Andriy B. Drapailo

Inhibition of Yersinia protein tyrosine phosphatase by phosphonate derivatives of calixarenes.

Inhibition of Yersinia protein tyrosine phosphatase by calix[4]arene mono-, bis-, and tetrakis(methylenebisphosphonic) acids as well as calix[4]arene and thiacalix[4]arene tetrakis(methylphosphonic) acids have been investigated. The kinetic studies revealed that some compounds in this class are potent competitive inhibitors of Yersinia PTP with inhibition constants in the low micromolar range. The binding modes of macrocyclic phosphonate derivatives in the enzyme active center have been explained using computational docking approach. The results obtained indicate that calix[4]arenes are promising scaffolds for the development of inhibitors of Yersinia PTP.

Unusually high selectivity of guest exchange in tert-butylthiacalix[4]arene clathrate producing more thermostable inclusion and memory of guest.

New properties, earlier unknown for calixarenes, were found for tert-butylthiacalix[4]arene (1) clathrate with 1,2-dichloroethane (DCE). Guest exchange in 1·1.90DCE for vapors of some organic compounds gives clathrates, which are more thermostable at 34-59 °C than those prepared by direct saturation of guest-free 1 with pure guests. Besides, guest exchange may produce clathrates that cannot be formed by direct saturation in binary host-guest systems. Some compounds, like water, toluene, and trichloroethylene, expel DCE from its clathrate with 1 but are not included above the trace level. Residual contents of DCE in clathrate may be controlled by variation of water and 1·1.90DCE ratio in the studied system. Host 1 can remember methanol after its elimination from the guest exchange product. This memory can be read as an exoeffect by differential scanning calorimetry. Only methanol and only after guest exchange is remembered giving an example of a genuine molecular recognition.

Dimeric Capsules Formed by Tetra-CMPO Derivatives of (Thia)Calix[4]arenes

Thiacalix[4]arene 2, calix[4]arene 3a and its tetraether fixed in the cone conformation 3b form homo- and heterodimeric capsules in apolar solvents, which are held together by a seam of NH...O=P hydrogen bonds between carbamoylmethyl phosphine oxide functions attached to their wide rim. Their internal volume of approximately 370 A(3) requires the inclusion of a suitable guest. Although neutral molecules such as adamantane (derivatives) or tetraethylammonium cations form kinetically stable complexes ((1)H- and (31)P-time scale), the included solvent is rapidly exchanged. The internal mobility of the included tetraethylammonium cation is distinctly higher (DeltaG=42.5 and 49.7 kJ mol(-1) for 3a and 3b) than that for similar capsules of tetraurea calix[4]arenes 1. Mixtures of 1 with 2, 3a, or 3b contain only the two homodimers but the heterodimerization occurs with the tetraloop tetraurea 6, which cannot form homodimers. Two dimers with cationic guests (2.(C(5)H(5))(2)Co(+).2 and 3a.Et(3)NH(+).H(2)O.3a) were confirmed by single-crystal X-ray analysis.

Dibutylphosphinoylmethyloxythiacalix[4]arenes. Synthesis, structure, americium, europium and technetium extraction

A series of thiacalix[4]arenes bearing one, two or four chelating dibutylphopshinoylmethoxy groups have been synthesised and studied in the context of this paper. The synthesis consisted of precise Williamson alkylation of thiacalixarene tetrols with tosylate of dibutylhydroxymethyl phosphine oxide in the presence of alkali metal carbonates or sodium hydride. Stereochemical yield of the reaction (cone or 1,3-alternate conformer) depends on the nature of alkali metal. Small-sized ‘hard’ sodium cation organises the macrocyclic platform in the cone conformation, but larger and ‘soft’ potassium and cesium cations stabilise the macrocycle in the 1,3-alternate conformation. All synthesised compounds (except monophosphine monoxide) possess either moderate or high extraction ability towards pertechnetate ion. The cone-shaped thiacalix[4]arene tetraphosphine tetraoxide due to cooperative (macrocyclic) effect of eight oxygen atoms of the phosphinoylmetoxy-binding groups effectively extract spherical americium, europium cations due to cooperative (macrocyclic) effect of eight oxygen atoms of the phosphinoylmetoxy-binding groups. The extraction ability is very similar to that of calix[5]arene pentaphosphine pentaoxide existing in the cone conformation.

