NMR Techniques Research Articles

Experimental study on the dynamic evolution of rock pore structure in real-time monitoring based on nuclear magnetic resonance

The rock structure determines the stability and reliability of underground engineering. Great achievements have been made in the study of rock structural damage, but there are few studies on real-time monitoring of rock structural changes under different increasing and unloading decreasing pressures. In this paper, the dynamic evolution rule of pore structure in rock under the combined action of water pressure and different confining pressure of increasing and decreasing is monitored by NMR technique. The porosity and permeability of rock under different confining pressures are consistent. The increase of confining pressure leads to the closure of pores, which leads to the decrease of porosity and permeability, but the amplitude and time of change are different. During the process of decreasing confining pressure, the T2 spectral curve, porosity and permeability of the rock did not fully recover due to the reduction of confining pressure, indicating that plastic deformation occurs inside the rock at this time. The mathematical relationship between porosity and permeability is established, and the permeability of rock is not only related to the size of porosity, but also closely related to the pore structure of rock.

Novel ferrocene cyclopalladated compounds: Synthesis, and in‐vitro antitumor activity study

AbstractMetal complexes have a significant impact on the treatment of human cancer. However, the scarcity of these compounds, resulting from their limited synthesis, hinders the comprehensive investigation of their anticancer mechanisms. Organic palladium compounds, known for their distinctive stability and properties, are thus an essential area of research in the development of anti‐tumor therapy. In our study, we synthesized two novel ferrocene cyclopalladated compounds (C2 and C4). Its configuration was thoroughly characterized by employing 1H, 13C NMR, ESI‐MS, and elemental analysis techniques. The molecular structures were determined by X‐ray single‐crystal diffraction. In an in vitro anticancer study, it was observed that both C2 and C4 exhibited excellent suppression of viability in various tumor cell lines. These compounds showed better potency than cisplatin and demonstrated lower toxicity in normal cells. Particularly, C4 displayed approximately 22 times greater potency than cisplatin in suppressing melanoma cells (B16F10). Our study suggests that ferrocene cyclopalladated compounds have the potential to be promising candidates for the development of innovative anticancer drugs.

Enhanced anticancer activity of (–)-epigallocatechin-3-gallate (EGCG) encapsulated NPs toward colon cancer cell lines

(–)-Epigallocatechin-3-gallate (EGCG), a bioactive polyphenol of green tea, has chemo-preventive effects against various cancer cells. Nanoparticles (NPs) carrying different ligands are able to specifically interact with their receptors on different cancer cells that can provide effective release of cytotoxic drugs. In the present study, we have prepared EGCG entrapped NPs using PLGA (poly(d,l-lactide-co-glycolide)). Polyethylene glycol (PEG) and folic acid (FA) via double emulsion solvent evaporation (DESE) method obtained PLGA-EGCG (P-E), PLGA-PEG-EGCG (PP-E), and PLGA-PEG-FA-EGCG (PPF-E). Nanoformulations had been characterized with 1H NMR and FT-IR techniques, AFM, and DLS. PPF-E NPs showed an average size of 220 nm. Analysis of zeta potential confirmed the stability of NPs. HCT-116, HT-29, HCT-15, and HEK 293 cells were treated with both the prepared NPs and free EGCG (0–140 μM). Result showed PPF-E NPs had improved delivery, uptake and cell cytotoxicity toward human folic acid receptor-positive (FR+) colorectal cancer (CRC) cells as mainly on HCT-116 compared to HT-29, but not on the folic acid-negative cells (FR−) as HCT-15. PPF-E NPs enhanced intracellular reactive oxygen species (ROS) level in absence of N-acetyl-l-cysteine (NAC), elevated DNA fragmentation level, and increased apoptotic cell death at higher doses compared to other two NPs and free EGCG. In conclusion, PPF-E NPs exerted greater efficacy than PP-E, P-E, and free EGCG in HCT-116 cells.

Unambiguous Characterization of Commercial Natural (Dihydro)phenanthrene Compounds Is Vital in the Discovery of AMPK Activators.

These days, easy access to commercially available (poly)phenolic compounds has expanded the scope of potential research beyond the field of chemistry, particularly in the area of their bioactivity. However, the quality of these compounds is often overlooked or not even considered. This issue is illustrated in this study through the example of (dihydro)phenanthrenes, a group of natural products present in yams, as AMP-activated protein kinase (AMPK) activators. A study conducted in our group on a series of compounds, fully characterized using a combination of chemical synthesis, NMR and MS techniques, provided evidence that the conclusions of a previous study were erroneous, likely due to the use of a misidentified commercial compound by its supplier. Furthermore, we demonstrated that additional representatives of the (dihydro)phenanthrene phytochemical classes were able to directly activate AMPK, avoiding the risk of misinterpretation of results based on analysis of a single compound alone.

