Chain Alkyl Groups Research Articles

Tribological Properties of Borate-Based Protic Ionic Liquids as Neat Lubricants and Biolubricant Additives for Steel-Steel Contact

A series of four novel halogen-free borate-based protic ionic liquids were synthesized with identical organoborate anions but dissimilar ammonium cations, to allow systematic discussion of the effects of cation alkyl chain group length on their physicochemical and tribological properties. The ionic liquids (ILs) studied showed up to a 30% friction reduction compared to a biolubricant and even displayed negligible wear when tested as neat lubricants. Blends of 1 wt.% ionic liquid and biolubricant were also investigated, leading up to maximum friction and wear reductions of 25% and 96%, respectively, compared to the base oil. Interestingly, the ionic liquid that performed least effectively as a neat lubricant due to the solidification of the fluid achieved the best tribological response as a lubricant additive. The tribological improvements were attributed to the formation of a self-assembled adsorbed layer that separated the frictional surfaces. This theory was supported by rheological studies and elemental analysis.

Anchoring Effect of Organosilanes on Hierarchical ZSM-5 Zeolite for Catalytic Fast Pyrolysis of Cellulose to Aromatics.

As an essential chemical feedstock, aromatics can be obtained from biomass by catalytic fast pyrolysis (CFP) technology, in which diffusion limitation is still a problem. In this study, several ZSM-5 zeolites with intercrystal stacking macropores were synthesized by adding organosilanes (OSAs) with different alkyl chain groups. Due to the structure-directing effect of the OSA, the prepared ZSM-5 zeolites possess a larger external surface area and pore volume than Blank-Z5. Moreover, the pore size is related to the extent of anchoring of the OSA and silicon–aluminum species in the zeolite precursor. Pyridine Fourier transform infrared (Py-FTIR) and NH3-temperature-programmed desorption (TPD) analyses show that the obtained ZSM-5 zeolites have a higher Brønsted acidity and total number of acid sites. In addition, excessive addition of OSA is not conducive to the growth of ZSM-5 zeolites. The catalytic performance of the synthesized ZSM-5 zeolites was evaluated by Py-GC/MS. The larger external surface area and pore volume improve the accessibility of the acid sites and thus promote the conversion of biomass into aromatics.

Structural Comparison of Sulfonamide-Based Derivatives That Can Improve Anti-Coagulation Properties of Metformin

Due to its high efficiency, good safety profile, and potential cardio-protective properties, metformin, a dimethyl biguanide, is the first-line medication in antihyperglycemic treatment for type 2 diabetic patients. The aim of our present study was to assess the effects of eight new sulfonamide-based derivatives of metformin on selected plasma parameters and vascular hemostasis, as well as on endothelial and smooth muscle cell function. The compounds with an alkyl chain (1–3), trifluoromethyl substituent (4), or acetyl group (5) significantly elevated glucose utilization in human umbilical endothelial cells (HUVECs), similarly to metformin. Our novel findings showed that metformin analogues 1–3 presented the most beneficial properties because of their greatest safety profile in the WST-1 cell viability assay, which was also proved in the further HUVEC integrity studies using RTCA DP. Compounds 1–3 did not affect either HUVEC or aortal smooth muscle cell (AoSMC) viability up to 3.0 mM. Importantly, these compounds beneficially affected some of the coagulation parameters, including factor X and antithrombin III activity. In contrast to the above-mentioned metformin analogues, derivatives 4 and 5 exerted more profound anticoagulation effects; however, they were also more cytotoxic towards HUVECs, as IC50 values were 1.0–1.5 mM. In conclusion, the chemical modification of a metformin scaffold into sulfonamides possessing alkyl substituents results in the formation of novel derivatives with potential bi-directional activity including anti-hyperglycemic properties and highly desirable anti-coagulant activity.

