Synthesis And Properties Of Nitrogen-Doped Polycyclic Aromatic Hydrocarbon Amphiphiles

Hexa-peni-hexabenzocoronene (HBC) consisting of 13 fused benzene rings is a one of representative compounds of the polycyclic aromatic hydrocarbon (PAH). The strong tendency to stack throughπ-πintermolecular interactions of PAHs make it easily self-assemble to form columnar structures, which can be utilized to fabricate nano soft materials with novel optical, electronic or magnetic features. Thus, the PAH derivatives plays a crucial role and occupied an important position in material science. Modificating molecular skeleton of PAH by incorporation with strong electronegativity and small atomic radius heteroatoms is an efficient method to improve the physicochemical properties without changing the molecular mophorlogies greatly, which reveals an unprecedented application prospects.The thesis was devided into two sections as follow:In the first section, three kinds of precusors 13,22 and 26 of nitrogen-doped amphiphilic PAH were designed and synthesized respectively using 5-bromo-2-iodopyrimidine as starting material, and the cyclization reaction conditions of 13,22 and 26 were investigated in detail. When 36 equivalents of FeCl3 was used as oxidant, a novel amphiphilic N-doped PAH 2 was successfully synthesized by dehydrogenative cyclization of corresponding precusor 22 for 4 hrous. Whereas oxidative cyclization of corresponding precursor 13 did not give the desired product, only a by-product with lessened about 10 in molecular weight compared with 13 was obtained. However, the clearfied sturcture could not be confirmed by NMR spectroscopy due to poor solubility of by-product. On the other hand, no reaction occurred when oxidization of 26 with FeCl3 as oxidant. Thus, the oxidation conditions for cyclization of 13 and 26 should be futher explored.In the second section, both the physicochemical properties and the self-assembling behaviors of compound 2 were studied. The essential physicochemical features of 2 were characterized with IR, UV-vis, fluorescence spectrometry, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) measurements, and the self-assembling performances of 2 were investigated in different solvents and temperatures. The results revealed that compound 2 exhibiting the preferable thermostability, and the self-assemblies were formed mainly as spherical shape. Compound 2 showed a goldish-yellow fluorescence in methylene chloride or THF and yellowish-green in toluene, respectively. By adding trifluoroacetic acid (TFA), the fluorescence was gradually quenched. Both UV-vis and fluorescence spectra resulted unstructured nature of peak bands, which suggested that compound 2 didn't exist in monomer, but in dynamic aggregats in these solutions.