Platinun(â…¡)-based Metallosupramolecular Polymers:Self-assembly And Photophysical Properties

Transition metal platinum(II) complexes have d8 electronic configuration and they exhibit strong triplet luminescence, such as long triplet luminescent lifetime, high quantum yield and adjustable excited state properties. These square-planar platinum (II) complexes allow the metal center frontier orbits of intramolecules and/or intermolecules close to each other, resulting in molecular packing, generating new MMLCT[da*â†'σ(Ï€*)] and Ï€-Ï€* excited states, respectively, and their emissions originated from Pt…Pt and/or Ï€-Ï€ interactions. On the other hand, block copolymers can self-assemble into functional nanostructures in selective solvents, such as spherical, rode-like micelles and vesicles. There are so many factors affecting the self-assembly morphology of block copolymers, such as chain structures, the two-block length ratios, molecular weights and their distributions, ionic strength. As the deepening of the basic research into the self-assembly of block copolymers, their potential applications continue to be discovered, especially in drug transfer, separation, catalysis, sensors and microelectronics and other fields. Therefore, a logical research is how to incorporate platinum(II) complexes into multi-function responsive soft materials. In this thesis, based on electrostatic interactions, we explore the self-assembly behaviors and photophysical properties of cationic platinum(II) complexes with anionic surfactants and block copolymers in solution.1. We fabricate rodlike and sheetlike dynamic metallosupromolecules via electrostatic, hydrophobic, Ï€-Ï€ packing and Pt…Pt interactions through a cationic platinum(II) complex that has two hydrophilic chains with anionic surfactants (sodium dodecyl sulfate, SDS, and sodium dodecyl carboxylate, SD) in aqueous solutions. The resulting solutions show strong luminescence enhancement, which can decrease back to the original emissive intensity of the platinum(II) complex as the adding of a-CD by disassembling the aggregates through host-guest recogonition of α-CD with anionic surfactant. This reversible supramolecular system can be used as molecular INHIBIT logic gate.2. We synthesize two cationic platinum(II) complexes with different N∧N∧N ligands, and they can form rodlike micelles with oppositely charged a hydrophilic block copolymer via electrostatic interactions in aqueous solutions. In this process, Pt…Pt and Ï€-Ï€ interactions lead to enhanced luminescence. On the other hand, cationic platinum(â…¡) complexes can be attached onto an amphiphilic block copolymer with an opposite charge by electrostatic binding, which led to the formation of rod-like and spherical micelles and vesicles in toluene.3. We prepare a star micelle with a platinum(â…¡) complex/polyacrylic acid hybrid material core and a polystyrene chain corona. Such a kind of star micelle can be used as a model to mimic their intra- and inter-star interactions and self-assembled behaviors in solvents of weakening quality. In chloroform/methanol mixture solvents, the star micelles shrink, pack and self-assemble to form vesicles. In these vesicles, the star micelles still keep their core-shell structure. This is completely different from amphiphilic molecules, which must be rearranged when transformed from micelle to vesicle.