Influence of the alkyl chain length on the physicochemical properties and microbial biocompatibility of phosphonium based fatty acid ionic liquids

Ionic liquids (ILs) have remarkable properties and applications in many areas of science. Phosphonium ILs have become important because of their unique chemical and thermal stabilities. The present work is focused on the synthesis, characterisation, physicochemical properties, and microbial toxicity assessment of phosphonium ILs bearing seven different fatty acid anions. The structures of the synthesised ILs were confirmed by1H and13C nuclear magnetic resonance (NMR) and FTIR spectroscopy. Physicochemical properties such as density and viscosity of pure ILs were measured at temperatures ranging from 298.15 to 313.15 K. The experimental density decreased, whereas the viscosity increased with an increasing number of carbon atoms in the anion. The derived properties were also found to be anion dependent. The thermal decomposition temperature was investigated by TGA. Subsequently, the toxicity profile of the ILs was determined for selected Gram positive and Gram negative bacteria and some species of fungi in terms of minimum inhibitory concentrations (MIC). The results show that the antimicrobial activities of the ILs are strongly related to the structures of the ILs, where an increase in toxicity was observed with increasing alkyl group chain length of the fatty acid anion.

Antioxidant and Antibacterial Activities of Dodecyl Tannin Derivative Linked with 1,2,3-Triazole.

Dodecyl tannin derivative linked with 1,2,3-triazole was prepared by the click reaction of dodecyl azide and alkynylated tannin. The structure of tannin derivative was identified by FT-IR spectrometer and elemental analyzer, and the surface activity, antioxidant activity and antimicrobial activity of tannin derivative were studied. The surface tension of tannin derivative was significantly reduced because of the introduction of long chain alkyl groups, and the lowest surface tension was 38.87 mN/m at 1.0 mg/mL. The tannin derivative had strong ability to scavenge 1,1-diphenyl-2-picrylhydrazyl radical, the scavenging rate could reach 89.08 % at 0.25 mg/mL. The tannin derivative exhibited strong antibacterial activity against E. coli and S. aureus due to the increased fat-solubility of tannin derivative and the introduction of antibacterial triazole groups in molecular structure of tannin derivative, and the bacteriostatic ratios of tannin derivative against E. coli and S. aureus were 92.16 % and 89.21 % at 2.0 mg/mL, respectively. The tannin derivative can be used as good candidates for antibacterial packaging or antioxidant supplements.

Prediction of novel liquid crystalline molecule based on BO2 superhalogen

Biphenyl ring-based liquid crystalline series (nXB) generally consists of an alkyl chain (CnH2n+1) and electronegative group (X) at terminals. These electronegative groups (X) include F, CN, NCS, etc, which possess high electron affinity (EA). In this communication, we use BO2 superhalogen, having higher EA than halogen, as a terminal group X and compare the various properties of 2XB for X = F, CN, NCS and BO2. The results of DFT calculations show that the geometric, electric, and electronic properties of BO2 substituted 2XB is quite similar to typical 2XB liquid crystalline molecule. Based on this, the BO2 substituted nXB molecules may be considered as a novel liquid crystalline series. The kinetic stability of this novel molecule was established by ab initio molecular dynamics simulations. Thus, our results predict not only a novel liquid crystalline molecule but also its feasibility at room temperature.

Optimization and Evaluation of Novel Antifungal Agents for the Treatment of Fungal Infection.

Due to the increased morbidity and mortality by fungal infections and the emergence of severe antifungal resistance, there is an urgent need for new antifungal agents. Here, we screened for antifungal activity in our in-house library through the minimum inhibitory concentration test and derived two hit compounds with moderate antifungal activities. The hit compounds' antifungal activities and drug-like properties were optimized by substituting various aryl ring, alkyl chain, and methyl groups. Among the optimized compounds, 22h was the most promising candidate with good drug-like properties and exhibited potent fast-acting fungicidal antifungal effects against various fungal pathogens and synergistic antifungal activities with some known antifungal drugs. Additionally, 22h was further confirmed to disturb fungal cell wall integrity by activating multiple cell wall integrity pathways. Furthermore, 22h exerted significant antifungal efficacy in both the subcutaneous infection mouse model and ex vivo human nail infection model.

Inorganic Pb(II)-P and Pb(II)-S Complexes as Photosensitizers from Primary and Secondary Amines in Dyes-Sensitized Solar Cells.

