Thiacalix[4]arene derivatives with proximally bridged lower rim

New types of lower rim proximally bridged thiacalix[4]arenes have been prepared by direct aminolysis of starting tetraacetate derivative in the cone conformation using aliphatic α,ω-diamines. X-ray crystallography revealed the highly preorganized array of -C(O)NH- bonds resulting in strong intramolecular hydrogen bonding between amide groups of both bridges. The length of the corresponding diamine was found to have an essential influence on the yield of these bridged molecules.     

Monosubstituted lower rim thiacalix[4]arene derivatives

A clean and partially green route to monoalkyled thiacalix[4]arenes has been demonstrated. We have discovered that tetraalkylammonium halide can cleave selectively one of the two aryl alkyl ethers of dialkylated para-tert-butylthiacalix[4]arenes. Thus, p-tert-butyl thiacalix[4]arenes differently monoalkyled at the lower rim with acetyl, propyl, and benzyl group were synthesized in good yield.     

Unique self-assembly patterns based on thiacalix[4]arene-silver interactions

Novel self-assembled supramolecular networks were prepared by the interactions of thiacalix[4]arenes bearing simple alkyl groups on the lower rim (4×MeO-, 4×n-PrO-) with silver triflate. Contrary to the classical calix[4]arenes (with CH₂ bridges between the aromatic moieties), the presence of four sulfur atoms enables the formation of S-Ag-S connections between the individual molecules leading to the coordination topology so far unknown in calixarene chemistry. These systems form infinite 1-D coordination polymeric structures in the solid state, where the thiacalixarene moieties are preorganized in a side-by-side arrangement. Interestingly, the linear coordination polymers were obtained using both the conformational immobilised (4×n-PrO, cone, 1,3-alternate conformers) and the conformational mobile (4×MeO) thiacalix[4]arenes, which indicates the generality of this behaviour in thiacalixarene series.     

Synthesis and conformational evaluation of p-tert-butylthiacalix[4]arene-crowns

Bridging of p-tert-butylthiacalix[4]arene afforded 1,3-dihydroxythiacalix[4]arene-monocrown-5 (3b), 1,2-alternate thiacalix[4]arene-biscrown-4 and -5 (4a,b), and 1,3-alternate thiacalix[4]arene-biscrown-5 and -6 (5a,b), depending on the metal carbonates and oligoethylene glycol ditosylates used. Starting from 1,3-dialkylated thiacalix[4]arenes, the corresponding bridging reaction gave 1,3-alternate, partial-cone, and cone conformers 10-19, depending on the substituents present. Temperature-dependent studies revealed that the conformationally flexible 1,3-dimethoxythiacalix[4]arene-crowns 10a-c exclusively occupy the 1,3-alternate conformation. Demethylation exclusively gave the cone 1,3-dihydroxythiacalix[4]arene-crowns (3a,c), which could not be obtained by direct bridging of thiacalix[4]arene. The different structures were assigned on the basis of several X-ray crystal structures and extensive 2-D (1)H NMR studies.     

Composition of thiacalix[4]arene complexes with monovalent metal ions in the gas phase: MALDI mass spectrometry

MALDI-TOF mass spectrometry was used to study the reaction of p-tert-butylthiacalix[4]arene (1) and a number of its derivatives disubstituted at the lower rim (2—9) with monovalent metal salts (Li, Na, K, Cs, Cu, Ag) in the gas phase. It was shown that the thiacalixarenes under study bind the metal ions through the substitution of hydrogen atoms of the hydroxy groups. The reactions of silver and copper salts with the thiacalix[4]arenes were found to form the cluster ions, which represent the macrocycle dimers with several metal ions, while the formation of such clusters is impossible in the case of alkali metal salts. The peak intensities of the cluster ions increase in the weakly basic medium, reaching in some cases 100%.     

