Synthesis And Characterization Of A Series Of Ln-MOFs Compounds Based On Dicarboxylic Acid Ligand

In recent years,MOFs have attracted wide attention owning to their applications in fluorescence probe.Currently,most of the MOFs fluorescent probe belong to "turn on" or "turn off" type based on single emission,whose sensitivity and detection limit can be easily affected by external environment and instrument parameters.Ratio fluorescent probe bears dual emission with self correction effect and represents an important research direction.However,the related research is still in its infancy.Accordingly,in this paper,a material with dual emission originate from incomplete energy transfer of ligand to Eu3+ was studied.Derails are described as below:1.Two di-carboxylic acid ligand H2L(5-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)isophthalic acid)and rigid imidazolate/carboxylate functionalized ligands H3DPBI(5-(5,7-dioxoimidazo[4,5-f]isoindol-6(1H,5H,7H)-yl)isophthalic acid),contains naphthalene ring and benzimidazole group respectively,were selected.The dihedral angle between aromatic groups makes energy transfer partially,which enable the realization of ratio fluorescence.2.Three new isostructural MOFs [Ln2(L)3(DMF)2(DMSO)1.5(H2O)0.5](Ln= La(1),Eu(2),Tb(3))were prepared based on H2 L,1-3 features two-dimensional(4,4)net structure,with a68.27? dihedral angle between the plane of naphthalene ring and benzene ring in L2-.The structure enables the partial energy transfer from ligand to Eu3+ in 2 and the double emission of L2-and Eu3+.By the ratio of the double emission,we can directly realize the 1 dimensional ratio fluorescence discrimination for different solvents.1-3 can be used as detection agent for Fe3+ ion(KSV are 27297.3M-1,14917.6M-1 and 68220.73M-1 respectively).1 and 2 are also good detection agent for dinoseb(Ksv for 1 and 2 are 70115.4M-1 and 69211.9M-1respectively),while 3 for 1-nitronaphthalene(Ksv = 59912.8M-1).3.Three isostructural compounds,[Mg(HDPBI)(HCOOH)0.3(DMSO)1.7]?DMSO(4),[Pb(HDPBI)(DMSO)2]?DMSO(5)and [Ca(HDPBI)(DMSO)2]?DMSO(6)are synthesized based on H3 DPBI.4-6 displays a 1D chain structure and can be used as detection agent for Fe3+ ion(KSV are 3833.33M-1,15397.14M-1,4784.57M-1 respectively).4 can also be used to detect1-nitronaphthalene(Ksv=61448M-1),while 5,6 can be used to detect dinoseb(Ksv are92272M-1,58143M-1 respectively).