Studies On The Syntheses,Structures And Fluorescence Properties Of Iron(?)Spin-Crossover Complexes

Recently,intersecting and mergeing with material science,life science,molecular magnetism has increasingly become one of the most active and popular frontiers in chemical research.And the research of bistable magnetic materials has made great progress,especially the study of multifunctional spin crossover materials.The design of a new molecular system combining SCO and other attractive properties,e.g.luminescence,has widely application prospect in biological labeling,drug delivery,biological imaging and temperature measurement,that could "feel" the spin-state transition signal ripping has become the focus of many researchers.and has The composite function of two-dimensional Fe this paper mainly discusses the design and assembly of different structures and properties of coordination polymers(?)and dual core spin crossover compounds and their crystal structure,magnetic properties and fluorescence properties were characterized and studied.The aim of this job is to design assembly 2D Hoffman-like coordination polymers and dinuclear Fe(?)spin crossover compounds.According to crystal structure,magnetic measurement,luminescent property,and simple discussion of quantum chemistry were investigated.As follows:In chapter one,we mainly introduce the molecular based magnetic materials,bistability and spin crossover phenomena,especially the progress of spin crossover,and the multi-step spin crossover.In addition,the progress of the research on the interaction between spin crossover and fluorescence is introduced in detail,and the theoretical knowledge,modern testing technology and the background of this thesis are introduced.In chapter two,2D Hofmann-like network compound that display three-stepped spin crossover(SCO)accompanying with structural transformation were prepared,and are rare in existence.Variable-temperature magnetic susceptibility measurements and single-crystal structure analysis of compounds showed different spin states:HS,HS0.67LS0.33,HS0.5L0.5,and LS,where four distinct electronic states 1-i?iv can be accessed.Two intermediate states of compounds exhibited phase-transition behavior.Here the emission intensity and diffuse reflectance of compounds was followed as a function of temperature and a striking multiple correlation with the SCO curve by variable-temperature fluorimetry and DRS,respectively,demonstrating multiple correlations between SCO and fluorescence or UV.The Forster-type resonant energy transfer process(FRET)scheme were confirmed.In chapter three,three new crystal structures of Fe(?)complex that combine spin crossover and luminescence were successfully prepared using ligands synthesized by ourselves and characterized using variable-temperature fluorimetry,crystal structure,and magnetic measurement.In addition,the effect of electron donating group on the structural and transition temperature were systematically investigated.The transition temperature of compounds(o-electron donating group)was found to be higher than that of complex(m-electron donating group).And compounds(p-electron donating group)fail to appear the spin crossover properties.The as-synthesized compounds(o-electron donating group)underwent a complete SCO.The resulting spin crossover materials show a synergistic effect between spin transition and fluorescence.In chaper four,summary and outlook.