Design,Synthesis And Properties Of Polymeric Materials Constructed From Aromatic Polycarboxylic Acids

In recent years,the rational design and construction novel metal–organic coordination polymers becomes a research hotspot in the field of inorganic chemistry.These materials not only have fascinating structures,but also show potential applications in many fields as gas separation and storage,heterogeneous catalysis,magnetism,optics,chemical sensor and etc..Among them,the CPs with luminescence and sensing properties are favored.Lanthanide coordination polymers?LnCPs?have special properties,such as high fluorescent efficiency,narrow emission peak and long fluorescence lifetime.Coordination polymers based on Eu?III?and Tb?III?can emit red and green light in the visible region.By choosing suitable organic ligands and using its“antenna effect”,Ln?III?ions are sensitized.Therefore,white-light emission materials are obtained through the doping of trichromatic light.In addition,the luminescent coordination polymers with sensor performance have a good prospect.Compared with the traditional detection methods,it has the advantages of fast response,convenient and high sensitivity.However,construct CPs with expected functions is still a challenge.Select proper organic ligand is crucial,because its shape,length,rigidity/flexibility,and steric effect will directly affect the final frameworks of the CPs.Among the many organic ligands,aromatic carboxylic acid is the best choice:?i?it not only coordinates with the transition metal,but also with lanthanide metal;?ii?it has diversity coordination modes;?iii?it has large?-conjugate system and can serve as chromophore to sensitize Ln³⁺ions.In addition,the N-donor ligands are used to modify the metal–polycarboxylate networks.These organic bases play an important role in the extension and stabilization of the metal–tetracarboxylate networks.Based on the above consideration,a series of aromatic carboxylic acids were selected to construct coordination polymers.The reactions of metal ions?transition/rare earth?and aromatic polycarboxylic acids were hydrothermal or solothermal carried out,obtaining 26 new coordination polymers.The effect factors influencing the system were discussed.The structure analysis and a series of basic characterization of the CPs were conducted,and their optical and magnetic properties were studied.1.Seven transition-metal CPs,three lanthanide-metal CPs and two doped CPs were successfully synthesized by using semi-rigid triangular carboxylic acid?H₃bcbob?.In the first section,under hydrothermal conditions,H₃bcbob constructed seven CPs with the assistance of N-donor ligands,[Ni?Hbcbob??1,4-bimb?]?1?,[Zn₃?bcbob?₂?bpe?₂]?2?,[H₂?bpp?][Mn₂?bcbob?₂]?3?,[Cd₂?OH??bcbob??bpe?_0.5]·H₂O?4?,[Cd₈?OH?₄?bcbob?₄]×0.5bpp?5?,[Ni₂?Hbcbob?₂?1,3-bimb?₂]?6?,[Ni?Hbcbob??bpb??H₂O?]?7?,?H₃bcbob=3,5-bis??4'-carboxylbenzyl?oxy?benzoic acid,1,4-bimb=1,4-bis?imidazol-1-yl-methyl?benzene,bpe=1,2-bis?4-pyridyl?-ethene?,bpp=1,2-bis?4-piperidyl?propane),1,3-bimb=1,3-bis?imidazol-1-yl-methyl?benzene,bpb=1,4-bis?imidazol-1-yl?butane).In 1,the bcbob molecules link the Ni²⁺centers into a 2-D layer with a?6,3?net,and then the1,4-bimb molecule serves as the pillar linker expands the 2-D layer into a three-fold interpenetrated 3-D structure.In 2,the bcbob molecules link two types of tetrahedral Zn²⁺ions into a 3-D network with a pcu topology,while the bpe molecule is only used to stabilize the 3-D network.The 3-D networks of 3-5 are all built up from carboxylate-bridged rod-shaped secondary building units?SBUs?by the bcbob molecules,and three types of 1-D channels are observed.However,since the rod-shaped SBUs contains different structures,the side walls of the channels exhibit different arrangements.In particular,the side wall in 4 and 5 adopt a helical arrangement.In 3,the[H₂bpp]²⁺molecules occupy the space of the largest channels,while in 4,the bpe molecules occlude one type of small channels by coordinating to the Cd²⁺ions on the side wall.Compound 6 has a multi-fold interpenetrated framework structure,and 7 is a 2-D layered compound.The photoluminescence analysis reveals that compounds 2,4,and 5 can serve as chemosensors