A series of octanuclear-nickel(II) complexes supported by thiacalix[4]arenes

A series of discrete complexes, [Ni(8)(BTC4A)(2)(μ(6)-CO(3))(2)(μ-CH(3)COO)(4)(dma)(4)]·H(2)O (1), [Ni(8)(BTC4A)(2)(μ(6)-CO(3))(2)(μ-Cl)(2)(μ-HCOO)(2)(dma)(4)]·2DMF·2CH(3)CN (2), [Ni(8)(PTC4A)(2) (μ(6)-CO(3))(2)(μ-CH(3)COO)(4)(dma)(4)]·DMF (3), and [Ni(8)(PTC4A)(2)(μ(6)-CO(3))(2)(μ-OH)(μ-HCOO)(3) (dma)(4)] (4) (p-tert-butylthiacalix[4]arene = H(4)BTC4A, p-phenylthiacalix[4]arene = H(4)PTC4A, dma = dimethylamine, and DMF = N,N'-dimethylformamide), have been prepared under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction analyses, powder XRD, and IR spectroscopy. These four complexes are stacked by dumbbell-like building blocks with one chairlike octanuclear-nickel(II) core, which is capped by two thiacalix[4]arene molecules and connected by two in situ generated carbonato anions and different auxiliary anions. This work implied that not only the solvent molecules but also the upper-rim groups of thiacalix[4]arenes have significant effects on the self-assembly of the dumbbell-like building blocks. The magnetic properties of complexes 1-4 were examined, indicating strong antiferromagnetic interactions between the nickel(II) ions in the temperature range of 50-300 K.     

Synthesis and Electrochemical Behavior of Electroactive Bistetrathiafulvalene-attached Thiacalix[4]arene Assemblies

Tetrabromoalkylthiacalix[4]arenes(1a and 1b) reacted with excess bis(tetraethylammonium)-bis(1,3- dithiole-2-thione-4,5-dithiol)zincate(2) to give thiacalix[4]arene-thiones(3a and 3b) in the presence of Na₂S. Two novel bistetrathiafulvalene-attached thiacalix[4]arene assemblies(5a and 5b) formed via triethyl phosphite-mediated cross-coupling of thiacalix[4]arene-thiones(3a and 3b) and 4,5-biscyanoethylthio-1,3-dithiole-2-one(4). All the four new compounds were characterized by ¹H NMR, ¹³C NMR, IR, MS spectra and elemental analysis. Meanwhile, the structures of thiacalix[4]arene-thiones(3a and 3b) were identified by X-ray analysis. In addition, the cyclic voltammograms of the resulting thiacalix[4]arenes containing electroactive TTF units(5a and 5b) were provided.     

Substituent control of potassium and rubidium uptake by asymmetric calix[4]-thiacalix[4]tubes

Herein we report on the synthesis and ionophore properties of the first asymmetric p-tert-butylcalix[4]-p-R-thiacalix[4]tubes 7a-c (R = t-Bu, H, 1-adamantyl). The target compounds were obtained by the condensation of tosyloxyethoxy-p-tert-butylcalix[4]arene with the corresponding p-R-thiacalix[4]arenes in the presence of K2CO3 in acetonitrile. The complexation with sodium, potassium and rubidium iodides was studied in CDCl3-CD3OD (4:1) medium by means of 1H NMR measurements. It was found that the ionophore properties of calixtubes 7a-c are controlled by the character of the substituents at the upper rim of the thiacalix[4]arene fragment and it was shown that only the molecular tube 7c with an adamantane-containing thiacalixarene unit is capable of quantitatively binding potassium (swiftly) and rubidium (slowly) cations.     

p-tert-Butyl thiacalix[4]arenes functionalized at the lower rim by o-, m-, p-amido and o-, m-, p-(amidomethyl)pyridine fragments as receptors for α-hydroxy- and dicarboxylic acids

A series of new p-tert-butyl thiacalix[4]arenes with o-, m-, p-amido and o-, m-, p-(amidomethyl)pyridine substituents at the lower rim in cone, partial cone, and 1,3-alternate conformations were synthesized. The ability of the obtained compounds to recognize the α-hydroxy (glycolic, tartaric) and dicarboxylic (oxalic, malonic, succinic, fumaric, and maleic) acids was investigated by UV-vis spectroscopy. Also, the efficiency and selectivity of binding, the association constants log K_a (10² to 10⁷ M⁻¹) and the stoichiometry were determined for the complexes of p-tert-butyl thiacalix[4]arenes with the acids. The receptors based on p-tert-butyl thiacalix[4]arenes with (amidomethyl)pyridine substitutes are most efficient in complexation in many cases.     

Upper rim substituted thiacalix[4]arenes

The synthesis and structure of new tetrahydroxythiacalix[4]arenes, existing in the cone conformation and possessing reactive bromide, chloromethyl or diorganylphosphoryl groups on the upper rim of the macrocycle are described. The molecular structure of tetrakis(diisopropoxyphosphorylmethyl)thiacalix[4]arene was examined by X-ray crystallography.     

