Methylene Chain Research Articles

High-performance dicationic ionic liquids based on imidazolium and quaternary ammonium for phenol extraction

Phenolic compounds serve as crucial chemical raw materials abundant in coal tar, so it is of great economic value to extract phenolic compounds from coal tar. Ionic liquids (ILs) are regarded as desirable extractants in this separation field due to considerable advantages over traditional methods. Compared to traditional mono-cationic ILs, dicationic ionic liquids (DILs) exhibit outstanding thermal stability and a wider operating temperature range. Our research focused on developing DILs based on typical imidazolium and quaternary ammonium structures for phenol separation, examining the impact of the methylene chain length between the cations on the extraction efficiency. Hydrogen bonding and π-π interactions between DILs and phenol were also investigated as driving forces in the extraction process. 1-methyl-3-(3-(trimethylammonio)propyl)-1H-imidazol-3-ium bromide ([MIMC3N111][Br]2) with a moderate chain length was selected as the optimal extractant due to its weaker coulomb force inside the DIL, facilitating stronger hydrogen bonding with phenol compared to the other two DILs. Under optimized conditions, [MIMC3N111][Br]2 exhibited the highest extraction efficiency of 96.03 % in model oil (toluene and phenol) with a phenol content of 200 g dm−3 and the DIL to phenol mole ratio was only around 0.3. [MIMC3N111][Br]2 also featured excellent recyclability, maintaining high extraction efficiency through multiple cycles. Importantly, its lower solubility in oil-phenol mixtures compared to mono-cationic ILs significantly reduced contamination of the oil phase. The DILs in this work can exhibit significant potential for separating phenolic compounds with certain advantages.

Synthesis of polyfumarates containing a 4-tert-butylcyclohexyl group and unique solid-state properties based on the orientation of rigid poly(substituted methylene) chains

Synthesis of polyfumarates containing a 4-tert-butylcyclohexyl group and unique solid-state properties based on the orientation of rigid poly(substituted methylene) chains

Stabilizing Dye-Sensitized Upconversion Hybrids by Cyclooctatetraene.

Lanthanide-doped upconversion nanoparticles (UCNPs) can convert low-energy near-infrared (NIR) light into high-energy visible light, making them valuable for broad applications. UCNPs often suffer from poor light-harvesting capabilities, which can be significantly improved by incorporating organic dye antennas. However, the dye-sensitized upconversion systems are prone to severe photobleaching in an ambient atmosphere. Here, we present a synergistic approach to mitigate photobleaching by introducing triplet state quencher cyclooctatetraene (COT). COT effectively suppresses the generation of singlet oxygen by quenching the triplet states of the dye and consumes the existing singlet oxygen through oxidant reactions. The inclusion of COT extends the half-life of IR806 by 4.7-times by preventing the oxidation of its poly(methylene) chains. Without significantly affecting emission intensity and dynamics, COT effectively stabilized dye-UCNPs, demonstrating a notable 3.9-fold increase in half-life under continuous laser irradiation. Our findings suggest a new strategy to enhance the photostability of near-infrared dyes and dye-sensitized upconversion nanohybrids.

Structural parameters and molecular model of Shendong subbituminous coal

Coal has a highly complex chemical structure, similar to polymers, coal is a macromolecular structure composed of a large number of “similar compounds”, which is called the basic structural unit. Understanding coal structure is the basis of its transformation and utilization. Shendong (SD) coal was analyzed by FTIR, XRD, XPS, and NMR. The results show that SD coal normalized structure formula is C100H68.5O35.7N1.2S0.2 and the average number of aromatic rings is 1.98. –CH2— content accounts for about 82% in aliphatic C–H region, and the ratio of ether bond C–O, aromatic ether C–O and CO is about 2:1:11 in oxygen-containing functional group region. The d002, LC, La and NC of SD coal microcrystalline structure parameters are 0.1832 nm, 1.4688 nm, 2.0852 nm and 9.017, respectively. Aromatic carbon and aliphatic carbon ratios of SD coal are 55.67% and 29.97%, aromatic cluster size and average methylene chain length are 0.224 and 1.817. Based on these structural parameters, molecular model of SD coal was constructed with 13C SSNMR experimental spectra as a reference. The model was constructed with an atom composition of C214H214O49N2S.

