Three new A,C-diamide bridged p-tert-butylcalix[6]arenes were synthesized from p-tert-butylcalix[6]arenes by bridging ClCH2CONH(CH2)nNHCOCH2Cl (n=3, 4, 6) in acetonitrile using K2CO3 as a base in 17%—25% yields. It was found that the bridged calix[6]arenes with shorter bridges (n=2, 3, 4 in N',N'-bischloroacetodiamines) adopt cone conformation, but the last one (n=6) adopts alternate conformation, i.e., accompanying the lengthening of bridge, the conformation of A,C-bridged calix[6]arenes changes from cone to alternate.
The calixarene crosslinked polysiloxanes were obtained by crosslinked (N-(β-aminoethyl)aminopropyl) modified silicon oil with 1,3-diglycidyl(calix[4]arene.)Their structures were characterized by infrared spectra and scanning electron microscopy.The thermal degradation behaviour of the calixarene crosslinked polysiloxanes with various content of calixarene under a nitrogen atmosphere was investigated by using thermogravimetry(TG),it showed that all the crosslinked polysiloxanes exhibited two-stage decomposition,the first decomposition peak was at about 391℃ and the second was at about 520℃,the ratio of the two fastest weight loss rates was varied with the content of calixarene.Under our experimental conditions,the calixarene crosslinked polysiloxane with 3% content of calixarene had the lowest rate of degradation during the first stage of decomposition.The thermal stability of calixarene crosslinked polysiloxanes was enhanced compared with that of (N-(β-aminoethyl)aminopropyl) modified silicon oil and 1,3-bis(2′,3′-epoxypropoxy)benzene crosslinked polysiloxane.
The synthesis and conformation of di-O-bridged homooxacalix[3]arenes were reported. Their recognition ability towards alkylammonium ions was studied with the aid of NMR. Two of them show selective binding ability towards relatively longer linear alkylammonium ions （CH3（CH2）nNH3^＋, n = 3-5）.
