Construction Of Na-Ln Heterometallic Coordination Polymers Based On Lanthanide Metalloligands And Their Fluorescence Sensing And Gas Adsorption Properties

Organic matter has caused serious potential harm to the ecosystem because of its easy migration and difficulty to remove.The development of efficient detection methods to detect these pollutants is the first condition to control their harm.At the same time,the storage and low-energy separation of light hydrocarbon energy gases such as C2H2,C2H4,C2H6,C3H4,C3H6,C3H8,n-C4H110,i-C4H10,CH4,CO2 are also a major difficulty facing the industry at present,and corresponding development is urgently needed.Heterometallic coordination polymers containing lanthanide metals(HCP@Ln)have great application potential in fluorescence sensing,gas adsorption-separation and bimetallic catalysis.Therefore,this paper is based on the lanthanide metalloligand strategy,using Na+as the structural template,and successfully constructed 5 Na-Ln heterometallic coordination polymer([Eu(ODA)3Na2]n(1),[Gd(ODA)3Na2]n(2),[TbODA)3Na3(H2O)2]n(3),{[Eu3(ODA)3(L2)3Na(H2O)]·H2O}n·9DMF(4),[Eu3(ODA)3(L3)3Na2]n·6H2O·3DMF(5)under solvothermal conditions.Through single crystal X-ray diffraction structure analysis,Fourier-infrared spectroscopy,thermogravimetry,powder X-ray diffraction,etc.,the structure and stability of the constructed Na-Ln coordination polymer were fully characterized.The fluorescence sensing of(1)(3)(4)for tetracycline antibiotics and aromatic amines and storage and separation of energy gases of(5)such as light hydrocarbons has been deeply discussed.Related work is as follows:1.Based on the lanthanide metalloligand[Ln(ODA)3]3-(Ln=Eu,Gd and Tb,H2ODA=oxodiacetic acid),using Na+ as the structural template,successfully assembled three novel Na-Ln heterometallic coordination polymer,[Eu(ODA)3Na2]n(1),[Gd(ODA)3Na2]n(2),[Tb(ODA)3Na3(H2O)2)n(3).Fluorescence sensing research found that:(1)can detect low concentrations of tetracycline and oxytetracycline can be efficiently achieved through the fluorescence ratio approach,and the corresponding detection limits are 0.16 ?M(71.92 ppb)and 0.09 ?M(45.54 ppb),respectively.At the same time,(3)can detect 4-(phenylazo)aniline through the quenching pathway,and the detection limit is 0.07 ?M(14.59 ppb).Competition and sensing cycle experiments show that(1)and(3)have good anti-interference ability and cyclability to the corresponding sensed objects,which shows that(1)can be used as a fluorescence probe for detecting tetracycline and oxytetracycline.Needle,(3)can be used as a fluorescent probe for detecting 4-(phenylazo)aniline.In addition,the related sensing mechanism has also been deeply studied.2.On the basis of the previous part of the work,with[Eu(ODA)2]-as the lanthanide metalloligand,Na-as the structural template,and N-containing dicarboxylic acid ligand[4,4'-(pyridazine-3,6-Diyl)dibenzoic acid](H2L2)assembled a new type of "pillar-layer" structure of Na-Eu heterometallic organic-framework,{[Eu3(ODA)3(L2)3Na(H2O)]·H2O·9DMF}n(4).Fluorescence sensing studies have shown that(4)can sensor tetracycline,oxytetracycline,chlortetracycline and 4-(phenylazo)aniline can be efficiently detected by fluorescence quenching,and the corresponding detection limits are 0.022 ?M(9.76 ppb),0.023 ?M(10.58 ppb),0.026?M(12.42 ppb),3.55nM(0.69 ppb),respectively.Comparing with(1)and(3),(4)has more outstanding detection ability,and successfully overcomes the shortcoming of(1)poor sensing ability to chlortetracycline.3.On the basis of(4)assembly,by using[2'-amino-[1,1':4',1"-terphenyl]-4,4"-dicarboxylic acid](H2L3)instead H2L2,we have successfully constructed a Na-Eu heterometallic-organic framework with a "pillar-layer" structure,?[Eu3(ODA)3(L3)3Na2]·6H2O-3DMF} n(5).Single crystal X-ray diffraction structure analysis showed that the amino group on the ligand L3 faces the pore in(5).Based on the characteristics of this channel,the gas adsorption performance of(5)was studied.The 77 K N2 adsorption experiment showed that its BET specific surface area was 954m2/g.At the same time(5)shows excellent adsorption capacity for propyne under normal pressure.The adsorption capacities are 168.67 and 155.73 cm3/g(STP)at 273 K and 298 K,respectively.At the same time,the adsorption capacity of(5)for propylene is significantly less than that of propyne,with 273 K and 298 K being 118.60 and 112.88 cm3/g(STP),respectively.The calculation results of the heat of adsorption(Qst)also further show that the Qst of(5)for C3H4 is 38 kJ/mol,which is significantly greater than its 26 kJ/mol for C3H6,indicating that there is a relatively high difference between C3H4 and-NH2 in the pores of(5).Strong interaction.Finally,with the help of ideal adsorption and dissolution theory(IAST),we calculated the separation selectivity of(5)to C3H4/C3H6(50:50)binary mixture at 298 K to be 2.8.These results show that(5)can be used not only as storage material for alkyne,but also has the ability to effectively separate C3H4/C3H6 under normal pressure.