P(MMA-co-MAA)/cellulose nanofibers composites: Effect of hydrogen bonds on molecular mobility

Cellulose nanofibers (CNFs) nanocomposites were prepared using poly(methylmethacrylate-co-methacrylic acid) (PMMA-co-MAA) to investigate the macromolecular mobility within the composite, with particular focus on the effect of H-bonding. Dynamic mechanical analysis (DMA) and broadband dielectric spectroscopy (BDS) were used to fully characterize the molecular mobility for which the effect of the introduction of H-bond forming moieties and the addition of CNFs (5 and 15 wt%) were assessed. Despite similar Tg values (determined by Differential Scanning Calorimetry), a deeper analysis of the relaxation times associated with the α-relaxation evidenced a significant effect induced by CNFs, which is in fact slowing down the macromolecular relaxation processes. The activation energy of the β-relaxation remained unchanged despite the introduction of MAA units in the main chain and the successive addition of CNFs. However, the latter led to the appearance at low frequencies of a new β’-relaxation correlated with the interactions between the CNF surface -OH groups and the -COOH groups of the matrix. The γ-relaxation showed a 45 % increase in activation energy from PMMA to PMMA-co-MAA + CNF nanocomposites regardless of the CNF content, due to the possibility of CNFs to interact and hinder the motion of the main chain methyl groups in α position.

Novel Solid‐State Fluorophores, a Series of Cyanostilbene‐Based Amorphous Molecular Materials

AbstractWe have designed and synthesized a novel series of cyanostilbene‐based amorphous molecular materials with different methylene chain lengths, BMAC‐n (n=3,4,5,6), and investigated their emitting properties in solution and various solid states. All BMAC‐n molecules showed solvatochromic fluorescence in solutions. Emission spectra of BMAC‐n molecules in the same solution were identical to one another irrespective of the methylene chain length while the spectra in crystalline states depended on their methylene chain length. As in solutions, emission spectra of their spin‐coated amorphous films were identical to each other irrespective of the methylene chain length. Emission spectra of rubbed amorphous films prepared by grinding their crystals were identical to those for spin‐coated amorphous films; however, comparative studies between spin‐coated and rubbed amorphous films indicated that fluorescence quantum yields and photochemical reactivity depend on the preparation method.

Analysis of enzyme activity and substrate specificity of dolichyl-phosphate β-glucosyltransferase

Protein folding and quality control processes primarily occur in the endoplasmic reticulum (ER). ER-resident molecular chaperones play a crucial role in guiding nascent polypeptides towards their correct tertiary structures. Some of these chaperones specifically recognize glucosylated N-glycan moieties on peptide. It is of great significance to study the N-glycan biosynthetic pathway and glycoprotein quality control system by analyzing the sugar donor of ER luminal glucosyltransferases, known as dolichol phosphate glucose (Dol-P-Glc), or its analogues in vitro. In this study, we investigated a range of dolichol analogues to synthesize lipid phosphate glucose, which served as substrates for dolichyl-phosphate β-glucosyltransferase E (Alg5E) derived from Trichomonas vaginalis. The results demonstrated that the recombinant Alg5E, expressed in Escherichia coli, exhibited strong catalytic activity and the ability to recognize lipid phosphate glucose with varying chain lengths. Interestingly, the enzyme's catalytic reaction was found to be faster with longer carbon chains in the substrate. Additionally, Alg5E showed a preference for branched chain methyl groups in the lipid structure. Furthermore, our study confirmed the importance of divalent metal ions in the binding of the crucial DXD motif, which is essential for the enzyme's catalytic function. These findings lay the groundwork for future research on glucosyltransferases Alg6, Alg8, and Alg10 in the synthesis pathway of dolichol-linked oligosaccharide (DLO).

