Oxyethylene Chain Research Articles

Low-Foaming Nonionic Gemini Surfactants Containing Hydrophilic Poly(oxyethylene) Chain and Hydrophobic Di-tert-pentylbenzenes Groups.

Low-foaming nonionic gemini surfactants have a wide range of applications in industrial cleaning and photoresist development. In this study, three low-foaming nonionic gemini surfactants (S1, S2, and S3) with different poly(oxyethylene) chain lengths have been synthesized by using methoxy poly(ethylene glycol) and 2,5-di-tert-pentylhydroquinone. The chemical structures of the novel surfactants are confirmed by 1H NMR, Fourier transform infrared, and gel permeation chromatography (GPC), and their properties such as surface tension, wetting properties, emulsifying properties, and foaming properties are investigated. The surface tension values of S1, S2, and S3 at the critical micelle concentration are 40.29, 37.14, and 41.64 mN/m, exhibiting good surface activity. When the surfactant concentration is higher than 2 mM, the contact angles of S1 and S2 no longer change and can maintain 62 and 64°, showing good wetting properties. In addition, S3 can keep an emulsion state for 2 months at high concentrations, exhibiting good emulsion stability. Furthermore, all the prepared surfactants show good low-foaming properties. The initial foaming volumes of S1 are very low, less than 0.1 mL at various concentrations, less than 2% of the conventional surfactant sodium dodecyl sulfate. For S2, the initial foaming volumes at the concentration of 0.1, 1, 2, and 3 g/L are 1, 0.5, 0.55, and 0.45 mL, respectively. For S3, the initial foaming volumes show a general trend of increasing with concentration. The surfactants with longer poly(oxyethylene) chains possess more initial foaming volumes at the same concentration, which is because the greater cohesion between the surfactant molecules can increase the elasticity of the bubble film. Our study enriches the design rationales for low-foaming surfactants and motivates researchers to develop more advanced surfactants for industrial cleaning and photoresist development.

Ratiometric Fluorescence Depending on In/Out Isomerism of Host‐Guest Conjugate Having a Fluorosolvatochromic Dye

Host‐guest conjugate is a promising strategy for providing outstanding molecules. Herein, we designed host‐guest conjugate HG1, which comprises a hydrophilic host unit, tetraaza[2.2.1.2.2.1]paracyclophane CPX2with a microhydrophobic cavity, and a guest unit, 2,3‐naphthalimide fused with two benzothiophenes G1 exhibiting fluorosolvatochromism, linked with an oxyethylene chain. HG1 initially showed a fluorescence band at 585 nm in MeOH/H2O (1/499 v/v); however, this band decreased with time, and instead, a new band at 430 nm appeared. The CIE chromaticity diagram showed that the fluorescent color changed from yellow‐orange to blue via white. NMR analysis of HG1 in methanol‐d4 exhibited different signals of the G1 unit between the blue and yellow fluorescent structures. The blue fluorescent structures showed asymmetrical signals assigned as the G1 unit, affected by the cavity environment of the CPX2 unit. Consequently, HG1 can form two conformations: In‐form and Out‐form. In In‐form, the G1 unit is inside the hydrophobic cavity of the CPX2 unit and shows blue fluorescence. In Out‐form, the G1 unit is outside the CPX2 unit and shows yellow fluorescence in an aqueous solvent. Therefore, HG1 performs as a ratiometric fluorophore depending on the in/out isomerism of the host‐guest conjugate.

Tailoring Rhodamine Probes: Oxyethylene Chains, Conjugation, and End Substituents in the Quest for Superior Hg2+ Sensing

