Synthesis of Bisthiacalix[4]arene: Reaction of Piperazine with Monoacrylamide Derivative of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butylthiacalix[4]arene

The reaction of acryloyl chloride with the monoamine derivative of p-tert-butylthiacalix[4]arene was used to synthesize p-tert-butylthiacalix[4]arene monoacrylamide in the 1,3-alternate conformation. The effect of the nature of the amine on the result of its Michael reaction with the synthesized p-tert-butylthiacalix[4]arene monoacrylamide was studied. The latter was reacted with piperazine to obtain bisthiacalix[4]arene with the macrocyclic fragments in the 1,3-alternate conformation.     

Modification of silica nanoparticles with stereisomers of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylthiacalix[4]arene containing four 2-oxo-2-{[3-(triethoxysilyl)prop-1-yl]amino}ethoxy substituents at the lower rim

Three stereoisomers (cone, partial cone, and 1,3-alternate) of p-tert-butylthiacalix[4]arene bearing four anchor propyltriethoxysilane substituents at the lower rim were synthesized for the first time. Surface modification of silica nanoparticles (d = 12 nm) with the synthesized macrocycles gave novel hybride thiacalix [4]arene?SiO₂ particles. The obtained nanostructured adsorbents were found to efficiently extract nitroaromatic compounds from aqueous solutions. The partial cone and 1,3-alternate thiacalix[4]arene–SiO₂ hybrid particles showed affinity to nitrophenols.     

Extraction of Cesium-137 and Americium-241 by Calix[n]arenes from Carbonate-Alkaline Media

Trends of cesium-137 and americium-241 extraction from carbonate–alkaline media with p-tert-butylcalix[n]arenes with macrocycles of different size (n = 4, 6, 8), including monofunctional derivatives with lipophilic substituents for increasing their solubility in organic media, were studied. It was demonstrated that O-n-octyl ethers of p-tert-butylcalix[6]arene appeared to be the most efficient extractants for Cs(I) cations, while it was p-tert-butylthiacalix[4]arene for and americium(III) cations.     

Chemoselective acylation of monosubstituted thiacalix[4]arene with di-<Emphasis Type="Italic">tert</Emphasis>-butyl dicarbonate

Mono-, di-, and tetrasubstituted derivatives of p-tert-butylthiacalix[4]arene containing tert-butylcarbamate, tert-butylcarbonate, and tert-butyl fragments have been prepared for the first time. Depending on the reaction conditions (reagents ratio, temperature, and the presence of a base), the interaction of the monoamine derivative of p-tert-butylthiacalix[4]arene with di-tert-butyl dicarbonate can lead to the formation of mono-, di-, and tetrasubstituted products.     

Synergistic extraction of cesium,strontium, and europium with adamantylated thiacalix[4]arenes in the presence of chlorinated cobalt dicarbollide

Synergistic extraction of long-lived fission products ¹³⁷Cs⁺, ⁸⁵Sr²⁺, and ¹⁵²Eu³⁺ from dilute HNO3 into dichloroethane with ligands derived from p-(1-adamantyl)thiacalix[4]arene in mixtures with chlorinated cobalt dicarbollide was studied. An extraordinary synergistic effect is observed in extraction of europium with p-(1-adamantyl)thiacalix[4]arene tetraacetate derivative. Amides of p-(1-adamantyl)thiacalix-[4]arene tetracarboxylic acid are selective toward europium, although their extraction ability toward the examined ions is lower than that of the classical extractant, p-(1-adamantyl)calix[4]arene tetracarboxylic acid diethylamide.     