Structure of Molecular Chains of Poly(trimethylene terephtalate) Studied by Low-Frequency Vibrational Spectroscopy and Quantum Chemical Calculations: In Comparison with That of Poly(ethylene terephthalate) and Poly(butylene terephthalate) from the Point of Parity of Methylene Chain Length

Structure of Molecular Chains of Poly(trimethylene terephtalate) Studied by Low-Frequency Vibrational Spectroscopy and Quantum Chemical Calculations: In Comparison with That of Poly(ethylene terephthalate) and Poly(butylene terephthalate) from the Point of Parity of Methylene Chain Length

#749 Components in blood collection tubes interfere with the spectral signatures of patients with kidney disease: analysis by infrared microspectroscopy

Abstract Background and Aims Kidney disease is a worldwide public health problem, affecting between 8%-16% of the global population. Chronic Kidney Disease (CKD) is a silent disease and its detection is often late, making the treatment difficult. Considering the emerging Fourier-Transform Infrared spectroscopy (FTIR) as a biophotonic resource for the biomedical sciences, we aimed to identify spectral signatures related to biomarkers of CKD in human blood serum using the microscopy FTIR option. Method Blood serum samples from 17 healthy in comparison to 33 CKD patients were analyzed by micro-reflectance FTIR spectroscopy. The first aspect to be addressed refers to the possible influence of components present in the container tube. Here we showed that separator gel in VACUETTE® tubes is a relevant source of spectral interference which could decrease the accuracy of discrimination from 85% to 65%. Acquiring a diluted gel signal as a background would improve the discrimination performance in spite of some gel bands still present in sample data. Results In this case, our results indicated that vibrations associated with galactose-4-sulfate, CH2 bending of the methylene chains, C=C in lipids and fatty acids, C=N stretching, CH bending vibration from the phenyl rings, N-H bending vibration coupled to C-N stretching and β-sheet of Amide II and ring base are modulated in blood serum samples of chronic kidney disease patients compared to healthy patients. Urinary trypsin inhibitors, fatty acids, phenolic derivatives, tryptophan, and plasminogen were the biomolecules related to these assignments were the biomolecules related to these assignments. Conclusion In conclusion, FTIR is a viable option for fast diagnosis of chronic kidney disease being also a powerful tool for monitoring the disease. Due to its capability of large batch analysis, the micro-FTIR would be an eligible technology for clinical laboratories in healthcare facilities. However, for direct clinical applications, ATR-FTIR would be the option of choice.

Novel insights into the molecular structure of lignite and its oxidation characteristics: A comprehensive characterization from single molecule of intermediates to complex coal

The structure of lignite is commonly believed to consist of fused aromatic rings (FARs) with 1 and 2 rings and short methylene chains, with few FARs with 3 or more rings and long aliphatic hydrocarbon (LAH) chains. This work presents a controlled stepwise alkali‑oxygen oxidation (AOO) of Xiaolongtan lignite to produce intermediates with characteristic structures. The humic acids and oxidative residues obtained were rich in aromatics and aliphatics, respectively. Based on complementary information of FARs with 3 or more rings and LAHs in the intermediates, a new structural model of lignite (C3661H3435O1036N81S7) from single molecules of intermediates to complex particles has been developed in conjunction with material characterization and computation. There are 43.7% one fused aromatic ring (1FAR), 39.3% 2FAR, 14.7% 3FAR, and 2.4% 4FAR, amount which there 15.9% pyrrole- and 2.4% pyridines- based aromatic rings. The controlled oxidation could prevent the ring-opening reaction of FARs and excessive oxidation of LAHs, thus leading to an in-depth understanding of the AOO process and lignite structure.

Gold-Catalyzed C(sp3)-C(sp2) Suzuki-Miyaura Coupling Reaction.

A gold-catalyzed C(sp3)-C(sp2) Suzuki-Miyaura coupling reaction facilitated by ligand-enabled Au(I)/Au(III) redox catalysis was developed. The cross-coupling of alkyl organometallics was first realized in the redox catalytic cycle in gold chemistry, without the use of external oxidants. This gold-catalyzed C(sp3)-C(sp2) coupling reaction allows a variety of alkyl chain and useful methyl trifluoroborates to react with aryl and vinyl iodides under very mild conditions, which provides a new reactivity pattern for challenging couplings with alkyl organometallics.