AbstractThis study explores the impact of incorporating oxyethylene (OE) chains into rhodamine‐based dye molecules for the enhancement of photophysical properties in the context of chemical sensing. The introduction of OE chains provides several advantages, including improved water solubility, photostability and resistance to self‐assembled nanoaggregates formation. Despite these, the compound with oxyethylene chains showed poor response (~2‐fold) towards Hg2+ ions than that of dimeric probe (~20 fold) with no such substituents. Notably, dimeric compound shows a remarkable three‐fold larger response to Hg2+ ion compared to monomeric compound. This intriguing outcome is attributed to the extended conjugation within the dimeric structure, which can induce conformational change of the overall molecule. Moreover, the study investigates the effects of end substituents, such as electron‐donating (−OMe, improved response) and electron‐withdrawing (−NO2, poor response) groups, on the interaction with Hg2+ ions. The excellent sensitivity of the probe molecules is also evident in significantly low detection limits for Hg2+ ion (5–8 ppb) in real‐life water samples. The high recovery values (>95 %) with sufficient low standard deviation (<5%) indicates that quantitative analysis of Hg2+ is achievable using the current protocol. Beyond that, we have employed the probe 1 for intracellular (HEK293T cells) fluorescence imaging of Hg2+.

Cyclodextrin‐Based Catenanes Platformed with meso‐Arylporphyrin

AbstractAmong mechanically interlocked supramolecular systems with cyclodextrins (CDs), successful examples of CD‐based catenanes are limited compared to a number of CD rotaxanes owing to the synthetic difficulties. We herein demonstrate an efficient synthesis of a CD‐based catenane using a meso‐arylporphyrin (Por) platform. Using Por modified with two olefin‐terminated oxyethylene chains at the cis‐meso‐positions, an interlocked Por‐CD catenane was synthesized via olefin metathesis in the presence of per‐O‐methylated β‐CD (TMe‐β‐CD) in water. The novel Por‐CD catenane was obtained in 30 % isolated yield, which was characterized by MALDI‐TOF mass and NMR spectroscopies. In the latter part, we demonstrate determination of the binding constants between TMe‐β‐CD and meso‐(4‐sulfonatophenyl)porphyrin using Por‐CD catenane, 2,6‐di‐O‐methyl‐β‐CD (DMe‐β‐CD), and 13C‐labeled TMe‐β‐CD (13C‐TMe‐β‐CD). The host‐guest exchange reaction from the Por‐CD catenane/DMe‐β‐CD to the Por‐CD catenane/TMe‐β‐CD complexes was directly monitored through 1D HMQC spectroscopy. The ratio of these complexes revealed the difference in the binding affinities of DMe‐β‐CD and TMe‐β‐CD to Por. The stable 1 : 2 inclusion complex between meso‐tetrakis(4‐sulfonatophenyl)porphyrin (TPPS) and TMe‐β‐CD has been well‐studied for many years. This study is the first to determine the respective binding constants, K1 and K2, using the model system, to be 3.0×107 M−1 and 3.4×107 M−1, respectively.

Aggregation Behavior of Ethoxylated Phytosterol Surfactants in Different Protic Solvents: An Insight from Dielectric Relaxation Studies.

The micellar aggregation behavior of biocompatible surfactants, phytosterol ethoxylates (BPS-n, n is the oxyethylene (EO) chain length), containing polyoxyethylene chains in four organic solvents (glycerol (G), ethylene glycol (EG), formamide (FA), and N,N-dimethylformamide (DMF)) was studied by dielectric spectroscopy in the frequency range of 40 Hz to 110 MHz. Only the BPS-n/EG and BPS-n/G systems show distinct dielectric loss peaks near 104 Hz, indicating that BPS-n forms micellar aggregates in EG and G solvents, and the interfacial polarization (IP) between the aggregates and solvents leads to this relaxation. The dielectric spectra were analyzed based on the IP theory and a columnar dispersion model. The dielectric parameters of micelles, the permittivity and conductivity of micelles and solvents, and the volume fraction of the aggregates in solvents were calculated. On this basis, the binding numbers of each EO group on the hydrophobic chain to the solvent molecules EG and G were calculated to be 0.42 and 0.22, respectively. It was suggested that the aggregation appears to be related to the magnitude of the hydrogen bonding interactions. The lower number of EO group-binding solvents is because of the strong steric effect of alcohol solvents and the magnitude of the hydrogen bonding force.

Reentrant 2D Nanostructured Liquid Crystals by Competition between Molecular Packing and Conformation: Potential Design for Multistep Switching of Ionic Conductivity.

