Controllable Porphyrin Nanostructure Through Micell Confined Self-assembly

Molecular self-assembly is a powerful method to the synthesis of nanostructured materials. Throughdesigning molecules and supramolecular entities, desired structure and function can be achieved. Theunique property of molecular assemblies has been demonstrated to depend not only on the size, shape, andcomposition of the molecule building blocks but also to a large extent on the precise control of moleculespatial arrangement within an assembly. Despite recent advances in synthesis and assembling moleculebuilding blocks into well-defined superstructures, technologies that leverage the structural advantages ofindividual molecules amenable to practical use still remain a significant challenge. The development ofmore facile and efficient methods for rationally designing and fabricating molecule assembly is criticallyimportant for the continued advancement of this area. While previous efforts have focused on controlled2Dand3D fabrication over a limited range of scales, developments of new molecular and building blockdesigns and strategies of functionalization are essential for directing structure and property control overmultiple scales. The functional porphyrin nanostructures might serve as basic building blocks that can berationally assembled into highly ordered arrays with enhanced applications such as metamaterials,nanophotonics etc. Here we report a facile self-assembly process to synthesize monodisperse porphyrinnanostructures of zinc meso-tetra (4-pyridyl) porphyrin (ZnTPyP). Self-assembly of ZnTPyP throughmicelle confined intermolecular interactions such as central metal-ligand axial coordination and π-πinteractions yields new nanostructured discs containing fluorescent and crystalline wall structures.Acid-base neutralization reaction deprotonates tetrapyridinium cation producing neutral ZnTPyPs that areinsoluble in water. The resulting hydrophobic ZnTPyPs are then encapsulated within the hydrophobicmicellar interiors like other hydrophobic nanoparticles or oil-like species. Further self-assembly driven bynon-covalent interactions such as hydrophobic-hydrophobic interactions, aromatic-stacking, and axialcoordination (Zn-N) between porphyrin molecules or surfactants initiates nucleation and growth of ZnTPyPnanostructures.1. The compound of myristyltrimethylammonium bromide (MTAB) was usede as an surfactant, bychanging the surfactant with porphyrin molar ratio and the pH of the self-assembly process, we got a series of different morphologies porphyrin assemblies, such as mono-dispersed porous nanoplate, nanoparticles,tetragonal nanorods, hexagonal nanorods and so on, and confirmed the experiment conditions of thesemorphologies. The morphology map provides an experimental basis for controlled synthesis of theporphyrin assembly. We has researched different morphologies of porphyrin assembly of the stackingmanner of porphyrin by XRD studies and theoretical calculation. We research the effect of the stackingmanner and assembly size on the nature of the assembly furtherly, such as optical properties, pore structureand catalytic degradation for organic dye of methyl orange (MO). Hexagonal stacking manner of methylorange (MO) degradation rate is much higher than molecular packing Yovtae.2. In order to study the influence of the surfactant in the assembly process, we selected a series ofdifferent types of surfactant including cationic surfactant (alkyl quaternary ammonium salts), the anionicsurfactant (Alkyl carboxylic acid salt and alkyl sulfates), amphoteric ionic surfactant and the non-ionicsurfactant for self-assembly of ZnTPyP. We also study the impact of different pH, different kinds ofsurfactant, the alkyl chain length of the same types of surfactant and the ionic properties of hydrophilic endof the surfactant for the assembly process detailed. At the end, we summarized the results to guided theself-assembly process in the future.