Phosphorylated Calixarenes in Design of Receptors for Metal Cations and Organic Molecules

A series of calix[4,6]arenes functionalized with phosphinoxyde, diphosphindioxyde, and carbamoylphosphinoxide groups, which possess high binding ability to metal cations or protodonative organic molecules and are linked to the wide rim of macrocyclic skeleton by different spacers, has been synthesized.

Synthesis and Extractive Properties of Hexaphosphorylated Calix(6)arenes

A series of calix[6]arenes substituted with phosphoryl functional groups were prepared by the Arbuzov reaction of hexakis(chloromethyl)calix[6]arene hexamethyl ether with isopropyl esters of trivalent phosphorus acids, followed by appropriate chemical transformations. Molecular modeling and NMR data show that phosphorylated calix[6]arenes exist in the stereochemically labile 1,2-alternate conformation. The extractive power of these compounds with respect to americium and europium was studied. Due to the cooperative binding of the metal cation with phosphoryl groups, the phosphorylated calixarenes are more effective extractants than their acylcic analogs and commercial organophosphorus extractants.

Extraction of americium and europium with functionalized calixarenes from alkaline solutions

Extraction of 241Am and 152Eu from alkaline carbonate solutions with solutions of functionalized calix[4]arenes and their nonmacrocyclic analogs in m-nitrobenzotrifluoride was studied. The dependence of the distribution ratios and separation factors of the radionuclides on pH of the aqueous phase in the interval from 9.8 to 13.5 and on the position and electronic nature of functional groups (alkyl, pyridine, phosphoryl) in the calixarene core was examined. The composition of the extractable solvates of americium and europium with functionalized calix[4]arenes was determined. From both alkaline and nitric acid solutions, calixarenes extract americium more efficiently than their nonmacrocyclic analogs do. The calix[4]arene with the pyridine functional group exhibits the highest selectivity, with the Am/Eu separation factor exceeding 3. Calix[4]arenebis-(methanediphosphonates) extract europium and americium from both alkaline and nitric acid solutions with similar magnitude of the cooperative effect.

HPLC Study of Phosphorylcalixarene Complexation with Organic Substrates

Abstract Host–guest complexation of the calixarenes as well as thiacalixarenes bearing phosphoryl or sulfonate residues at the upper rim with a series of amino acids, uracils, adenines, and nucleotides (ADP and ATP) in water or water–organic solutions was investigated by high-performance liquid chromatography. Association constants of the 1:1 stoichiometry complexes were calculated from a ratio between the capacity factor of the guests and calixarene concentration in the mobile phase.

Supramolecular Chemistry of Phosphorus-Containing (Thia)Calixarenes

Molecular modeling, synthesis, and structural investigations of the phosphorus-containing (thia)calixarenes and their supramolecular complexes with biorelevant or ecologically hazardous molecules and ions are discussed within the context of cationic and molecular recognition, extraction properties, and bioactivity.

Complexation of thiacalix[4]arene methylphosphonic and sulphonic acids with amino acids

In this paper, host–guest complexation process of thiacalix[4]arene tetrakis–methylphosphonic and tetrakis–sulphonic acids with amino acids by HPLC and molecular modelling methods has been studied. It was shown that thiacalix[4]arene tetrakis–methylphosphonic acid due to transformability of macrocyclic skeleton and flexibility of methylphosphonic substituents can adopt its conformation for strong multicentre binding of the amino acids with association constant values 530–10,140 M− 1 in water.