Design,Synthesis Covalent Organic Frameworks And Storage Properties

Covalent Organic Frameworks（COFs）are a class of crystalline porous polymers that allow the atomically precise integration of organic units to create predesigned skeletons and nanopores.They are composed of light-weight elements（C、H、N、O、B、Si）and termed as "Organic Zeolites".Since the pioneering work reported by Yaghi in 2005.COFs usually exhibit high chemical and thermal stability,low density and high surface area.Therefore,these COF materials have become new candidates for potential applications such as in gas storage,optoelectronics and catalysis.This thesis mainly focuses on the design,synthesis,properties and applications of imine-linked functional covalent organic frameworks.Taking advantages of the particularly intrinsic properties of these functional COFs,we achieved the various applications of the COFs on confined ionic liquid,iodinecapture,CO₂ capture and separation and removal of Hg²⁺.The contents of this thesis are summarized in the following chapters:1、Encapsulation of an ionic liquid[Emim][Tf2N]into the nanopores of 3D covalent organic frameworks（COF-320）.The confined ionic liquid was remarkably solidified due to the nanosized effect of the COF on the ionic liquid.The confined[Emim][Tf2N]within the nanopores of COF-320 exhibited no phase transition down to-160 ℃ and up to 190 ℃.The solid-state 19F NMR spectura further confirmed that the[Emim][Tf2N]within the nanopores of COF-320 was solidified dramatically.2、Introduce the iodine molecule into the nanopores of COFs at iodine vapor states for the first time.Iodine molecule is easy to condense into COFs when it aggregates in a nano container.These COFs possess excellent adsorption properties to iodine owing to their "breathing" dynamic frameworks.These materials show ultrahigh iodine adsorption and retention capability.The formation of charge transfer（CT）complexes between I2 and π-electron wall of COFs is considered to contribute to the excellent I2 capture and retention performances.3、A novel covalent organic framework（TP-OP-COF）was prepared by schiff-base condensation reaction between alkynyl-functionalized diamine and aldehyde.TP-OP-COF with "—C ≡ C—" in pore walls,exhibited abundant electrons and excellent micoporous characteristics,which led to admirable CO₂ uptake capacity and CO₂/N₂ selectivity（33.5 at 273 K,IAST）.Good chemicaland thermal stablity were also founded.The high surface area（1183 cm3 ·g-1）of TP-OP-COF and rich electronic sites make it a wonderful candidate for hydrogen adsorption.4.Utilizing the above synthesized TP-OP-COF to capture element sulfur,a kind of new complex was obtained（S@TP-OP-COF）.Due to the adsorption of sulfur,a strong affinity active site was introduced for mercury in the TP-OP-COF channels.The mercury adsorption capacity can reach up to 9.92 mg·L-1.This result clearly shows that the sulfur loading within the nanopores of the COF can improve the performance of Hg²⁺ removal.So,this work provides a new strategy for Hg²⁺ adsorption.