Preparation And Properties Of Substituted(Poly)Acetylene Chirally Functionalized Graphene

In recent years, chiral polymers have developed rapidly, because of their broad applications in areas such as asymmetric catalysis, enantioselective crystallization and chirally controlled release. Based on our earlier studies concerning chiral helical polymers, we have successfully prepared a variety of optically active materials, like core/shell particles, hollow particles, magnetic particles,(hydro)gels, etc. Such novel materials have large potentials in the fields of biomedicine, catalysis and so on, due to their unique properties. On the other hand, graphene shows remarkable thermal, electrical, mechanical properties and large surface area, so it is considered to be one of the most promising materials recently. Relevant studies demonstrated that graphene-derived materials have a wide range of potential applications in catalysis, adsorbents, sensors, film, life sciences, electronics and other fields. However, application of graphene in the field of chiral science and chiral materials has not been explored deeply yet. Therefore, the main theme of this thesis is to create methods by which to easily and effectively combine synthetic chiral helical polymers with graphene, to form novel chiral functionalized graphene materials. Totally two approaches have been established to prepare chiral graphene hybrid materials.In the first one, optically active helical substituted (co)polyacetylenes containing pendent pyrene groups are prepared, and then they were noncovalently immobilized on the surface of graphene via π-π interactions. The as-prepared chiral graphene hybrids were characterized by UV-vis absorption, circular dichroism, TEM, TGA, FTIR, XRD, Raman and fluorescent spectroscopy techniques. The helical polyacetylenes endowed graphene with the desired optical activity. Also interestingly, the dispersibility of the functionalized graphene in tetrahydrofuran (THF) was remarkably improved due to the presence of the helical polymer chains. The methodology opens new opportunities and serves as a versatile platform toward preparing novel graphene-based materials.In the second technique, we prepared a new propargyl amide (MCA) derived from cholic acid and graphene oxide (GO) bearing-N3functionality. Then we successfully grafted MCA onto the surface of GO through the "click reaction" between-C≡C and-N3. The prepared MCA/GO hybrid was further characterized by FTIR, XRD, Raman spectroscopy, UV-vis absorption, TGA, etc. The dispersibility of the MCA/GO hybrid in solvent was significantly improved; additionally we explored its applications in heterogeneous chiral resolution of racemic alanine and the enantioselective crystallization experiments. Based on the two methods developed in this thesis for chirally functionalized graphene, more chiral hybrids derived from graphene are anticipated, which will find significant applications in chiral-related fields.