Reentrant phenomena in soft matter and biosystems have attracted considerable attention because their properties are closely related to high functionality. Here, we report a combined experimental and computational study on the self-assembly and reentrant behavior of a single-component thermotropic smectic liquid crystal toward the realization of dynamically functional materials. We have designed and synthesized a mesogenic molecule consisting of an alicyclic trans,trans-bicyclohexyl mesogen and a polar cyclic carbonate group connected by a flexible tetra(oxyethylene) spacer. The molecule exhibits an unprecedented sequence of layered smectic phases, in the order: smectic A-smectic B-reentrant smectic A. Electron density profiles and large-scale molecular dynamics simulations indicate that competition between the stacking of bicyclohexyl mesogens and the conformational flexibility of tetra(oxyethylene) chains induces this unusual reentrant behavior. Ion-conductive reentrant liquid-crystalline materials have been developed, which undergo the multistep conductivity changes in response to temperature. The reentrant liquid crystals have potential as new mesogenic materials exhibiting switching functions.

Syntheses and properties of amphiphilic zinc(II), nickel(II), and palladium(II) phthalocyanines with eight tri(oxyethylene) chains introduced at non-peripheral α positions

Amphiphilic zinc(II) (1), nickel(II) (2), and palladium(II) (3) complexes of 1,4,8,11,15,18,22,25-octakis(1,4,7,10-tetraoxaundecyl)phthalocyanine were synthesized and characterized by elemental analysis and MALDI-TOF mass and 1H NMR spectroscopies. Electronic absorption spectra showed aggregation of the phthalocyanine molecules in [Formula: see text]O for 2 and 3, while the monomeric form for 1 in [Formula: see text]O, and 1, 2, and 3 in [Formula: see text]. The cyclic voltammograms of 1, 2, and 3 in [Formula: see text] showed that oxidation of the phthalocyanine ring occurs easily in these complexes. This may be due to the energetically increased HOMO, coming from the deformation of the phthalocyanine ring. Steric hindrance between the [Formula: see text]-introduced 1,4,7,10-tetraoxaundecyl groups (tri(oxyethylene) chains) within the phthalocyanine molecule gives rise to the deformation of the phthalocyanine ring, which decreases the aggregating nature of the present complexes.

Electrically and Thermally Controllable Visible‐to‐Near‐Infrared Light Trapping Smart Window with Tunable Optical States

AbstractIn this work, active viologen anchored on poly(2‐isopropyl‐2‐oxazoline) (PiPO) segments spaced with triazole‐bearing oxyethylene chain (POEm‐PiPO‐HPV) molecule is discovered to be an effective single‐component dual‐band chromic material. Unlike most reported materials of this type, POEm‐PiPO‐HPV not only is electrochromic but thermochromic as well, showing optical switching from clear to hazy at ≈55–59 °C as a result of phase transformation when triggered by heat attaining >60% optical contrast (ΔT) both in the visible and near infrared (NIR) range. Likewise, >75% ΔT is achieved when switched from clear state to colored state at an applied potential (≈0.45–2.9 V). Each distinct mode of chromism uniquely and autonomously modulates visible and NIR light. Multiple color states—hazy, burgundy, brown, dark purple, and royal blue—are also displayed when the spacer length is modified and when the counteranions undergo metathesis. A coloration speed of 25 s resulting in purple color and a bleaching speed of 11 s are attained by PiPO with hepta‐oxyethylene chain and hexafluorophosphate anion (POE7‐PiPO‐HPV‐PF6) with a coloration efficiency of 295.0 cm2 C−1 and cyclic stability of >200 cycles.

Non-ionic surfactants-mediated green extraction of polyphenols from red grape pomace

Around 80% of grape production is towards winemaking, generating large amounts of polyphenol-rich waste. Conventional techniques, commonly employed in polyphenols extraction from grape pomace, are often environmentally unfriendly or time and energy-consuming. Green surfactant-based extraction of polyphenols has not been thoroughly investigated for the utilization of red grape pomace. This study aimed at investigating the potential of eleven non-ionic surfactants belonging to poloxamer, Brij, Triton, and Tween subgroups. Aqueous solutions of surfactants in different concentrations and variable solvent-to-material ratios were investigated. The extraction efficiency was evaluated through quantification of individual phenolic compounds, total phenolic content, and antioxidant activity. Generally, surfactants with longer oxyethylene chains provided greater efficiency (Brij S20 and poloxamer 407). It has been shown that surfactants' chemical structure affects the solubilization mechanism of polyphenols. Extraction rate depended on concentration and solvent-to-material ratio, as well. The dominant phenolic compounds in extracts were quercetin and catechin. Investigated non-ionic surfactants aqueous solutions have been shown as effective mediums suitable for low-cost and straightforward extraction of polyphenols and for obtaining extracts with a favorable phenolic profile.

