Multi-responsive Supramolecular Assemblies

Multi-responsive supramolecular assemblies is the thesis here including two parts:1, multi-responsive assemblies based on supramolecular cyclodextrin amphiphiles;2, synthesis of functionalized pillar[5]arene and its supramolecular assemblies.The part, supramolecular assemblies based on supramolecular cyclodextrin amphiphiles includes three contents,(1) Designation, synthesis and preparation of novel supramolecular cyclodextrin amphiphiles.Using supramolecular chemistry as the background, after summarizing huge papers and literatures, this thesis proposes the concept "supramolecular cyclodextrin amphiphiles" and explains in details for the first time.Supramolecular cyclodextrin amphiphiles here are divided into three classes:(a) The first class is covalently modified amphiphilic cyclodextrin derivatives.(b) The second class is prepared by host-guest inclusion complexes between surfactants and cyclodextrins.(c) The third class is constructed by amphiphilic inclusion complexes between hydrophobic compounds and cyclodextrins.The first class of supramolecular cyclodextrin amphiphiles has been fully investigated by the world renowned groups of Prof. Reinhoudt, Prof. Ravoo and Prof. Darcy, and some basic principles, e.g. six-carbon principle, has been proposed. Thus, this thesis is mainly focusing on the two latter ones.It should be noted that this thesis is the first to prepare, investigate and report the third class. In addition, the types of third class can be controlled by adjusting solvent and hosts. The structural comformation, complex stoichiometry and complex constant of supramolecular cyclodextrin amphiphiles were determined by the instruments such as one and two dimensional nuclear magnetic resonance (NMR), cyclic voltammetry (CV) and ultra-violet (UV) spectra, and the methods such as Jobs’plot, Benesi-Hildbrand Equation and Hao’s Equation.(2) Multi-responsive properties of supramolecular assemblies based on supramolecular cyclodextrin amphiphiles.Based on investigations on the second class, a series of fluorescent vesicles are obtained and can perform reversible process with variable moiphologies upon pH changes. The third class has two main types now including the tadpole one and bola one. This class has multi-responsive properties to external stimuli such as solvent, redox, oxidizing, pH and metal ions. All morphologies and sizes are confirmed by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), atomic force microscopy (AFM), confocal laser scattering microscopy (CLSM) and dynamic light scattering (DLS). These vesicles have potential applications to the fields such as supramolecular smart materials.(3) Applications of multi-responsive assemblies based on supramolecular amphiphiles to successive drug delivery and release system.The first successive drug delivery and release system based on supramolecular cyclodextrin amphiphiles is constructed here. The novel system has high drug-loading value confirmed by comparing nuclear magnetic resonance (NMR), UV spectra and TEM. In addition, the supramolecular assembly system can be responsive to pH and oxidizing, and release drugs successively.2, investigations on functionalized pillar[5]arene derivative and its assemblies.(1) The concept "dynamic smart clicked surfaces" was proposed for the first time in this thesis, and azobenzene modified pillar[5]arene here has been used to construct the dynamic smart clicked surfaces.The novel azobenzene modified pillar[5]arene derivative was designed, synthesized and fully characterized. The critical assembly concentration (CAC) indicates the possible assemblies in mixed solvents. Supramolecular assemblies based on azobenzene modified pillar[5]arene in mixed solvents were investigated by negative-stained transmission electronic microscopy (TEM), cryo-TEM, scanning electronic microscopy (SEM), environmental SEM (ESEM), atomic force microscopy (AFM) and dynamic light scattering (DLS). In addition, the mechanisms for supramolecular assemblies were studied by one and two dimensional nuclear magnetic resonance (NMR). By varying the visible and UV light, the morphologies assembled by the novel pillar[5]arene derivative can be switched between vesicles and solid particles.(2) This is the first reversible assemblies constructed by functionalized pillar[5]arene derivative.These dynamic smart clicked surfaces can be responsive to external stimuli switching between visible and UV light with variable morphologies. The responsive properties were investigated by UV spectra, TEM and DLS.Different from previous reported azobenzene derivatives in literatures, these novel assemblies do not disappear by exposing in UV light and can carry out reversible variable morphologies. Thus, these assemblies are both sensitive and resistant upon UV irradiating. Owing to huge host recognition sites on the surfaces, these assemblies have potential applications such as logic gate, smart materials and UV sensor.