The Complexation Properties of the Water-Soluble Tetrasulfonatomethylcalix[4]resorcinarene toward α-Aminoacids

The flexible bowl-type water-soluble molecule1, consisting of a resorcinol core and fourconvergent tetrasulfonatomethylene groups, existingas a tetraanion in neutral water solution, was studiedas the host molecule for recognition of-aminoacids. Out of 12 examined guestmolecules only those possessing aromatic hydrophobicmoieties or a long hydrophobic chain with a second ionogenic groupform inclusion complexes with 1. The complex formationwas considered with the help of both ¹H NMRand pH-metric titration in a broad range of pH.The role of host and guest geometric complementarity aswell as additional – and hydrophobic interactionsis discussed. The lack of these interactions inaqueous media provides domination of the guestsolvation by water over the 1 : 1 complexformation with 1.     

Synthesis of Triterpene Derivatives of D-Glucosamine - Modified Analogs of Glycyrrhizic Acid

Triterpene D-glucosamine amides containing 18α- and 18β-glycyrrhetic acid succinates were synthesized.__________Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 7–9, January–February, 2005.     

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.     

Synthesis of per-O-(carboxymethyl)calix[4]pyrogallols and their complexation with some alkaline metal and lanthanide ions

Complexones of a new class, viz., carboxy-functionalized calix[4]pyrrogallols, were synthesized. The per-O-(carboxymethyl)calix[4]pyrogallols obtained were established to exist in the (rel, cis, trans, trans)-configuration by 2D NMR spectroscopic data. According to the pH-potentiometric data, the interaction of these compounds with alkaline metal ions (Li⁺, Na⁺, K⁺, Cs⁺) and lanthanide ions (La³⁺, Gd³⁺, Lu³⁺) in a water—DMSO system produces 1 : 1 complexes. The specific features of complexation of per-O-(carboxymethyl)calix[4]pyrogallols, as compared to their acyclic analogs, with alkaline metal and lanthanide ions are due to the cooperative effect of donor groups preorganized on the calixarene matrix.     

Complex formation of O-carboxymethylcalix[4]resorcinolarene with alkaline metal and ammonium ions

Complex formation of 3,5,10,12,17,19,24,26-octa(carboxymethoxy)-1,8,15,22-tetraundecylcalix[4]arene (H₈X) with Li⁺, Na⁺, K⁺, and NH₄ ⁺ ions was studied by ¹H NMR spectroscopy and pH-metry in water—DMSO solutions. Binding of one cation occurs during the stepped deprotonation of four carboxymethyl groups in H₈X. The K⁺ ion was found to be bound more efficiently than Li⁺ and Na⁺. The further deprotonation to the penta- and hexaanion leads to the coordination with two cations. The most stable binuclear complex is formed with the Li⁺ ion.     

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.     

Synthesis of tris(β-diketones) and study of their complexation with some transition metals

New chelating ligands consisting of three β-diketone fragments, viz., 1,3,5-tris[(acetylaceton-3-yl)methyl]benzene, 1,3,5-tris[(benzoylaceton-3-yl)methyl]benzene, and 1,3,5-tris[(dibenzoylmethan-1-yl)methyl]benzene, linked to each other through the mesitylene spacer were synthesized by the reaction of 1,3,5-tris(bromomethyl)benzene with the corresponding β-diketone sodium salt. The acidity of these compounds and their complexation properties were studied by pH-potentiometry in aqueous-ethanol solutions. Tris(β-diketones) form mononuclear complexes with lanthanide ions, whose stability increases in the series La³⁺ < Gd³⁺ < Lu³⁺. 1,3,5-Tris[(acetylaceton-3-yl)methyl]benzene forms both mononuclear and polynuclear complexes with the Ni²⁺ and Cu²⁺ ions. The stability constants and selectivity of complex formation increase substantially with an increase in the degree of deprotonation of the ligands, thus indicating that all deprotonated chelate groups are involved in coordination with the metal ion. The replacement of the methyl groups by the phenyl substituents in the β-diketone fragments of the molecules affects substantially the composition and stability of the complexes formed. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1926–1933, November, 2006.     

Spectral-luminescence and magnetic relaxation properties of lanthanide—<Emphasis Type="Italic">p</Emphasis>-sulfonatothiacalix[4]arenes in aqueous solution of surfactants

The influence of nonionogenic, anionic and cationic surfactants on the magnetic relaxation and luminescence properties of gadolinium(III), terbium(III), and dysprosium(III) complexes with p-sulfonatothiacalix[4]arene (TCAS) was studied. It was shown that the presence of both neutral and anionic surfactant does not influence the magnetic relaxation properties of GdTCAS as well as on the luminescence intensity of the TbTCAS and DyTCAS complexes. The presence of cationic surfactant at the concentration less than critical micellar concentration led to the formation of associates with stoichiometric composition with the Tb (Dy, Gd) TCAS complexes. These associates are characterized by more intensive luminescence, as compared to the initial TbTCAS and DyTCAS complexes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 555–560, March, 2008.     

Composites Based on Polystyrene Microspheres with Nano-Scaled Titanium Dioxide

This study produced for the first time composites based on polystyrene microspheres with nano-sized titania synthesized by sulfate and sol-gel methods, as well as commercial Hombifine N, Hombikat UV100, and Degussa P25. The starting samples and the composites were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption capacity, and IR spectroscopy. The highest content of nano-titanium dioxide both in the bulk and on the surface of microspheres was obtained with the use of Hombikat UV100. This sample has the largest specific surface area and a high content of reactive OH groups. The adsorption properties of composites were investigated.     

Diverse effect of PEO-PPO-PEO and PPO-PEO-PPO triblock copolymers on temperature responsive behavior of luminescent hard-soft colloids

The present work introduces the interaction of hard and soft colloids in aqueous solutions at various temperatures and concentrations, as well as at critical conditions of temperature induced phase separation. Hard and soft colloids are represented by luminescent silica nanoparticles and aggregates of PEO-PPO-PEO and PPO-PEO-PPO triblock copolymers correspondingly. The formation of the mixed aggregates between hard and soft colloids in equilibrium conditions has been revealed by dynamic light scattering measurements. The distribution of silica nanoparticles between aqueous and surfactant rich phases after phase separation highlights the effect of pH, architecture and concentration of triblock copolymers on the mixed hard-soft colloids aggregation at cloud point conditions. The peculiar aggregation and phase behavior of PPO-PEO-PPO pluronics should be assumed as the main reason of the enhanced mixed aggregation with SNs at increased temperatures and concentrated conditions.