| Metal-organic complexes are porous materials with specific spatial structures formed by self-assembly of metal clusters and organic ligands under the action of coordination bonds.Because of its regular orderly,high specific surface area,adjustable pore size and shape.As well as being easy to function,it is widely used in the fields of gas storage,electrochemical sensors,electromagnetic and medical carrier In recent years,long afterglow luminescent materials have been widely used in emergency indication,instrument display,optoelectronic devices,and defense and military fields.Due to their long life,large Stokes shift,and excited state properties,they are used for anti-counterfeiting,encryption and bio-imaging.Coordination polymers have special and rare persistent room-temperature phosphorescence afterglow modulation,and have broad application prospects in the fields of optical recording and encryption or multi-mode bio-imaging.To the best of our knowledge,this special and rare afterglow modulation exploration in this area may open a new door for newly emerging technologies such as optical recording and encryption or multimodal bio-imaging.This paper mainly includes the following two parts:(1)By designing and synthesizing two ligands 1-(pyridine-4-m ethyl)-1H-pyrazole-3,5-dicarboxylate(Li2ppb)and 1-(3,5-dicarboxymethylbenzyl)-1H-pyrazole-3,5-dicarboxylate lithium(Li4dpb),using the method of hydrothermal synthesis with metal ions Zn(Ⅱ)、Cd(Ⅱ)、Co(Ⅱ)、Mn(Ⅱ)、Ba(Ⅱ)、Dy(Ⅲ)、Eu(Ⅲ)、Tb(Ⅲ)、Nd(Ⅲ)、Ho(Ⅲ)、Sm(Ⅲ)、Tm(Ⅲ),and successfully obtained 14 complexes:[Zn(ppb)(H2O)]n(1)、{[Cd2(ppb)2(H2O)]·2H2O}n(2)、[Co(ppb)(H2O)]n(3)、{[Mn2(ppb)(pcb)(H2O)3]·H2O}n(4)、[Ba2(ppb)2(H2O)]n(5)、{[Dy2(ppb)3(H2O)5]·H2O}n(6)、[Eu(ppb)1.5(H2O)]n(7)、{[Tb(ppb)1.5(H2O)]·H2O}n(8)、[Mn2(dpb)2(DMF)]n(9)、{[Ln(dpb)0.75]·OAc·2H2O}n[Ln=Dy(10),Nd(11),Ho(12),Sm(13),Tm(14)].By analyzing the structure of the above complexes,complexes 1,3 and 4 show a two-dimensional network structure,while complexes 2,5-14 all show a three-dimensional framework structure,of which 1 and 3,7 and 8,10-14 are heterogeneous isomorphous structures,respectively.X-ray single crystal diffractometer was used to analyze the crystal structure of the newly synthesized 14 complexes,and the elemental analyzer and infrared spectrometer were used for characterization.The magnetic properties of complexes 3,4,9 and 10 were investigated,the experimental results showed that antiferromagnetic interactions existed in all four complexes.At the same time,we also performed research on the solid-state fluorescence and phosphorescence properties of complex 5 and crystal｛[Zn3(dpb)2(H2O)]·4H2O}n(HL).The results showed that both complex 5 and HL exhibited naked-eye visible MOF long afterglow phenomenon.(2)Seven new crystal complexes were obtained by hydrothermal synthesis of 4-(2,4,6-tricarboxylphenyl)-4,2’,6’,4"-terpyridine(p-tcpt),4-(2,4,6-tricarboxylphenyl)-3,2’,6’,3"-terpyridine(m-tcpt),4-amino-5-hydrazino-4H-1,2,4-triazole-3-thiol(ahtt),5-(1H-1,2,4-triazol-1-yl)nicotinic acid(Htynca)ligands and transition metal ions Zn(Ⅱ)、Cd(Ⅱ)、Co(Ⅱ)、Pb(Ⅱ)、Ni(Ⅱ)using the method of hydrothermal synthesis,among which {[Cd(p-tcpt)]·2H2O}n(15)and {[Co(p-tcpt)]·2H2O}n(16)were three-dimensional spatial structures.{[Pb(p-tcpt)(Cl)]·2H2O}n(17)、{[M(m-tcpt)(H2O)3]·CH3CN-H2O}n[M=CoNi](18)、{[Zn(ahtt)(CH3OH)]·CH3OH·0.5SO4·H2O}n(19)、[Cd(tynca)2(pbbbm)]n(20)and[Cd(tynca)2(bbbi)]n(21)are two-dimensional reticulated structure,and complexes 20 and 21 were found to have obvious phosphorescence long afterglow at room temperature.We further studied the six complexes that have been synthesized based on Htynca ligand research in our laboratory and found that they also have room-temperature phosphorescence long afterglow.These six crystal complexes are as follows:{[Cd(tynca)2(H2O)4]·2H2O}n(22)、{[Cd(tynca)2(bix)]·H2O}n(23)、{[Cd(tynca)2]·H2O}n(24)、[Cd(tynca)2(H2O)2]n(25)、[Cd(tynca)2]n(26)和{[Cd(tynca)(mbbbm)(Ac)]·3H2O}n(27).The room-temperature solid fluorescence and phosphorescence properties of the above eight complexes from 20 to 27 were investigated.the experimental results showed that a single green phosphorescence was observed in complexes 22 to 25,in which the excited states of T2(π,π*)were stabilized by the π-stacking interaction of the phosphorescent group tynca-,which helped to prolong their luminescence lifetime.In contrast,when the π-stacking interaction of the phosphorescent group tynca-was absent in the rigid matrix,20、21、26 and 27 exhibited an intriguing time-resolved afterglow modulation,in which yellow[T1(n,π*),short lifetime]and green[T2(π,π*),long lifetime]phosphorescences were sequentially observed during the decay process when the common UV light was turned off. |
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