Effect of temperature and salinity on interfacial behavior of alkyl ether carboxylate surfactants

This work investigates the interfacial behavior of alkyl ether carboxylate (AEC) surfactants in examples of sodium laureth-11 carboxylate and sodium trideceth-7 carboxylate. AECs have two hydrophilic groups and demonstrate both anionic and nonionic properties, displaying stability under harsh reservoir conditions during surfactant flooding. The interfacial tension measurements were conducted with a spinning drop tensiometer; n-decane, and oil were used as the hydrocarbon phase. The influence of surfactant concentration, temperature (25 °C and 70 °C), and various ions (Na+, Ca2+, Mg2+, Cl−, SO4 −, and HCO3 −) were evaluated. It was found that the temperature increase has no significant effect on critical micelle concentration (CMC) for both surfactants but influences interfacial tension values in pre-CMC and post-CMC regions. According to data obtained, the temperature rise has a stronger impact on a surfactant with a longer oxyethylene chain sodium laureth-11 carboxylate. In contrast, brine salinity has a more substantial effect on sodium trideceth-7 carboxylate interfacial behavior.

Conductivity of polymer films formed by PEO-containing intramolecular polycomplexes

Block copolymers comprising chemically complementary poly(ethylene oxide)/polyacrylamide have been evaluated as proton conducting materials. With this aim in mind, two series of block copolymers PAAm-b-PEO (DBC) and PAAm-b-PEO-b-PAAm (TBC) with the variable PEO-block length have been synthesized. Polymer electrolyte membranes (PEM) based on DBCs, TBCs and also their partially hydrolyzed derivatives (DBChydr and TBChydr respectively) were prepared by using a solution casting technique, and their ion (proton) conductivity was studied at the ambient temperature and at different relative humidity (RH). The rise in RH from 33% to 98% resulted in the increase in conductivity of DBC and TBC membranes up to 10−4 S∙cm−1. The study of the kinetics of the water absorption at 98% RH showed that the introduction of –COOH-groups into PAAm chains could accelerate the process of water absorption. The increase in conductivity of DBC and TBC membranes with the PEO-block lengthening has been noticed. This proved the significant contribution of oxyethylene chains in ensuring the conductivity. The reason for the application of DBCs and TBCs as potantial ion-conducting membranes have been discussed.

Enhanced salt thickening effect of the aqueous solution of peaked-distribution alcohol ether sulfates (AES)

Alcohol Ether Sulfates (AES) are emerging as a potent category of surfactant in consumer product industry owing to their much better hard water resistance, foaming/wetting ability, and less irritating than alkyl sulfate. These excellent performances are attributed to the presence of oxyethylene (EO) chain between the hydrophilic and the hydrophobic portions which endows AES the combined advantages of both nonionic and anionic surfactants. Most strikingly, addition of NaCl would considerably enhance the viscosity of the aqueous solution of AES, which is very important for a better retention of the surfactant to the interacting substrate. Recent study shows that the number distribution of EO groups considerably affects this salt-thickening performance, yet its mechanism is not clear. We report in this work that the narrower number distribution of the EO groups in the AES chains would generate an order alignment of the stretched EO chains, which can then bind with Na+ efficiently to form supramolecular crown ethers. In contrast, as the EO numbers are polydispersed, it is hard for them to align orderly, resulting in poor supramolecular crown ether formation ability with Na+. As a result, the wormlike micelles formed in the AES with narrower EO number distribution has much pronounced salt-thickening effect. This finding may help people in relating fields to create products with desired performance.