Pb(II) complexes of bis(N-1,4-phenyl-N-(4-morpholinedithiocarbamato)) as Pb(II)–S and bis(N-diisopropyl-N-octyldithiocarbamato) as Pb(II)–P were prepared and characterized by optical, structural, morphological, and electrochemical techniques. The scanning electron microscopy analysis of Pb(II)–P and Pb(II)–S complexes consists of cubic crystals. X-ray diffraction and high-resolution transmission electron microscopy spectral studies revealed that the diameter increases in length for alkyl chain groups. This study demonstrates that the cubic shape of Pb(II) complexes can be synthesized from aromatic and aliphatic dithiocarbamate ligands. Photoluminescence analysis of both complexes fell within the blue shift region. The CV curve for Pb(II)–S revealed redox curves and the box-like shape as an indicative of a capacitive behavior, signifying limited catalytic redox activity. The J–V results for both sensitizers displayed satisfactory conversion efficiency (% η) between 3.77 and 3.96%.

Facile stearoyl chloride grafted cotton filter fabric and its application in oil-water separation

Surface hydrophobic modification for oil–water separation based on membrane filtration is essential but still challenging in dealing with various industrial and environmental problems like sewage treatment and oil spill. Chemical graft technology can arm membranes with more efficient durability for applications due to the stronger chemical interaction between modified layers and surfaces compared with physical coating technology. As cellulose-based material, cotton filter fabric is a flexible and degradable material with abundant hydroxyl groups, providing great possibility for graft reactions. Stearyol chloride has both hydrophobic alkyl chain and active acyl group, making it easily to be grafted onto cotton filter fabrics. Therefore, we propose to use stearoyl chloride as hydrophobic layer and one-step modify cotton filter fabric after activation. The obtained hydrophobic modified cotton filter fabric exhibits high contact angles (CAmax = 147o, CAavg = 141.8o), which only decrease slightly after 5 h droplet holding time (CAmax = 141o, CAavg = 126.3o). Besides, experiments also confirm that this modified membrane displays excellent anti-fouling property against different drinks as well as anti-washing property for 10 cycles. Much more surprised is that the obtained membrane displays outstanding anti-abrasion performance that the CA values can remain above 131o after 390 cycles abrasion with hektogram counterweight. As for filtration application, the modified membrane also shows hydrophobic durability after three times gravity-driven oil–water separation (CAmax = 137o, CAavg = 132.6o). This hydrophobic modified cotton filter fabric may have potential application in future oilwater separation and the stearoyl chloride graft technology is an both effective and efficient way in surface hydrophobic modification.

Novel Trifluoromethyl Pyrimidinone Compounds With Activity Against Mycobacterium tuberculosis.

The identification and development of new anti-tubercular agents are a priority research area. We identified the trifluoromethyl pyrimidinone series of compounds in a whole-cell screen against Mycobacterium tuberculosis. Fifteen primary hits had minimum inhibitory concentrations (MICs) with good potency IC90 is the concentration at which M. tuberculosis growth is inhibited by 90% (IC90 < 5 μM). We conducted a structure–activity relationship investigation for this series. We designed and synthesized an additional 44 molecules and tested all analogs for activity against M. tuberculosis and cytotoxicity against the HepG2 cell line. Substitution at the 5-position of the pyrimidinone with a wide range of groups, including branched and straight chain alkyl and benzyl groups, resulted in active molecules. Trifluoromethyl was the preferred group at the 6-position, but phenyl and benzyl groups were tolerated. The 2-pyridyl group was required for activity; substitution on the 5-position of the pyridyl ring was tolerated but not on the 6-position. Active molecules from the series demonstrated low selectivity, with cytotoxicity against eukaryotic cells being an issue. However, there were active and non-cytotoxic molecules; the most promising molecule had an MIC (IC90) of 4.9 μM with no cytotoxicity (IC50 > 100 μM). The series was inactive against Gram-negative bacteria but showed good activity against Gram-positive bacteria and yeast. A representative molecule from this series showed rapid concentration-dependent bactericidal activity against replicating M. tuberculosis bacilli with ~4 log kill in <7 days. Overall the biological properties were promising, if cytotoxicity could be reduced. There is scope for further medicinal chemistry optimization to improve the properties without major change in structural features.