A study on the structures and primary reaction products of kerogens in Longkou oil shale with different densities through supercritical ethanolysis

The difference in the density of oil shale significantly affects the structural characteristics of the kerogen, which brings the change in the pyrolysis behavior, thus leading to different retorting oil yields. The primary reaction (the cleavage of weak covalent bonds into free radicals) in the pyrolysis of oil shale greatly affects the retorting oil yield and quality. In this work, the structural characteristics and primary reaction products of the kerogens in Longkou oil shale (LKOS) with three different densities (<1.3, 1.4 − 1.5, 1.8 − 1.9 g/cm3) were investigated by supercritical ethanolysis, 13C nuclear magnetic resonance (13C NMR) and Fourier transform infrared spectroscopy (FTIR). The weak covalent bonds in the kerogens were broken by ethanolysis at 350 °C to obtain small molecular substances (SMSs) with the carbon conversions of 28 %, 47 % and 54 %, respectively. The SMSs can be divided into aliphatic acid esters, aromatics, alkanes and N-containing organic compounds (NCCs). Among the SMSs, the relative contents of the aliphatic acid esters, whose aliphatic chain lengths distribute in C3-C23, C1-C24 and C1-C28, are the highest. The aromatics are mainly monocyclic, and the NCCs mainly exist as amines. The possible pathways for these ethanolysis products were proposed. The 13C NMR and FTIR analyses of the kerogens and their ethanolysis residues show that the aliphaticity (fal) and average methylene chain length (Cn) increase, while the aromaticity (fa) and average aromatic cluster size (Xb) decrease with the increasing oil shale density. After ethanolysis, the value of fa gradually increases, while that of fal and Cn decrease. Furthermore, the contents of C=O and O-C=O decrease, while that of O-C-O and C-OH increase. The results suggest that the SMSs are connected to the kerogen matrix by weak covalent bonds. The cleavage of C=O, O-C=O and C-O bonds dominates the early stage of the oil shale pyrolysis. During the pyrolysis of oil shale, these weak covalent bonds are first broken and the above SMSs are the most primary reaction products and then undergo the second reactions to yield oil and gas.

Construction of multidimensional structure model of the Mesoproterozoic Xiamaling shale kerogen, northern North China

In the southeastern Xuanlong sag of Northern China, the organic-rich black shale of the Mesoproterozoic Xiamaling Formation holds significant potential as a source rock. Through advanced analytical techniques including elemental analysis, 13C NMR, XPS, FTIR, and XRD, the elemental composition and chemical structure were thoroughly characterized, and the molecular structure of the Xiamaling shale kerogen was established. The 13C NMR analysis revealed the carbon composition of kerogen, indicating 75.19 % aliphatic carbon, 22.06 % aromatic carbon, and 2.75 % carbonyl carbon, with quantitative support from FTIR and XRD spectra. The dominant methylene carbons exhibited a low average methylene chain length (Cn) of 3.87, suggesting that they are primarily short-branched or alicyclic compounds rather than long straight chains. This conclusion was verified by the absence of a sharp peak at a wavenumber of 719.95 cm−1 in the FTIR spectrum. Oxygen-containing functional groups observed in 13C NMR spectra were also identified in FTIR spectra at a wavenumber range of 3500–1000 cm−1. XPS analysis indicated that nitrogen-containing groups were amino, quaternary, pyridine, and primary pyrrole groups, and sulfur existed as sulfoxide, aromatic sulfur, aliphatic sulfur, and sulfone. Finally, a relatively rational 2D molecular structure with the chemical formula of C278H346N6O26S2 was established by comparing the predicted and experimental 13C NMR spectra. Using MD simulation, five optimized 2D molecules were combined to construct a robust 3D kerogen model with a physical density of 1.067 g/cm3. Comparatively, the aliphatic structure of the Mesoproterozoic Xiamaling kerogen model consists of some monocyclic alkanes and polycyclic saturated structures, resembling Paleozoic kerogen models but differing from Mesozoic counterparts. The constructed kerogen model addresses the gap in the Precambrian kerogen modeling and sets the stage for in-depth exploration of pyrolysis mechanisms in the future.

