Number Of Alkyl Chains Research Articles

A non-symmetric room-temperature tristriazolotriazine liquid crystal

Tristriazolotriazine (TTT) has emerged as an easily accessible electron-deficient heterocyclic core for discotic liquid crystals (LCs). Materials that are liquid-crystalline at room temperature, i.e., do not crystallize in ambient conditions, are of particular interest when the LC state is prone to offer advantages in optoelectronic devices, e.g., for anisotropic charge or exciton transport, or anisotropic light emission. However, there has been no report of non-symmetric TTT LCs, i.e., with unequal arms. Here, we report two non-symmetric compounds derived from the TTT core. Their non-symmetry, combined with a high number of peripheral alkyl chains, is found to promote Colh mesomorphism over a broad temperature range including room temperature. The non-symmetry also induces an increase in the emission quantum yield, compared to symmetric analogs.

Ligand structure optimization leads to efficient acid-resist Am(III)/Eu(III) separation in n-octanol

Liquid-liquid extraction is the most wildly adopted industrial Lns/Ans separation approach which takes advantages of the subtle atomic size differences for Lns and Ans. Preorganized ligand architecture with coordination configuration locking strategy has been proven to be very efficient to enhance the separation factors by size exclusive effect from the preset ligand cavity while drawbacks such as sophisticated ligand synthesis, unbalanced extraction/stripping performances and limited solubility in environmental benign solvents prevent the economic practicability. In the current contribution, calculation-guided ligand structure optimization was utilized to optimize the hard/soft tetradentate phenanthroline diamide ligands. Reducing the number of alkyl chains around the binding sites from amide to imide led to less rotation energy barriers, eventually boosted both metal distributions and separation factors. Additionally, the formation of hydrogen bonds in the imine ligands enhanced their solubility in industrial-friendly solvent, such as n-octanol, leading to superior extraction performances. Finally, balanced extraction, stripping and recycling of the reported ligands were demonstrated to unravel the potential to be integrated into current industrial plants. The ligand design philosophy as discussed in this work could inspire the searching for new environment-friendly high-performance lipophilic ligand to close the current nuclear fuel cycle.

Modulating the Product Distribution of the Electrochemical Reduction of CO2 on Copper at Relevant Current Densities

The electrochemical reduction of CO2 (CO2RR) has the potential to be an economically-viable method to produce platform chemicals synergistically with renewable energy sources. Copper is one of the most used electro-catalysts for this purpose, as it allows carbon-carbon bond formation, crucial for broader product distribution. Despite great achievements, controlling selectivity is yet a stepping stone between R&D and an actual industrial application. Among others, a kinetic resolution could be applied to enhance the selectivity toward targeted products, for which exploiting available and inexpensive additives or co-electrolytes such as ionic liquids is a promising direction. Herein, we present an initial systematic analysis of the effect of various tetra alkyl ammonium salts on the CO2RR products distribution with the aim on ethylene, important industrial feedstock or building block. A selected ammonium salts of different alkyl chain length and number of charges provided very concise but sufficient chemical space to overview a structure-activity relationships, including changes in the reactions’ onset potentials and limiting currents. The overall experimentation progress was intensified by the employing a developed in our lab a gas diffusion electrode (GDE) cell, coupled to a mass spectrometer. This enabled to scan the selected library of salts during CO2RR under dynamic operations with detection of transients in real-time at relatively high current densities, between 10 to 400 mA/cm2, within further quantitative validation over standard long-term steady-state experiments. These results have broad implications for effectively stirring the CO2RR selectivity towards products containing either one or two carbon atoms.Key words: CO2, Electroreduction, Copper, Electrocatalysis, Modifiers, Real-time, GDE

Photovoltaic properties of novel reactive azobenzoquinolines: experimental and theoretical investigations