Asymmetric calix[4]-thiacalix[4]arene tubes: Synthesis and ionophore properties

Asymmetric p-tert-butylcalix[4]-p-R-thiacalix[4]arene tubes (R = tert-Bu, H, 1-adamantyl) were prepared for the first time by reaction of tosyloxyethoxy derivative of p-tert-butylcalix-[4]arene and the corresponding p-R-thiacalix[4]arenas in acetonitrile in the presence of K₂CO₃. Complex formation of compounds obtained with sodium, potassium, and rubidium iodides in CDCl₃-CD₃OD, 4:1, was studied by means of ¹H NMR. The ionophore properties of the molecule were governed by the character of substituents on the upper rim of the thiacalixarene fragment, and only the molecular tube containing a fragment of the p-(1-adamantyl)-thiacalix[4]arene quantitatively bound potassium ions (quickly) and rubidium ions (slowly).     

Quantum chemical study of the self-assembly of tetrathiacalix[4]arenes and their oxygen analogs functionalized by hydrazide groups

The self-assembly of tetrathiacalix[4]arene and tetraoxacalix[4]arene molecules functionalized by hydrazide groups was studied by DFT calculations at B3LYP/6-31G(d,p) level. The calculations were performed for the cone and 1,3-alternate conformations. The associates of calix[4]arenes in the cone conformation are stabilized by multiple hydrogen bonds with inclusion of all hydrazide groups in the formation of the globule, which suppresses the formation of extended structures.     

Synthesis and crystal structures of palladium(II) complexes of bis-(<Emphasis Type="Italic">N</Emphasis>-heterocyclic carbenes) on a calix[4]arene platform

A series of calix[4]arene supported N-heterocyclic carbene palladium complexes were successfully prepared and characterised. Their X-ray crystal structures were obtained and are discussed. Notably, the dimeric compound b[5-(3-N-4,5-diphenylimidazol-2-yliden-1-yl)-25,26,27,28-tetrapropyloxy calix[4]arene] palladium(II) dibromide (cone) showed pseudo-polymorphism.     

Effect of copper(I) on the conformation of the thiacalixarene platform in azide-alkyne cycloaddition

New lower-rim tetrasubstituted p-tert-butylthiacalix[4]arene derivatives bearing alkyl, propargyl, or triazole-containing substituents were synthesized. The structures of these compounds were determined by 1D and 2D NMR spectroscopy in solution and by X-ray diffraction in the solid phase. The copper-catalyzed azide-alkyne cycloaddition (CuAAC) of azides to a mixture of 1,3-alternate–partial cone stereoisomers of dipropargyl derivatives of thiacalix[4]arene affords triazole-containing products exclusively in the 1,3-alternate conformation.     

Comparative macrocycle binding of the anticancer drug phenanthriplatin by cucurbit[<Emphasis Type="Italic">n</Emphasis>]urils, β-cyclodextrin and <Emphasis Type="Italic">para</Emphasis>-sulfonatocalix[4]arene: a <Superscript>1</Superscript>H NMR and molecular modelling study

The potential anticancer drug phenanthriplatin, [cis-(NH₃)₂(phenanthridine)Cl]⁺, forms supramolecular complexes with cucurbit[n]urils (CB[n], n?=?7 or 8), β-cyclodextrin and para-sulfonatocalix[4]arene (sCX[4]) as determined by ¹H NMR spectroscopy and molecular modeling. The results show that cucurbit[7]uril binds over the long arm of the drug, where hydrophobic effects and two hydrogen bonds stabilise binding. For cucurbit[8]uril, two phenanthriplatin molecules can bind simultaneously within the macrocycle’s cavity. Unfortunately, Na⁺ was able to displace the drug from both CB[7] and CB[8] making the macrocycles unsuitable as delivery vehicles for phenanthriplatin. Drug binding to β-cyclodextrin occurs at the portal of the macrocycle with no part of the phenanthriplatin located within the cavity. Phenanthriplatin binding to sCX[4] occurs in a 2-to-1, macrocycle-to-drug, ratio with the formation of a capsule-like complex where each sCX[4] binds over opposing ends of the drug. The results indicate that para-sulfonatocalix[4]arene is the only suitable macrocycle of the four studied for further research into phenanthriplatin drug delivery.     

