Synthesis of New Calix[4]arenes Functionalizated by Acetylhydrazide Groups

A series of new calix[4]phenols, calix[4]resorcinols and calix[4]pyrogallols with acetylhydrazide substitutes has been␣synthesized with high yields by hydrazinolysis of ester group containing calix[4]arenes. The synthesized calix[4]phenols adopt the cone conformation while the calix[4]resorcinol and calix[4]pyrogallol derivatives prefer the boat conformation. The amide fragment of the hydrazide groups predominantly exists in the trans-conformation. The binding ability of synthesized calix[4]arenes toward transition and alkali metals by solvent extraction has been investigated.     

Benzylation of tetraalkylcalix[4]resorcinols

New amphiphilic benzylated calix[4]resorcinols were synthesized by the reaction of tetra-alkylcalix[4]resorcinols with 3,5-di(tert-butyl)-4-hydroxybenzyl acetate. The reaction pathway and the type of the products formed are determined by the structure of the alkyl substituent at the lower rim of tetraalkylcalix[4]resorcinols and the nature of acid used as a catalyst of the process. Self-organization of some synthesized compounds in nonpolar media was studied.     

Calix[4]resorcinols functionalized with amino acid residues

By the Mannich reaction in ternary systems calix[4]resorcinol-amino acid (amino acid ester, amino acid ester hydrochloride)-formaldehyde calix[4]resorcinols were obtained functionalized on the upper molecule rim by amino acid residues.     

New calix[4]resorcinols containing aldehyde fragments in the molecule

A reaction of calix[4]resorcinols with 3-ethylamino-2,2-dimethylpropanal and aqueous formaldehyde results in new calix[4]resorcinol derivatives including aldehyde fragments aminomethylated at the higher rim of the molecule. Depending on the structure of calixarenes and experimental conditions, products of mono and tetra substitution can be obtained.     

Synthesis of rccc- and rctt-diastereoisomers of novel triazole-containing calix[4]resorcinols

Novel calix[4]resorcinols containing four triazole fragments on the aromatic substituents of the calixarene framework were synthesized via a one-step condensation of resorcinol and its derivatives with 4-(1-benzyl-1H-[1,2,3]triazol-4-ylmethoxy)benzaldehyde. The macrocyclic products are rctt- and/or rccc-isomers, which were isolated and characterized by NMR and single crystal X-ray diffraction studies. The same products were also prepared via the click-reaction of benzyl azide with previously synthesized calix[4]resorcinols containing four alkyne terminal groups on the aromatic substituents. In this case, only rctt-diastereomers of the corresponding calixarenes were isolated, which is governed by conformational features of the starting macrocycles.     

Novel calix[4]resorcinols with sulfamide fragments in the lower rim

Russian Journal of General Chemistry - Novel calix[4]resorcinols modified by sulfamide fragments were synthesized via acid-catalyzed opening of the pyrrolidine ring in...     

Solubilization of new calix[4]resorcinols with amino acid substituents at the upper rim in surfactant micellar solutions

Russian Chemical Bulletin - A spectrophotometric method was used to select conditions for the development of aqueous systems based on new calix[4]resorcinols containing amino acid moieties at the...     

Reaction of N-cyclohexyl-2-(2-hydroxynaphthalen-1-yl)pyrrolidine-1-carboxamide with resorcinol and its derivatives and synthesis of polyphenols

Russian Chemical Bulletin - An acid-catalyzed pyrrolidine ring opening in 2-(2-hydroxynaphthalen-1-yl)pyrrolidine-1-carboxamides in the presence of resorcinols furnished new calix[4]resorcinols or...     

Novel first-generation dendrimers on calix[4]resorcinol core equipped with multiple triazole units

Novel first-generation dendrimers on the calix[4]resorcinol core with four branches each containing multiple 1,2,3-triazole units have been synthesized in one-step by acid catalyzed condensation of resorcinols with a new aldehyde dendron, namely, 4-{3,5-bis[(1-benzyl-1H-1,2,3-triazol-4-yl)- methoxy]benzyloxy}benzaldehyde (obtained by alkyne–azide cycloaddition). The reaction proceeds stereoselectively to form rccc-diastereoisomers in high yields.     

Electricoswitchable bonding of metal ions and complexes by calixarenes

The results of authors on designing electroswitchable supramolecular systems based on calix[4]arenes, calix[4]resorcinols, and transition metal ions and complexes are summarized. We consider systems in which the switching is performed owing to electrochemical reactions both of groups grafted to the macrocycle and bound substrates. Examples of electrochemically switchable luminescence are given.     

Single step preparation and conformational analysis of novel thiophosphorylated ligands based on calix[4]resorcinol matrix

We have synthesized novel calix[4]resorcinols with four 2-thioxo-1,3,2-dioxaphospholane groups introduced in aromatic substituents in the methylidene bridges of macromolecules by the condensation of new thiophosphorylated benzaldehyde with resorcinol and its derivatives in acidic media with high yields. The formation of only one rctt isomer with corresponding chair conformation is observed, which was determined by 2D NMR-experiments.     

