Synthesis And Properties Of Hydrazone-based Porous Organic Cages

Porous organic cages（POCs）,as one of the emerging porous materials are assembled by covalently linking organic building blocks（OBBs）to form discrete,zero-dimensional covalently bonded macromolecule with guest-accessible voids.They have shown promising applications in adsorption,separation,sensing,catalysis,environment,energy,etc.However,systematic design and synthesis of robust and functional POC materials are full of challenge.This thesis synthesized a series of water-stable hydrazone-linked POCs using functional calixarene and different dihydrazides as OBBs.On the one hand,the application of these POC materials in removing water pollutants has been explored;on the other hand,the influence of post-modification metallization on POC materials’gas adsorption and separation abilities has also been studied.The details are as follows:1.A series of water-stable hydrazone-linked（C=N-N）POCs are constructed from tetraformylresorcin[4]arene and three different types of dihydrazide OBBs,which include[2+4]lantern,[3+6]triangular prism,unprecedented[4+8]square prism and gigantic[6+12]octahedron.Their structures,stability and porosity were characterized by X-ray single-crystal diffraction,proton nuclear magnetic resonance,mass spectrometry,Fourier-transform infrared spectroscopy and gas adsorption.Thanks to the abundant multidentate N/O chelating sites andπ-rich cavities within POCs’skeleton,they can efficiently and quickly remove radioactive iodine ions,heavy metal ions and organic micropollutants from water.2.The octahedral calix[4]resorcinarene-based hydrazone-linked porous organic cage（HPOC-401）was post modified and functionalized by V,Cu,Zn and Mo transition metal（TM）ions.The formation and uniformity of metals of HPOC-401-TM were verified by scanning electron microscope energy-dispersive X-ray spectra,Fourier-transform infrared spectroscopy,inductively coupled plasma-optical emission spectroscopy,X-ray single-crystal diffraction and other characterization methods.Such metalation leads to the porosity of pristine HPOC-401 from barely porous to highly porous of metalated products with Brunauer–Emmett–Teller（BET）surface area up to 1456 m² g^-1 as determined by N₂ gas sorption at 77 K.Moreover,the porosity increases further influence their gas capture properties,e.g.,the HPOC-401-TM exhibit higher CO₂,H₂,C2 hydrocarbon gas uptake,and higher C₂H₆/C₂H₄selectivity compared to the parent HPOC-401.