Effects of the number of imidazoline ring and the length of alkyl group chain of imidazoline derivatives on corrosion inhibition of carbon steel in HCl solution: Molecular simulation and experimental validation

Abstract The effects of the number of imidazoline ring and the length of alkyl group chain of imidazoline derivatives were investigated using quantum chemical calculation, molecular dynamics simulation and experimental techniques. Three corrosion inhibitors including Symmetrical lauric acid imidazoline (SAI), Tetracyclic lauric acid imidazoline (LAI), and Symmetric stearic acid imidazoline (SPI) were synthesized and their inhibition performance was evaluated using weight loss measurement, electrochemical techniques and surface characterization. The results show that SAI and LAI with the same length of alkyl group chain, LAI with more imidazoline rings could supply a better inhibition performance since the increase of active sites. The increase of active sites attached to the metal surface may also change the distribution of corrosion inhibitor, which could limit inhibition performance improvement. While, SAI and SPI with the same number of imidazoline rings, SPI with longer alkyl group chain shows a better inhibition efficiency due to the better hydrophobic performance of alkyl groups. Among the three inhibitors, SPI show the best inhibition performance, indicating that the alkyl group chain length affects the inhibition performance more obvious than the number of the imidazoline rings.

Design, synthesis and biological evaluation of novel 1,2,3-triazole analogues of Imidazo-[1,2-a]-pyridine-3-carboxamide against Mycobacterium tuberculosis

Twenty-eight novel 1,2,3-triazole analogues of imidazo-[1,2-a]-pyridine-3-carboxamide were designed and synthesized based on hybridization approach. The structure of the final compounds are characterized using 1HNMR, 13CNMR, LCMS and elemental analyses and are screened in vitro for anti-tubercular activity using low-oxygen recovery assay (LORA) non-replicating and using microplate alamar blue assay (MABA) against replicating M. tuberculosis. MIC was determined. From the obtained results, it was observed that, among (2,7-dimethylimidazo[1,2-a]pyridin-3-yl)(4-((1-subtituted phenyl-1H-1,2,3-triazol-4-yl)methyl)piperazin-1-yl)methanones and (6-chloro-2-methylimidazo[1,2-a]pyridin-3-yl)(4-((1-substituted phenyl-1H-1,2,3-triazol-4-yl)methyl)piperazin-1-yl)methanones, compounds with substitution at para position with electron electron releasing groups exhibited the best activity (< 34 μg/mL). Amidst, (2,7-dimethylimidazo[1,2-a]pyridin-3-yl)(4-(2-(4-alkyl/substituted aryl-1H-1,2,3-triazol-1-yl)ethyl)piperazin-1-yl)methanones and (6-chloro-2-methylimidazo[1,2-a]pyridin-3-yl)(4-(2-(4- alkyl/substituted aryl -1H-1,2,3-triazol-1-yl)ethyl)piperazin-1-yl)methanones, compounds with long alkyl chain or cyclo propyl group were most active (< 21 μg/mL) in MABA method against the tested strain of MTB. Compound 10b emerged to be the most active compound in MABA and LORA with MIC values 13.74 and 24.63 μg/mL respectively. In-silico ADMET parameters were also predicted for the significantly active compound. Finally, molecular docking study was carried out to predict the feasible binding pattern of the most active compound at the active site of enoyl acyl carrier protein reductase from Mycobacterium tuberculosis (PDB-4TZK) using Glide module of Schrodinger software.

Alpha-beta transition induced by C18-conjugation of polyalanine and its implication in aqueous solution behavior of poly(ethylene glycol)-polyalanine block copolymers