Abstract In this work, synthesis, characterization, DFT, TD-DFT study of some novel reactive azobenzoquinoline dye structures to elucidate their photovoltaic properties. The azobenzoquinoline compounds were experimentally synthesized through a series of reaction routes starting from acenaphthene to obtained aminododecylnaphthalimide and finally coupled with diazonium salts to get the desired azobenzoquinoline. Azo dye synthesized differ in the number of alkyl chains designated as (AR1, AR2, AR3, and AR4) which were experimentally analyzed using FT-IR and NMR spectroscopic methods. The synthesized structures were modelled for computational investigation using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) combined with B3LYP and 6-31+G(d) basis set level of theory. The results showed that the HOMO-LUMO energy gap was steady at approximately 2.8 eV as the alkyl chain increases, which has been proven to be within the material energy gap limit for application in photovoltaic. The highest intramolecular natural bond orbital (NBO) for the studied compounds is 27.60, 55.06, 55.06, and 55.04 kcal/mol for AR1, AR2, AR3, and AR4 respectively and the donor and acceptor interacting orbitals for the highest stabilization energy (E (2)) are LP(1)N 18 and π*C 16−O 19 respectively. The photovoltaic properties in terms of light-harvesting efficiency (LHE), Short circuit current density (J SC), Gibbs free energy of injection (ΔG inj), open-circuit voltage (V OC) and Gibbs free energy of regeneration (ΔG reg) were evaluated to be within the required limit for DSSC design. Overall, the obtained theoretical photovoltaic results were compared with other experimental and computational findings, thus, are in excellent agreement for organic solar cell design.

Polyfluoroalkyl Chain-Based Assemblies for Biomimetic Catalysis.

Amphiphobic fluoroalkyl chains are exploited for creating robust and diverse self-assembled biomimetic catalysts. Long terminal perfluoroalkyl chains (Cn F2n+1 with n=6, 8, and 10) linked with a short perhydroalkyl chains (Cm H2m with m=2 and 3) were used to synthesize several 1,4,7-triazacyclononane (TACN) derivatives, Cn F2n+1 -Cm H2m -TACN. In the presence of an equimolar amount of Zn2+ ions that coordinate the TACN moiety and drive the self-assembly into micelle-like aggregates, the critical aggregation concentration of polyfluorinated Cn F2n+1 -Cm H2m -TACN⋅Zn2+ was lowered by ∼1 order of magnitude compared to the traditional perhyroalkyl counterpart with identical carbon number of alkyl chain. When 2'-hydroxypropyl-4-nitrophenyl phosphate was used as the model phosphate substrate, polyfluorinated Cn F2n+1 -Cm H2m -TACN⋅Zn2+ assemblies showed higher affinity and catalytic activity, compared to its perhyroalkyl chain-based counterpart. Coarse-grained molecular dynamic simulations have been introduced to explore the supramolecular assembly of polyfluoroalkyl chains in the presence of Zn2+ ions and to better understand their enhanced catalytic activity.

Modular Bicyclophane-Based Molecular Platforms.

The modular synthesis of a series of nanoscale phenylene bicyclophanes with an intraaanular orthogonal pillar is described. The compounds are obtained by a Suzuki cross-coupling condensation and are characterized by mass spectrometry and NMR spectroscopy as well as in situ scanning tunneling microscopy at the solid/liquid interface of highly ordered pyrolytic graphite. In addition, their structures and conformations are supported by quantum chemical calculations, also after adsorption to the substrate. A set of two alkyl chain substitution patterns as well as a combination of both was investigated with respect to their ability to form extended 2D-crystalline superstructures on graphite. It shows that not the most densely packed surface coverage gives the most stable structure, but the largest number of alkyl chains per molecule determines the structural robustness to alterations at the pillar functionality.

Excellent corrosion inhibition and lubrication properties of carbon dot-based ionic liquids as water-based additives

Ionic liquids (ILs) and carbon dots (CDs) have gained more attention as versatile materials. Noticeably, the carbon dot-based ionic liquids (CDILs), a novel ionic combination of the two materials, will be endowed with superior performance and promote the application of CDs in fields of corrosion inhibition and lubrication. In this work, three CDILs with different alkyl chain numbers were synthesized as water-based multifunctional additives. CDILs show excellent corrosion inhibition effect in corrosive aqueous solution and superior lubricating behavior in water. Interestingly, CDILs with medium numbers of alkyl chains in cationic moiety exhibits optimal corrosion inhibition and lubrication performance. Both the physical adsorption of CDILs and the structures of cations influence the quality of adsorption and lubricating film.

