Synthesis And Properties Of Micro- Or Nano-sized Porous Coordination Polymers

Porous Coordination Polymers （PCPs） are porous materials consist of multidentate organic ligands and metal ions. Zeolitic Imidazolate Frameworks （ZIFs）, a novel class of MOFs, combine the advantage of zeolites and MOFs materials which exceptional thermal and chemical stabilities as well as tunable structure. Therefore, these have led to a wide range of attractive and potential applications for various ZIF materials.In this paper, nanocrystals of ZIF-8 have been successfully prepared under microwave irradiation and hydrothermal. The products were characterized by powder X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscope, thermogravimetric analyzer and N₂ sorption.The influence of ligand to metal ion molar ratio, the salt anion and the synthesis time were also investigated and discussed. According to datum of PXRD and SEM, pure phase ZIF-8 crystals were successfully prepared with Hmim/Zn²⁺ molar ratio larger than 10 and showed showed homogeneous hexagonal and rhombic dodecahedral shapes. The obtained products from metal source zinc sulfate and zinc chloride have good crystallinity than zinc nitrate, zinc bromide, zinc perchlorate. The obtained samples from metal source zinc acetate, zinc sulfate and zinc chloride showed homogeneous hexagonal and rhombic dodecahedral shapes. The reaction of kinetic control can be transformed to the reaction of thermodynamic control via increasing the synthesis time.We have investigated a new strategy for the surfactant-assisted rapid synthesis of ZIF-8 nanocrystals under microwave irradiation. The influence of different surfactant, the amount of surfactant and the microwave irradiation time were also investigated and discussed. Noticeably, the reaction time could be significantly reduced down to 1 min. There is no significant variation upon changing the surfactant and its the amount. The obtained ZIF-8 exhibited a high BET surface area of 1599 m² g^-1. The PEO-PPO-PEO type amphiphilic triblock copolymer P123 and F127 can form surfactant micelles in aqueous solutions to facilitate the formation process of the ZIF-8 structure. The strategy of microwave-assisted is environmentally friendly and can lead to fast homogeneous nucleation.