molecules were injected into the rhombus-shaped cavities.Whereas the host molecule template became flower-like pattern when COR with a lower concentration was added on the HOPG,and COR molecules were injected into the small cavities of flower-like structure.When adding into the flower-like template of IPETPP,COR molecules were injected into the small cavities,but no guest molecule injected into the large cavities.When the COR molecule was added to the rectangular cavity pattern of IPETPP,the host template changed,forming a stable host-guest co-assembly system.However,C₆₀ molecules did not co-assemble with IPETPP,which further demonstrated the selective adsorption of host molecules by different guest molecules.（3）The external regulate and control can change the molecular assembly structure,so we further explore the regulation of a series of pyridine molecules on the host molecule IPETPP.The following pyridine derivatives were selected for the study:1,2-di-4-pyridylethene（DPE）,1,4-bis（pyridin-4-ylethynyl）benzene（BPYB）,4,4’-（（1E,1’E）-（2,5-dibutoxy-1,4-phenylene）bis（ethene-2,1-diyl））dipyridine（PEBP-C4）,4,4’-（（1E,1’E）-（2,5-bis（octyloxy）-1,4-phenylene）bis（ethene-2,1-diyl））dipyridine（PEBP-C8）,etc.The IPETPP/pyridines co-assembly structures are successfully obtained,revealing the regulation rules and principles of different pyridine derivatives on the porphyrin molecule.