Synthesis and aggregation properties of novel amino acetals with the calix[4]resorcinol platform

Reactions of calixarenes with methylaminoacetaldehyde dimethyl acetal and formalin gave Mannich bases with the calixarene platform. It was found by dielcometric titration that calix[4]resorcinols with acetal groups in the aminomethyl fragment form head-to-head supra-molecular aggregates in chloroform at low concentrations. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 888–891, May, 2006.     

Reaction of resorcinol and its derivatives with urea acetals

Reaction of 2-methylresorcinol and pyrogallol with urea acetals of various structures was studied. Depending on the structure of the acetal used, reaction was established to result in eiter calix[4]resorcinols containing urea fragment or in imidazolidin-2-one derivatives.     

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.     

Reactions of trialkyl(aryl)phosphonium-substituted acetals with resorcinol and its derivatives

The reactions of 2-tributylphosphonioacetaldehyde acetal with resorcinol and 2-methylresorcinol in an acidic aqueous-ethanol medium afford calix[4]resorcinols containing four tributylphosphonium groups at the lower rim. The corresponding reactions of the triphenylphosphonium analog give phosphonium salts containing the 2,2-diarylethyl moiety.     

Analytical applications of nano-baskets of calix[4]pyrroles

Calix[4]pyrrole is one such class which holds a great promise in the fields of sensors and their unique behavior as sensors owes to its structural flexibility. Anion binding ability of calix[4]pyrrole has been modified in a variety of ways. Introduction of electron releasing and electron withdrawing groups at the meso position or at β-pyrrolic positions leads to calix[4]pyrrole with deep cavities and fixed walls which shows increased selectivity and modified binding effects. Strapping of calix[4]pyrrole is another way to modify its structural behavior which is responsible for its binding behavior. Choice of strap could play a profound role not only in increasing the intrinsic anion binding affinity of calix[4] pyrrole, but also in modulating the receptor anion stoichiometry, thereby modifying potentially the inherent anion binding selectivity. Calix[n]pyrroles with extended cavities have also been synthesized. Such as calix[3]bipyrrole binds bromide substantially with high affinity than calix[4]pyrrole. Calix[4]pyrrole has also been used to produce anion sensors that can report the presence of anion by means of a color change. The medium effect on the complexation of calix[4]pyrrole and anion has been investigated in various solvents. Calix[4]pyrrole has also been used to increase the ionic conductivity of solid polymer electrolyte by anion complexation of the metal salt. Calix[4]pyrrole has been used to obtain optical sensors using surface plasmon resonance technique. Composite films of cellulose acetate containing calix[4]pyrrole has also been reported which has potential usage in packaging, storage and preservation. In nut shell, calix[4]pyrrole can be modified in a variety of ways to form versatile sensors which can be used in variety of ways in various areas.     

Electrochemical synthesis of the calix[4]resorcinol nickel complexes modified with thiophosphoryl fragments

Nickel complexes of 1:1 composition with calix[4]resorcinols (L) modified with thiophosphyl fragments were synthesized. In the process of electrochemical reduction these complexes are capable of providing spherical homogeneous Ni(0)L particles with a narrow size distribution, stable both on the electrode and in the solution. The redox properties of the metal complexes were studied. The dimensions of the complexes obtained were estimated using the atomic force microscope (AFM) equipped with an electrochemical attachment.     

Regioselective ipso-nitration of calix[4]arenes

A novel protection/deprotection method leading to the regioselective ipso-substitution of calix[4]arenes is described. The introduction of nosyl (p-nitrobenzenesulfonyl) groups into the lower rim of partly alkylated tert-butylcalix[4]arenes leads subsequently to the exclusive ipso-nitration of the alkylated phenol rings, while the protecting groups can be easily removed in the next step. This method gives dialkoxy- or trialkoxy-substituted calix[4]arenes with nitro groups on the alkylated rings and tert-butyl groups on the remaining ones. The above substitution pattern is complementary to the isomers so far known in the chemistry of calix[4]arenes and could be used in the design of novel type of calixarene-based receptors.     

Facile synthesis of oligophenylene-substituted calix[4]arenes and their enhanced binding properties

[reaction: see text] A facile and efficient protocol for the synthesis of oligophenylene OPP(n)-substituted calix[4]arenes (with n up to 4) via iodo-substituted oligoarylcalix[4]arenes has been developed. The cooperation effect of the proximate fluoroionophores in hexylsulfanyl end-capped OPP(n)-substituted calix[4]arene assemblies leads to metal ion binding enhancement.     

Fourfold [2]rotaxanes based on calix[4]arenes

Tetraurea calix[4]arenes with four loops form exclusively heterodimers with open-chain urea calix[4]arenes when they are dissolved in aprotic solvents. These assemblies can be considered as pseudorotaxanes. If open-chain tetraureas ending with maleic imide functions are used, their Diels-Alder reaction with 1,4,5,8-tetrapentoxyanthracene leads to tetra[2]rotaxanes which cannot be split into the single calixarene parts by hydrogen bond breaking solvents.