Research On Synthesis And Properties Of Azobenzene-Modified Schiff Base Metal Complexex

With C=N double bonds and a flexible structure which can supply ample coordination modes,Schiff Base could be potential catalysts,magnetic meterials,functional materials and therapeutic drugs,etc.As a typical photoisomerization molecule,azobenzene has very high application value in the field of optical switches,temperature sensors,information storage and memory materials.Therefore,the synthesis of new Schiff base with azobenzene structure and their complexes has important scientific value and significance.In this paper,two new Schiff base L1 and L2 was synthesized via the reaction between Chrysoidin(DAAB)and salicylaldehyde or p-aldehydobenzoic acid(CPA),then coordinated with transition metal ion(Co2+,Fe3+,Fe2+,Mn2+ and Ni2+)to give complexes M-L1 and M-L2,respectively.The synthesis processes and conditions were studied and optimized.The resulting products were characterized by UV-vis,FT-IR,TG-DTA and so on.The photosensitivity,fluorescence and magnetic properties of Co-Li were discussed.The main conclusions are as follows:1.The synthesis process of Ligand Asaa(Li)and its complexes were studied and optimized.(1)The new Schiff base L1,2-amino-4-(salicylidene-anilino)-azobenzene(Asaa),was synthesized by the reaction of DAAB and salicylaldehyde.Synthetic process conditions were optimized.DAAB:salicylaldehyde = 1:2.5(molar ratio),refluxing 9h,yield 88.77%(orange-red solid powder).(2)Orange-red needle crystals were obtained by solution diffusion(benzene/n-hexane)method at 25?,20 day.And Li was characterized by EA,UV-vis,FT-IR and TG-DTA.Single-crystal X-ray diffraction test shows:monoclinic crystal system,space group C2/c.L1 molecules were "Zigzag" shape along y-axis in space.(3)The complexes M-Li were obtained via Li coordinated with metal ion(Co2+,Fe3+ and Fe2+)respectively,and characterized by UV-vis,FT-IR and TG-DTA.2.The synthesis process of Ligand Acaa(L2)and its complexes were studied.(1)The new Schiff base L2,4-amino-2-(p-carboxylidene-anilino)-azobenzene(Acaa),was synthesized by the reaction of DAAB,CPA and NaOH.Synthetic process conditions were optimized.DAAB:CPA= 1:2(molar ratio),refluxing 4h,yield 96.4%(orange-red solid powder).(2)Red hexagon crystals of L2 was obtained by slow evaporation(ethanol)method at 25 ?,18 day.And L2 was characterized by EA,UV-vis,FT-IR and TG-DTA.Single-crystal X-ray diffraction test shows:monoclinic crystal system,space group C2/c.Crystal molecules were"wave" shaped along z-axis in space.(3)The complexes M-L2 were obtained via L2 coordinated with metal ion(Co2+,Mn2+ and Ni2+)respectively,and characterized by UV-DRS,FT-IR and TG-DTA.3.The photosensitivity,fluorescence and magnetic properties of Co-Li were discussed.(1)Under the irradiation of mercury lamp,the photoisomerization feature occurs in 5min in Co-Li.The peaks near 450nm gradually turn into single peak and strength grows.The peak strength decreases near 290nm and increases near 226nm.And it has an absorption point at about 410nm.It shows that the photoisomerization was happened.(2)Fluorescence test shows that Co-Li has a weak fluorescence peak around 450nm.The peak move to the short-wave direction and strength grows as the increase of illumination time.It may caused by the photoisomerization of Co-Li.(3)DC magnetic susceptibility test showed that Co-L,is paramagnetic and ?mT gradually decreases from 300K to 150K with T.Decreases rapidly below 50K and reaches the minimum at 2K.This indicates that existence of weak antiferromagnetic exchange coupling effect during Co2+ ion.After mercury lamp irradiate 15min,?MT decreases from 300K to 25K gradually and the ?mT value decreases relatively faster.