Correlation between the structure of low-rank coal and its yield and characteristics of thermal dissolution extracts

To investigate the effect of structure difference of coals on its yield and characteristics of thermal dissolution extracts (TDEs), four Xinjiang low-rank coals were chosen for thermal dissolution extraction using 1-methylnaphthalene (1-MN) as the solvent at 380 °C. The low-rank coals were divided into TDEs consisting of deposit (DP) precipitated at room temperature in 1-MN and soluble (SL) dissolved in 1-MN, along with a minor proportion of liquid and gas products, as well as residue. The results showed that TDEs yields of Qidaowan (QDW), Heishan (HSC) and Runbei (RBC) coal samples increased with the increase of volatiles. However, almost the same TDEs yield was obtained for Hefeng coal (HFC) as RBC despite of higher volatiles content of the former. Further analysis suggested that both higher volatiles content and aromatic carbon ratio contributed to the formation of TDEs when 1-MN was used as the solvent. Besides, significant differences of carbon types for the above coal samples were observed, wherein, HFC possessed the lowest aromatic carbon of 45.59%, yet the value for all the DPs and SLs were above 60%, falling in the range of 60%-68% and 66%-71%, respectively. Furthermore, the aromatic ring cluster of DPs was composed of 2–3 rings, while that for SLs was 1–2 rings on average. Moreover, the TDEs obtained from coals with higher oxygen content were also characterized by a relatively higher oxygen content, and a higher content occurred on DPs. The molecular weight, polydispersity index and methylene chain length of DPs and SLs located in the range of 1000–1800 amu, 2.0–4.4, and 0.8–2.3, respectively. And it was found that good caking properties similar to coking coals occurred on the DPs and SLs, ranging from 88 to 97. Results also exhibited that there was a positive synergistic effect for caking index of DP & SL mixture. This work provides a theoretical basis for low-rank coal as an alternate to coke coal by thermal dissolution extraction.

Hydroxyhexylitaconic acids as potent IMP-type metallo-β-lactamase inhibitors for controlling carbapenem resistance in Enterobacterales.

Metallo-β-lactamases (MBLs) represent one of the main causes of carbapenem resistance in the order Enterobacterales. To combat MBL-producing carbapenem-resistant Enterobacterales, the development of MBL inhibitors can restore carbapenem efficacy for such resistant bacteria. Microbial natural products are a promising source of attractive seed compounds for the development of antimicrobial agents. Here, we report that hydroxyhexylitaconic acids (HHIAs) produced by a member of the genus Aspergillus can suppress carbapenem resistance conferred by MBLs, particularly IMP (imipenemase)-type MBLs. HHIAs were found to be competitive inhibitors with micromolar orders of magnitude against IMP-1 and showed weak inhibitory activity toward VIM-2, while no inhibitory activity against NDM-1 was observed despite the high dosage. The elongated methylene chains of HHIAs seem to play a crucial role in exerting inhibitory activity because itaconic acid, a structural analog without long methylene chains, did not show inhibitory activity against IMP-1. The addition of HHIAs restored meropenem and imipenem efficacy to satisfactory clinical levels against IMP-type MBL-producing Escherichia coli and Klebsiella pneumoniae clinical isolates. Unlike EDTA and Aspergillomarasmine A, HHIAs did not cause the loss of zinc ions from the active site, resulting in the structural instability of MBLs. X-ray crystallography and in silico docking simulation analyses revealed that two neighboring carboxylates of HHIAs coordinated with two zinc ions in the active sites of VIM-2 and IMP-1, which formed a key interaction observed in MBL inhibitors. Our results indicated that HHIAs are promising for initiating the design of potent inhibitors of IMP-type MBLs.IMPORTANCEThe number and type of metallo-β-lactamase (MΒL) are increasing over time. Carbapenem resistance conferred by MΒL is a significant threat to our antibiotic regimen, and the development of MΒL inhibitors is urgently required to restore carbapenem efficacy. Microbial natural products have served as important sources for developing antimicrobial agents targeting pathogenic bacteria since the discovery of antibiotics in the mid-20th century. MΒL inhibitors derived from microbial natural products are still rare compared to those derived from chemical compound libraries. Hydroxyhexylitaconic acids (HHIAs) produced by members of the genus Aspergillus have potent inhibitory activity against clinically relevant IMP-type MBL. HHIAs may be good lead compounds for the development of MBL inhibitors applicable for controlling carbapenem resistance in IMP-type MBL-producing Enterobacterales.

Suberoylanilide Hydroxamic Acid Analogs with Heteroaryl Amide Group and Different Chain Length: Synthesis and Effect on Histone Deacetylase.