Effect of Oxyethylene Groups of Fatty Alcohol Polyoxyethylene Ether Sodium Sulfates on Equilibrium and Dynamic Surface Tension in Relation to Wetting Properties

Abstract The effect of hydrophilic chain of surfactants fatty alcohol polyoxyethylene ether sodium sulphates (AEnS, n = 2, 3, 7) on surface properties and wetting properties was investigated by the measurement of equilibrium surface tension, dynamic surface tension and dynamic contact angle. The fatty alcohol polyoxyethylene ether sodium sulphates with different head group sizes were used. From the results of equilibrium surface tension measurements, we could obtain the critical micellisation concentration, adsorption efficiency, maximum surface excess concentration and Langmuir equilibrium adsorption constant at air/liquid interface. The dynamic surface tension results showed that the adsorption of aqueous solutions at the air/liquid interface follows a mixed-diffusion kinetic adsorption mechanism. In conclusion, for both studied surfactant, the longer the oxyethylene chains, the higher the maximum rate of surface tension reduction, the higher the diffusivity and wetting properties in terms of contact angle.

Injectable and In Situ Gelling Dextran Derivatives Containing Hydrolyzable Groups for the Delivery of Large Molecules.

Recently, we reported the synthesis and characterization of a new dextran derivative obtained by grafting polyethylene glycol methacrylate to a polysaccharide backbone through a carbonate bond. This moiety was introduced because it allows for the fabrication, through a photo-induced crosslinking reaction, of biodegradable hydrogels particularly suitable for the release of high molecular weight molecules. Here, we investigate the influence of the oxyethylene chain length and the molecular weight of the starting dextran on the main properties of the polymeric solutions as well as those of the corresponding hydrogels. All synthesized polymeric derivatives were characterized by FTIR, NMR, and rheological analyses. The photo-crosslinking reaction of the polymers allowed us to obtain biodegradable networks tested for their mechanical properties, swelling, and degradation behavior. The results showed that both the oxyethylene chain length as well as the molecular weight of the starting dextran influenced swelling and degradation of the hydrogel network. As a consequence, the different behaviors in terms of swelling and degradability were able to affect the release of a large model molecule over time, making these matrices suitable candidates for the delivery of high molecular weight drug substances.

Nonionic surfactant stabilized polytetrafluoroethylene dispersion: Effect of molecular structure and topology

Polytetrafluoroethylene (PTFE) is a kind of fluoropolymer with many critical applications. Nonionic surfactant stabilized concentrated PTFE aqueous dispersions are widely used to prepare corresponding products via dipping, spraying, spinning, or film casting, as these surfactants exert a negligible effect on the properties of the products. Although many nonionic surfactants have been used to stabilize PTFE dispersions in industry, the effects of molecular structure and topology are not well-documented; thus, currently, there is no basis for selecting or designing suitable novel surfactants to enhance dispersion stability. In this work, five nonionic surfactants with different topological structures including Tween 20, Tween 60, Tween 80, Brij L23, and Brij O20, were used to prepare concentrated PTFE dispersions. The variation of particle morphology before and after concentration was examined by scanning electron microscopy, and the static stability of the dispersions was quantitatively and objectively characterized using a Turbiscan analyzer based on multiple light scattering. Then the effect of surfactant molecular structure and topology on dispersion stability was discussed. We found that, after the enrichment process, the PTFE microspheres were tightly packed, and some were deformed. Brij surfactants which bears a linear hydrophilic oxyethylene (EO) chain can form a thicker hydration layer on the surface of PTFE particles than those of Tween surfactants which contains a branched hydrophilic EO chain. Accordingly, PTFE dispersions with Brij surfactants show better static stability. Moreover, in comparison with the saturated hydrophobic tail, the unsaturated hydrophobic chain is more flexible, so it can adhere to the surface of PTFE particles better, improving the stability. In addition, the increase of surfactant concentration contributes to the increase of micelles density and viscosity of the bulk dispersion, which can also enhance the stability. These findings are beneficial to design or choose suitable surfactants for high stability and high-quality concentrated PTFE dispersions.

