The synthesis and characterization of azocalix[4]arene based chemosensors and investigation of their properties.

In the present study, azocalix[4]arenes were prepared by linking 4-methoxy, 4-methyl, 4-ethyl, 4-chloro, 4-bromo and 4-nitroaniline to calix[4]arene through a diazo-coupling reaction. A new family of azocalix[4]arene tetraester derivatives, (4a-f), have been prepared with the incorporation of ethyl ester units to azocalix[4]arene. Characterization of the synthesized azocalix[4]arenes was carried using elemental analyses, UV-vis, FT-IR and (1)H NMR spectroscopic techniques.

Identification of radiation-induced radical structure in azocalix[4]arene: an EPR study.

A macrocyclic azocalix[4]arene (1) based ester derivative was synthesized. The single crystals of azocalix[4]arene were produced by slow evaporation of concentrated ethyl acetate solutions. These single crystals were exposed to (60) Co gamma rays with a dose rate of 0.

Synthesis and structure elucidation of 25,26,27,28-tetramethylcalix[4]arene tetraketone using 1D and 2D NMR spectroscopies.

The (1)H and (13)C NMR spectra of the new calix[4]arene-based tetraketone were completely assigned by one- and two-dimensional homo- and heteronuclear experiments ((1)H-(1)H COSY, (1)H-(13)C HMQC, and HMBC) at 400 and 100MHz, respectively, at 25 degrees C standard pulse sequence. (1)H and (13)C spectra were measured at room temperature for 25,26,27,28-tetramethylcalix[4]arene tetraketone (1). (13)C[(1)H], DEPT and NMR techniques were used to distinguish the methyl, methylene and methine carbon resonance signals of calix[4]arene 1.

Transition metal cations extraction by ester and ketone derivatives of chromogenic azocalix[4]arenes.

The molecule of azocalix[n]arene is a macrocyclic used effectively in the complexation of the heavy metal pollutants (like silver and mercury). In this work, our main aim is to prepare new chromogenic azocalix[n]arene molecules to elaborate an extractant with high extractant selectivity for metal ions able to detect this type of pollutant. The solvent extraction properties of four acetyls, four methyl ketones and four benzoyls derivatives from azocalix[4]arenes which were prepared by linking 4-ethyl, 4-n-butyl, 4-acetamid anilin and 2-aminothiazol to calix[4]arene through a diazo-coupling reaction, the alkaline earth (Sr2+) and the transition (Ag+, Hg2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Cr3+) metal cations have been determined by extraction studies with metal picrates.

Comparative studies on the solvent extraction of transition metal cations by calixarene, phenol and ester derivatives.

The ionophore solvent extraction of various alkali metal and transition metal cations from the aqueous phase to the organic phase was carried out by using diazo-coupling calix[n]arenes [p-(4-phenylazophenylazo)calix[4]arene (L1) and p-phenylazocalix[6]arene (L2)], phenol derivatives [2,6-dimethyl-3-phenylazophenol (L3), 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol (L4), 2-chloro-4-nitro(phenylazo)-5-sec-butyl-2-phenol (L5) and 2-chloro-4-nitro(phenylazo)-5-tert-butyl-2-phenol (L6)], and ester derivatives [quinoline-8-benzoate (L7), phenyl-1,4-dibenzoate (L8), p-tolyltiobenzoate (L9)]. It was found that, all the compounds (L1-L9) examined showed selectivity for transition metal cations such as Ag+, Hg+ Hg2+, and poor efficiency for alkali metal cations (Na+ and K+). The best extraction efficiency was obtained with L1 and L4.