Aminomethylated calix[4]resorcinolarenes with NH groups on the upper rim of the molecule

The reaction of calix[4]resorcinolarenes with N,N-dimethylethylenediamine and aqueous CH₂O in a molar ratio of 1 : 5 : 5 affords calixarenes containing secondary amino groups arranged on the upper rim of the molecule. When the double amount (with respect to primary amine) of formalin is used (ratio of reactants 1 : 5 : 10), cavitands with four oxazinyl fragments are synthesized.     

Cyclic Phosphorochloridites and Phosphorochloridates Derived from Bromocalix[4]resorcinolarenes

Reactions of bromocalix[4]resorcinolarenes with PCl₃ and POCl₃ in the presence of triethylamine give the corresponding phosphorochloridito and phosphorochloridato cavitands in good yields. Phosphorochloridito cavitands were converted into phosphoramidito cavitands by treatment with piperidine.     

Effect of Micellar Media on Electrochemical Oxidation of Calix[4]resorcinolarenes

Aminomethylated calix[4]resorcinolarenes in aqueous solutions of nonionic (Triton X-100) and ionic (cetyltrimethylammonum bromides) surfactants undergo selective oxidation controlled by the hydrophobicity of the substrates. In the inverted micellar system sodium bis(2-ethylhexyl) sulfosuccinate-decanewater after the percolation threshold, hydrophobized aminomethylated calix[4]resorcinolarenes undergo reversible one-electron oxidation to give the stable phenoxyl radical.     

Reactivity of Amphiphilic Calix[4]resorcinolarenes and Phenols in the Reverse Micellar System Sodium Bis(2-ethylhexyl) Sulfosuccinate-Decane-Water

The mechanism of reaction of calix[4]resorcinolarene, aminomethylated calix[4]resorcinolarene, and 2-(dimethylaminomethyl)-4-isononylphenol with ethyl 4-nitrophenyl (chloromethyl)phosphonate in the reverse micellar system anionic surfactant-sodium bis(2-ethylhexyl) sulfosuccinate-decane-water changes compared with direct micellar systems and aqueous-organic solutions. It was shown that the calix[4]resorcinolarenes and phenol studied increase the percolation threshold of the system.     

The aggregartion and catalytic activity of amphiphilic calix[4]resorcinolarenes and phenols in hydrolysis of phosphonous esters in water—dimethylformamide media

The amphiphilic calix[4]resorcinolarenes, aminomethylated calix[4]resorcinolarenes, o-aminomethylphenols, and their quaternary derivatives in water—dimethylformamide media (10—75 vol.% DMF) form aggregates, which catalyze the hydrolysis of phosphonous esters. The ability to self-association and the catalytic activity of the aggregates depend on the hydrophobicity of the amphiphilic compound, the pH of solution, and the content of DMF.     

One-Electron Transfer in Electrochemical Oxidation of Calix[4]resorcinolarenes and Their Aminomethylated Derivatives

Calix[4]resorcinolarenes in the presence of amine and aminomethylated calix[5]resorcinolarenes in DMF undergo similar multistage electrochemical oxidation. The first stage proceeds at low potentials and involves reversible one-electron transfer with formation of stable phenoxy radicals.     

Effective Synthesis of β-Ketophosphonate Derivatives of Calix[4]resorcinolarenes

An effective method for introduction of -phosphonate fragments to a calix[4]resorcinolarene matrix is presented octa(ketophosphonate)calix[4]resorcinolarenes are prepared. The effectiveness of 2,8,14,20-tetramethyl-4,6,10,12,16,18,22,24-octa[3-(dimethoxyphosphoryl)-2-oxopropyl]calix[4]-resorcinolarene for extraction of lanthanum ions from water to chloroform in the presence of picrate ions, accompanied by formation of a complex is demonstrated.     