BackgroundThe aqueous solution behavior of thermosensitive PEG-PA block copolymers as well as secondary structure of PA is expected to significantly change through modification of the hydrophobic PA by long chain alkyl (C18) groups with different configurations.MethodOleoyl and stearoyl (C18) groups were conjugated to poly(ethylene glycol)-poly(L-alanine) (PEG-PA; EG45A16) diblock copolymers to compare their conjugation effect on nano-assemblies and corresponding aqueous solution behavior of the polymers.ResultsDue to the nature of a hydrophilic PEG block and a hydrophobic PA or C18-modified PA, PEG-PA, oleoyl group-conjugated PEG-PA (PEG-PAO), and stearoyl group-conjugated PEG-PA (PEG-PAS) block copolymers form micelles in water. Compared with PEG-PA, the micelle size of PEG-PAO and PEG-PAS increased. Circular dichroism and FTIR spectra of aqueous polymer solutions showed that β sheet content increased, whereas α helix content decreased by C18 modification of PEG-PA. PEG-PAS showed better performance in ice crystallization inhibition than PEG-PAO. The sol-to-gel transition temperatures of aqueous PEG-PAO solutions were 25–37 °C higher than those of aqueous PEG-PA solutions, whereas aqueous PEG-PAS solutions remained as gels in the temperature range of 0–80 °C. 1H-NMR spectra indicated that the oleoyl groups increased core mobility, whereas stearoyl groups decreased the core mobility of the micelles in water. The difference in micromobility between PAO and PAS interfered or promoted gelation of the aqueous polymer solutions, respectively.ConclusionsThis study suggests that a hydrophobic C18-modification of polypeptide induces α helix-to-β sheet transition of the polypeptide; however, aqueous solution behaviors including ice recrystallization inhibition and gelation are significantly affected by the nature of the hydrophobic molecule.Graphical abstract

Compatibility of water treatment agents and produced water from oilfield

Aimed at corrosion inhibition and sterilization requirements from conventional produced water (CPW) and polymer-containing produced water (PCPW) in Shengli oilfield, functional agents screening was conducted through agent performance, suspended solids content (SSC), turbidity and filtration time. The interaction between polymer in PCPW and functional agent was discussed based on molecular structure and zeta potential of the functional agents. Results show that SSC of PCPW were significantly increased with addition of diquaternary ammonium salt, polyorganoguanidine and 9-octadecenoic acid imidazoline respectively, while slightly increased with addition of quaternary phosphonate and 9-octadecanoic acid epoxy imidazoline, respectively. Poor water-soluble aggregates were formed between anionic polymer and cationic agent with long chain alkyl groups through electrical attraction coming up with turbidity increased. Retention of aggregates and smaller suspended solid particles on filter membrane generated an increase on SSC, a prolonged filtration time and a darker color of filter membrane. “Deterioration” of water quality will happen with addition of such cationic agents with long chain alkyl groups. For the first time, the influence of polymer on selection of functional agents is figure out, and SSC should be taken into consideration besides functional performance when screening of water treatment agents. Also, the types of functional agents applicable to different produced water are proposed.

Phosphine catalyzed addition of long-chain dialkyl phosphites to electron-deficient alkenes

Conjugate addition of the long chain dialkyl phosphites to electron-deficient alkenes under PBu3 catalysis afforded the corresponding phosphonates in good yields in a short reaction time. Long chain alkyl groups in the phosphites were well tolerated in this transformation. The products of this reaction are of particular interest as components of lubrication oil composition.

A tailored positively-charged hydrophobic surface reduces the risk of implant associated infections

Implant-associated infections is one of the most challenging post-operative complications in bone-related implantations. To tackle this clinical issue, we developed a low-cost and durable surface coating for medical grade titanium implants that uses positively charged silane molecules. The in vitro antimicrobial tests revealed that the titanium surface coated with (3-aminopropyl) triethoxysilane, which has the appropriate length of hydrophobic alkyl chain and positive charged amino group, suppressed more than 90% of the initial bacterial adhesion of S. aureus, P. aeruginosa, and E. coli after 30 min of incubation. In terms of growth inhibitory rate, the treated surface was able to reduce 75.7% ± 11.9% of bacterial growth after a 24-hour culturing, thereby exhibiting superior anti-biofilm formation in the late stage. When implanted into the rat model infected by S. aureus, the treated surface eliminated the implant-associated infection through the mechanism of inhibition of bacterial adhesion on the implant surface. Additionally, the treated surface was highly compatible with mammalian cells. In general, our design demonstrated its potential for human clinical trials as a low-cost and effective antibacterial strategy to minimize post-operative implant-related bacterial infection.