Polydiacetylene/Zn2+/ZnO nanocomposites for colorimetric detection of cationic surfactants: Effects of ZnO ratios, solvents, and stimuli structures

Polydiacetylenes (PDAs) are smart materials that have been utilized as colorimetric sensors of various stimuli. Fine-tuning the sensitivity of PDAs often requires structural modification of their side chains and/or headgroups, involving complicated synthesizing and time-consuming purifying processes. This contribution presents a simple approach for controlling the sensitivity of PDA/Zn2+/ZnO nanocomposites to cationic surfactants. We have found that the detection of cationic surfactants in different concentration regions can be achieved by varying the ZnO ratios and the alkyl chain lengths of PDAs. The nanocomposites with higher ZnO ratios or longer alkyl side chains exhibit the color transition at higher concentrations of cationic surfactants. The nanocomposites can also detect the cationic surfactants in different organic solvents and buffer solutions. Moreover, the sensors can be used to differentiate the structures of cationic surfactants. The cationic surfactants with shorter alkyl chains result in the color transition at higher concentrations. The number of alkyl chains and headgroups in cationic surfactants also affects the color-transition behaviors. Our results extend the utilization of PDA materials with tunable sensitivity for sensing the cationic surfactants in various media.

Coordination-Induced Multivalent Self-Assembling Catalysts for Spectral Sensing Zn2+ with High Selectivity and Sensitivity.

The introduction of signal amplification to molecular spectral sensing systems is an intriguing topic in supramolecular analytical chemistry. In this study, click chemistry was used to generate a triazole moiety to bridge with a long hydrophobic alkyl chain (Cn) and another short alkyl chain (Cm) bearing a 1,4,7-triazacyclonane (TACN) group for efficiently generating a self-assembling multivalent catalyst, Cn-triazole-Cm-TACN·Zn2+ (n and m represent the carbon numbers of both alkyl chains, respectively; n = 16, 18, and 20; m = 2 and 6), to catalyze the hydrolysis of 2-hydroxypropyl-4-nitrophenyl phosphate (HPNPP) when Zn2+ was added. The triazole moiety introduced adjacent to the TACN group plays an important role in improving the selectivity of Zn2+ because the triazole moiety can participate in the coordination interaction between the Zn2+ and neighboring TACN group. The supplementary triazole complexing increases the space requirement for coordinated metal ions. This catalytic sensing system also shows high sensitivity, with a favorable limit of detection down to 350 nM, even if only UV-vis absorption spectra rather than more sensitive fluorescence techniques were used for signaling, and can be used to determine the concentration of Zn2+ in tap water, which demonstrates the practical application feasibility.

Corrosion Inhibition Studies of 8-Hydroxyquinoline Derivatives for N80 Steel in a 1.0 M HCl Solution: Experimental, Computational Chemistry, and Quantitative Structure-Activity Relationship Studies.

Twelve kinds of 8-hydroxyquinoline derivatives were synthesized and characterized. The weight loss method was used to evaluate their inhibition efficiencies (IEs) in a 1.0 M HCl solution at 333 K. The results showed that the alkyl chain length, heteroatoms (S, N, and O), and number of benzene rings significantly affect the IE. Herein, the IE of 5-[(dodecylthio)methyl]-8-quinolinol reached 98.71%. Meanwhile, the potentiodynamic polarization results indicated that all 8-hydroxyquinoline derivatives were mixed-type inhibitors. Electrochemical impedance spectroscopy results revealed that 8-hydroxyquinoline derivatives can increase polarization resistance, supporting their adsorption on the N80 steel surface. Moreover, according to density functional theory (DFT), the frontier orbital distribution and quantum chemical parameters (EHOMO, ELUMO, dipole moment μ, etc.) were calculated, and the results confirmed that the substituents of protonated 8-hydroxyquinoline derivatives significantly influenced the frontier orbital distribution. Molecular dynamics simulation illustrated that all protonated 8-hydroxyquinoline derivatives were adsorbed parallel to the Fe(110) surface, and the interaction energy (Eint) evidenced that the molecular size would affect their strength of adsorption on the Fe(110) surface. The linear and nonlinear quantitative structure-activity relationship models were established by linear regression (LR) methods and BP neural networks (NN), respectively. The LR model was established by using Eint and μ, and the coefficient of determination (R2) was 0.934. In addition, the nonlinear NN model was obtained according to IE and all parameters (DFT parameters and Eint). Then, the two calculation inhibition efficiencies (IEcal) were obtained from the LR and NN models, and the R2 values of the linear correlation between the IEcal and the experimental IE were 0.940 and 0.951, respectively. In addition, the IE of the tested inhibitor was 51.86% and the IEcal values predicted by the LR and NN models were 52.68% and 53.06%, respectively. Our results demonstrate that both the LR and NN models have good fits and predictive ability.

