| Since the 21st century, information technology has been in the high-speed development stage, information industry based on the generation, storage, transmission, control and manipulation of information has accounted for more than a half of the total value of production in developed countries, so the information technology has become an important symbol of the development of economy and technology in developed countries. Magnetic materials as a basis for information storage, impect the development of information technology. In the field of magnetic materials, an important research direction is the preparation of molecular magnets, which can be regulated magnetically. So far, the research of intramolecular electron transfer induced by light, heat, pressure, and guest molecules is still very limited, only a few multidimensional coordination polymers and clusters molecules were reported. And multidimensional coordination polymers can not be applied to the nanoscale electronic devices, duing to their poor solubility and difficult to machining, so they are not conducive to apply in the high density information storage materials. Therefore, molecule-based magnetic materials with the advantages of ordered structure, chemical selectivity extensive and easy modification and tailoring of molecules by chemical methods provides a beneficial way for the construction of multi-function information storage materials.The syntheses, structures and properties of cyano-bridged complexes of {Fe2Co2} square molecules,{Fe4Co4} cubic molecules and {Fe4Ni4} cubic molecules based on tricyanometalate building blocks were studied in this dissertation.1. Two new cyano-bridged square molecules based on tricyanometalate building block [(Tp)Fe(CN)3]- and Co2+ were rationally prepared by introducing a neutral secondary ligand DCEB (DCEB= 4,4'-bis(ethoxycarbonly)-2,2'-bipyridine), and all of them were characterized structurally and magnetically. Complex 1,{[(Tp)Fe(CN)3]2[Co(DCEB)2]2}(ClO4)2·2MeOH was in a low spin state with the Fe?(?-CN)Co?linkage, while complex 2,{[(Tp)Fe(CN)3]2[Co(DCEB)2]2}(ClO4)2 was in a high spin state with the Fe?(?-CN)Co? linkage. Complex 2 presented temperature- and pressure-induced intramolecular charge-transfer induced spin transition (CTIST) behaviour and showed reversible single crystal-to-single crystal transformation between diamagnetic and paramagnetic states switched specifically by losing and absorbing methanol at room temperature in the solid state. The transition between the two complexes accompanied by distinct color change, making it possible for complex 2 to distinguish methanol duing to its specificity.2. A series of new cyano-bridged cubic molecules [(L')4Fe4(CN)12][Co4(L)4](X)4·nsolv (complex 3,7,8,10) and a series of new cyano-bridged cubic molecules containing alkali metal ions, A+c[(L')4Fe4(CN)12][Co4(L)4](X)4·nsolv (A+= Rb+, Cs+; L= MeTPM, EtTPM; X= ClO4-, OTf-, PF6-) (complex 4,5,6,9,11,12,13) based on tricyano-metalate building blocks [(L')Fe?(CN)3]-(L'=Tp, pzTp, TpBr), [(pzTp)Fe"(CN)3]2- and Co2+ were rationally prepared by introducing a neutral secondary ligand MeTPM, EtTPM(MeTPM= 2,2,2-tris-(pyrazolyl)ethane, EtTPM= 2,2,2-tris-(pyrazolyl)propane), and some of them were characterized structurally and magnetically, and the change of structure and magnetic properties of the cubic molecules containing alkali metal ions was studied preliminarily. Complex 3, [(pzTp)Fe?(CN)3]4[Co?(pz3CCH3)]4(Cl04)4·3DMF·MeOH·H20, showed therm- and photo-induced intramolecular electron transfer behaviour. The structure of complex 5, Cs+c [(pzTp)4Fe?3 Fe"(CN)12][Co?(pz3CCH3)]4(ClO4)4·13DMF·MeOH·H2O, was different from complex 3 duing to the Cs+. the valence configuration of Fe center was{Fe?3Fe?} confirmed by infrared data and single crystal diffraction data. And the valence configurations of Fe center of complex 11-13 might be {Fe?2Fe?2},{Fe?Fe?3},{Fe?4}. Complex 4 was very similar to complex 5, and this phenomenon not only existed in mother liquor, but also in the solid state. Complex 5 exhibited temperature-induced CTIST behaviour, and the transition temperature increased significantly.3. A new cyano-bridged cubic molecule [(pzTp)4Fe?4(pz3CCH3)4Ni4(CN)i2](ClO4)4·7H2O·3Et2O· 5DMF (complex 17) and a series of new cyano-bridged cubic molecules containing alkali metal ion, Cs+c[(pzTp)4Fe4(CN)12][Ni4(L)4](X)4·nsolv (L= MeTPM, (pz)3CCH2OH; X= ClO4-,ClO4-+OTf-, PF6-) (complex 14,15,16,18) based on tricyanometalate building block [(pzTp)Fe(CN)3]- and Ni2+ were rationally prepared by introducing a neutral secondary ligand MeTPM, (pz)3CCH2OH ((pz)3CCH2OH= 2,2,2-tris-(pyrazolyl)ethanol), and some of them were characterized structurally and magnetically, and the change of structure and magnetic properties of the cubic molecules containing alkali metal ions was studied preliminarily. The valence configuration of Fe center of complex 15 was {Fe?3Fe?}, which was confirmed by infrared data, mossbauer spectrum and single crystal diffraction data. The structures of complex 14,16,18 were similar to complex 15. For complex 14, Cs+(?)[(pzTp)4Fe?3Fe?(pz3CCH2OH)4Ni4(CN)12](ClO4)4·7H2O·5DMF·3Et2O and complex 15, Cs+c [(pzTp)4Fe?3Fe?(pz3CCH2OH)4Ni4(CN)12](PF6)2(ClO4)2·2DMF-4Et2O, the ?MT vs T suggested that the Fe? and Ni? centers were ferromagnetically coupled, and the calculated values of giso and Jjso were 2.36 and 8.5(5) K, respectively. Complex 14 and complex 15 exhibited frequency-independent ?'values and ?" values, so they were single-molecule magnets. |
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