Condensation of resorcinol with phosphorylated acetals, synthesis of calix[4]resorcinolarenes with phosphorus-containing alkyl fragments in the lower rim

The reaction of resorcinol with phosphorylated acetals leads to formation of calix[4]resorcinolarenes having phosphonate, phosphinate, or (phosphinothioyl)sulfanylmethyl fragments in the lower rim of the molecule.     

Calix[4]resorcinolarenes with alkylphosphonic fragments: Protolytic properties and interaction with lanthanum(III)

The protolytic and complexing properties of phosphorylated derivatives of calix[4]resorcinolarenes were studied by pH-metric titration at 298 K in water-2-propanol (80 vol % 2-propanol). It was shown that calix[4]resorcinolarene containing the propylphosphonic acid fragment at the C atom linking the aryl groups exists in solution mainly as tetramer. At pH > 4, the anions of tetrameric, dimeric, and monomeric forms of this compound are formed. The neutral form of aminomethylated calix[4]resorcinolarene contaning, along with the propylphosphonic acid fragment, the CH₂NEt₂ group on the opposite side of the molecule is monomeric. It exists as a zwitterion and contains four betaine protons. Three dimeric species of this compound, one protonated and two deprotonated, were revealed. The dissociation constants of the phosphonate groups and two betaine protons were evaluated. The other two betaine protons and the protons of hydroxy groups do not dissociate. The equilibrium constants of the complex formation with lanthanum(III) and in some cases the stability constants of the complexes were calculated. Probable modes of coordination of calix[4]resorcinolarenes are discussed. Depending on the acidity of the medium, the competition between the phosphonic group and the phenolate ions takes place, and complexes with the coordination via phosphonic groups can rearrange into complexes with the coordination via phenolate groups.     

The effect of self-association on the reactivity of calix[4]resorcinolarene anions with respect to esters of phosphorus acids

The kinetics of reactions of amphiphilic anions derived from calix[4]resorcinolarenes and their aggregates withp-nitrophenyl esters of phosphorus acids were studied by spectrophotometry. The effect of hydrophobicity of the substituent R and of the composition of aqueous dimethylformamide solvent (30, 50, 80% (v/v) DMF) on these processes was investigated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 275–279, February, 1998.     

New artificial receptors from selectively functionalized calix[4]arenes

Abstract

The development of new synthetic methods for the monoalkylation of calix[4]arenes at the lower rim allows the synthesis of a new class of trihydroxamate siderophores. Three chelating hydroxamic acid units are introduced through a sequence of reactions which blocks the macrocycle in the cone conformation. The new ligands obtained form neutral 1:1 complexes (FeL) with iron (III), which are stable in EtOH/H₂O 9:1 at pH 2–7. Calix[4]arene bis-crown ethers are prepared by exploiting the selective 1,2-(proximal) functionalization of calix[4]arenes at the lower rim. These ligands are, however, less effective in complexing alkali metal cations compared with the 1,3-calix[4]arene crown-ethers which, in their partial cone structure, offer a better shielding for the complexed cations. Rigid upper rim-bridged calix[4]arenes potentially useful for the inclusion of neutral molecules are prepared by exploiting the selective 1,3-diformylation of calix[4]arene at the upper rim. Finally a new chloromethylation method for calix[4]arenes blocked in the cone conformation is described together with the synthesis of new cavitands.     

Synthesis of novel, boron-containing cavitands derived from calix[4]resorcinarenes and their molecular recognition of biologically important polyols in Langmuir films

An efficient synthetic route for the synthesis of cavitands derived from calix[4]resorcinarene and its tetrabromo derivative was elaborated. A large-scale preparation was achieved in excellent yield, by replacing the high-boiling solvents with acetone. The tetrabromocavitands were transformed into tetra-boronic acid cavitands via lithiation with butyllithium and reaction with triethylborate. Two lipophilic cavitands bearing four boronic acid residues were demonstrated to form stable Langmuir monolayers at the water-air interface. These cavitand receptors differ in bridging unit between oxygen atoms, i.e. one contains a one-carbon unit and the other a two-carbon unit. l-sorbose, d-galactose, d-glucose, and d-cellobiose were selected for molecular recognition studies using the Langmuir techniques. The unsubstituted tetra-n-undecyl calix[4]resorcinarene was used as a reference receptor compound. Differences in surface potential were diagnostic of the different types of binding forces, which can occur.     

