Design And Synthesis Of 1D Nitrogen-rich Metal-organic Nanotubes And Their Adsorption And Molecular Recognition Properties

As a new subclass of MOFs,one-dimensional metal-organic nanotubes（MONTs）are structurally analogous to carbon nanotubes.Nanotubes with nanoscale diameter and macroscopic length are model materials for studying molecular microscopic and macroscopic properties.Due to the structural characteristics of MONTs,they have excellent properties in adsorption,conduction,catalysis,molecular recognition and so on.The design and synthesis of novel MONTs is one of the research hotspots.In particular,designing and constructing MONTs with nanoscale inner diameters is more challenging.In this thesis,we synthesized a series of V-shape nitrogen-rich pyrimidine ligands.Employing the mixed-ligand strategy,seven new nitrogen-rich MONTs were successfully constructed by coordinating with zinc ions under solvent-thermal conditions.These MONTs had large inner diameters（about 1.76 nm）and abundant nitrogen atoms on the tube wall.In addition,these materials exhibited excellent stabilities in acidic and alkaline aqueous solution.The contents are as follows:1.Two series of MONTs were constructed for rare earth adsorption,they are named NCD-166-R（[Zn（bpndc）（beim-R）]·H₂O）and NCD-167-R（[Zn（obba）（beim-R）]·H₂O）（R=-CH₃,-Ph）,respectively.Benefiting from abundant exposed nitrogen and oxygen atoms in their tube walls and open nanoporous channels,the prepared MONTs（NCD-166-R and NCD-167-R）showed superior adsorption capacities for rare earth elements（REEs）even in the low-concentration solutions,especially for Eu³⁺.The maximum adsorption capacity for Eu³⁺was achieved as high as 150.90 mg g^-1.Meanwhile,these MONTs had higher adsorption selectivities for REEs over coexistent metal ions(K⁺,Cd²⁺,Ca²⁺,Ni²⁺,Mn²⁺,and Co²⁺)solutions,and the selectivity was larger than 95%.Additionally,it was revealed that the adsorption effect of ether oxygen on rare earth was significantly better than that of carbonyl oxygen.The adsorption of rare earths by NCD-166-R and NCD-167-R conformed to the Langmuir isothermal model,and the adsorption kinetic obeyed quasi-second-order model.2.The MONT（NCD-166-NH₂）with nanoporous channels,namely[Zn（bpndc）（beim-NH₂）]·H₂O was successfully synthesized by a bottom-up approach.The composite adsorbent（NCD-166-NH₂-PDA）was successfully prepared by simple self-polymerization of dopamine（DA）on the NCD-166-NH₂ under alkaline conditions,which had a porous structure and contained abundant active groups.It showed high affinity for Congo Red（CR）,and its maximum adsorption capacity reached to 1849.4 mg g^-1.Moreover,NCD-166-NH₂-PDA showed higher removal rate in low concentration wastewater.The CR adsorption over NCD-166-NH₂-PDA was fitted according to Langmuir and followed quasi-second-order kinetic model.And the monolayer chemisorption can be concluded.XPS and FT-IR analysis showed thatπ-πand hydrogen bonding played important roles in dye adsorption.3.Two fluorine-containing nitrogen-rich MONTs,NCD-166-CF₃（[Zn（bpndc）（beim-CF₃）]·H₂O）and NCD-168-NH₂（[Zn（bpndc）（beim-NH₂）]·H₂O）were constructed.These two MONTs showed highly selective toward phenolic nitroaromatic compounds（NACs）,especially for 2,4,6-trinitrophenol（TNP）.In addition,NCD-166-CF₃ and NCD-168-NH₂can selectively recognize antibiotics,such as nitrofuracillin（NFZ）,nitrofurantoin（NFT）and so on.They showed high sensitivity,strong anti-interference ability,and recyclability.The photoinduced electron transfer（PET）and resonance energy transfer（RET）played important roles in detection.