Design,Syntheses And Properties Of Naphthalimide Derivatives With Pyridine Groups And Its Complexes

In the mid-1980s,scientists realized that spin-crossover(SCO)complexes and valence-tautomeric(VT)compounds could be used as molecular materials for display,information storage,sensing and optical switches,which led to a research boom Some of the spin-crossover(SCO)complexes,containing transition-metal ions,can exhibit high and low spin state transitions under appropriate external conditions such as light irradiation,temperature,pressure,etc.,to allow such complexes to have the characteristic of bistability.We found that the coordination of Fe(II)ions with pyridine derivatives as bridging ligands can form[ML2(NCX)2]·nSolvent(X=S,Se)structure of coordination polymers,and exhibit spin-crossover(SCO)behavior.They can also coordinate with 3,5-di-tert-butylcatechol to form[Co(Q)2(L)2](Q=3,5-di-tert-butylcatecholate or semi-quinonate)structure and exhibit valence tautomerism.In this thesis,a series of complexes Fe(NDI)2(NCX)2,Co(NDI)2(NCX)2(NDI=1,4,5,8-naphthalenediimide;X=S,Se)and[Co(Q)2(L)2](Q=3,5-di-tert-butylcatecholate or semiquinonate)were synthesized by using 1,4,5,8-naphthalenediimide compounds containing pyridine deri-vative groups as ligands,and their structures and properties were studied.In Chapter 1,the research and development of molecular based magnetic materials are briefly introduced and the spin-crossover(SCO)complexes and valence-tautomeric(VT)compounds are emphatically introduced.In addition,the properties and applications of the naphthalenediimide derivatives were introduced.Finally,we give a short account of the research purposes.In Chapter 2,six 1,4,5,8-naphthalenediimide compounds containing pyridine derivatives were synthesized and characterized.The ligands were irradiated with UV light at a wavelength of 365 nm in CH2Cl2 and DMF solvent,respectively,then measured and analyzed soluntions by UV-vis absorption spectroscopy.We found that the absorption intensity of characteristic peaks(341,358,378 nm)in DMF solvent decreased with the increase of illumination time,and the characteristics of NDI·-radical anion appeared at 400～800 nm.The fluorescence emission spectra of the six ligands were determined in DMF solvent,and some of the ligands showed double fluorescence emission We introduced the PICT model to explain it.Besides,we investigated the factors influencing the LUMO level of six ligands by Cyclic Voltammetry.In Chapter 3,the appropriate 1,4,5,8-naphthalenediimide ligands were reacted with the transition metal Fe(Ⅱ)and Co(Ⅱ)ions respectively,and six crystals of the complexes were obtained by solution diffusion method,and the crystal structures of two complexes were measured:[Fe(cis-NDI-DSC)(NCS)2(CH3OH)]n·2nCH3OH·nCH2Cl2(1)and[Co-(cis-NDI-DSC)(NCSe)(CH3OH)(NO3)]n·2nCH2Cl2(3).The complex 1 and complex 3 were determinated the properties of magnetic by Quantum Design SQUID magnetometer.The results suggest that complex 1 and 3 both present antiferromagnetic behavior.And the structure,intermolecular,intramolecular hydrogen bonds and π…π interaction of the complexes could affect the magnetic properties.The magnetic susceptibility data of compound 3 under different external magnetic fields imply that the compound shows metamagnetic behavior.Besides,we also tried different methods of reacting the naphthalenediimide derivatives with 3,5-di-tert-butyl-catechol and cobalt salts,and it is desirable to obtain compounds having valence tautomerism.In Chapter 4,we made a summary and a further prospect of this thesis.