Construction Of Functional Supramolecular Integrated Structures By Use Of Ammonium Template-Directed Clipping Approach

Self-assembly phenomenon is one of the most essential content in the life science, and biological system can accurately utilize non-covalent interactions to form highly ordered functional assembly. Inspired by nature, in recent years, building mechanically interlocked molecules by self-assembly, such as rotaxanes, catenanes and so on, has become a research hotspot in supramolecular chemistry. At present, the research focus and existing issue for supramolecular self-assembly mainly are:(1) To develop some new and efficient methods to construct the topology structures;(2) To construct novel topology structures;(3) To realize the function of mechanically interlocked molecules as far as possible. Herein, this thesis carried out a series of research on constructing the novel and functional mechanically interlocked molecules by use of clipping approach. The specific contents are shown as following:The first part:A detailed review was carried out about recent research progress of building mechanically interlocked molecules (rotaxane and catenane) by use of clipping approach, and we put forward the design ideas and research topics based on above review.The second part:Two kinds of symmetric and asymmetric macrocycle ammonium salts were designed and synthesized. Subsequently, they were used to construct efficiently a series of [2]catenanes by a template-directed clipping approach. Their structures were characterized by means of NMR spectroscopy, ESI-MS spectrometry and elemental analysis. And their spatial structures were investigated by2D ROESY and DFT theoretical calculation. And it was found that it was the energy-minimized structure when the pyridine or benzene ring located the outside of macrocycle ammonium salt. This method will provide a novel idea and strategy to build more complicated mechanically interlocked molecules in the future because of its efficiency of constructing catenanes.The third part:A series of dual-functional molecules which possess both host and guest were successfully constructed as the building blocks, and they were utilized to synthesize the hetero (pseudo) rotaxanes possessing the novel topology structures, the specific contents are as follows:(1) Three kinds of dual-functional molecule which possess both host and guest were designed and synthesized. And they were used to construct six different [n] rotaxanes (n=2,3,4) by clipping approach. Subsequently, these [n]rotaxanes were used to further build four novel hetero[n]-rotaxanes (n=3,4) by the threading followed by stoppering method, while [4]rotaxane was threaded by phenanthroline based ammonium to obtain a hetero[5]pseudorotaxane. These structures of [n]rotaxanes and hetero[n]rotaxanes were characterized by means of NMR spectroscopy, ESI-MS (or MALDI-TOF-MS) spectrometry and elemental analysis. These results demonstrated feasibility of utilizing dual-functional molecules to synthesize novel hetero[n]rotaxanes.(2) On the basis of the above research, the other two dual-functional molecule which possess both host (bis(m-phenylene)-26-crown-8or dibenzo-24-crown-8) and guest (ammonium templates) was also designed and synthesized. And they were used to construct four novel [3] rotaxanes by the clipping approach. And their structures were characterized by means of NMR spectroscopy, ESI-MS (or MALDI-TOF-MS) spectrometry, elemental analysis and X-ray diffraction. Then these [3]rotaxanes were carried out binding experiments with the dibenzylammonium, and it was found that only the [3]rotaxanes connecting the dibenzo-24-crown-8formed stable complexes with the dibenzylammonium. Therefore, the novel "H shaped" hetero[5]pseudorotaxanes were obtained. These results demonstrated the feasibility of utilizing dual-functional molecules to build novel hetero[n]pseudorotaxanes. This work will provide a novel design strategy and research foundation to build more complicated hetero[n]rotaxane and hetero[n]pseudorotaxane in the future.The fourth part:A series of novel switchable mechanically interlocked molecules and switchable receptors were designed and synthesized by introduction of dithienylethene unit into supramolecular systems, the specific contents are as follows:(1) Two kinds of switchable macrocycle ammonium salts were designed and synthesized. Subsequently, they were used to construct a series of switchable [2]catenanes by the clipping approach. And their structures were characterized by means of NMR spectroscopy, ESI-MS spectrometry and elemental analysis. Investigation on photochromic properties indicated that these switchable [2]catenanes had good photochromic properties and excellent fatigue resistance upon irradiation with UV or visible light. It was worth mentioning that the formation of [2]catenanes enhanced the photochromic properties compared with the corresponding macrocyclic ammonium salt, implying that the noncovalent components on the [2]catenanes could affect the photochromic properties. Furthermore, it will be significant to design novel optical materials with excellent properties.(2) Four new switchable [n]rotaxanes (n=2,3) were designed and synthesized. And their structures were characterized by means of NMR spectroscopy, MALDI-TOF-MS spectrometry and elemental analysis. Investigation on optical properties indicated that these switchable [2]rotaxanes had good photochromic properties and excellent fatigue resistance. And they displayed excellent fluorescence switchable behavior. Furthermore, it could significantly improve their optical properties after self-assembly to rotaxanes, and it was found that the photochromic signal could integrate well without any interrelationship among two components bridged by noncovalent hydrogen bond, which may have potential applications for a logic circuit in the future.(3) On the basis of the two part research above, two novel diswitchable [2]catenanes bridged by noncovalent hydrogen bond were designed and synthesized. And their structures were characterized by means of NMR spectroscopy, MALDI-TOF-MS spectrometry and elemental analysis. Investigation on optical properties indicated that these diswitchable [2]catenanes had good photochromic properties and excellent fatigue resistance. And they displayed excellent fluorescence switchable behavior. And it was found that the two different photochromic component of diswitchable [2]catenanes underwent a photocyclization reaction upon UV light irradiation, simultaneously. So two components bridged by noncovalent hydrogen bond were not mutually affected. Furthermore, two different photochromic signal could integrate well without any interrelationship among two components bridged by noncovalent hydrogen bond. Therefore, it will be meaningful to design and synthesize novel multiswitchable system.(4) The above research work was further extended, template-directed clipping approach was also used to synthesize three switchable macrocycles. And their structures were characterized by means of NMR spectroscopy, ESI-MS spectrometry and elemental analysis. And their photochromic properties were also investigated, which displayed excellent photochromic properties. Additionally, the theoretical calculation suggested that photoirradiation could change effectively the size and shape of the macrocyclic cavity. Therefore, these macrocyclic compounds can be used as the potential switchable cation receptor, which may be applied in many aspects such as cation recognition and release, cation ionophore and so on.(5) The novel amide and urea functionalized switchable anion receptor was designed and synthesized. And its structure was characterized by means of NMR spectroscopy, ESI-MS spectrometry and elemental analysis. The photochromic properties and recognition properties were investigated, and it was found that it had good photochromic properties and excellent fatigue resistance and it showed switchable affinity for chloride and bromide anions upon irradiation with UV/vis light, and the binding ability of open isomer was stronger than that of the corresponding closed isomer. The results indicated that the adjustment of the binding ability could be easily achieved by the simple photoirradiation. Therefore, this research supplied an alternative model for the design of novel anion receptor with a switchable recognition function.