Thiacalix[4]arene derivatives as radium ionophores: a study on the requirements for Ra2+ extraction

The synthesis and NOE-based structural characterization is described of thiacalix[4]arene tricarboxylic acid (7), thiacalix[4]crown-5 and -6 monocarboxylic acids (2 and 5), and the bis(N-methylsulfonyl)thiacalix[4]crowns-5 and -6 (4a,b). The 226Ra2+ selectivity coefficients, log(K(Ra)ex/K(M)ex), of the new thiacalix[4]arene derivatives are compared directly with those of thiacalix[4]crown-5 and -6 (1a,b), thiacalix[4]crown-5 and -6 dicarboxylic acids (3a,b), and thiacalix[4]arene di- and tetracarboxylic acids (6 and 8). Thiacalix[4]arene dicarboxylic acid (6) already exhibits a high 226Ra2+ selectivity, but this is significantly improved in the case of 3b, having an additional crown-(6-)ether bridge. The covalent combination of a crown ether and carboxylic acid substituents as in the thiacalix[4]arenes 2,3a,b,4a,b, and 5 gives a better 226Ra2+ selectivity in the presence of Sr2+ or Ba2+ than mixtures of dibenzo-21-crown-7 and thiacalix[4]arene dicarboxylic acid (6) or of pentadecanoic acid and thiacalix[4]crown-6 (1b).     

p-tert-Butylthiacalix[4]arenes containing guanidinium groups: synthesis and self-assembly into nanoscale aggregates

New p-tert-butylthiacalix[4]arenes with several different substituents at the lower rim have been synthesised. A method for the selective introduction of one or two guanidinium fragments into the structure of p-tert-butylthiacalix[4]arenes has been developed. The 1,3-alternate thiacalix[4]arenes containing guanidinium groups interact with silver nitrate and oxalic acid in methanol with a logK_assoc of about 3.5 and 1:1 stoichiometry, while the macrocycle in the cone conformation interacts with oxalic acid with logK_assoc of 7.4 and 2:1 stoichiometry. The new p-tert-butylthiacalix[4]arenes form nanoscale aggregates with hydrodynamic radii of about 70 nm by self-association and by mediation with silver cations and oxalic acid.     

Supramolecular self-assemblies of stereoisomers of p-tert-butyl thiacalix[4]arenes functionalized with hydrazide groups at the lower rim with some metal cations

Novel p-tert-butyl thiacalix[4]arenes functionalized with hydrazide groups at the lower rim in cone, partial cone and 1,3-alternate conformations were synthesized and their receptor properties toward metal ions of p- (Al³⁺, Pb²⁺) and d- (Fe³⁺, Co³⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺) elements were investigated by picrate extraction and dynamic light scattering (DLS). It was shown that the p-tert-butyl thiacalix[4]arenes functionalized with hydrazide groups are effective extractants of soft metal cations. The complex stoichiometry depended on the receptor configuration. All the p-tert-butyl thiacalix[4]arene derivatives with hydrazide fragments were able to form nanoscale aggregates but did not show self-association abilities.     

Solvent extraction and self-assembly of nanosized aggregates of p-tert-butyl thiacalix[4]arenes tetrasubstituted at the lower rim by tertiary amide groups and monocharged metal cations in the organic phase

New p-tert-butyl thiacalix[4]arenes functionalized with morpholide and pyrrolidide groups at the lower rim in cone, partial cone, and 1,3-alternate conformations were synthesized, and their receptor properties for monocharged cations (alkali metal and silver ions) were studied using the picrate extraction method and dynamic light scattering (DLS). To evaluate the ability of the p-tert-butyl thiacalix[4]arene derivatives to recognize metal ions, liquid-liquid extraction of their picrate salts has been carried out in a mutually saturated water-dichloromethane system. The degrees of extraction and the extraction constants for monocharged metal cations (Li⁺, Na⁺, K⁺, Cs⁺) have been determined. The ability of the systems, consisting of host and guest molecules, to self-assembly was proved by DLS using a Zetasizer Nano ZS particle size analyzer. It was shown that all the investigated thiacalix[4]arenes are able to form nanoscale particles with silver cations under the experimental conditions. The pyrrolidide derivative in the cone conformation showed both self-association and aggregation processes with lithium cations. The degree of extraction for all the investigated systems that formed nanoscale aggregates in the organic phase was more than 67% and the extraction constants, log K_ex determined by the picrate extraction method, more than 6.     

