Design, Synthesis & Studies On Molecular Sensor And Molecular Assembly Of Novel Host Based On Glycoluril

Fluorescent chemosensors have attracted much attention and got a rapid development over the years for their high sensitivity and simplicity. The design and synthesis of fluorescent chemosensor based on host-guest interaction has been an important area of chemosensors. The characteristic of this kind of fluorescence sensor is that the hosts including cavity interact with the guests and formed host-guest complex by the interactions between hosts and detected substrates, which lead to the change of luminescent micro-environment and result in the variety of luminescent capability. Therefore, the selective recognition and detection of guest species can be monitored through recording the changed light signals of the illuminant. Based on the glycoluril, we designed and synthesized a series of novel fluorescent chemsensors including different three-dimensional cavities by introducing the fluorophores into the receptor. Their recognition and sensing abilities toward various metal ions, anions and neutral guests were studied. In addition, the crystal engineering is an important section of the molecular engineering, which involves the assembly behavior of molecules or chemical groups in crystal, the design of crystal and the control of the structure and performance. The synthesized molecules with specific topological three-dimensional structure could be used as excellent building blocks in the studies of molecular assembly. Hence, the other emphasis of this thesis focuses primarily on studying the special crystal structure modality of two series of two-unit glycoluril-based derivatives in the course of assembly.The main contents are shown as following:1. In recent years, the fluorescent chemosensors based on the classical traditional supramolecular host molecules have gained the rapid development. A detailed review was carried out about their research progress with a classification according to different hosts and different photoinduced process. We put forward our design ideas and research topics based on the above review.2. Ten fluorescent molecular clips based on glycoluril were designed and synthesized by using Sonogashira coupling reaction to covalently attach terminal aryl alkynes to the aromatic sidewalls of bromized molecular clip and buildÏ€-systems that function as fluorophore moieties. Their photophysical characteristics were studied. The results demonstrated that these fluorescent molecular clips exhibited very strong fluorescence responses to Fe³⁺ and had remarkably high selectivity to Fe³⁺ over other metal ions including alkali metals, alkaline-earth metals and Ag⁺, Hg²⁺, Cu²⁺, Ni²⁺, Cd²⁺, Zn²⁺, Mn²⁺, Pb²⁺, Cr³⁺ ,Co⁺ et al. On the other hand, these fluorescent molecular clips had also an excellent selective recognition for 4-nitrophenol. They bound 4-nitrophenol through hydrogen bonds andÏ€-Ï€stacking interactions and had no affinity with other eight hydroxybenzene derivatives such as hydroquinone. The complexes were characterized through ¹H NMR, IR and Job-plot analyses and the possible mechanism was proposed.3. Eight novel fluorescent anion receptors of two unit glycoluril derivatives with double ureidyl N-H used as the binding sites were designed and synthesized. Their recognition behaviors toward various anions in CH₃CN solvent were studied. Results indicated anion receptors were capable of selectively binding F^-, OAc^- and H₂PO₄^- over other anions. However, the changes of fluorescence emission were unobvious with low sensitivity.4. Methylene-bridged glycoluril C-shaped dimmers----four unit molecular clips with larger cavity were topologically synthesized. The fluorophores were attached to C-shaped dimmer and fluorescent four unit molecular clip was obtained. Also, its photophysical properties for recognitions of metal ions and hydroxybenzene derivatives were investigated. It was found that the chemosensor could selectively recognize Fe³⁺ and 4-nitrophenol and displayed fluorescence quenching.5. Eight building blocks in which different aryl alkynes moieties were linked to two unit glycoluril derivatives were synthesized and five systematic structures of single crystal were obtained. We found a novel tetrameric molecular bowl crystal packing morphology formed by hydrogen bond and C-H…πinteractions.6. Based on the tandem assembly strategy of assembly and biassembly, we designed and synthesized a series of two unit glycoluril derivatives bearing pyridine moieties and successfully predicted and constructed a novel type of molecular grid network.In summary, the stage results were obtained in this thesis. We obtained forty-two new compounds and twenty-three systematic structures of single crystal which afforded abundant experiment data for further expanding.