Study On Synthesis And Characteristics Of Covalent Organic Frameworks And Conjugated Microporous Polymers

In recent years, organic porous polymer materials which are a class of crystalline porous have more attention of academic scientists and industry entrepreneurs. Organic porous polymer materials have the rapid development of gas adsorption, heterogeneous catalysis, chemical sensors and optoelectronic materials. New organic porous polymer materials inculding Hypercross-linked Polymers(HCPs), Conjugated Microporous Polymer(CMPs), Porous Aiomatic Frameworks(PAFs) and Covalent Organic Frameworks(COFs) are successively synthesized and applied many fields. CMPs and COFs have high surface area, good thermal and chemical stability. However,COFs also have permanent porous and high crystallinity. Herein we demonstrated three novel conjugated Covalent Organic Frameworks and one novel Conjugated Microporous Polymer which structures were fully characterized and properties were systematically researched.A new azine-linked covalent organic framework, ACOF-1 was synthesized by condensation of hydrazine hydrate and 1,3,5-triformylbenzene under solvothermal conditions. ACOF-1 has high surface area and small pore size, and it can store up to 177 mg g-1 of CO2 and 11.5 mg g-1 of CH4, at 273 K and 1 bar, with high selectivity towards CO2 over N2 and CH4.An azine-linked covalent organic framework, COF-JLU2, was designed and synthesized by condensation of hydrazine hydrate and 1,3,5-triformylphloroglucinol under solvothermal conditions for the first time. New covalent organic framework material can be combined permanent microporous, high crystallinity, good thermal and chemical stability, and abundant heteroatom activated sites in skeleton. COF-JLU2 possesses a moderate BET surface area of over 410 m2 g-1 with a pore volume of 0.56 cm3g-1. Specifically, COF-JLU2 has remarkable carbon dioxide uptake(up to 217 mg g-1) and methane(38 mg g-1) at 273 K and 1 bar, as well as high CO2/N2(77) selectivity. Furthermore, we further highlight that it exhibits higher hydrogen storage capacity(16 mg g-1) than those of reported COFs at 77 K and 1 bar.A highly crystalline two-dimensional covalent organic framework(COF-JLU3) has been designed and successfully constructed through Schiff-base condensation reaction of hydrazine hydrate and 1,3,5-tris(3`-tert-butyl-4`-hydroxy-5`-formylphenyl)benzene under solvothermal conditions. The azine-linked framework materials assisting by hydrogen bond feature permanent porosity with large surface area and display excellent chemical and thermal stability. Interestingly, the microporous framework possesses a strong emission peak at 603 nm with high absolute quantum yield of 9.91% at the solid state. COF-JLU3 with abundant heteroatom activated sites on the pore surface was exploited for the binding and specific sensing of metal ions via acid-base interactions in tetrahydrofuran suspension. In particular, the new COF exhibited a highly selective response to copper ions which suggests that this COF is a promising luminescent probe for selectively sensing copper ions. This is the first crystalline COF that can serve as functional fluorescent sensor for selectively detecting trace amounts of toxic metal ions.A luminescent conjugated microporous polymer(BCMP-3) has been synthesized by carbon-carbon coupling reaction using triarylboron as building unit with a high yield. BCMP-3 was fully characterized using powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, 13C-solid state NMR spectrascopy, field emission scanning electron microscopy, thermogravimetric analysis, nitrogen and carbon dioxide adsorption. The new three-dimensional conjugated framework possess a high BET specific surface area up to 950 m2g-1 with a pore volume of 0.768 cm3g-1, good stability and abundant boron sites in the skeleton. Under excited-light irradiation, BCMP-3 exhibits strong fluorescent emission at 488 nm with high absolute quantum yield of 18% in the solid state. The polymer BCMP-3 acts as a colorimetric and fluorescent chemosensor with high sensitivity and selectivity for F– over other common anions. In addition, the polymer also works as adsorbents for F– removal and shows good adsorption capacities of up to 24 mg g-1 at equilibrium fluoride concentrations of 16 mg L-1 and temperature of 298 K. The adsorption kinetics and isotherm were analyzed by fitting experimental data with pseudo-second-order kinetics and Langmuir equations. Furthermore, we further highlight that BCMP-3 as an adsorbent for fluoride removal can be efficiently reused for many times without loss of adsorption efficiency.