The Design, Synthesis And Magnetic Properties Of Organosilica-based Metal-thiazole Complexes

Organosilica-based metal-thiazole complexes were designed and synthesized through the sol-gel processes in this paper, and the magnetic behaviors of these complexes were studies. The aim is quest for the relationship of the chain structure, the kind of metal ions and the magnetic property of the corresponding complex, which will provides some useful information for the novel functional magnetic materials.A novel bridged polysilsesquioxane containing bithiazole rings (PBSIBTH) and its complexes (PBSIBTH-Ni, PBSIBTH-Cu, PBSIBTH-Eu, PBSIBTH-Tb) were firstly designed and synthesized in this paper, and dimethylsiloxane chain (-Me2SiO-) was introduced to the silica backbone of the organic-inorganic hybrids to get a kinds of novel liquid state non-solvent bridged polysilsesquioxane (PBSIBTHM, PBSIBTMeM)and their complexes (PBSIBTHM-Ni, PBSIBTMeM-Ni, PBSIBTHM-Cu(S), PBSIBTHM-Cu, PBSIBTHM-Nd). In addition, we have also designed and synthesized poly y-(2-thiazole-Ureido)propyltriethoxysilane metal complexes(PTUPTES-Ni, PTUPTES-Cu), poly [y-(2-thiazole-Ureido)-propyl] methyl-diethoxysilane metal complexes (PTUPMDES-Ni, PTUPMDES-Cu, PTUPMDES-DMS-Ni) and a novel low-molecular-mass organic gelator based bithiazole(CHOLFABT) and its metal complex (CHOLFABT-Ni).These materials and their precursors have been characterized by 1H NMR, FT-IR, XRD, DSC, SEM, UV-Vis and EDS etc. The magnetic properties of these complexes were examined as a function of magnetic field strength at 5 K and as a function of temperature (5-300 K) at magnetic field strength of 30 kOe with a physical properties measurement system (PPMS) magnetometer.The measurement results reveal that bridged polysilsesquioxane metal complexes with bithiazole rings all feature different ferromagnet properties at low temperature. PBSIBTH-Eu exhibits special ferromagnetism, it has a magnetic switch appears at about 105 K. When the temperature is less than 105 K, the complex exhibits weak ferromagnetic behaviors, otherwise, it is a diamagnet. PBSIBTH-Ni, PBSIBTH-Tb displayed paramagnetic behaviours at most range of temperature measurement. It is a ferromagnet certain limits of ultra low temperature. Their Curie-Weiss temperature(θ) were 21K,6K respectively. They have, however, relatively high relative saturation magnetization (Ms) 11.6emu/g,15.8emu/g. The Curie-Weiss temperature of PBSIBTH-Cu was very highθ=263K, but has relatively low Ms=1.9emu/g. We discovered that lanthanide ions (Tb3+) was a good paramagnetic spins, and different metal ions exhibited different magnetic properties. Kinds of liquid state non-solvent organosilica-based metal-bithiazole complexes exhibit magnetic behaviours at low temperature. They have all relatively low relative saturation magnetization (Ms) from 0.39emu/g to 1.9emu/g, with a transition temperature (Tt=160K,65K, 120K 140K for PBSIBTMeM-Ni, PBSIBTHM-Cu, PBSIBTHM-Cu(S), PBSIBTHM-Nd), and exhibit special ferromagnetism at low temperature. The Curie-Weiss temperature of PBSIBTHM-Ni is 256K, which displayed ferromagnetic behaviors at low temperature. The DSC results indicated that its phase transformation temperature is at range of 160-180K, which means that it exhibited magnetic behaviors in liquid phase. The AFM images showed that they have excellent properties for film-forming, and the surface of the film prepared by the spin coating process is satisfactorily smooth, void-free, whose root means quare roughness (Rrms) is 0.200-0.588nm.The Ms of poly y-(2-thiazole-Ureido)propyltriethoxysilane metal complexes (PTUPTES-Ni, PTUPTES-Cu) were all 5.0emu/g. The latter has higher the Curie-Weiss temperature (θ=119K) than the former (θ=75K). Their Coercivity were 18.8Oe,18.1Oe at 5 K. Compared with poly y-(2-thiazole-Ureido)propyltriethoxysilane metal complexes, the Ms and Coercivity of poly [γ-(2-thiazole-Ureido)propyl]methyldiethoxysilane metal complexes (PTUPMDES-Ni, PTUPMDES-Cu) did not change obviously, However, it was found that the Curie-Weiss temperature became 163K,168K. It was discovered for PTUPMDES-DMS-Ni that the Curie-Weiss temperature almost increase twice (θ=263K), when the dimethylsiloxane chain was introduced to the polysiloxane main chain, and the Ms have few change.As for the novel low-molecular-mass organic gelator based bithiazole (CHOLFABT), it exhibited good gelation properties and induced a wide variety of organic solvents into gelation. The FE-SEM images exhibited that the xerogels contain sheet structure, which piled up and formed incompact structure. FT-IR and UV-vis absorption spectra showed that hydrogen bonds between amide group andπ-πstacking interaction between bithiazole were the main driving forces for the formation of organogels besides for the van der Waals forces among cholesterol groups. When adding Ni2+, the relative interactions were greatly affected due to the formation of complex compound. The measurement results that it was a soft ferrimagnet with the Curie-Weiss temperature (θ=112K), Ms=3.8emu/g.