This review covers the last 25 years of the literature on analogs of suberoylanilide hydroxamic acid (SAHA, known also as vorinostat) acting as an HDAC inhibitor. In particular, the topic has been focused on the synthesis and biological activity of compounds where the phenyl group (the surface recognition moiety, CAP) of SAHA has been replaced by an azaheterocycle through a direct bond with amide nitrogen atom, and the methylene chain in the linker region is of variable length. Most of the compounds displayed good to excellent inhibitory activity against HDACs and in many cases showed antiproliferative activity against human cancer cell lines.

Enhanced energy storage characteristics of the epoxy film with rigid phenyl-flexible etherified methylene chains

The introduction of highly polarized flexible segments into polymer molecular chains is an effective means to improve the dielectric constant and mechanical flexibility of polymers, which is important for improving the energy storage characteristics and applicability for the roll-to-roll process of metallic film capacitors. However, the introduction of flexible segments may adversely affect the heat resistance of polymer materials, which limits their application at high working temperatures. In this work, we have prepared a novel epoxy film with excellent comprehensive properties by introducing rigid phenyl and flexible etherified methylene side chains. For instance, the optimal epoxy film showed an energy storage density of 7.06 J cm–3 and 85% charge-discharge efficiency at room temperature and 420 kV mm–1. At 200 kV mm–1 and 110 °C, a working condition for the application of the electric vehicle, the prepared film still showed an energy storage density of 1.5 J cm–3 and charge-discharge efficiency of 86%, which is 3 times that of BOPP film. This work provides an idea for material designs of high-performance polymer film capacitors.

Periphery engineering to enhance the chiroptical response of β-isoindigo-based aza-BODIPY analogs

Helicene-type compounds possess appealing chiroptical features, but most helicenes typically show chiroptical response primarily in the ultraviolet region. In our earlier research, we developed a series of helical β-isoindigo-based B–O–B bridged aza-BODIPY analogs (BIABs), which exhibited strong absorbing/emission at the red/NIR region. However, BIABs with less π-extension had low Cotton effect (Δε = 1.3 M−1cm−1) and absorbance dissymmetry factor (gabs = 3 × 10-5) values. Herein, we reported a simple strategy to boost chiroptical response by introduction of alkyl chain (methyl or ethyl) at the periphery of the BIAB core. The resulting BIAB derivative displayed strong Cotton effect (Δε = 49 M−1cm−1) and absorbance dissymmetry factor (gabs = 1.69 × 10-3), resulting in 38 and 56-fold enhancement compared with BIAB core, respectively. This strategy is expected to offer a new opportunity to boost chiroptical response.

Synthesis and Performance of Biobased Surfactants Prepared by the One-Pot Reductive Amination of l-Arabinose and d-Galacturonic Acid.

Herein, we report a method for the synthesis of biobased surfactants derived from sugar beet pulp (SBP) monosaccharides, l-Ara and d-GalA. The surfactants were prepared via one-pot reductive amination, allowing the introduction of different alkyl chain lengths and methyl modifications. Optimal reaction conditions were established to achieve high yields and easy purification. The synthesized surfactants including the tertiary amines exhibited desirable properties, including solubility, foamability, and reduction of surface tension. Notably, the anionic surfactants derived from d-GalA demonstrated better solubility and foam performance compared to those derived from l-Ara. In addition, these surfactants exhibited surface tension and critical micelle concentration (CMC) comparable to those of the commercial surfactant sodium lauryl ether sulfate (SLES). Furthermore, the biodegradable surfactant GalA1.8 displayed excellent emulsifying properties and low skin irritation potential. On the l-Ara surfactant with a short chain, Ara1.6 has potential as a hydrotrope. These findings suggest that biobased surfactants derived from SBP monosaccharides have promising applications in various industries, including pharmaceuticals, cosmetics, detergents, and chemicals.

Crystal structures and conformational effects in bis-fluorenyl based ligands and related ruthenium nitrosyl complexes

Four crystal structures (two ruthenium complexes and two ligands) are presented containing a bis-fluorene fragment on which alkyl chains (methyl and hexyl) are grafted. The possibility to get both cisoid and transoid conformations in the bis-fluorene units is discussed. A computational investigation using the density functional theory indicates a tendency for a gradual stabilization of the cisoid form, as the length of the chains increases. The effect of the conformation on the charge transfer electronic properties of bis-fluorene based materials is discussed computationally at one-photon absorption (OPA) level and tentatively at two-photon absorption (TPA) levels, but it is found to be modest.