| In recent decades, metal–organic frameworks(MOFs) have beendeveloping at a rapid pace with an exponential growth in the numberof complexes, and reports have been broadcast and covered onhundreds of overseas and domestic magazines. The materialscombine inorganic ‘nodes’ with organic ‘linkers’ by strongcoordination bonds, leading to diverse structures, properties andapplications. In this paper, by using lanthanide clusters as buildingblocks and achiral picolinic acid/terephthalic acid as organiclinkers, twelve chiral complexes have been successfullysynthesized by fine tuning the reaction conditions. These twelvecomplexes can be devided into two groups: one-dimensional andthree-dimensional. This thesis mainly concentrates on syntheses,structures and properties of these compounds. The nonlinearoptical properties of all complexes have been well studied, andsome other properties have also been explored. Four parts areincluded as follows:1. Firstly, the research background and the status quo of MOFs,especially Ln-MOFs, are introduced in the preface, in which the properties and the limitations of the applications of Ln-MOFs areconcisely summarized. The photoluminescent properties ofLn-MOFs and the mechanism are well introduced. Besides, theluminescent properties of mixed Ln-MOFs (bi-or three-component)are described and some reported examples have been given.2. Five isostructural lanthanide compounds Ln(pic)3[Ln=La (1),Gd (2), Nd (3), Sm (4) and Eu (5), pic=picolinic acid] with1D21right-handed helical chains built from N,O-chelated pic-ions andLnN3O6polyhedron were hydrothermally synthesized and all of themcrystalized in chiral P21space group. Thereinto, complexes (3),(4)and (5) have already been reported by some other researchers, but wealso systematically investigated their unheard properties. With thetemperature decreasing from293K to100K, complex (1) went throughan extraordinary transformation of space group. Thermal analysisshows that all the complexes have excellent stability and thecomplexes are not decomposed until400oC. Whereafter, Ultraviolet-Visible-Near-infrared spectroscopy tests indicated that (1)-(5) haveoptical band gap of about3.29eV, corresponding to the short-wavelength absorption edge at about377nm. Besides, powderSecond-Harmonic-Generation measurements exhibited that SHGintensities of complexes (1),(2),(4) and (5) were approximately1.2,2.0,0.9and0.75times that of KDP. Both (1) and (3) showhigh-efficiency photocatalytic degradation for organic dyes such asMethylene Blue upon Ultraviolet. What′s more,(1) and (2) display blueemission excited by328nm.3. Both picolinic acid and terephthalic acid have been addedinto the reaction using Ln(NO3)36H2O(Ln=Gd，Tb，Dy，Ho，Er，Tm， Yb) as metal source and water as solvent, as a result, the structurewas turned from one-dimension to three-dimension after adjustingthe regimen, while seven isostructural complexes Ln3(tpa)3(pic)3[tpa=erephthalic acid, pic=picolinic acid, Ln=Gd(6), Tb(7), Dy(8),Ho(9), Er (10), Tm(11) and Yb(12)] are well obtained. Complexes(6)-(12) crystallize in chiral P61or P65space group. TG-DSC studiesdemonstrated that all isologues have good thermal stability.Complex(7) shows strong green luminescence corresponding to thecharacteristic emission peak of Tb(Ⅲ), the lifetime is1.3ms and thequantum yield is about33%. SHG research indicates that the NLOproperties of (6)-(12) are not very excellent, values are0.30KDP,0.57KDP,0.25KDP,0.15KDP,0.20KDP,0.15KDP and0.13KDP,respectively.4. A concise conclusion is drawn and an outlook of this researcharea is anticipated. |
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