Synthesis And Spectal Properries Of Monazo-calix[4]araene Derviatves

Azocalixarenes are very attractive macrocyclic compounds which are synthesized by introduction of azo unit into calix[4]arene framework through azo-coupling reaction. They can not only presents a variety of colours, but also exhibit good solution and selectivity to metal ion and organic molecules, so they can be used in dyes and metal indicators.At present, a large number of azocalixarenes were synthesized, most of them bear multiple azo groups in upper rim due to autoacceleration, few monoazocalix[4]arenes was synthesized. Major works herein were synthesis of monoazocalix[4]arene derivatives and study their properties by UV-visible spectroscopy.（1）5,11,17,23-tetra-t-butyl-25,26,27,28-tetrahydroxycalix[4]arene and 25,26,27, 28-tetrahydroxycalix[4]arene were synthesized as basic reactants.（2）25,27-bis[（ethoxycarbonyl）methoxy]-26,28-dihydroxycalix[4]arene were synthesized from 25,26,27,28-tetrahydroxycalix[4]arene.（3）25,26,27-tri[（ethoxycarbonyl）methoxy]-28-hydroxycalix[4]arene were synthesized from 25,27-bis[（ethoxycarbonyl）methoxy]-26,28-dihydroxycalix[4] arene.（4） A series of azocalix[4]arene derivatives were synthesized: 5-[（3-nitrophenyl）azo]-25,27-bis[（ethoxycarbonyl）methoxy]-26,28-dihydroxycalix[4]arene;5,17-bis[（3-nitrophenyl）azo]-25,27-bis[（ethoxycarbonyl）methoxy]-26,28-dihydroxycalix[4]arene;5-（phenylazo）-25,26,27-tri[（ethoxycarbonyl）methoxy]-28-hydroxycalix[4]arene;5-[（2-methylphenyl）azo]-25,26,27-tri[（ethoxycarbonyl）methoxy]-28-hydroxycalix[4]arene;5-[（4-methylpheny）lazo]-25,26,27-tri[（ethoxycarbonyl）methoxy]-28-hydroxycalix[4]arene;5-[（2-nitrophenyl）azo]-25,26,27-tri[（ethoxycarbonyl）methoxy]-28-hydroxycalix[4]arene;5-[（3-nitrophenyl）azo]-25,26,27-tri[（ethoxycarbonyl）methoxy]-28-hydroxycalix[4]arene;（5）All the products were characterized by 1H-NMR and IR, part of the products were characterized by MS. Three of the compounds were characterized by X-ray diffraction.（6）The recognition of azocalix[4]arene upon metal ions were investigated by UV-visible spectroscopy. All of azocalix [4] arenes can selective recognition of Ca²⁺metal ion. Trisubstituted azocalix[4]arenes exhibit high selectivity compared to disubstituted azocalix[4]arene. In addition, we also studied the complexation ratio and association constant between host and metal ions.