| Lanthanide complexes have been widely used in the fields of luminescence,sensing,catalysis,biological activity and molecular magnetism.In recent years,great breakthroughs have been made in the block temperature and energy barrier of Dy-based single-molecule magnets(SMMs),which has brought the idea of SMMs to be applied in the fields of high density information storage,quantum computing and molecular spintronics.The metal centers based on ligand coordination with different geometric configurations can accurately control the magnetic anisotropy of molecules,i.e.SMMs generated by a single metal center,also known as Single-Ion Magnets(SIMs).It is noteworthy that great progress has been made in SMMs,the directional construction and serialization of intelligent responsive and multifunctional Dy-based complexes have also emerged quietly.In this paper,we mainly rely on quinoline derivative ligands with good photo-luminescence activity to construct responsive and multifunctional dysprosium complexes,and further study their magnetic structure,photo-luminescence and structure-magnetic relationship before and after external stimulation(heating,grinding,etc.).The synthesis methods and optimum reaction conditions were attempted and summarized,and the assembly rules were explored to provide examples for the further design and synthesis of more sensitive responsive magnetic materials and multifunctional dysprosium complexes.The first chapter is introduction,which suggests the significance and scientific contribution of this paper.It focuses on the development of single-molecule magnets(some lanthanide-based SMMs and3d transition metal SMMs),the research status of multifunctional lanthanide complexes(focusing on photoluminescent lanthanide-based SMMs),the stability of clusters by high resolution mass spectrometry conditions(HRESI-MS),and the research of lanthanide-based porous hydrogen bonded organic frameworks.The research status and the latest research progress of intelligent lanthanide-based magnetic materials provide a solid foundation for the further development of this paper.Inchapter2,blockcrystalsweresynthesizedbymixed5,7-dichloro/dibromo-2-methyl-8-quinolinol(L1/L2)and 2,9-dimethyl-1,10-phenanthroline(Phen)with stoichiometric ratio of 1:1 and adding Dy(NO3)3·6H2O in methanol at 80?,X-ray single crystal diffraction analysis shows that the block crystals are dysprosium-based hydrogen-bonded organic frameworks(Dy-HOFs,complex 1-2).The Dy-HOFs are three-dimensional framework structures formed by weak interaction of mononuclear dysprosium complexes.The weak interaction links of the repetitive structural units consist of mononuclear dysprosium complexes and free organic molecules Phen.Mononuclear dysprosium complex is in the N3O4coordination environment constructed by L1/L2 and terminal coordination methanol.The organic molecule Phen is not involved in the coordination,but dissociates in the channels of Dy-HOFs through supramolecular weak interaction.Magnetic susceptibility studies show that all the original samples of Dy-HOFs exhibit unconspicuous single-ion behavior under zero dc-field condition,but after mechanical grinding,all Dy-HOFs exhibit more obvious relaxation behavior than the original samples.It is worth noting that after heating Dy-HOFs with a thermogravimetric analyzer at 5 K/min and staying at 260?for 2 hours,the organic molecule Phen was removed,but the main framework was not destroyed.Magnetic susceptibility studies suggest that all heated samples exhibit much obviously single-ion magnetic behavior under zero-field conditions.By further changing the concentration of Phen in the synthesis method,Dy-HOFs(complex 3)with different structure types were obtained.There were two free Phen in complex 3,Dy(III)core is coordinated by one L2,three nitrate anions and one methanol.By changing Phen to 2-methylquinoline,Dy-HOFs(complex 4)with2-methylquinoline as free organic molecule was obtained under the same condition.The coordination environment of Dy(III)in the structure of complex 4 is similar to that of complex 2,only the terminal coordination methanol replaced by Cl-ion.In chapter 3,complexes[Dy(L1)3(H2O)](5),[Dy(L2)2(NO3)3](6),and[Dy(L3)3(H2O)](7)were synthesized by the reaction of 5,7-dibromo-2-methyl-8-quinolinol(L1),1,10-phenanthroline(L2),and 5,7-dichloro-2-methyl-8-quinolinol(L3)with Dy(NO3)3·6H2O under solvothermal conditions at80°C with the volume ratio of methanol to acetonitrile 1:1,respectively.Further stoichiometric reactions of mixed organic luminescent ligands L1,L2 and Ln(NO3)3·6H2O with the volume ratio of methanol to acetonitrile 1:1 at solvothermal conditions resulted in a complex[Ln(L1)2(L2)(NO3)][Ln=Dy(8),Ho(9),Er(10)and Tb(11)].Complexes 5 and 6 exhibited yellow-green and red lights under excitation of a certain wavelength of light.Interestingly,8–11 showed superimposed luminescence of 5 and 6.Moreover,the series of complexes[Ln(L3)2(L2)(NO3)][Ln=Dy(12),Ho(13),Er(14),and Tb(15)]were also obtained under the same conditions by replacing L1 with L3.Similarly,12-15 shows the superimposed luminescence of 6 and 7.Density Functional Theory(DFT)electron cloud density calculation showed that the electron cloud densities of complexes 8 and 12 are mainly concentrated in the quinoline ring.Furthermore,analysis of the molecular ion peaks of the electrospray mass spectrometry(ESI–MS)of the neutral ligand complexes 8–15 of the mixed ligand showed that only ligand L2 was found to cleave in the above complexes.Therefore,the coordation ability of different chelating ligands followed the order L1/L3>L2.Finally,magnetic measurements revealed Dy-containing complexes exhibited field-induced single-ion magnet behavior.In chapter 4,the phenomena of methanol-and temperature-induced dissolution-recrystallization structural transformation(DRST)was observed among two novel Cu(II)complexes.This is first time that the combination of X-ray crystallography,mass spectrometry and DFT theoretical calculation was used to describe the fragmentation and recombination of a mononuclear Cu(II)complex(Cu1,16)at 60°C methanol to obtain a binuclear copper(II)complex(Cu2,17).We screened the anti-tumor activities of L,Cu1 and Cu2,respectively,and found that the anti-proliferative effect of Cu2 on some tumor cells was much greater than that of L and Cu1.In chapter 5,we have obtained two cobalt complexes with different structures and topologies induced by solvents:[Co(L)2(SCN)2](Co1,18)and[Co2(L)2(SCN)(OAc)3](Co2,19)(L=8-methoxyquinoline).The synthesis method of Co1 and Co2 is similar except for solvents.Co(II)ion in Co1 is six-coordinated octahedral geometry,and every Co(II)ions in Co2 are also six-coordinated octahedral geometry,Co(II)ions are bridged by three acetate radicals.Weak interaction analysis revealed that complexes Co1 and Co2 exhibited 6-connected shp and14-connected fcu nets,respectively.Magnetic studies showed that Co1 demonstrated weak frequency dependence under zero-field conditions and single-ion magnet behavior under 2,000 Oe.These behaviors are indicative of clear field-induced SIM behavior.The energy barrier and relaxation time were Ueff=23.9 K and?0=2.7×10-7s under 2,000 Oe dc field,respectively.By contrast,Co2 lacked frequency dependence under zero-field conditions.Electrospray ionization mass spectrometry indicated that two complexes were stable in N,N-dimethylformamide(DMF). |
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