Synthesis And Characterization Of Azocalix[4] Arene Derivatives With Long Alkylmercapo Functional Groups

The research of the synthesis,configuration and application of azocalix[4]arenes is in progress.Azocalix[4]arenes,formed by azo group and calixarene,had special configuration and could be used as building blocks to construct well preorganized host molecular,which have widely applying potential in the molecular recognition,molecular switch,supramolecular chemistry and so on.Because the configuration of azocalix[4]arenes affect their character and application,the control of configuration is important.Reportedly,alkane thiols with chain lengths greater than around ten carbon could form ordered layers on Au(â…¢).It was decided to synthesize calix[4]arenes with an alkyl spacer of more than five methylene units and a thioether head group.1)A series ofω-alkylmercapo acid were synthesized by two methods:one involved the reaction of the appropriateω-bromoalkyl acid with mercaptide under the presence of base;the other method was used only for the long alkyl compound by the reaction ofω-alkenyl acid and alkanethiol in the presence of AIBN.Theω-alkylmercapo acid chlorides were synthesized by the reaction of appreciate acids and SOCl₂.2)Tetra(ω-alkylmercapo carboxy)calix[4]arenes(compounds 9-11)were synthesized by calix[4]arene and appropriateω-alkylmercapo acid chlorides in the presence of NaH. Tetra-substituted calix[4]arenes were main product.All products were characterized by ¹H NMR, ¹³C NMR,IR,MS and elemental analyses.According to the ¹H NMR and ¹³C NMR data,all calix[4]arene derivatives were in cone conformation.3)Azocalix[4]arene was first synthesized by coupling reaction of calix[4]arenes with BF₄^-salt of p-nitrobenzene diazonium.Then,azocalix[4]arenes reacted with appropriateω-alkylmercapo acid chlorides in the presence of Nail to give tetra-substituted compounds 19-21. All products were characterized by ¹H NMR,¹³C NMR,IR,UV,MS and elemental analyses. According to the ¹H NMR and ¹³C NMR data,all calix[4]arene derivatives were in 1,3-alternate conformation.4)Although all reactions were taken place under the same condition,the calix[4]arenes with different p-substituted groups on upper rim gave different conformations:compounds 9-11 were all in cone conformation synthesized from p-H substituted calix[4]arene,while compounds 19-21 were all in 1,3-alternate conformation synthesized from p-azo substituted calix[4]arene.