Construction Of New Organometallic Supramolecular Systems Via Hierarchical Self-assembly

Since entering the new century, researches on the designing and synthesis of supramolecular chemistry have developed rapidly, not only in molecular model construction but also in function exploring. Due to proper bond energy and good direction of coordination bond, it can be used to construct a series of regular 2D discretes and 3D supramolecular systems. In recent years, the concept of supramolecular chemistry has been widely utilized in chemical, biological and material science. Hierarchical self-assembly of non-covalent bond by utilizing hydrogen bonding, metal-ligand interaction and electrostatic interaction, can be successfully applied to prepare a variety of novel structures with potential applications in the photoelectric chemistry, host-guest chemistry, drug delivery, biological simulation, catalysis and so on. Thus, many supramolecular chemists used their knowledge in biological protein and DNA as supramolecular is a multi-disciplinary and comprehensive subject, to realize the post-modification of supramolecular structures, thereby expanding the supramolecular research field and opening a class of supermolecular structures with this property. This paper mainly introduced a new supramolecular system via coordination bond directed self-assembly based on a series of functionalized blocks, and then explored the mesoscopic aggregation behavior of hierarchical self-assembly drived by weak interactions, and preliminary inquired its property. Secondly, extending the concepts of hierarchical self-assembly into supramolecular system with three components, construct two kinds of novel structures and the fluorescence probes with stimuli responsive properties, using the host-guest interaction to introduce tetraphenyl ethylene moieties with the aggregation induced emission (AIE) properties into supramolecular system. Finally, the utilization of post modification strategy made a successful designing and synthesis a series of supramolecular self-assembly systems with active reaction sites for post-modification. In these systems, through covalent reaction and ligand exchanging reaction, the transformation of supramolecular macrocycles could be realized, and the preliminary study of their function has been carried out as well.The main contents and results of this thesis included the following aspects:In Chapter one, a briefly review about the concept of supramolecular chemistry, recent development status and future developing trend is indicated, which introducing the coordination-oriented self-assembly supramolecular system with emphasis, supramolecular hierarchical self-assembly system, host-guest chemistry, the application in functional materials of AIE system based on tetraphenyl ethylene moieties and the application and advantages of post-modification strategies in the construction of new supramolecular self-assembly system. And on this basis, put forward the research of this paper.In Chapter two, relates to the convergent synthesis strategy, a series of peripheral modified building blocks with different hydrophobic properties have been designed and synthesized. A class of amphiphilic supramolecular self-assembly system using organometallic macrocycles as the central framework could be built via the directional bonding between platinum and nitrogen. The structure were characterized by’H NMR, 13C NMR,31P NMR and other testing methods. Aggregation behavior in subsequent solution phase showed that weak interaction provided by hydrophilic and hydrophobic chains could make building blocks and amphiphilic self-assembly system form second state of aggregation, showing a well-organized aggregation morphology.In Chapter three, carbazole dendrimers with stronger interaction were introduced into 120° dipyridine ligands through esterification reaction, and then through coordination-directed self-assembly, two series of [2+2] or [3+3] supramolecular self-assembly systems comprising different generations of carbazole dendrimers with different sizes were successfully constructed. These metallacycles were characterized by various characterization techniques, and scanning electron microscope (SEM) revealed that well-ordered aggregation morphology could be formed via intermolecular interaction. At the same time, through the UV absorption spectra and fluorescence emission spectra, these supramolecular self-assemblies showed unique luminescent properties. It was found that in the mixed system of dichloromethane and n-hexane, multicarbazole functionalized hexagons have presented a better AIE properties.In Chapter four, based on the idea of host-guest chemistry, two kinds of supramolecular polymers were designed and synthesized based on pillar[n]arenes and tetraphenyl ethylene via host-guest chemistry. One is from the exo-functionalized pillar[5]arenes building block, and then [2+2] diamond and [3+3] hexagon metallacycles were synthesized. Host-gust interaction between two or four cyano groups modified tetraphenyl ethylene and pillar[5]arenes, a detailed investigation of the intermolecular interaction and aggregation induced emission properties has been made by researching in different metallacycles, different guests, different ratios of subject and object and different concentrations. Furthermore, introducing competitive objects and other external stimuli, reversible AIE property of supramolecular polymers were successfully realized. Another one is the guest macrocycles with cyano modified tetraphenyl ethylene moieties were constructed via [2+2] and [3+3] self-assembly. Hierarchical self-assembly with three components could be successfully realized by host-guest interaction. Preliminary exploration of its aggregation behavior were carried out by SEM. Concentration-dependent multinuclear NMR (1H,31P), concentration-dependent fluorescence emission spectra gave further research on AIE property.In Chapter five, a new family of endo-functionalized modified building blocks with terminal alkenes were synthesized. Different sizes and shapes of metallocycles were constructed via coordination-based self-assembly. Through a variety of covalent reaction of terminal olefins, post-modification can be used in supramolecular system. But as a result of the steric hindrance and limit of cavity, there still lack a reaction with 100% conversion rate. While this work provided novel ideas and methods of constructing diverse supramolecular structures and introducing various functional groups.In Chapter six, from more efficient ligand exchanging strategy, trans-platinum-acetylide moiety with triphenylphosphine (PPh3) ligands could be transferred into the corresponding cis-platinum-acetylide derivative under mild condition through phosphorous ligand exchage, thus allowing for the facile structural and property modification of platinum-acetylide complexes, realizing multiple-station sequential transformation. The use of ligand exchange strategy could also efficiently realize supramolecular transformation from achiral structures to chiral ones, providing a facile approach to the divergent preparation of enantiometric supramolecular architectures.