to detec the ppm-grade nitrobenzene.In the second section,H₃bcbob ligands construct three 2-D isomorphic LnCPs in the solvothermal conditions,namely,[Ln?bcbob??H₂O??DMF?](Ln=Tb?8?,Eu?9?,Gd?10?.Luminscence investigation reveals that 8 and 9 show characteristic green and red emission of the corresponding Tb³⁺and Eu³⁺,while 10exhibits blue emission arising from the bcbob^3-ligand.Based on their luminescence properties,we successfully designed and synthesized two doped white-light emitting compounds 11 and 12.Compound 11 has a longer lifetime and a higher quantum yields.In addition,compound 8 not only can sense trace amounts of nitro-pollutants(for PA,K_sv=3.6?10⁴ M^-1),but also can selectively detected Fe³⁺(K_sv=3.18?10⁴M^-1)and Al³⁺?enhance the ligand luminescence?.2.We employed a rigid bridging-type tetracarboxylic acid molecule,namely5,5'-?pyridine-3,5-diyl?diisophthalic acid?H₄L?,to construct three new isomorphic Ln-MOF materials[?CH₃?₂NH₂]₂[Ln₂?L?₂?H₂O?₂]×2DMF×2H₂O?Ln=Tb?13?,Eu?14?,Gd?15??.Since the pyridyl N atom does not coordinate to Ln³⁺,the larger pores are observed in the 3-D networks of 13-15.Based on their photoluminescence properties,the white-light emitting materials 16-19 with longer fluorescence lifetime?ms grade?and higher quantum yield?e.g.48.29%for 17?are fabricated.We also find that the title Ln-MOF materials not only can selectively sense polychlorinated benzenes,but also can highly sensitively detect the Fe³⁺ion(K_sv=7.58×10⁴ M^-1).This should be associated with these three structural factors in 13-15:the largerp-conjugated structure of L^4-;the larger porous structures in 13-15;the existence of uncoordinated N atom on L^4-.The test paper experiments reveal that 13 can be made into the test paper?a naked eye probe?to quickly detect the analytes.3.Under the hydrothermal conditions,the reactions of transition-metal salts,tetracarboxylic acids and N,N?-donor ligands yield seven new coordination polymers,namely[Cu₄?fph?₂?bpe?₃?H₂O?₂]×2H₂O?20?,[Co₂?fph??bpa?₂?H₂O?₂]×3H₂O?21?,[Ni?H₂O??H₂oph??bpa?]?22?,[Zn₂?fph??tib?]×H₂O×DMF]?23?,[H₂?bpp?]₂[Zn₂?sph?₂]×H₂O?24?,[H₂?bpp?]₂[Ni₂?oph?₂?H₂O?₂]×2H₂O?25?,[H₂?bpe?]₂[Ni?Hfph?₂?bpe?]?26?,?fph=4,4?-?hexafluoroisopropylidene?diphthalate,oph=4,4?-oxydiphthalate,oph=4,4?-oxydiphthalate,bpe=1,2-bis?pyridyl?ethylene,bpa=1,2-bis?pyridyl?ethylene,tib=1,3,5-tris?1-imidazolyl?-benzene,bpp=1,3-bis?piperidyl?propane?.For 20,the fph molecules first link the Cu²⁺ions into a2-D wave-like layer with a?4,4?topology.The bpe molecules act as the second linkers,extending the 2-D layers into a 3-D network.For 21,the fph molecules still serve as the first connectors,linking the Co²⁺ions into a 1-D tube-like chain.Then the bpa molecules propagate the chains into a 3-D?4,4,4?-connected network.The3-D structure of 22 is constructed by coordination water molecules and bpa and Ni²⁺,while oph molecules only play a bridging role.For 23,the penta-bridged fph^4-molecules first link two types of tetrahedral Zn²⁺ions into a 1-D double-chain structure.Then the tib molecules extend the 1-D double chains into a 3-D network.For 24,the quadruple-bridged sph molecules propagate the tetrahedral Zn²⁺ions into a 2-D layer network,while the diprotonated bpp molecule acts as a templating agent.In 25,the bpp molecule is also diprotonated.The triple-bridged oph molecules extend the octahedrally coordinated Ni²⁺ions into a 2-D layer network,in which a carboxylate-bridged Ni²⁺chain is observed.In 26,the non-protonated bpe molecules link the Ni²⁺ions into a 1-D linear chain.We also study the performance of the title compounds.Compounds 20-22,25 all exhibit the predominant antiferromagnetic magnetic behavior.23 emit the strong blue light,and can sense nitro aromatic explosives and Pb²⁺ions.(for 2,4-DNT,K_sv=2.74?10⁴ M^-1,for Pb²⁺,K_sv=3.65×10⁴ M^-1).In conclusion,26 CPs have been successfully prepared under hydrothermal or solvothermal conditions.The structure analysis and a series of basic characterization of the CPs were conducted,and their optical and magnetic properties were studied.Some data and methods are accumulated to realize the functionalization of coordination polymer,which points out the direction for the future work.