Synthesis of aminobismethylenephosphonic acids on a platform of <Emphasis Type="Italic">p-tert</Emphasis>-Butylthiacalix[4]arene in 1,3-<Emphasis Type="Italic">alternate</Emphasis> configuration

Aminobismethylenephosphonic acids on a platform of p-tert-butylthiacalix[4]arene were obtained by reacting macrocyclic amines with phosphorous acid and formaldehyde under acid catalysis. Free phenol hydroxy groups on the lower rim of p-tert-butylthiacalix[4]arene were found to inhibit the interaction with the amino moieties of the macrocycle. In the case of amino derivatives of thiacalix[4]arene containing no hydroxy groups the reaction led to the formation of target compounds in good yields.     

XPS,XES, and quantum chemical investigation of the electronic structure of thiacalix[4]arenes and calix[4]arene thioesters

The X-ray photoelectron and X-ray emission spectra as well as the charge state of thiacalix[4]arenes in the cone and 1,3-alternate conformations and calix[4]arene thioesters were studied. The donor ability of sulfur bridging atoms in the studied compounds was shown to be close to that in dialkyl sulfides. The internal X-ray transitions (K _α and K _β) were described by the energy of Kohn-Sham orbitals calculated by DFT method with relaxation corrections.     

Synthesis of Mono- and Tetraalkylamide Derivatives of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butylthiacalix[4]arene

Mono- and tetrasubstituted derivatives of p-tert-butylthiacalix[4]arene containing acrylate and acrylamide fragments are synthesized for the first time. The Michael aza-addition of benzylamine to the synthesized acrylamide and acrylate thiacalixarene derivatives is studied.     

Synthesis of Tetraazide Derivatives of <Emphasis Type="Italic">p-tert</Emphasis>-Butylcalix[4]arene Using Copper-Catalyzed Nucleophilic Aromatic Substitution

Aromatic azido derivatives of p-tert-butylcalix[4]arene have been obtained for the first time using copper-catalyzed nucleophilic aromatic substitution of azide anion for bromide in 5,11,17,23-tetrabromo- 25,26,27,28-tetrabuthoxycalix[4]arene in a dioxane–water (3: 1) solvent mixture with N,N-dimethylethylenediamine as a stabilizing ligand for copper(I). When the reaction is carried out under with microwave heating, partial substitution products (mono-, distally di-, proximally di-, and trisubstituted) can be isolated in satisfactory yields.     

Synthesis of Macrocyclic Stereoisomers Substituted with Oligolactide Fragments

Acylation of cone and 1,3-alternate stereoisomers of hydrazides of p-tert-butylthaicalix[4]arene tetrasubstituted at the lower rim with S,S-lactide in dimethylsulfoxide has afforded the macrocyclic oligolactide derivatives containing 16 (cone) to 24 (1,3-alternate) lactide fragments. It has been shown that nanosized aggregates (80 nm) are formed with silver nitrate in the case of the cone stereoisomer containing the oligolactide fragments at one side of the macrocyclic rim, whereas submicron particles (400 nm) are formed in the case of the 1,3-alternate conformation when the substituents are at different sides of the macrocycle.     

Tetra-<Emphasis Type="Italic">O</Emphasis>-acetyl-tetra-<Emphasis Type="Italic">O</Emphasis>-phosphoryl-tetra-<Emphasis Type="Italic">C</Emphasis>-naphthyl-resorcin[4]arene. Synthesis and receptor properties toward organic amines

Directed modification of rctt-tetra-C-naphthyl resorcin[4]arene afforded a heterofunctionalized derivative containing specifically oriented phosphoryl and acetyl groups, and its ability to form complexes with organic amines was studied. The structure and stereochemistry of the resulting complexes depended on the amine nature.     