Micelle and Nanotape Formation of Benzene Tricarboxamide Analogues with Selective Cancer Cell Cytotoxicity.

Analogues of benzene-1,3,5-tricarboxamide bearing combinations of different alkyl chains (dodecyl to octadecyl) and ester-linked PEG (polyethylene glycol) chains are shown to self-assemble into either micelles or nanotapes in aqueous solution, depending on the architecture (number of alkyl vs PEG chains). The cytotoxicity to cells is selectively greater for breast cancer cells than fibroblast controls in a dose-dependent manner. The compounds show strong stability, retaining their self-assembled structures at low pH (relevant to acidic tumor conditions) and in buffer and cell culture media.

Alkylated Polyphenyl Ethers as High-Performance Synthetic Lubricants

Lubricants exhibiting both thermal and chemical stability that consequently generate less hydrogen during friction are required to avoid the hydrogen embrittlement of moving mechanical components. The present work studied the effects of the length and number of alkyl chains on the tribological properties of polyphenyl ethers (PPEs), which feature good thermal and radiation resistance. PPEs were found to have much lower friction coefficients compared with a poly-alpha-olefin and alkyldiphenyl ether, and the effect of the running-in process on friction appeared to be negligible. The formation of polymers on the friction track evidently decreased the friction coefficients of the lubricants and the wear rates were almost zero for all the PPEs, indicating excellent anti-wear properties. Analyses with a quadrupole mass spectrometer connected to a friction tester under vacuum indicated negligible hydrogen generation from 4P2E, which had no alkyl chains, after the running-in. R1-4P2E, having a C16H33 chain, showed hydrogen desorption similar to that of the alkyldiphenyl ether, which had a C18H37 alkyl chain. R2-4P2E, with two C16H33 chains, produced significant hydrogen, but with a long induction period; thus, it provided good wear protection. Although alkyl chains increased the risk of hydrogen generation, PPEs with such chains may have applications as standard lubricants.

Experimental and theoretical studies of the influence of alkyl groups on the photovoltaic properties of (E)-6-((2, 3-dihydroxylnaphthalene)diazenyl)-1H-benzoisoquinoline-1,3-dione-based organic solar cell.

The manipulation of the active dye material for application in dye-sensitized solar cell (DSSC) using simple or bulky group substituents is necessary for improved dye performance. Herein, we carried out a combined experimental and theoretical studies of different alkylated novel reactive (E)-6-(2,3-dihydroxyl naphthalene diazinyl)-1H-benzoisoquinoline-1,3-dione azo-based dyes using spectral (FTIR, UV-visible, and NMR) analysis and electronic structure theory method based first principle density functional theory (DFT) calculations to investigate the molecular electronic properties, structural analysis, excitation behavior, and the theoretical potential application in photovoltaic cell. The synthesized azo dye (azoD) was theoretically modeled by varying the number of alkyl chains denoted as AzoD1, AzoD2, AzoD3, and AzoD4 to represent azo dyes having ten (10), twelve (12), fourteen (14), and sixteen (16) alkyl chain length respectively. From the natural bond orbital (NBO) analysis, the higher stabilization energies, 227.80 and 227.77kcal/mol respectively, recorded for AzoD1 and AzoD4 may be due to extra orbital contribution by π*(N21-N22) to π*C54-C56 31.19eV for AzoD1 and π*(N21-N22) → π*(C53-C55) 31.43eV AzoD4 confirming that chain length affected the orbital interaction of the molecules. The driving force (ΔGinject) of electron injection into the TiO2 surface (- 1.92 to - 1.93) shown in this study is indicative that alkylated azo dyes are good for improved DSSCs performance. Again, the open circuit voltage (Voc) of 1.090 (AzoD1), 1.092 (AzoD2), 1.093 (AzoD3), and 1.095 (AzoD4) are also evidence of the suitability of azo dyes as photosensitizers. All the spectroscopic analysis, FTIR, UV-visible, and NMR combined with theoretical calculations, provided accurate data for characterizing the titled azo dye compound and showed that it has good photophysical properties. The presence of alkyl groups and chain length promoted the stability of the dyes thereby making them suitable for application in DSSCs. Increase in chain length as well enhanced the electron injection into the conduction band of the semiconductor.

