Dehydroabietylamine-based thiazolidin-4-ones and 2-thioxoimidazolidin-4-ones as novel tyrosyl-DNA phosphodiesterase 1 inhibitors

Molecular Diversity - Tyrosyl-DNA phosphodiesterase 1 (TDP1) is a DNA repair enzyme that plays a key role in repairing damage caused by various antitumor drugs. It is a promising target in...     

Amination of 5-Spiro-Substituted 3-Hydroxy-1,5-dihydro-2H-pyrrol-2-ones

The 3-hydroxy-1,5-dihydro-2H-pyrrol-2-one motif is a valuable scaffold in drug discovery. The replacement of the 3-oxy fragment in 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones-based compounds with a 3-amino one (3-amino analogs of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones, 3-amino-1,5-dihydro-2H-pyrrol-2-ones) can play a crucial role in their biological effect. Thus, approaches to 3-amino-1,5-dihydro-2H-pyrrol-2-ones are of significant interest. We developed an approach to 5-spiro-substituted 3-amino-1,5-dihydro-2H-pyrrol-2-ones that could not be obtained using previously reported approaches (reactions of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones with amines). The developed approach is based on the thermal decomposition of 1,3-disubstituted urea derivatives of 5-spiro-substituted 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones, which were prepared via their reaction with carbodiimides.     

Step-By-Step Modeling and Demetallation Experimental Study on the Porous Structure in Zeolites

The organization of microporous space in zeolites is discussed. A new step-by-step model is proposed that explains the principles of organizing the hierarchy of microporous space at the stage of assembling zeolites from elements of minimal size: a primary building unit, secondary building units, tertiary building units or building polyhedra, a sodalite cage, and a supercage. To illustrate the stepwise hierarchical porous structure of nanomaterials, the following zeolites with small and large micropores have been selected as the model objects: sodalite (SOD, the maximum diameter of a sphere that can enter the pores is 0.3 nm) and zeolites of type A (LTA, the maximum diameter of a sphere that can enter the pores is 0.41 nm), type X, Y (FAU, the maximum diameter of a sphere that can enter the pores is 0.75 nm), and type BETA (the maximum diameter of a sphere that can enter the pores is 0.67 nm). Two-dimensional and three-dimensional modeling in 3Ds Max software was used. We believe that such an approach will be useful for developing ways to create complex zeolite compositions for specific applications, such as catalysis, where the geometry of the pores determines the size of the molecules entering the voids and computer modeling can play an important predictive role. This work takes a look at specific aspects of using the heat desorption method to study mesoporous materials with a BETA zeolite as an example and presents the results of experimental research into the characteristics of the porous structure of hierarchically structured zeolite materials (specific surface area 180–380 m²/g, external surface area 120–200 m²/g, micropore volume 0.001–0.1 mL/g).     

Testing of a Laboratory Prototype for Recording Dolphin Signals with an Extended Frequency Band of the Through Path

Acoustical Physics - New technologies for the digital recording of broadband complex signals have made it possible to develop and create laboratory autonomous multichannel equipment to record...     

Effect of the Silicon-Containing Phase on the Hierarchy of the Structure of Epoxy–Silica Nanocomposites

Theoretical and Experimental Chemistry - Structural features of epoxy–silica nanocomposites obtained by cationic polymerization were studied by small-angle X-ray scattering. An increase in...     

The Extended Legendre Transform and Related Variational Principles

Mathematical Notes - Variational principles for functionals on the space C(X) of continuous functions that can be written as a representation of a functional in the form of the Legendre transform...     

Pyridinium bromide as a new mediator for electrochemical transformations involving CH-acids

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ESI-MS Analysis of Thiol-yne Click Reaction in Petroleum Medium

Petroleum contains a large number of heteroatomic compounds, but today, most of them are not efficiently utilized. The constant development of the sustainability concept recalls for rethinking the usage of fossil resources with improved chemical utility. In order to initiate research aimed at involving active petroleum compounds in chemical transformations, a new analytical method for product detection is needed. Here, we study the click reaction of thiols with alkynes, leading to the formation of α-vinyl sulfides directly in the petroleum environment. The reaction was carried out using an (IMes)Pd(acac)Cl catalyst, which demonstrated tolerance to petroleum components. In this study, the concentration of thiols ranged from 1 M to 0.01 M (from 8% to 0.1%). To detect products at low concentrations, a special alkyne labeled with an imidazole moiety was used. This approach made it possible to observe the formation of vinyl sulfides by electrospray ionization mass spectrometry (ESI-MS), which provides an opportunity for further optimization of the reaction conditions and future developments for the direct involvement of oil components in chemical reactions.     

Microstructure of the LaSrCuO<Subscript>4 − δ</Subscript>|Ce<Subscript>0.9</Subscript>Gd<Subscript>0.1</Subscript>O<Subscript>2 − δ</Subscript> interface and its reversibility with respect to oxygen

The conditions of formation of electrode/electrolyte interfaces LaSrCuO_{4 − δ}|Ce_0.9Gd_0.1O_{2 − δ} are optimized. It is shown that electrode layers formed by the screen printing method have better developed surfaces and are more uniform and strong as compared with thick film layers applied by a brush. Symmetric LaSrCuO_{4 − δ}|Ce_0.9Gd_0.1O_{2 − δ}|LaSrCuO_{4 − δ} cells with porous electrodes are studied by impedance spectroscopy and cyclic voltammetry in the temperature range of 773–1173 K at the oxygen partial pressure of (28–2.1) × 10⁴ Pa. The oxygen process is shown to be limited by the charge transfer across the electrode/electrolyte interface. The exchange currents are calculated in the temperature range of 773–1173 K to amount from 1 × 10⁻³ to 3.5 × 10⁻² A/cm², which points to the high reversibility of the electrode/electrolyte interface with respect to oxygen.     

Effects of hydrophobic substituents and salt on core-shell aggregates of hydrophobically modified chitosan: light scattering study

In this study we examine two methods of enhancement of aggregation of hydrophobically modified chitosan in dilute aqueous solutions: by increasing the content of n-dodecyl substituents, favoring hydrophobic association, and by increasing the amount of added low molecular weight salt, screening the electrostatic repulsion between similarly charged aggregating chains. By static and dynamic light scattering it was demonstrated that at the growth of the content of hydrophobic groups in the polymer (2-4 mol %) and of the amount of salt in solution (0.025-0.1 M) the weight fraction of aggregates increases, but the aggregation number remains unchanged. This behavior was attributed to the core-shell structure of the aggregates, which provides a low surface energy and strong attraction of associating groups inside the core. At the same time, the effects of the content of hydrophobic groups in the polymer and the ionic strength of the solution on the radii of the aggregates are quite different. Increasing the content of hydrophobic groups induces growth of the gyration radii of the aggregates, but does not affect their hydrodynamic radii. These data suggest the expansion of the hydrophobic core of the aggregates and the contraction of their highly swollen shell. On the other hand, increasing the salt concentration leads to a decrease of both the gyration and hydrodynamic radii of the aggregates, which is due to partial screening of electrostatic repulsion between similarly charged units and lowering of the osmotic pressure of counterions confined inside the aggregates.