Structure of the stereoisomers of tetrasubstituted <Emphasis Type="Italic">p-t</Emphasis>-butylcalix[4]arene containing a morpholine fragment: Data of 1D and 2D (NOESY) NMR spectroscopy

The structure of three isomers of 5,11,17,23-tetra-t-butyl-25,26,27,28-tetrakis[(morpholidocarbonyl) methoxy]-2,8,14,20-tetrathiacalix[4]arene in conformations of partial cone, 1,3-alternant and cone was studied by the methods of 1D and 2D (NOESY) ¹H and ¹³C NMR spectroscopy in conjunction with computational modeling (semiempirical quantum-chemical PM3 calculations). Characteristic cross-peaks for each conformer in the two-dimensional NOESY spectra were established. It is found that unsymmetrical conformation of partial cone is more “flattened” as compared with highly symmetrical 1,3-alternant and cone conformations, while OCH₂C(O)NC₄H₈O substituent is located in the exo-position. Theoretical modeling is found to be more consistent with the experimental data for highly symmetrical conformations.     

Synthesis and structural studies of arene ruthenium and Cp*Rh/Cp*Ir complexes containing pyridylpyrazole- and pyridylthiazole-based ligands

The reactions of [(arene)RuCl₂]₂ (arene = p-cymene or benzene) and [Cp*MCl₂]₂ (M = Rh or Ir) with N,N′-bidentate chelating ligands 2-[3-(2-pyridyl)pyrazolyl]pyrimidine (L1) and 4-phenyl-(2-pyridyl)thiazole (L2) leads to the formation of mononuclear complexes of general formula [(arene)/Cp*M(L)Cl]PF₆. Eight such complexes have been prepared and characterized by spectroscopic techniques. In addition, five of the complexes were also characterized by single-crystal X-ray diffraction. These complexes have typical piano-stool geometries around the metal center, with five-membered metellacycles in which L1 and L2 both act as N,N′-chelating ligands. Moreover, L1 prefers to coordinate through its pyrimidine and pyrazolyl nitrogen atoms, rather than the pyridine nitrogen.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-aryl-3-oxobutanethioamides with 2-amino-1,3-thiazole and 2-amino-1,3-benzothiazole

N-Aryl-3-oxobutanethioamides react with 2-amino-1,3-thiazole (2-amino-1,3-benzothiazole) in acetic acid to give mixtures of 7-methyl-5H-[1,3]thiazolo[3,2-a]pyrimidine-5-thione (2-methyl-4H-pyrimido-[2,1-b][1,3]benzothiazole-4-thione) and 5-arylimino-7-methyl-5H-[1,3]thiazolo[3,2-a]pyrimidines (4-arylimino-2-methyl-4H-pyrimido[2,1-b][1,3]benzothiazoles), whose ratio depends on the nature of the aryl substituent in the initial butanethioamide.     

New functionalization opportunities for <Emphasis Type="Italic">peri</Emphasis>-hydroxynaphthoyl and <Emphasis Type="Italic">peri</Emphasis>-fused heterocyclic compounds

A capability was studied of hydrogenated α-pyrone heterocycle in 7-methoxy-4-(4-methoxy-phenyl)-3,4-dihydro-2H-benzo[h]chromen-2-one to undergo aminolysis under the treatment with hydrazine hydrate, primary and secondary aliphatic and aromatic amines. A new approach was developed to the preparation of perihydroxyketone of naphthalene series containing a specific functional substituent in the ortho-position with respect to hydroxy group. The effect was revealed of an acetyl group in the position 9 of 7-methoxy-4-(4-methoxyphenyl)-3,4-dihydro-2H-benzo[h]chromen-2-one on the reaction of this compound with aliphatic amines and hydrazine hydrate. 9-Methoxy-1-(4-methoxyphenyl)-6-methyl-3H-benzo[de]pyrido[3,2,1-if]cinnolin-3-one [9-methyl-6-methoxy-3-(4-methoxyphenyl)-10,10a-diazapyren-1-one] was obtained, a new bis-peri-fused heteroaromatic system.