The Design, Synthesis And Magnetic Properties Of Novel Hyperbranched Polymeric Coordination Compounds And Coordination Polymers Containing Fullerene

In the early of1960s, Mclonnel proposed that organic compounds may also exist ferromagnetic, which gave the intermolecular ferromagnetic exchange and even gave the mechanism. Later, Wickman synthesized the first molecular ferromagnet, molecule-based magnets soon became a hot topic. With the development of coordination chemistry, the structure and magnetic properties of coordination polymers have become an increasing concern. In recent years, the synthesis of the polymer with novel structure, the discovery of new magnetic phenomena and explore the magnetic interaction mechanism to explore the system of magnetic and structural relations have entered a new period of vigorous development. Organic magnetism has also become one of the multi-disciplines across materials science, physics, chemistry, and other cutting-edge research areas.In this paper, three kinds of new hyperbranched polymers containing bithiazole ring and the two fullerene derivatives were successfully synthesized, and the corresponding complex were prepared by chelation of fullerene derivatives with transition metal ions or rare earth metal ions. Also their magnetic properties were explored. The main purpose is to explore the relationship between the structure and the magnetic properties of the complexes.The non-conjugated hyperbranched polyamide (PBD) containing bithiazole ring with excellent solubility was synthesized by the polycondensation of bifunctional2,2’-diamino-4,4’-bithiazole (DABT) and trifunctional1,3,5-benzenetricarbonyl trichloride (BTC). Based on the polycondensation of1,3,5-benzenetricarboxaldehyde and2,2’-diamino-4,4’-bithiazole (DABT), the conjugated hyperbranched polymer containing bithiazole rings (PBTADB) was obtained. Due to the presence of bithiazole ring, PBD and PBTADB can coordinate well with the different metal ions. Trifunctional melamine react with bifunctional inter-phthalaldehyde via the Schiff base reaction, then the hyperbranched polymer (PDTI) was prepared by adding ferrocenecarboxaldehyde to react with the remaining amino. Polyazidoated fullerene derivatives (C60(N3)x, x<24) were prepared via brominating of fullerene (C60) and then substituting with nucleophnic reagent (NaN3) as well as polycyno fullerene derivatives (C60(CN) x, x≤24). Their metal complexes were prepared by chelation of fullerene derivatives with Co2+or Cu2+in the presence of4,4’-bipyridine. Polymers and coordination compounds were characterized by using FT-IR, UV-vis, NMR, and elemental analysis et al. The content of metal elements of the complex was determinated via EDTA complexometric titration or X-ray photoelectron spectroscopic.In this paper, magnetic properties of the complex are explored. The results show that PBD-Cu2+and PBD-Ni2+are soft ferromagnets at low temperature. PBD-Cu2+follows the Curie-Weiss law over250K with Tθ=102K. PBD-Ni2+follows the Curie-Weiss law in the temperature of225K-300K, with the Curie-Weiss temperature Tθ=53K. The magnetic hysteresis loops of PBD-Cu2+and PBD-Ni2+showed the’S’shape at5K, so that both of them are organic soft ferromagnetic materials. The magnetic behavior of PTBABT-Sm3+and PTBABT-Co2+is special with a magnetic transition temperature at112K and48K respectively. The magnetic susceptibility of PTBABT-Sm3+is positive, below112K, which means that it is a ferromagnet. However, the coordination polymer is diamagnetism over112K. The magnetic behavior of PTBABT-Co2+is similar to PTBABT-Sm3+’s with the magnetic transition temperature at48K. The magnetic hysteresis loops of PTBABT-Sm3+and PTBABT-Co2+have a typical ’S’ shape at5K. And the remanence and the coercivity of them are also small. The results indicate that PTBABT-Sm3+and PTBABT-Co2+are organic soft ferromagnet at low temperature. From the magnetic test of PDTI, there is also a magnetic transition temperature (Tp=187K). When the temperature is over187K, the magnetic behavior of PDTI is diamagnetism. Otherwise. PDTI is ferromagnetism. The hysteresis loops of PDTI have a typical ’S’ shape at5K with Mr=17.7Oe and He=6.6×10-4emu/g. It can be concluded that PTDI exhibits the properties of soft ferromagnetic materials at low temperature. Due to the long distance of the metal ion, magnetic exchange interaction should be very weak in coordination polymers, which the metal ion spin centers are separated by4,4’-bipyridine as the bridging agent However, from the magnetic test of coordination polymers containing of fullerene (C60) derivatives in this paper, the results indicate that four kinds of coordination polymers have a strong magnetic exchange interaction at low temperature, and the Curie-Weiss temperature is positive, that is to say, which means that they are ferrimagnetic materials. Four coordination polymers shift to paramagnets with increasing temperature, the reason is that the ordered magnetic structure would be destructed with increasing thermal motion of the electrons. From the hysteresis loop of four coordination polymers at5K, the cobalt divalent ion complexes have a typical ’S’ shape and the saturation magnetization reach30emu/g, so they are organic soft-ferrimagnet.