Iron Redox Shuttles with Wide Optical Gap Dyes for High-Voltage Dye-Sensitized Solar Cells.

A series of iron polypyridyl redox shuttles were synthesized in the 2+ and 3+ oxidation states and paired with a series of wide optical gap organic dyes with weak aryl ether electron-donating groups. High voltage dye-sensitized solar cell (HV-DSC) devices were obtained through controlling the redox shuttle energetics and dye donor structure. The use of aryl ether donor groups, in place of commonly used aryl amines, allowed for the lowering of the dye ground-state oxidation potential which enabled challenging to oxidize redox shuttles based on Fe2+ polypyridyl structures to be used in functional devices. By carefully designing a dye series that varies the number of alkyl chains for TiO2 surface protection, the recombination of electrons in TiO2 to the oxidized redox shuttle could be controlled, leading to HV-DSC devices of up to 1.4 V.

Surface structure of the mixture of 1-alkyl-3-methylimidazolium iodide and polyiodide observed by surface tension measurement and X-ray reflectivity

The mixtures of 1-alkyl-3-methylimidazolium iodide ([Cnmim][I], n is the alkyl chain number) and iodides are promising candidates for electrolytes used in a dye-sensitized solar cell with high performance. However, thus far, the effect of surface structure on electroconductivity at the electrode surface and how to avoid the disadvantage of corroding metals or electrodes remain unclear. Thus, we investigated the surface tension and X-ray reflectivity of the mixtures to clarify the molecular arrangement at the liquid–vapor interface. It was shown that surface tension steeply decreased upon mixing iodides; polyiodides localized around the liquid–vapor interface and localization behaviors were independent on n, and the surface was hindered well by longer alkyl chains.

Synthesis and characterization of tannic acid esters and their performances as asphaltenes dispersants

Asphaltene aggregation and flocculation in upstream and downstream industries cause severe problems due to phase separation and asphaltene particle growth. This work aims to esterify tannic acid (TA) at different molar ratios of heptanoyl chloride (HC) 1:3, 1:6, and 1:9, producing species TA-HC3, TA-HC6, and TA-HC9, respectively. The synthesized esters were characterized by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and thermal analyses. Their performances as asphaltene dispersants of Arabian heavy crude oil were assessed by dynamic light scattering (DLS), ultraviolet–visible (UV–Vis) spectroscopy, and viscosity measurements. All specimens (TA-HC3, TA-HC6, and TA-HC9) dispersed asphaltene, and their dispersal abilities increased with increasing number of alkyl chains (i.e., TA-HC3 > TA-HC6 > TA-HC9).

Properties of DNA- and Protein-Scaffolded Lipid Nanodiscs.

The properties of natural lipid bilayers are vital to the regulation of many membrane proteins. Scaffolded nanodiscs provide an in vitro lipid bilayer platform to host membrane proteins in an environment that approximates native lipid bilayers. However, the properties of scaffold-enclosed bilayers may depart significantly from those of bulk cellular membranes. Therefore, to improve the usefulness of nanodiscs it is essential to understand the properties of lipids restricted by scaffolds. We used computational molecular dynamics and modeling approaches to understand the effects of nanodisc size, scaffold type (DNA or protein), and hydrophobic modification of DNA scaffolds on bilayer stability and degree to which the properties of enclosed bilayers approximate bulk bilayers. With respect to achieving bulk bilayer behavior, we found that charge neutralization of DNA scaffolds was more important than the total hydrophobic content of their modifications: bilayer properties were better for scaffolds having a large number of short alkyl chains than those having fewer long alkyl chains. Further, complete charge neutralization of DNA scaffolds enabled better lipid binding, and more stable bilayers, as shown by steered molecular dynamics simulations that measured the force required to dislodge scaffolds from lipid bilayer patches. Considered together, our simulations provide a guide to the design of DNA-scaffolded nanodiscs suitable for studying membrane proteins.

