Construction And Properties Of A Supramolecular Self-assembled Framework Based On The Role Of The Outer Wall Of The Cucurbit Ring

Porous materials have been widely used in the fields of adsorption and separation,heterogeneous catalysis,as well as chemical sensing,among which supramolecular organic framework materials（SOFs）have attracted more and more researchers’attention.SOFs are usually constructed by organic molecules and are self-assembled with good reversibility by virtue of weak intermolecular interactions such as hydrogen bonds,ion–dipole interactions,C–H???πinteractions,π???πstacking.However,SOFs lack sufficient strength and stability because of the weak interactions between supramolecules.It is an effective method to overcome these defects if organic molecules with rigid structures are selected as the building blocks.Cucurbit[n]urils（Q[n]s）are suitable as building blocks for constructing porous Q[n]-based supramolecular framework materials because they have a rigid hydrophobic internal cavity and two negatively charged portals with carbonyl oxygens.On the other hand,due to the positive electrostatic potential of the outer surface,Q[n]s can not only interact with the carbonyl port with negative electrostatic potential of the adjacent Q[n]s,but also interact with a variety of inorganic metal anions,namely the two most common outer surface interaction of Q[n]（OSIQ）,self-induced and anion induced OSIQs.This makes Q[n]s easy to construct the Q[n]-based supramolecular frameworks with novel structure and special properties.Therefore,the strategy of constructing Q[n]-based supramolecular frameworks by using these induced OSIQs,not only can establish an effective method to construct various supramolecular frameworks in Q[n]chemistry.More importantly,the Q[n]-based supramolecular frameworks obtained by using the mentioned strategy has broad application prospects in adsorption,selective trapping of metal ions,and special structure catalysts.In this thesis,14 kinds of Q[n]-based supramolecular frameworks（QSFs）were constructed based on the outer surface interactions between Q[n]s.The formation process of these QSFs were investigated.Several QSFs were screened and studied their functional properties thoroughly,including the possible application in gold recovery of Q[8]-based supramolecular framework;Catalytic performance of the composite material Au@Q[8]that gold nanoparticles（Au NPs）supported on Q[8]supramolecular framework.The main content of this dissertation mainly includes the following four parts.1)Four kinds of QSFs were constructed by recrystallized Q[6]and Q[8]in HCl and HNO₃aqueous solutions,respectively.Three of them were formed by dipole interactions between the positively charged methine,bridged methylene on the outer surface of Q[n]s and portal carbonyl carbon atoms of adjacent Q[n]s.However,the QSF that constructed by Q[6]in HNO₃solution,which was driven by the dipole interactions between Q[6]itself,the interactions between[NO₃]^-anions and the methine blocks,bridged methylene blocks and portal carbonyl carbon atoms on the outer of Q[6]molecules.2)Ten kinds of QSFs were constructed by Q[n]s and[Pt Cl₆]^2-,[Au Cl₄]^-,[Zn Cl₄]^2-and[Cd₆Cl₁₉]^7-.The construction of the QSFs is attributed to the ion–dipole interactions between the inorganic anions/cluster and the positive electrostatic outer surface of the Q[n]s.The main driving force for the formation of these QSFs from the anion-induced outer surface interaction between Q[n]s and inorganic anions or anion cluster,as well as the dipole interactions between the positively charged methine,bridged methylene on the outer surface of Q[n]s and portal carbonyl carbon atoms of adjacent Q[n]s.3)The potential application of QSF 2 and QSF 3 for selective capture and recovery of Au,which was explored by co-precipitating Q[8]with[Au Cl₄]^-anions.The results showed that the recovery efficiency of Q[8]on HAu Cl₄was 95.5%when the molar ratio of Q[8]to HAu Cl₄was 1:1 in the 6.0 mol/L HCl solution.However,the recovery efficiency increased slightly to 96.3%as the ratio of Q[8]to Au increased from 2:1 to 5:1.Furthermore,in 4.0mol/L HCl aqueous solution,the capture and recovery efficiency could reach the highest99.6%when the molar ratio of Q[8]to HAu Cl4 is 1:1.Finally,hydrazine hydrate（N₂H₄·H₂O）was used to reduce the[Au Cl₄]^-anions that trapped in QSF 10 to gold（Au⁰）.Thus,a new method for gold collection and recovery was established.4)A new type of composite material Au@Q[8]that Au NPs supported on the Q[8]supramolecular framework carrier was prepared by heating the complex that constructed by Q[8]and HAu Cl₄gently under N₂/H₂mixed atmosphere（95:5）.The experimental results showed that the optimal treatment condition for the preparation of Au@Q[8]was to keep the temperature at 200℃for 2 hours.The diameter of Au NPs nanoparticles obtained was about30 nm.In the presence of Na BH₄,the catalytic reduction of 4-nitrophenol（4-NP）was used as a model reaction to evaluate the catalytic performance of the Au@Q[8].Therefore,the Au@Q[8]has a great application prospect in wastewater treatment.It also provides a new synthesis strategy for the preparation of Q[n]s mediated metal nanoparticles.