Argentivorous Molecules with Oxyethylene Chains in Side-Arms: Silver Ion-Induced Selectivity Changes toward Alkali Metal Ions

Argentivorous molecules with mono, di, tri, tetra, and penta-oxyethylene chains in aromatic side-arms were prepared (L1-L5). Titration experiments using proton nuclear magnetic resonance and cold electrospray ionization (cold-spray ionization, CSI) mass spectrometry showed that silver ions were trapped in the cyclen moiety and the arranged oxyethylene chains of the side-arms when two equivalents of silver ions were added. The silver complexes formed by adding one equivalent of silver ion to L2-L5 bind alkali metal ions using the oxyethylene chains; alkali metal ion-induced CSI mass spectral changes of L2-L5 were measured in the absence and presence of silver ions to compare the binding properties of the ligand for Li+, Na+, and K+ ions. As a result, the intensity ratios of [L + H + M]2+/[L + H]+ in L1-L3 were almost zero or very low. L4 and L5, which have tetra(oxyethylene) and penta(oxyethylene) chains, respectively, bind a larger size of alkali metal ions. On the other hand, in the presence of silver ions, the ratio for [L + Ag + M]2+/[L + H]+ (M = Li, Na, K) in L2-L5 was increased. The highest [L + Ag + M]2+/[L + H]+ ratios for K+ were observed in L4 and L5, while selectivity for Na+ was observed in the case of L2 and L3. These results indicate that the increased binding ability and selectivity by L2-L5 are due to the arrangement of oxyethylene chains by the conformational change of the aromatic side-arms. The Ag+-induced carbon-13 nuclear magnetic resonance spectral changes suggested that the second and third oxyethylene units, close to the benzene, are involved in the coordination of the second metal ion.

Molecular dynamics simulation study of the effect of a strong electric field on the structure of a poly(oxyethylene) chain in explicit solvents

Molecular dynamics simulations are carried out to investigate the structure of a single poly(oxyethylene) (POE) chain in aqueous and methanolic solutions in a strong external electric field. The conformational changes of the polymer chain induced by the strong external electric field are monitored by measuring the radius of gyration, the components of the gyration tensor, the end-to-end distance, dihedral angle distribution, and the helical content. The isotropic coil size measures, i.e., the radius of gyration and the end-to-end distance mostly decrease with growing intensity of the electric field except a small increase occurring between 0 and 1 V/nm in water. Therefore, in most cases the field compresses the polymer coil. Nevertheless, the deformation is anisotropic, leading to an average spheroid which is prolate in water (again with the exception of fields less or equal to 1 V/nm) and oblate in methanol. Analysis of dihedrals suggests that POE chain’s partially helical structure is promoted at electric fields above 1 V/nm. Changes caused by the strong external electric field in the solvent–solvent and solvent–polymer hydrogen-bonding structure are monitored by measuring the number of hydrogen bonds, their strength, and the volume of the bonding region. Results show non-trivial, solvent-specific effects, which are yet to be fully understood.

Design and synthesis of novel electroactive 2,2′:5′,2″-terthiophene monomers including oxyethylene chains for solid-state flexible energy storage applications

