Search

Phosphorylation of 1,3-bis(2-hydroxyethoxy)benzene and octa(2-hydroxyethyl) calix[4]-resorcinarenes with P(III) acid amides and chloramides has been studied. It has been determined that the nature of phosphorous acid amides affects significantly the synthetic result of the reaction. [ABSTRACT FROM AUTHOR]

The reactions ofdialkyl[(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienyl)methyl]phosphonates with N-nucleophiles (aminoacetaldehyde dimethyl acetal and diethyl [(2,2-dimethoxyethyl)aminomethyl]phosphonate give new aminophosphonates containing the 3,5-di-tert-butyl-4-hydroxyphenyl substituent, in addition to the acetal group. The crystal structure of diethyl {(3,5-di-tert-butyl-4-hydroxyphenyl)[(2,2-dimethoxyethyl)amino]methyl}phosphonate is elucidated. The presence of a chiral carbon atom and prochiral phosphorus atom in the aminophosphonate products is responsible for the complicated pattern in the1H NMR spectra, the features of which are discussed. [ABSTRACT FROM PUBLISHER]

The condensation of thiophosphorylated aldehydes 1 and 2 with resorcinol and its derivatives leads to the formation of the new type of calix[4]resorcinols with four thiophosphoryl groups inserted to the substituents located in methylidene bridges of the molecule. The conformation of these compounds was found to be 'flattened partial cone' or 'chair,' which was determined by NMR methods and a single-crystal X-ray diffraction study. GRAPHICAL ABSTRACT [image omitted] [ABSTRACT FROM AUTHOR]

New de-tert-butyltetrathiacalix[4]arenes with acetylhydrazide substituents in cone and 1,3-alternate conformations have been synthesised with good yield by the hydrazinolysis of calix[4]arene ester derivatives. The recognition ability of synthesised macrocycles towards transition and alkali metals has been investigated by the picrate extraction method. The stoichiometry of complexes and the extraction constants have been determined. It has been found that tetrahydrazides do not extract alkali metal ions, but show an excellent affinity towards transition and heavy metal cations. The 1,3-alternate conformer of de-tert-butyltetrathiacalix[4]arene has revealed a remarkable selectivity for Ni2+ and Ag+ in the row of d-elements and for Cd2+ ion among the toxic heavy metals. The experimental data show that the removal of tert-butyl groups from tetrathiacalix[4]arene framework leads to the drastic improvement of extraction efficiency and selectivity of new tetrahydrazides. [ABSTRACT FROM AUTHOR]

Two amphiphilic water-soluble sulfonatomethylated calix[4]resorcinarene derivatives were studied by various 1H NMR techniques (1H NMR titration, 2D NOESY, NMR diffusion measurements). The derivative with methyl moieties at the lower rim (1) was found to be non-aggregated in the range 0-10 mM in aqueous solutions. Lengthening of the lower rim substituent to pentyl (2) results in self-aggregation of 2 in aqueous solutions with the aggregation number varying from 3 at 1 mM to 20 at 10 mM. The 2D NOESY 1H NMR spectroscopy data reveal an unusual head-to-tail packing mode in aqueous solutions, resulting from the cooperative effect of weak hydrophobic interactions. Binding of guests (tetramethylammonium and N-methylpyridinium) results in additional stabilization of the aggregates whilst the head-to-tail packing mode of the aggregate is retained. [ABSTRACT FROM AUTHOR]

The binding properties of the cone conformer of O,O,O,O-tetrakis[hydrazinocarbonylmethyl]-4-tert-butylcalix[4]arene, the cone and the 1,3-alternate conformers of the corresponding thia analogue have been evaluated by means of liquid-liquid extraction for a large variety of metal ions. The extraction constants and the stoichiometries of the complexes formed have been determined. Comparison of the extraction properties of calix[4]arenes with their acyclic monomeric analogue clearly demonstrated, that the preorganization of acetylhydrazide groups on the calix[4]arene platform is the cause for a significant improvement of its binding properties. The presence of additional “soft” nitrogen binding sites in acetylhydrazide derivatives of calix[4]arenes compared to their amide derivatives leads to a shift from their classical selectivity for alkali and alkaline earth cations to transition metals. The cone conformer of tetrathiacalix[4]arene shows higher selectivity in a series of d-metal ions compared with its “classical” analogue. The 1,3-alternate conformer exhibits an excellent extraction selectivity for Cu2+ and Hg2+. [ABSTRACT FROM AUTHOR]