Synthesis and some properties of tetrakis-3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-hydroxybenzylated calix[4]resorcinols

A method for the synthesis of new calix[4]resorcinols tetra-3,5-di-tert-butyl-4-hydroxybenzyl derivatives is developed. Their interaction with methyldichlorophosphonate, dimethyldichlorosilane in the presence of a base leads to formation of organophosphorus-organosilicon cavitands. Acetylation of hydroxybenzylated calix[4]resorcinols with acetic anhydride leads to products of either incomplete or full acetylation depending on experimental conditions.     

Synthesis and Properties of Functionalized Schiff Bases of 5α,10α-Di（4-hydroxylphenyl）calix[4]pyrrole and 5α,15β-Di（4-hydroxylphenyl）calix｜4] pyrrole

A series of calix[4]pyrrole meso-substituted Schiff bases was synthesized with 5α,10α-di（4- hydroxylphenyl）calix[4]pyrrole or 5α,15β-di（4-hydroxylphenyl）calix[4]pyrrole as starting materials. The synthetic routes included alkylation with methyl a-chlroroaceate, ammonolysis with alkylene diamine, and condensation with salieylladehyde or 2-hydroxynaphthaldehyde. The crystal structures of the new calix[4]pyrroles and their Schiff bases were determined by X-ray diffraction. The coordination properties of the representative ealix[4]pyrrole Sehiff bases to transition metal ions were also investigated by UV-Vis spectra.     

Liquid extraction of La<Superscript>III</Superscript>, Gd<Superscript>III</Superscript>, and Yb<Superscript>III</Superscript> ions by phosphorylated calix[4]resorcinarene derivatives

New phosphorylated calix[4]resorcinarene and cavitands were synthesized. Their extraction ability toward La^III, Gd^III, and Yb^III ions was studied. The cavitands are more efficient extracting agents than octasubstituted calix[4]resorcinarenes. The nature of substituents at the nitrogen atom at the upper rim and hydrophobic substituents at the lower rim exerts a substantial effect on the solubility of the extracted complex in chloroform. Coordination of two lanthanide ions with an extragent molecule results in their efficient but non-selective extraction. The literature and our spectral (³¹P NMR) data suggested that the ligand in the extracted complex has most probably a “kite” conformation. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 303–308, February, 2007.     

Cyclic Phosphorochloridites,Phosphorochloridates, and Phosphorochloridothioates Based on Calix[4]resorcinolarenes

Phosphorylation of calix[4]resorcinolarenes with PCl₃ yields cyclic phosphorochloridites. Cavitands containing cyclic phosphorochloridite fragments in the upper rim are readily oxidized with SO₂Cl₂ to the corresponding phosphorochloridates and take up four equivalents of sulfur on heating to form cyclic phosphorochloridothioates.     

A facial microwave-assisted synthesis, spectroscopic characterization and preliminary complexation studies of calix[4]pyrroles containing the hydroxamic-acid moiety

The synthesis, spectroscopic characterization and preliminary complexation properties of functionalized calix[4]pyrroles are described. To date, two generalized preparative approaches have been pursued (i) modifying the basic pyrrole-plus-ketone synthesis of calix[4]pyrrole by using microwave irradiation protocol, (ii) the basic meso-tetra(methyl) meso-tetra(p-nitrophenyl) calix[4]pyrrole skeleton was functionalized to give hydroxamic acids, especially in the meso-position of the macrocycles. The structures of novel calix[4]pyrrole hydroxamic acid derivatives were confirmed on the basis of various physico-chemical techniques such as elemental analysis, FT-IR, ¹H NMR and FAB-Mass. The results of preliminary studies on the extraction of vanadium (V) with the host calix[4]pyrrole hydroxamic acids were elucidated by significant examination of UV–Vis spectroscopy and ICP-AES. Single crystal structure of basic meso-tetra(methyl) meso-tetra (p-nitro phenyl) calix[4]pyrrole moiety has also been reported.     