Here, we present the synthesis of novel poly(2,2′:5′,2″-terthiophene) derivatives containing oxyethylene pendant groups for the fabrication of high performance flexible redox-active electrode materials. The poly(3′,4′-bis(2-methoxyethoxy)-2,2′:5′,2″-terthiophene) (PSEDEN1), poly(3′,4′-bis(2-(2-methoxyethoxy)ethoxy)-2,2′:5′,2″-terthiophene) (PSEDEN2) and poly(3′,4′-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2′:5′,2″-terthiophene) (PSEDEN3) have been electrochemically polymerized on flexible stainless steel substrates without any binder and directly employed as redox-active materials. The effect of pendant group chain length on morphological characteristics of conducting polymer films have been systematically evaluated and correlated to the charge storage properties of redox-active electrode materials. Capacitive performance tests reveal that PSEDEN1, PSEDEN2 and PSEDEN3 could reach up to specific capacitances of 135 F g−1, 212.8 F g−1 and 403.3 F g−1, respectively, at constant current density of 2.5 mA cm−2 in the potential range of 0.4–1.8 V with good rate capability performances. In addition, symmetrical flexible solid-state supercapacitor devices based on polymer gel electrolyte have also been assembled using PSEDEN1, PSEDEN2 and PSEDEN3 coated flexible stainless steel substrates and tested by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy techniques in detail. Fabricated devices (Cell 1, Cell 2 and Cell 3) have delivered maximum specific capacitances of Cspec= 29.3 F g−1, 92.1 F g−1 and 162.4 F g−1, energy densities of SE= 6.35 W h kg−1, 22.9 W h kg−1 and 41.1 W h kg−1 and power densities of SP= 929 W kg−1, 937.7 W kg−1 and 986.4 W kg−1 at a current density of 2.5 mA cm−2 in two-electrode cell configuration. Furthermore, flexible supercapacitor devices have achieved high cycle life performances with good capacitance retention values of 80.2%, 84.7% and 91.4% over 10 000 consecutive galvanic charge/discharge cycles at 2.5 mA cm−2 constant current density from 0.4 to 1.8 V. Similarly, excellent mechanical stabilities have also been observed with 3.4%, 4.66% and 1.97% capacitance losses under various bending conditions from 0° to 170° for all flexible supercapacitor devices. These results confirm that PSEDEN1, PSEDEN2 and PSEDEN3 redox-active materials with gratifying capacitive performances and excellent flexibilities have a great potential for utilization in innovative flexible or wearable energy storage solutions.Keywords

Атомная дипольная поляризация в прогнозах химических сдвигов амидных и пирролидиновых протонов

A quantitative relationship has been established between the localization indices of electrons in atomic basins and chemical shifts of protons in amide and pyrrolidine fragments when they are present together in organic molecules. The fragments under consideration are important as key functional groups in the molecules of chiral inducers involved in stereoselective syntheses, in order to obtain drugs based on pyrimidinone heterocyclic systems. Integral properties of electron density, such as the magnitude of intra-atomic dipole polarization and charges of hydrogen atoms, calculated by integration of the electron density over the volumes of atomic basins, correlate with chemical shifts significantly better than the point atomic charges. Our proposed parametric model for the rapid prediction of chemical shifts is based on an equation that includes the electron localization index in the hydrogen atom basin as a factor. The developed approach offers a theoretical model for a rapid quantitative assessment of chemical shifts and makes it possible to formulate the main structural factors that provide correlation between the calculated and experimental chemical shifts of hydrogen atoms involved in intramolecular hydrogen bonds. It has been revealed that intramolecular hydrogen bonds are the main structural features that ensure the correlation of atomic integral characteristics with chemical shifts in the considered molecules. The results obtained in the course of theoretical modeling have been verified by comparison with the experimental 1H NMR data for 4-hydroxyproline-2-carboxanilide podands with different oxyethylene chain lengths, which are chiral inductors of stereoselective syntheses of drugs based on pyrimidinone heterocyclic systems.

Effects of Modifying Thioflavin T at the N3-Position on Its G4 Binding and Fluorescence Emission.

We previously synthesized thioflavin T (ThT) with a hydroxyethyl group introduced at the N3-position (ThT-HE), which binds predominantly to the parallel G-quadruplex (G4) structure found in c-Myc and emits strong fluorescence. In this study, to investigate the effects of introduced substituents on G4 binding and fluorescence emission, a ThT derivative in which the hydroxyl group of ThT-HE was replaced with an amino group (ThT-AE) was synthesized for the first time. Furthermore, three other N3-modified ThT derivatives (ThT-OE2, ThT-SP, and ThT-OE11) having different substituent structures were synthesized by the N-acylation of the terminal amino group of ThT-AE, and their G4-binding and emission properties were investigated. The results showed that, although ThT-AE shows binding selectivity depending on the type of G4, its emission intensity is significantly decreased as compared to that of ThT-HE. However, ThT-OE11, which features an 11-unit oxyethylene chain attached to the terminal amino group of ThT-AE, regained about one-half of the emission intensity of ThT-HE while retaining selectivity for G4s. Accordingly, ThT-OE11 may be used as a key intermediate for synthesizing the conjugates of G4 binders and probes.