New DNA-sensor based on thiacalix[4]arene-modified polydiacetylene particles

Russian Chemical Bulletin - New p-tert-butyl thiacalix[4]arene derivative in the 1,3-alternate stereoisomeric form containing two diethylenetriamine groups and pentacosa-10,12-diynoic moieties on...     

Preorganization of diglycolamides on the calix[4]arene platform and its effect on the extraction of Am(III)/Eu(III)

Different diglycolamide (DGA)-substituted calix[4]arene-based extractants were synthesized and evaluated for the extraction of Am(III) and Eu(III), representative trivalent actinide and lanthanide ions, respectively. On the narrow rim of the calix[4]arene platform, the DGA moiety was either 1,3-di- or tetrasubstituted with a varying spacer length between the oxygen and amide nitrogen atom. In addition, DGA groups were appended both to the wide rim and to both rims of calix[4]arenes and their efficiencies were compared for Am(III) and Eu(III) extraction at three different feed acidities. The extraction and separation efficiencies strongly depended on the N-alkyl substituent as well as the spacer length. 1,3-Di-DGA-substituted calix[4]arenes are inferior extractants to the corresponding tetra-DGA-substituted ones. Narrow rim DGA-functionalized derivatives resulted in high extraction efficiencies, while the wide rim DGA-functionalized calix[4]arenes showed practically no extraction.     

Alkali-metalated forms of thiacalix[4]arenes

The alkali metal salts [TCALi4] (1), [TCANa4] (2), and [TCALK4] (3) of fully deprotonated p-tert-butyltetrathiacalix[4]arene (H(4)TCA) are readily available from the reactions of thiacalix[4]arene and n-BuLi, NaH, or KH as deprotonating reagents. Crystals of the sodium salts 2 and the potassium salt 3 suitable for X-ray diffraction were obtained in the form of the pyridine solvates [(TCA)2Na8.8py] (2.8py) and [(TCA)2K(8).8py] (3.8py). These molecules are dimers in the solid state but are structurally not related. In addition, the reaction of H(4)TCA and lithium hydroxide afforded the structurally characterized complex [(TCA)Li5(OH).4THF] (4). The molecular structure of 4 as well as the structures of 2.8py and 3.8py reveal a close relationship to the corresponding alkali metal salts of the calix[4]arenes.     

上端含长链烷基的手性杯[4]芳烃合成

脱叔丁基的杯[4]芳烃与长链的叔醇或者叔氯代烷烃进行傅-克反应, 在其上端引入长链烷基. 然后在下端引入光学活性的1-苯基乙胺基团, 得到了一系列上端含长链烷基的手性杯[4]芳烃.     

Novel dendritic cores based on thiacalix[4]arene derivatives

Thiacalix[4]arenes possessing carboxylic groups were used for the design of potential dendritic cores with amino surface groups. The known tetraacetic acid in the 1,3-alternate conformation gave the desired product in very low yield because of steric hindrance on thiacalix[4]arene moiety. Therefore, synthetic strategy based on withdrawing of the carboxyl groups via benzylic spacer from the thiacalix[4]arene moiety was successfully applied for the realization of novel thiacalix[4]arenes bearing two or four protected lysine units.     

New Azothiacalix[4]arenes Containing Biheterocyclic Subunits: Extraction and Complexation Properties

New thiacalix[4]arenes 2a, 3a, 4 and 5 functionalized with biheterocyclic and azophenyl groups at the lower rim and the upper rim of the macrocycle, respectively, were synthesized and their extraction properties towards Cu²⁺, Ag⁺, Ni²⁺ and Pb²⁺ studied. The complexation properties of the bithiazolyl receptors 2a, 4 and the bipyridyl receptors 3a, 5 were investigated by fluorescence and UV–visible titrations, respectively. The stoichiometries of the complexes were determined. A stoichiometry of 1:1 was found for the Cu-2a, Ag-3a complexes and 2:1 for the Cu₂-4, Ag₂-5 complexes as a function of the number of grafted bithiazolyl groups. The association constants for the 1:1 complexes were calculated using the Benesi–Hildebrand plot and by linear regression analysis.