Impact of Substitution Pattern and Chain Length on the Thermotropic Properties of Alkoxy-Substituted Triphenyl-Tristriazolotriazines.

Tristriazolotriazines (TTTs) with a threefold alkoxyphenyl substitution were prepared and studied by DSC, polarized optical microscopy (POM) and X-ray scattering. Six pentyloxy chains are sufficient to induce liquid-crystalline behavior in these star-shaped compounds. Thermotropic properties of TTTs with varying substitution patterns and a periphery of linear chains of different lengths, branching in the chain and swallow-tails, are compared. Generally, these disks display broad and stable thermotropic mesophases, with the tangential TTT being superior to the radial isomer. The structure–property relationships of the number of alkyl chains, their position, length and structure were studied.

Odd-Even Effect Observed in the Electro-Optical Properties of the Homologous Series of HnCBP Liquid Crystal Studied under the Impact of the Electric Field: A Theoretical Approach

The liquid crystal (LC) 4-4′-disubstituted biphenyls (HnCBP) of the general line formula HO-(CnH2n+1)-O-C6H4-C6H4-CN (n=1-12) shows the odd-even effect under the applied electric field. The odd-even effects are observed in the HOMO-LUMO gap, birefringence, order parameter, and dipole moment. The odd carbon atom number of alkyl chain shows HOMO-LUMO gap, birefringence and order parameter in the upward direction and even carbon atom number of alkyl chain shows in the downward direction; however the dipole moment exhibits a shift of even carbon number of alkyl chain in the upward direction and odd carbon number of alkyl chain in the downward direction.

Simulations of Double Layer Structure and Differential Capacitance of Quaternary Ammonium-Based Ionic Liquids: Effect of Switching the Length of Alkyl Chains

Quaternary ammonium-based ionic liquids (QaILs) have non-flammability, non-volatility, and thermal/chemical/electrochemical stabilities and are expected to be electrochemically applied. QaILs are superior to well-known imidazolium-based ILs in the wide potential window and high cationic designability. While the number of studies focusing on QaILs is limited,[1] further knowledge is needed to utilize the characteristics of QaILs. In this study, we performed molecular dynamics simulations at the interface between QaILs and the graphene electrode. The QaILs are composed of a common anion, bis(trifluoromethanesulfonyl)amide (TFSA−) and different cations: butyltrimethylammonium (N1114 +) dibutyldimethylammonium (N1144 +), tributylmethylammonium (N1444 +), tetrabutylammonium (N4444 +). By substituting methyl and butyl groups in Qa cations, we investigated how the number of long alkyl chains affects the potential dependence of differential capacitance and the electric double layer structure.[2] The Qa cations have major two orientations on the electrode: lying orientation where all the butyl chains are parallel to the electrode (Figure a) and standing orientation where one or more butyl chains are pointing to the ILs bulk (Figure b). N4444+ only shows standing orientation because of its geometric restriction. Compositions of the first interfacial layer reflect both the cationic orientation and surface charge density. As the electrode is negatively charged up, the compositions indicate the increase in the number of cations and different behavior of butyl chains depending on the Qa cations. Orientation analysis of the butyl chain indicates that the increase in lying orientation occurs at moderately negative (< ~−2 V) potentials, and the increase in standing orientation occurs at further negative potentials.As the potential deceases, the differential capacitance of all the QaILs drastically decreases in the potential range from 0 to ~−2V and gradually decreases at more negative potentials (Figure c). In the latter potential range, the differential capacitances show an upward discrepancy from predicted curves from Kornyshev model.[3][4] The discrepancy begins at the potentials where the standing orientation starts to increase, which implies a correlation between the differential capacitance and the cationic orientation. The discrepancy is greater for QaILs composed of cations with fewer butyl chains. The orientation effect is significant for such cations because those in lying and standing orientation have a great difference in occupation space in the first ionic layer.