The Synthesis Of Some Mono-modified And Bridged Bis (β-cyclodextrin)s And Their Photophysical Behaviors

Supramolecular chemistry is an advanced field in current chemistry, and plays a crucial role in nanoscale science and technology. As the second generation of the host compound, cyclodextrins have become one of the main focuses of supramolecular chemistry. To further reveal the molecular recognition and assembly mechanisms of cyclodextrins during the binding processes, a series of novel mono-modified and bridged bis(β-cyclodextrin)s possessing different functional moiety were synthesized to investigate their binding and photophysical behaviors with heavy metal ions and organic guest molecules;Some novel supramolecular architectures were constructed by modifiedβ-cyclodextrin and functional guests. Furthermore, the potential applications of these assemblies in the fields of environmental surveillance, fluorescent sensing, and material science were exploited. The major contents of this thesis are as follows:1. The general aspect of supramolecular chemistry was discussed briefly. Some representative achievements on molecular recognition and self-assembly of cyclodextrins, fullerene, tetrathiafulvalene and carbon naotubes were reviewed.2. The interactions between the radical cation of tetrathiafulvalene(TTF)- modifiedβ-cyclodextrin and cucurbit[7]uril were investigated by means of UV/Vis spectroscopy, EPR, kinetics experiment, and cyclic voltammetry. On the other hand, a bridged bis(β-cyclodextrin) 3 with a tetrathiafulvalene (TTF) linker was synthesized to investigate the photo-induced electron transfer behaviors of the host compound and water-soluble porphyrin derivatives.3. A novelβ-cyclodextrin derivative bearing 8-hydroxyquinolino and triazole groups was synthesized by "click chemistry", which exhibited an effective switch-on fluorescence response to Cd2+ over other common metal ions under physiological conditions. Studies on the recognition mechanism indicated that the cooperative coordination of Cd2+ with both the 8-hydroxyquinolino moiety excluded from theβ-CD cavity and the triazole moiety was a crucial and basic factor to achieve the fluorescent sensing process. Significantly, spectrophotometric studies also demonstrated that, after inclusion complexation with 1-adamantane- carboxylic acid sodium salt (AdCA), the resultant cylcodextrin/AdCA system gave a more effective fluorescent sensing to Cd2+ through a cyclodextrin/ substrate/Cd2+ triple binding mode.4. A new fullerene-bridged bis(permethyl-β-cyclodextrin) was synthesized by the Hirsch-Bingel reaction and comprehensively characterized by NMR, ESI-MS and elemental analysis. The photo-induced electron transfer (PET) process between porphyrin and C6o moieties would take place within supramolecular architectures under the light irradiation, leading to the highly efficient quenching of the fluorescence of porphyrins. The PET process and the charge separated state were investigated by means of fluorescence spectroscopy, fluorescence decay, cyclic voltammetry and nanosecond transient absorption measurement.5. We utilized a synthetic linker, which contained a planar pyrene moiety as a binding group connected to an adamantane moiety that is accommodated in the cyclodextrin cavity. A novel supramolecular architecture to solubilize single-walled carbon nanotubes (SWCNTs) in the aqueous phase was described by employing supramolecular surface modification. Significantly, this supramolecular assembly can adhere to the cell and could be used for imaging of Cd2+ in vitro.