Proton-acceptor properties of azahomofullerene and fullerenoaziridine containing a cyanuric acid fragment

¹³C and ¹H NMR and UV spectral studies on 1,3-diallyl-5-[4-(azahomo[60]fullereno)butyl]hexahydro-1,3,5-triazine-2,4,6-trione ([5,6]-open isomer) and 1,3-diallyl-5-[4-(aziridino[60]fullereno)butyl]hexahydro-1,3,5-triazine-2,4,6-trione ([6,6]-closed isomer), as well as quantum-chemical calculations, showed that only the latter possesses weakly basic properties.     

1,3-Diketone Calix[4]arene Derivatives—A New Type of Versatile Ligands for Metal Complexes and Nanoparticles

The present review is aimed at highlighting outlooks for cyclophanic 1,3-diketones as a new type of versatile ligands and building blocks of the nanomaterial for sensing and bioimaging. Thus, the main synthetic routes for achieving the structural diversity of cyclophanic 1,3-diketones are discussed. The structural diversity is demonstrated by variation of both cyclophanic backbones (calix[4]arene, calix[4]resorcinarene and thiacalix[4]arene) and embedding of different substituents onto lower or upper macrocyclic rims. The structural features of the cyclophanic 1,3-diketones are correlated with their ability to form lanthanide complexes exhibiting both lanthanide-centered luminescence and magnetic relaxivity parameters convenient for contrast effect in magnetic resonance imaging (MRI). The revealed structure–property relationships and the applicability of facile one-pot transformation of the complexes to hydrophilic nanoparticles demonstrates the advantages of 1,3-diketone calix[4]arene ligands and their complexes in developing of nanomaterials for sensing and bioimaging.     

Temperature induced phase separation of luminescent silica nanoparticles in Triton X-100 solutions

The aggregation and cloud point behavior of Tb(III)-doped silica nanoparticles has been studied in Triton X-100 (TX-100) solutions at various concentration conditions by fluorimetry, dynamic light scattering, electrophoresis and transmission electron microscopy methods. The temperature responsive behavior of nanoparticles is observed at definite concentration of TX-100, where the aggregation of TX-100 at the silica/water interface is evident from the increased size of the silica nanoparticles. The reversible dehydration of TX-100 aggregates at the silica/water interface should be assumed as the main reason of the temperature induced phase separation of silica nanoparticles. The distribution of nanoparticles between aqueous and surfactant rich phases at the phase separation conditions can be modified by the effect of additives.     

Synthesis and photophysical properties of colloids fabricated by the layer-by-layer polyelectrolyte assembly onto Eu(III) complex as a core

The luminescent colloids have been synthesized through the layer-by-layer assembly of poly(sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) onto the luminescent core. The latter has been obtained by the reprecipitation of complex Eu[(TTA)(3)1] (where TTA(-) and 1 are thenoyltrifluoroacetonate and 2-(5-chlorophenyl-2-hydroxy)-2-phenylethenyl-bis-(2-methoxyphenyl)phosphine oxide, respectively) from organic solvent to aqueous solution. The variation of Eu(III) complexes indicates the role of the complex core in the development of such core-shell colloids. Complex Eu[(TTA)(3)1] is most convenient precursor of Eu-doped luminescent nanocomposites. The fluorometric measurements at each step of the layer-by-layer polyelectrolyte assembly onto Eu[(TTA)(3)1] core, at various pHs and additives reveal the quenching of Eu-centered luminescence as a result of the interfacial interaction of the core and the dye. The AFM images and electrochemical behavior of PSS-(PEI-PSS)(n)-Eu[(TTA)(3)1] colloids deposited on the surface indicate the stability of the polyelectrolyte multilayer in the dried state.     

Photomagnetic effect in molecular magnets based on nitrosyl complexes of ruthenium and rare-earth ions

The magnetic properties of new bifunctional molecular magnets based on nitrosyl complexes of ruthenium and thiacalix[4]arenes of rare-earth ions (Gd³⁺, Dy³⁺) have been investigated. A photoinduced decrease in the magnetization of the molecular magnet with rare-earth ions Gd³⁺ and the absence of a photomagnetic effect in crystals with rare-earth ions Dy³⁺ have been revealed at a temperature of 2 K. It has been found that, in the sample containing Dy³⁺ ions, the magnetization deviates by 6% from the calculated value for noninteracting ions. A comparison of the results obtained for two groups of isostructural samples, which differ only in the type of rare-earth ions, has demonstrated that the observed deviation of the magnetization is caused by the interaction of the orbital moment of the Dy³⁺ ions with the crystal field.     

Electrocatalytic activity of palladium–polypyrrole nanocomposite in the formaldehyde oxidation reaction

Palladium–polypyrrole nanocomposite materials with high electrocatalytic activity toward formaldehyde in an alkaline solution (methylene glycolate) have been synthesized via a one-step redox route. Key factors that have an effect on the sensor properties of palladium nanoparticles have been determined. It has been demonstrated for the first time that the emergence of not only the forward but also the reverse wave of formaldehyde oxidation on palladium particles is associated with the oxidation of methylene glycolate rather than intermediate species.     

Optimization of Catalytic Processes and Reactors

Efficient methods and algorithms have been developed for the optimization of catalytic processes and reactors. In mathematical terms, these problems reduce to finding the extremum of a functional of a large number of variables whose domain of variation is subject to various constraints as sets of partial differential equations and algebraic inequalities. This implies solving problems in which the domain of extremals is closed. Applying Pontryagin's maximum principle to catalytic processes described by sets of differential equations with constrained phase and control variables allows the necessary set of optimal conditions to be found. A numerical algorithm has been developed for solving nonlinear boundary-value problems that arise when the maximum principle is employed. The efficiency of this algorithm is demonstrated by the example of the catalytic oligomerization of α-methylstyrene, a typical process requiring various kinds of optimization problems to be solved. The theoretical optimization of the process has served as the basis for the engineering optimization of an industrial reactor. Optimal controls were determined in both the theoretical and engineering optimization steps.     

pH-Driven Variation of the Outer-Sphere Binding Mode of cis-[Co(Ad)(en)2Cl]Cl (en-Ethylendiamine, Ad-Adeninate) with p-Sulfonatothiacalix[4]arene

The non-symmetrical cobalt (III) complex cis-[Co(Ad)(en)₂Cl]Cl (1Cl), possessing two flexible ethylendiaminate chelate rings (en) and monodentate N(9)-bound adeninate (Ad^-) was chosen as the guest of p-sulfonatothiacalix[4]arene (STCA) to study the inclusion complex formation at wide range of pH 2–10. It was shown by ¹H, NOE NMR methods and pH-metric procedure, that pH-driven variation of the inclusion mode of 1 ⁺ into calixarene cavity is the result of the protonation of 1 ⁺ via adeninate moiety.     

Outer-sphere interactions between octahedral chiral cobalt(iii) complexes and water-soluble calixarenes

The structures and stability of outer-sphere associates of sulfonate derivatives of thiacalix[4]arene and calix[4]resorcinarene with coordinatively saturated cobalt(iii) bis- and tris-chelates ([Co(L-His)₂]⁺, [Co(en)₂ox]⁺, [Co(en)₃]³⁺, and [Co(dipy)₃]³⁺) were compared based on the data from UV, CD, 1D ¹H NMR, and 2D (2D NOESY) ¹H NMR spectroscopy and conductometry. Outer-sphere association is accompanied by partial penetration of the chelate rings of the complexes into the hydrophobic cavity of calixarene, which induces changes in the spectroscopic and spectropolarimetric properties of the cobalt(iii) complexes.