The Syntheses and Binding Properties of the Novel Organophosphorus Calixarenes

Phosphorylation of bromo, dialkylaminomethyl calix[4]resorcinarenes with various long chain aliphatic radicals with a number of P(III) derivatives i.e. triamido-and diamidophosphites, and polyhalogenides of P(III), P(IV) is described. A series of phosphoamide cavitands were obtained. Structures and properties of synthesized compounds were discussed on the basis of physical and quantum chemical methods.     

Sulfonic cation exchangers based on immobilized cis-Calix[4]resorcinolarenes

New sulfonic cation exchangers based on immobilized calix[4]resorcinolarenes were prepared. Their ion-exchange properties toward Na⁺, Cu²⁺, [Pd(NH₃)₄]²⁺, In³⁺, and Sn⁴⁺ ions were studied in a wide pH range, and their chemical stability was examined.     

Synthesis of functional aromatic multisulfonyl chlorides and their masked precursors

The synthesis of functional aromatic bis(sulfonyl chlorides) containing an acetophenone and two sulfonyl chloride groups, i.e., 3,5-bis[4-(chlorosulfonyl)phenyl]-1-acetophenone (16), 3,5-bis(chlorosulfonyl)-1-acetophenone (17), and 3,5-bis(4-(chlorosulfonyl)phenyloxy)-1-acetophenone (18) via a sequence of reactions, involving in the last step the quantitative oxidative chlorination of S-(aryl)- N,N'-diethylthiocarbamate, alkyl- or benzyl thiophenyl groups as masked nonreactive precursors to sulfonyl chlorides is described. A related sequence of reactions was used for the synthesis of the aromatic trisulfonyl chloride 1,1,1-tris(4-chlorosulfonylphenyl)ethane (24). 4-(Chlorosulfonyl)phenoxyacetic acid, 2,2-bis[[[4-(chlorosulfonyl)phenoxyacetyl]oxy]methyl]-1,3-propanediyl ester (27), 5,11,17,23-tetrakis(chlorosulfonyl)-25,26,27,28-tetrakis(ethoxycarbonylmethoxy)calix[4]arene (38), 5,11,17,23,29,35-hexakis(chlorosulfonyl)-37,38,39,40,41,42-hexakis(ethoxycarbonylmethoxy)calix[6]arene (39), 5,11,17,23,29,35,41,47-octakis(chlorosulfonyl)-49,50,51,52,53,54,55,56-octakis(ethoxycarbonylmethoxy)calix[8]arene (40), 5,11,17,23-tetrakis(tert-butyl)-25,26,27,28-tetrakis(chlorosulfonyl phenoxyacetoxy)calix[4]arene (44), 5,11,17,23,29,35-hexakis(tert-butyl)-37,38,39,40,41,42-hexakis(chlorosulfonylphenoxyacetoxy)calix[6]arene (45), and 5,11,17,23,29,35,41,47-octakis(tert-butyl)-49,40,51,52,53,54,55,56-octakis(chlorosulfonylphenoxyacetoxy)calix[8]arene (46) were synthesized by two different multistep reaction procedures, the last step of both methods consisting of the chlorosulfonation of compounds containing suitable activated aromatic positions. 2,4,6-Tris(chlorosulfonyl)aniline (47) was obtained by the chlorosulfonation of aniline. The conformation of two series of multisulfonyl chlorides i.e., 38, 39, 40 and 44, 45, 46, was investigated by (1)H NMR spectroscopy. The masked nonreactive precursor states of the functional aromatic multisulfonyl chlorides and the aromatic multisulfonyl chlorides reported here represent the main starting building blocks required in a new synthetic strategy elaborated for the preparation of dendritic and other complex organic molecules.