Researches on imidazoles

A number of derivatives of imidazo [5, 1-b] thiazole, imidazo [5, 1-b] thiazoline, and imidazo [5, 1-b] thiazolid-3-one are synthesized by cyclizing 2-alkyl-4(5)-nitro-5(4)-formylmethyl (-ketoalkyl-,-hydroxyethyl-, and carboxymethyl) mercaptoimidazoles.For Part XXVI see [18].     

Modification of epoxy polymers with epoxy thiirane derivative of benzimidazolone-2

An epoxy thiirane derivative of benzimidazolone-2 was synthesized. An addition of epoxy thiirane derivative of denzimidazolone-2 to epoxy rubber and epoxy composites was shown to increase their thermal stability, elasticity modulus, and cohesion and adhesion strengths, especially at higher test temperatures. The effect depends on the concentration of additive, hardening temperature, type of rubber, and other factors.     

A new torsion-rotation fitting program for molecules with a sixfold barrier: Application to the microwave spectrum of toluene

A new program is described for fitting rotation-torsion energy levels in molecules like toluene, in which the frame (C₆H₅) has C_2v symmetry and the methyl top has C_3v symmetry, i.e., for molecules where the internal rotation barrier is expanded in cos6nα, where α is the internal rotation angle and n = 1,2,…. The program is based on the theoretical framework developed by Sørensen and Pedersen in their application of the Longuet-Higgins permutation-inversion group G₁₂ to the microwave spectrum of CH₃NO₂. It is specifically designed for sixfold barrier molecules, and allows the user to select almost any symmetry-allowed torsion-rotation term for inclusion in the fitting Hamiltonian. This program leads to a very successful fit of transitions in the microwave spectrum of toluene characterized by J ? 30, K_a ? 12, and by the free-rotor quantum number ∣m∣ ? 3. In these fits we included both published and rather extensive unpublished new measurements, for which fits using other torsion-rotation programs have not been very successful. The fit presented here uses 28 parameters to give an overall standard deviation of 7.4 kHz for 372 line frequencies, and results in a much improved value for the sixfold barrier for toluene, V₆ = 13.832068(3) cal mol⁻¹.     

Properties of epoxy polymers cured with polyoxypropylene diamine

The results of investigations of epoxy polymers cured with polyoxypropylene diamine D-230 depending on the molecular weight of epoxide oligomer, the content of the curing agent, active diluents, and plasticizers are presented. It is shown that epoxy polymers cured with polyoxypropylene diamine are characterized by a rather high complex of physicomechanical and adhesion properties.     

Adjustment of properties of epoxide compositions cured with polyoxypropylene triamine

The effect of the temperature for mixing epoxy-diane resin ED-20 with a curing agent, specifically polyoxypropylene triamine, the ratio of the components, and the introduction of diluting agents and fillers on the strength properties and water absorption of cured compositions is investigated. It was shown that, by using these methods, one can affect the parameters of characteristics of epoxide compositions.     

Four-Step Spin Crossover in a New Cyano-Bridged Iron-Silver Coordination Polymer

Spin-crossover complexes with multistep transitions attract much attention due to their potential applications as multi-switches and for data storage. A four-step spin crossover is observed in the new iron(II)-based cyanometallic guest-free framework compound Fe(2-ethoxypyrazine)₂{Ag(CN)₂}₂ during the transition from the low-spin to the high-spin state. A reverse process occurs in three steps. Crystallographic studies reveal an associated stepwise evolution of the crystal structures. Multiple transitions in the reported complex originate from distinct Fe^II sites which exist due to the packing of the ligand with a bulky substituent.     

