Reasearch On The Self-Assembly Behavior Of Alkyne Derivatives And The Photochemicak Reactions

Supramolecular self-assembly, as an important concept of the bottom-up strategy, has been known as the best way to prepare novel nano-strutures or nano-devices. Scanning tunneling microscopy (STM) has proven to be a strong technique to monitor and characterize the behavior of supramolecular self-assembly at the atomic level.In this thesis, we focus on the self-assembly of organic functional molecules which containing acetylenic groups on liquid-solid or gas-solid interface by employing STM as the main research technique. The main conclusions are as following:(1) We first focused on the self assembly behaviors of diacetylenic acid compounds with different chain lengthes at the 1-phenyloctane/graphite interface. The results showed the molecules tend to form similar assemblies for the molecules with similar molecular structures. Additionally, the position of the functional groups had a great influence on the assembly structure of the molecules. If the distance between acetylenic group and carboxyl group was too short for diacetylenic acid molecules, they will form parallel structure with the alkyl chain on one side interdigitated. Otherwise, they tended to form a new structure with the alkyl chains on both sides in a parallel arrangement in head to head and tail to tail way, when the distance between acetylenic group and carboxyl group was long enough.(2) On the basis of the above research, we further studied the photo-polymerization reactions of diacetylenic acid under UV irradiation. The assembly structures formed before and after irradiation were compared, their similarities and differences were discussed. The results showed that the structure of the molecules had a main effect on the arrangement. The length of alkyl chains can also have certain effect. For example, under certain external triggers, like the same intensity and same irradiation time of the UV light, the efficiency of photo-polymerization reactions was found to be proportional to the length of alkyl chains. It should be noted that photo-polymerization reaction was also sensitive to temperature, intensity of the irradiation light and other factors.(3) We commenced an initial research on the assembly behaviors of amine triazine derivatives containing acetylene groups on highly oriented pyrolytic graphite surface. The functional groups in the molecules played an important role in forming the final arrangement. For example, a parallel structure with big cavities can only be formed by molecules involving acetylene bond. The number of functional groups can also influence the assembly behaviors. The parallel structure or parallel arrangement with the hexagonal cavities could be selectively formed depending on the number of functional groups in molecules.