Construction Of Novel Organometallic Rotaxane Systems

Rotaxanes, as a representative type of mechanically interlocked molecules (MIMs), have proven to not only be privileged candidates for the construction of molecular switches, molecular machines and nanoscale molecular devices, but also show diverse potential applications in sensing, catalysis, smart materials etc. In order to further extend and enrich the rotaxane systems, the research described in this dissertation focuses on the construction of novel organometallic rotaxane systems. By the introduction of organometallic bulding blcoks, a series of organometallic rotaxane systems have been successfully constructed, and the in-depth investigations of their related properties and applications have been further performed. The dissertation can be divided into six parts, the details are shown below.In Chapter One, an overview of the progress of the construction of rotaxanes, including the development of the synthentic approaches and representive rotaxanes based on diverse macrocycles, is presented. In addition, the introduction of linear oligorotaxanes, rotaxane dendrimers and the applications of rotaxanes are also demonstrated.In Chapter Two, by the combination of orthogonal self-assembly and self-sorting approach, an integrated strategy towards the construction of multicomponent supramolecular rotaxane systems with high-level complexity has been developed. By the rational design of key building blocks with specific interaction sites and molecular codes, five types of simple components (up to eighteen precursors) were successfully self-assembled into two novel tris[2]pseudorotaxanes in one pot through a highly selective manner.In Chapter Three, starting from a novel organometallic [2]rotaxane, two rotaxane-containing pre-functionalized building blocks were succesffully synthesized. Through the combination of rotaxane-containing building blocks with the corresponding different organoplatinum(â…¡) acceptor building blocks, diverse discrete multirotaxanes with well-defined metallacycles (rhomboid or hexagons) as supramolecular cores as well as certain numbers of rotaxane units were successfully obtained quantitatively by means of coordination-driven self-assembly. Furthermore, owing to the existence of dynamic metallacycles as the supramolecular cores, the investigations of the resultant multirotaxanes on their stimuli-responsive properties were carried out.In Chapter Four, starting from a novel organometallic [2]rotaxane as the key building block, the synthesis of high-generation branched rotaxane dendrimers with diverse functional end groups has been successfully realized by using the controllable divergent approach. The further investigations on the "rotaxane effect" indicated that the rotaxane units could not only enhance the rigidity and reduce the tendency of these assemblies to collapse by self-folding, but also display protection effect on the stability of the rotaxane dendrimers.In Chapter Five, as the extension of the properties and applications of rotaxane dendrimers, daisy chain dendrimer, as a novel mechanically interlocked dendrimer, was proposed. In order to synthesis the targeted daisy chain dendrimer, a series of key building blocks with [c2]daisy chain as the cores were designed and synthesized, and their stimuli-responsive bahaviours were further investigated. In addition, starting from the selected building block, the synthentic attempt to the targeted daisy chain dendrimers was carried out.In Chapter Six, taking advantage of the unique transformation properties of the trans-platinum-acetylide moiety, a novel supramolecular transformation system within diverse [3]rotaxanes has been successfully constructed. Starting from an organometallic [3]rotaxane bearing platinum-acetylide moiety as the central link, the addition of various chelating diphosphines and sequential deplatinum processes resulted in the formation of diverse [3]rotaxanes featuring both structure and property diverstity, thus affording a novel supramolecular transformation approach for the synthesis of diverse rotaxanes.