Screening of Synthetic Cathinones by Potentiometric Sensor Array and Chemometrics

This work demonstrates the analytical applicability of single ion-selective membranes (ISMs) and potentiometric sensor array to distinguish and detect cathinone derivatives. Potentiometric data from ISMs based on cation exchanger and varying content of calix[4]arene derivative were processed by principal component analysis (PCA). Such a combination of methods allowed discriminating various individual synthetic cathinones and their recognition from the mixture comprising primary amines (substituted amphetamines+aminoindane). Analytical parameters of ISM containing 1wt % of calix[4]arene derivative were sufficient to detect 1.0×10⁻⁴ mol.l⁻¹ 1-(4-fluorophenyl)-2-(ethylamino)butan-1-one and 2-(methylamino)-1-phenylbutan-1-one (buphedrone) in both model and saliva samples.     

The Effect of Growth Parameters on Electrophysical and Memristive Properties of Vanadium Oxide Thin Films

We have experimentally studied the influence of pulsed laser deposition parameters on the morphological and electrophysical parameters of vanadium oxide films. It is shown that an increase in the number of laser pulses from 10,000 to 60,000 and an oxygen pressure from 3 × 10⁻⁴ Torr to 3 × 10⁻² Torr makes it possible to form vanadium oxide films with a thickness from 22.3 ± 4.4 nm to 131.7 ± 14.4 nm, a surface roughness from 7.8 ± 1.1 nm to 37.1 ± 11.2 nm, electron concentration from (0.32 ± 0.07) × 10¹⁷ cm⁻³ to (42.64 ± 4.46) × 10¹⁷ cm⁻³, electron mobility from 0.25 ± 0.03 cm²/(V·s) to 7.12 ± 1.32 cm²/(V·s), and resistivity from 6.32 ± 2.21 Ω·cm to 723.74 ± 89.21 Ω·cm. The regimes at which vanadium oxide films with a thickness of 22.3 ± 4.4 nm, a roughness of 7.8 ± 1.1 nm, and a resistivity of 6.32 ± 2.21 Ω·cm are obtained for their potential use in the fabrication of ReRAM neuromorphic systems. It is shown that a 22.3 ± 4.4 nm thick vanadium oxide film has the bipolar effect of resistive switching. The resistance in the high state was (89.42 ± 32.37) × 10⁶ Ω, the resistance in the low state was equal to (6.34 ± 2.34) × 10³ Ω, and the ratio R_HRS/R_LRS was about 14,104. The results can be used in the manufacture of a new generation of micro- and nanoelectronics elements to create ReRAM of neuromorphic systems based on vanadium oxide thin films.     

Exploring the Interplay between Drug Release and Targeting of Lipid-Like Polymer Nanoparticles Loaded with Doxorubicin

Targeted delivery of doxorubicin still poses a challenge with regards to the quantities reaching the target site as well as the specificity of the uptake. In the present approach, two colloidal nanocarrier systems, NanoCore-6.4 and NanoCore-7.4, loaded with doxorubicin and characterized by different drug release behaviors were evaluated in vitro and in vivo. The nanoparticles utilize a specific surface design to modulate the lipid corona by attracting blood-borne apolipoproteins involved in the endogenous transport of chylomicrons across the blood–brain barrier. When applying this strategy, the fine balance between drug release and carrier accumulation is responsible for targeted delivery. Drug release experiments in an aqueous medium resulted in a difference in drug release of approximately 20%, while a 10% difference was found in human serum. This difference affected the partitioning of doxorubicin in human blood and was reflected by the outcome of the pharmacokinetic study in rats. For the fast-releasing formulation NanoCore-6.4, the AUC_0→1h was significantly lower (2999.1 ng × h/mL) than the one of NanoCore-7.4 (3589.5 ng × h/mL). A compartmental analysis using the physiologically-based nanocarrier biopharmaceutics model indicated a significant difference in the release behavior and targeting capability. A fraction of approximately 7.310–7.615% of NanoCore-7.4 was available for drug targeting, while for NanoCore-6.4 only 5.740–6.057% of the injected doxorubicin was accumulated. Although the targeting capabilities indicate bioequivalent behavior, they provide evidence for the quality-by-design approach followed in formulation development.