Designed Synthesis And Properties Of Covalent Organic Framework Materials Based On Cage Units

Covalent Organic Frameworks(COFs)are synthesized by dynamic covalent bonding.They are constructed via ordered organic building blocks comprising light elements(typically C,H,O,N,B,Si,S,etc.),which are assembled using dynamic and reversible covalent chemistry to form 1D,2D or 3D structures porous and crystalline skeletons with a predictable topology.In virtue of their a low weight density,specific surface area,physicochemical stabilities against moisture and highly ordered structures can be regulated,significant research progress has extended the application scope of COFs spanning across adsorption and separation in gas or liquid phase,multifarious catalysis,sensing,drug delivery,organic photoelectric,energy storage,and various other potential applications.Nowadays,COFs are obtained via a handful reversible chemical reactions.The common forms of bonding are boron oxygen linkages,amide linkages,imine linkages,enone amine linkages,triazine linkages,carbon-carbon double bond linkages,polyaryl ether linkages,and ester linkages.In this thesis,we report the synthesis of novel COFs based on cage-based molecules utilizing cyanuric chloride as reagent,aim to explore their luminescent properties and liquid adsorption,so as to expand COFs'functions and potential applications.This work is constituted of five chapters.The first section focused on thedevelopment,preparation,applications of COFs as well as the purpose and meaning of the subject.In the second section,this study focuses on the use of a luminescent covalent organic framework(COF)that acts as a turn-off fluorescent sensor for both cations(Fe³⁺)and anions(Cr O₄^2-,Cr₂O₇^2-,and Mn O₄^-)in aqueous solution.The COF also shows excellent recyclability during repeated washing and re-exposure cycles.We believe that our study makes a significant contribution to the literature because our COF can be used in aqueous solutions rather than in organic solvents over a wide p H range for the detection of Fe³⁺,Cr O₄^2-,Cr₂O₇^2-,and Mn O₄^-.Our COF provides insight into luminescent COF development as a sensor that detects both cations and anions in aqueous solution.Insights gained from this study can be used to further explore other luminescent COFs for use in aqueous solutions,with potential use in environmental and industrial applications.In the third chapter,we report the synthesis of a novel hexagonal covalent organic framework(COF)prepared from a C₃-symmetric knotted cage molecule and terephthalaldehyde as the C₂ linker.This COF,which we refer to as“Cage-COF-2”,is highly thermally stable and has a high surface area.We examined the utility of Cage-COF-2 as a drug-delivery vehicle in vitro experiments.Cage-COF-TT exhibited almost no toxicity toward L929 and L-02 cells in MTT assays and showed good uptake and release performance for ibuprofen,5-fluorouracil,and captopril,which are common drugs that can be characterized by UV-vis spectroscopy.The results of our study will facilitate the development of COFs for future pharmaceutical applications.Furthermore,it not only describes the synthesis of a novel COF and its characterization,which will be of interest to materials scientists,it also describes how this novel compound can be used to effectively deliver three drugs from different classes.Cage-COF-2 will also be an effective platform for chemotherapy drugs,and to treat diseases with high suppression efficiencies.In fourth chapter,a novel two-dimensional covalent organic skeleton,nucleophilicly substituted with cyanuric chloride analogue,was designed and synthesized,noted as Cage-COF-3,which would combine the merits of structure order,permanent porosity and a low cost.We employed it as a cost-effective alternative adsorbent for the intermittent adsorption of organic dyes in aqueous solutions.The results exhibit that the adsorbent is an extremely effective and efficient adsorbent with reference to simulating the removal of malachite green(MG)in aqueous solution at ambient temperature,which theoretical value is close to 2000mg/g.The adsorption study were according to the initial dye concentration,contact time and solution p H.The thermodynamic experiments followed the Langmuir isotherm model and the adsorption kinetics results were consistent with the pseudo second-order model.Furthermore,we analyzed that high adsorption behavior attribute to Cage-COF-3 have nitrogen-rich triazine cores which enhance their strong affinity for guest molecules,also reward by the strong interaction and charge transfer between Cage-COF-3 and malachite green.The last chapter is related to the summary of this thesis.