Design And Synthesize Of Covalently Linked Organic-amino Acid Conjugated Compounds And SPM Study On Their Self-assembly Behaviors At Interface

Amino acid is the basic unit of protein. It is an essential nutrient in life system. It is of greatsignificance for understanding the structures and properties of proteins if we can reveal theinteractions between structures and properties of amino acids at single molecular level. In thisthesis, firstly, a series of organic-amino acid covalently compounds are designed, synthesized andcharacterized based on organic conjugated molecules as nucleus. Secondly, their molecularself-assembly behaviors are studied by using scanning tunneling microscopy (STM) at interface,and we endeavor to analyze amino acid steric effect introducing organic intermediate nucleus atthe single molecule level studied by STM. Finally, the different factors for self-assemblingstructures have been investigated including solvent, concentration and pH by atomic forcemicroscopy (AFM). The main contents are as follows:(1) Design, synthesize and characterize of covalently linked organic-amino acidconjugated compounds. The different covalently linked organic-amino acid conjugatedderivatives have been synthesized based on perylene-3,4,9,10-tetracarboxylic dianhydride,naphthalene-1,4,5,8-tetracarboxylic dianhydride and L-type amino acids as raw materials, whichhave been characterized by fourier transform infrared spectroscopy (FT-IR), nuclear magneticresonance spectrum (1H NMR) and mass spectrum (MS).(2) Study on molecular self-assembly behaviors of organic-amino acid conjugatedcompounds at interface. The molecular self-assembly nanostructures of covalently linkedorganic-amino acid conjugated derivatives are investigated by STM. The experimental resultsshow that the two-dimensional self-assembly structures of organic-amino acid conjugatedcompounds are different from each other for the different side groups of amino acids.(3) Study self-assembly morphologies of organic-amino acid conjugated compounds atinterface. The sub-molecule self-assembly morphologies of covalently linked perylene-aminoacid and naphthalene-amino acid conjugated derivatives are investigated by AFM. The resultsshow that it is given priority to form nanofibers in perylene derivatives, while formed nanospheresin naphthalene derivatives. It is indicated that the drive forces may be attributed to thehydrogen-bonding interactions of the intermolecular-COOH and π-π stacking interactions ofperylene nucleus and naphthalene nucleus.(4) Modulation of molecular self-assembled structure of organic-amino acid conjugatedcompounds at interface.(a) The self-assembling structures of perylene-tyrosine (NTPD) compound have been modulated by concentration.(b) The self-assembled structures ofperylene-phenylalanine (NPPD) compound have been modulated by three kinds of representativesolvents (ethanol, THF and H2O).(c) The self-assembled structures of perylene-aspartic acid(NAAPD) have been modulated by pH. These results show that their self-assembly behaviors ofamino acid derivatives can be modulated by the different external factors such as solvent,concentration and pH.