Study On The Regulation Of Spin Crossover And Single Molecule Magnet With Layer Anions

In recent years,molecule-based magnetic materials have been an important focal research field in chemistry,physics and material science.because of their potential appications in such as high density magnetic storage,quantum computation and spintronic devices.This research field contains:single molecule magnets,molecule-based photomagnets,chiral magnets,ferromagnetic molecular conductors,magnetic superconductors and so on.One of the most spectacular examples of molecular bistability is the spin-crossover phenomenon.The complexes with spin-crossover may exhibit a transition between a low-spin(LS)and a high-spin(HS)state by applying external stimuli(temperature,light irradiation or pressure).Therefore,these complexes could be used in many molecular or electronic devices such as memory devices,thermal or optical switches and pressure sensors.Spin crossover compounds generally in the form of neutral compounds or cationic exist in the crystal Using the spin crossover partial and organic radical to synthesis a new type of spin conducting compounds by the co-crystallization or stacking salts.This may be able to break through the bottleneck of the application of molecular based magnets.In addition,organic and metal-organic radicals could bear one or more unpaired electrons in their ?-system arising from the overlap between 2p atomic orbitals,they have rapidly become recognised as interesting building units for molecule-based magnetic materials.They can also exhibit exotic physical properties,such as ferromagnetic interaction by ?…? stacking and spin-Peierls transition.In this work,we synthesized four molecule-based magnets.The preparation,structures and magnetic properties for all complexes were investigated in details.The content includes two parts as follow:Part I:We used TCNQ as counteranions for tuning spin-crossover phenomenon of mononuclear M?(terpy)2+(M=Co,Fe,Ru).To study the regulation of the spin crossover properties of the compound with cobased photomagnets,chiral magnets,ferromagnetic molecular conductors,magnetic njugated counter ions,and to study the interaction between them and their electrical conductivity.Part ?:we synthesized a Co? complex[Co(Tp*)2](4)in a distorted octahedral coordination environment,which shows SMM behaviour.Two relaxation processes of magnetization were observed in complex 4,while the origins of the two processes have been an open question in the field of mononuclear SMMs.In this work,through analysing the slow relaxation behaviour under different external dc fields and magnetic dilution system,two processes are clearly assigned as intermolecular dipolar interaction and spin reversal Then,with tripyrazolmathane instead of Tp*,anti triangular prism configuration mononuclear Co? cation cluster can be obtained,which can pack with TCNQ radical in crtstal lattice.It provied a carrier to study the change of slow magnetic relaxation behavior and qumtun tunnelling of magnetizition phnomenon under external superexchange interaction.