Synthesis Of Pillararenes-Based Solid-State Functional Materials For The Adsorption And Separation Of Small Molecules

Supramolecular materials,as a new class of functional materials,were constructed by molecular recognition and self-assembly technologies driven by non-covalent interactions,such as hydrogen bonding,Van Der Waals force,electrostatic interactions,hydrophobic effects andπ-πstacking,which have shown excellent application prospects in the fields of sensing and detection,adsorption and separation,targeted drug delivery,catalysis and antimicrobials.The research and development of supramolecular materials are closely related to the design of macrocyclic compounds.Pillararenes and derivatives,as a superior class of macrocyclic compounds,have played an important role in the construction of various functional systems,dye to their electron-rich cavities and modifiable skeletons.The design,synthesis and property development of pilararenes-based solid-state functional materials provides great opportunities for the prosperity of materials science,energy science and environmental science.With the maturity of petrochemical industry,the use of fertilizers and pesticides,the treatment of municipal domestic waste and the manufacture of drugs,many toxic organic micro-pollutants are discharged in large quantities,which are dissolved in water or dispersed in the atmosphere and difficult to metabolize in organisms.In spite of present in trace amounts in the environment,they have the characteristics of wide distribution,strong diffusibility,high stability,poor degradation or oxidization.Organic micro-pollutants gradually accumulate in the environment,which may cause severe water pollution and trigger incalculable environmental concerns.Therefore,it is imperative to develop new materials to effectively remove organic micro-pollutants in the environment.In the past few years,supramolecular chemistry and macrocyclic chemistry have developed rapidly,and the combination of macrocyclic molecules and solid-state adsorption materials has produced remarkable advantages in various application systems.This thesis combined the advantages of host-guest chemistry with the long-range ordered solid structure due to the excellent performance of pillararenes-based solid-state adsorption materials in the field of selective adsorption and separation.We utilized the host-guest interaction of pillararenes to build a solid adsorbent platform with specific recognition performance,providing new strategies and inspirations for preparing new adsorption materials.The research results were summarized into the following three parts:Firstly,we designed and synthesized a pillar[5]arene-based crosslinked polymer（P1）with the performance of fast and selective removal of organic dyes.The structures and morphologies of P1 and the control material P2 without pillararenes were fully characterized by solid-state ¹³C cross-polarization magic angle spinning NMR spectroscopy,Fourier transform infrared spectroscopy,scanning electron microscopy and elemental analysis.The electron-rich cavity of pillar[5]arene and the hydrogen bond donor of the acylhydrazine group provided effective adsorption sites,which made P1 advantageous in adsorbing small cationic dyes with superior selectivity and efficiency.Kinetic experimental results proved that the adsorption behaviors for methylene blue（MB）and neutral red（NR）were accurately matched with the pseudo-second-order model and Freundlich isotherm model.In addition,the integral adsorption rate was determined by both external diffusion and intra-particle diffusion.The pillararene-based polymer adsorbent could be recycled five times without lossing adsorptive efficiency,holding great potential to function as an available material for wastewater regeneration and purification.Secondly,tailor-made leggero pillararene derivative,namely leggero pillar[4]arene[1]quinone（P[4]Q[1]L）,were prepared by partial oxidation of Me P[5]L with ammonium cerium nitrate in the mixture of dichloromethane and water.P[4]Q[1]L was fully characterized by ¹H NMR,¹³C NMR,mass spectrometry,and X-ray single-crystal diffraction.The activated crystalline adsorptive materials of P[4]Q[1]L were performed by a simple recrystallization and desolvation process.It was worth noting that p X molecule after being absorbed could be used as connectors to induce solid-state molecular motion to realize bottom-up self-assembly and build ordered supramolecular architectures.Interestingly,the specific recognition ability could not be interfered by m-xylene,o-xylene and ethylbenzene with similar properties,thus realizing the purification of p-xylene from C8 alkylaromatic mixture（xylenes and ethylbenzene）,which created a new thinking for designing and exploiting specific adsorption materials.Thirdly,inspired by the above research,we further studied an energy-efficient separation of the toluene/methylcyclohexane mixture using nonporous adaptive crystals of P[4]Q[1]L.According to the approach of lossless solid–vapor phase adsorption,P[4]Q[1]Lαcrystals separated Tol from a Tol/MCH isometric mixture with a high purity of about 97.7%.This selectivity derived from the stronger host–guest interactions between Tol and P[4]Q[1]Lαand the relative stability of the complex.Moreover,recycled samples of P[4]Q[1]αwith simple heating operation could be used for Tol adsorption experiments at least five times without any performance decrease.Therefore,nonporous adaptive crystals possess enormous potential for applications in the chemical industry,and may be used in more demanding adsorptive separation systems in the future.