| The research of cyclophane compounds started from 1950s.Because of the unique structure and special characters,they were earned more and more attention.Many articles reported the achievements of research in this field,for example,the synthesis of cyclophane compounds which contains aromatic rings,or pyridine analogue or pyrazine cyclophane conpounds,the coordination with metal,the characters of spectrum and electrochemistry,and so on.But until now,the researches are mainly on the thia-cyclophane compounds.There had no report on the structure of heterocyclic cyclophane compounds.In this article,we took 2,6-dimethylpyrazine as start material,through double chlorinated reaction,cyclization of tosylamide monosodium salt,then removal of Ts under the help of Con.H2SO4,we finally systhesized the 2,11-diaza[3.3](2,6)pyrazinophane.In the step of forming the ring structure,after removed the solvent,N,N’,N"-tritosyl-2,11,20-triaza[3.3.3](2,6)pyrazinophane was got.In this article,we also researched the pyrazinophane-linked macrocycles.It was easily synthesized through dihalogenate-2,6-dimethylpyrazine and 2,11-diaza[3.3](2,6)pyrazinophane refluxing in the CH3CN-H20 with Cs2CO3.And we also characterized the compound through ’H-NMR and LCMS.Compared the UV absorption spectras of 2,6-dimethylpyrazine 26 N,N’-ditosyl-2,11-[3.3](2,6)-pyrazinophane 31、N,N’,N"-tritosyl-2,11,20-triaza-[3.3.3](2,6)pyrazinophane 32 and 2,11-diaza[3.3](2,6)pyrazinophane 33,we found that the λmax of cyclized pyrazinophane 31 and 33 shifted to long-wave direction than their parent conpound 26.The reason of this phenomenon is the bridge in the structure connected two pyrazine rings that makes the π-electron systems overlap.This overlap leads to the HOMO energy of both of the pyrazine rings higher than a single one and the LUMO energy lower than it,thus decreases the △E of HOMO-LUMO,and finally causes the long-wave shift in the UV absorption spectra.But compared the UV absorption spectras of binary pyrazinophane 31、ternary pyrazinophane 32,we found that increased the amount of pyrazine rings made the λmax shift to short-wave direction.That because when the pyrazine ring increased,the overlap of π-electron systems became weaker and weaker,that made the increase the △E of HOMO-LUMO,and finally lead to the short-wave shift of compound 31 and 32.About to ternary pyrazinophane 32,its structure tends to plannar,so the π-electron systems had no overlap,the λmax had no obvious difference from its parent compound.In the fluorescence spectra,both of 26、32 do not have spectra band in long-wave field,but compound 31 and 33 have moderate-high and relative broad absorption band.We think the band in 600-800nm may be cause by the dimerization of two pyrazine chromophores.Through the study of the UV aborption spectra and fluorescence spectra,we realized one character of this compound that was if the π-electron systems overlap decrease,the effection of π-π declined.This article first reported the synthesis azapyrazinophane and the character of its spectra,riched the kinds of cyclophane.In the further work,we will make deep research on the synthesis,spectrum.electrochemistry and coordination with metal of this kind compound,which will help them be widely used... |
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