Minimizing aromatics entrainment in dephenolization of coal-based liquids by deep eutectic solvents

Reducing the aromatics entrainment during coal-based liquids dephenolization has been investigated by deep eutectic solvents (DESs) as designed. Results showed that aromatics with a chain alkyl group were more easily entrained and phenolic compounds promoted the transfer of aromatics from oil to DESs. Among the DESs investigated, ChCl–glycerol was the best for separation of phenolic compounds from coal-based liquids, having a lower aromatics entrainment. Although adding H2O to ChCl–glycerol reduced the aromatics entrainment, simultaneously suppressed the phenol removal efficiency. A narrow boiling range of phenol oil fraction was benefit for phenols extraction with lower aromatics entrainment. The O–H…π and C–H…π among aromatics and phenolic compounds and/or DESs contributed for the aromatics entrainment, and compounds with specific structures were bound to be entrained.

Surface‐modification effect of MgO nanoparticles on the electrical properties of polypropylene nanocomposite

Polypropylene (PP)-based nanocomposite is a promising insulation material for recyclable high-voltage direct current (HVDC) cables, where the coupling agent plays an important role. In this study, four silane coupling agents with different alkyl chain groups (methyl, propyl, octyl, and octadecyl) were used to surface-modify magnesium oxide (MgO) nanoparticles. The surface-modification effect on the electrical properties of PP/MgO nanocomposites was investigated. The results show that surface-modified nanoparticles introduce quantities of deep traps, whose quantity increases as the alkyl chain length increases. The similar tendency also occurs on DC volume resistivity. All these nanocomposites show remarkable space charge suppression ability and improved DC breakdown strength. Among them, the nanocomposites with octyl-modified MgO show the best electrical properties, which could be attributed to the introduction of a large quantity of deep traps. The work may give a reference for the selection of coupling agents in PP-based nanocomposite insulation material for HVDC cable.

Pyrene-Based Co-Assembled Supramolecular Gel; Morphology Changes and Macroscale Mechanical Property.

Two pyrene derivatives having the perylenediimide (1) or the alky chain (2) in the middle of molecules were synthesized. Co-assembled supramolecular gels were prepared at different molar ratios of 0.2, 0.5, and 0.8 equiv. of 2 to 1. By SEM observation, the morphology of co-assembled supramolecular gels changed from spherical nanoparticles to three-dimensional network nanofibers as the ratio of 2 increased. In addition, the pyrene-excimer emission of co-assembled gels increased with increasing concentration of 2, and was stronger when compared with the condition without 1 or 2, indicating the formation of pyrene interaction between 1 and 2. In addition, the sol-gel transition was found to be reversible over repeated measurement by tube inversion method. The rheological properties of co-assembled supramolecular gels were also improved by increasing the ratio of 2, due to the increased nanoscale flexibility of supramolecular packing by introducing alkyl chain groups through heterogeneous pyrene interaction. These findings suggest that macroscale mechanical strength of co-assembled supramolecular gel was strongly influenced by nanoscale flexibility of the supramolecular packing.

In-depth investigation on THz spectrum of 1-butyl-3-methylimidazolium dicyanamide spreading on graphene surface by computational calculation

Understanding dynamic change of ionic liquid (IL) THz spectrum under certain conditions is a real challenge. Herein, through spreading 1-butyl-3-methylimidazolium dicyanamide ([Bmim][DCA]) nanodroplet on graphene surface, dynamic change of [Bmim][DCA] THz spectrum in the range from 30 to 300 cm−1 is probed by computational calculation at 300 K. Analyzing the calculated THz spectra it can be found that vibrational bands at 49.95 (cation-anion bend), 216.45 cm−1 (rocking of CH3 in alkyl chain) show a 16.65 cm−1 blue shift as spreading time increases from 0 to 5 ns and further blue-shift 16.65 cm−1 as spreading time increases from 10 to 20 ns, while vibrational band at 266.40 cm−1 (bend of CH3 in methyl) only blue-shifts 16.65 cm−1 as spreading time increases from 0 to 20 ns. The underlying mechanism is revealed to be the stronger adsorbed layer forming on graphene-IL interface which enhances the hydrogen bonds between cations and anions, and constrains the torsion and out-of-plane bend of CH3 group in alkyl chain and methyl respectively. The findings described here represent an important step in developing a comprehensive understanding of dynamic manipulation IL THz spectrum by spreading IL nanodroplet on graphene surface.