Syntheses And Magnetism Of SCO Coordination Polymers Based On Pyridyl Ligands

Spin crossover?SCO?is a form of molecular magnetism for which switchingbetween two magnetic states(high-spin(HS,?S=2?and low-spin?LS,?S=0??is possible through the application of temperature,pressure,and light irradiation.This phenomenon has long been recognised for its potential ininformation technology and optical data display applications.More recently in this ever-expanding field of magnetic materials science,it was recognised that by combining SCO with nanoporous coordination polymer chemistry,materials could be generated with the ability to magnetically sense the presence,absence,and typeof host molecules present within the pore networks.Such materials offer a highly sought-after platform from which to systematically investigate themechanism of absorbed guests affecting the magnetic switchingGiven the aforentioned consideration,by using different strategies,we have prepared a series of spin-crossover coordination polymers and studied theirproperties and the magneto-property relationship.The main achievements of thisthesis are listed as below:1.We have successfully obtained a series of Fe? complexes with the general formula Fe?dpsme?₂?XCN?₂?X=S,Se,BH₃;dpsme=4,4'-di?pyridylthio?methane?.The variation of solvent medium affords different topological structures for all 7 complexes which indicate the formation of supramolecular isomers that originate from solvent effects.Complexes 1-6 are paramagnetic in whole temperature range;whereas complex 7 undergo incomplete and gradual SCO.2.With the using of 4,4-bipyridine,we obtained a typical Hofmann complex[Fe?bpy?M?CN?₄].And we found this complex displays"single-crystal-to-single-crystal" transition after immersed into CH₂Cl₂ for an whole day.complex 8 is paramagnetic.It becomes SCO complex 10 with a hysteresis loop about 1 OK after immersed into acetone for a week.3.Two Hofmann-like 2D coordination polymer were synthesized and characterized.Both of them are paramagnetic.4.We characterized a series of mixed-ligand complex with the general formula Fe?3-Fpy?_n?3-Clpy?_2-n[Pt?CN?₄]and found a simple way to precise control spin transiton temperature.