N-heterocyclic carbene promoted one-pot synthesis of 1,2-diols and ɑ-Hydroxyketones from simple aldehydes

The α-hydroxyketones and 1,2-diols are versatile building blocks for the preparation of many natural and synthetic bioactive compounds. In this study, N-heterocyclic carbon (NHC) promoted coupling of several aldehydes with formaldehyde enabled the synthesis of 1,2-diols in moderate to high yields. The highly selective conversion of several aldehydes and formaldehyde into 1,2-diols and α-hydroxyketones was achieved in a one-pot two-step process via [BHMIm][OAc] as a key intermediate. In the first step, formaldehyde was quantitatively converted to [BHMIm][OAc] through the carbene addition. In the second step, 1,2-diol was produced through the intermediate-promoted aldol reaction. The results showed that benzaldehyde was capable to react with [BHMIm][OAc] efficiently, with a 54.1% yield of 1,2-diol after the 3-hour reaction at 85 °C. Among the tested benzaldehyde derivatives, the 4-nitrobenzaldehyde showed the highest yield of 1,2-diol (73.3%) under the optimized reaction conditions. Incorporation of an electron rich group on benzaldehyde promoted carbene regeneration. With 4-methoxybenzaldehyde as the substrate, the yield of α-hydroxyketone reached a maximum of 30.6%. Additionally, dihydroxyacetone derivatives were detected in the system. In situ NMR technique confirmed that it was generated from the further reaction of the carbene/1,2-diol complex with another aldehyde. Based on the results of NMR spectroscopy and mass spectrometry, a possible reaction pathway was also proposed.

Synthesis, characterization, computer-aided docking studies, and anti-fungal activity of two-armed quinazolin-2,4‑dione derivatives

A new series of two-armed quinazolin-2,4-diones incorporating N- heterocyclic moieties such as β-lactam, piperidine and/or morpholine, 2-thioxo imidazolidin-4-one and 2-iminothiazolidin-4-one 2–7 were designed and synthesized as attractive anti-fungal scaffolds. The structural elucidation of newly compounds was performed by means of FT-IR, 1H NMR, 13C NMR and MS techniques. Subsequently, the newly synthesized compounds were screened for their antifungal activity against Candida albicans via measuring the inhibition zone diameter around the fungal growth. The results obtained revealed varied response activity toward the tested fungal pathogen. Three most potent compounds 1, 3, and 4 exhibited noted inhibitory effects. Since, there was found superiority of the compound 1 in terms of inhibition zone diameter (mm) about the standard drug (i.e. Amphotericin B). Additionally, the MIC value was assessed for the potent compounds using different concentrations (5–400 μg/mL). A significant MIC value (20 μg/mL) was recorded for compound 1. Moreover, the molecular docking simulation was performed against sterol 14-alpha demethylase. In particular, compound 1 exhibited the best binding profile among the synthesized compounds (- 13.6 kcal/mol), followed by compounds 3 (-12.7 kcal/mol) and 4 (-11.9 kcal/mol). The structure activity relationship revealed the importance of electron withdrawing groups (chlorine atoms) on biological activity of compounds. Further, the eight compounds exhibited good ADMET profile and satisfied the Lipinski rule of drug likeness.

Synthesis, Characterization, Antimicrobial and In Silico Studies of Isatin Schiff Base Linked 1,2,3-Triazole Hybrids.

A new series of isatin-Schiff base linked 1,2,3-triazole hybrids has been synthesized using CuAAC approach from (E)-3-(phenylimino)-1-(prop-2-yn-1-yl)indolin-2-one derivatives in high yield (73-91 %). These synthesized derivatives were characterized using FT-IR, 1H NMR, 13C NMR, 2D-NMR and HRMS spectral techniques. The in vitro antimicrobial activity assay demonstrated that most of the tested hybrids exhibited promising activity. Compound 5 j displayed significant antibacterial efficacy against P. aeruginosa and B. subtilis with MIC value of 0.0062 μmol/mL. While, 5 j also showed better antifungal potency against A. niger with MIC value of 0.0123 μmol/mL. The docking studies of most promising compounds were performed with the well-known antibacterial and antifungal targets i. e. 1KZ1, 5TZ1. Molecular modelling investigations demonstrated that hybrids 5 h and 5 l exhibited good interactions with 1KZN and 5TZ1, with binding energies of -9.6 and -11.0 kcal/mol, respectively. Further, molecular dynamics studies of the compounds showing promising binding interactions were also carried out to study the stability of complexes of these hybrids with both the targets.

Preparation of barium alumino-silicate based ceramsite from bauxite, coal gangue and barite: Physical properties, microstructure, and γ-ray shielding behavior

Improving the strength of radiation shielding concrete and the safety of corresponding structures is crucial. However, radiation shielding ultra-high performance concrete (RS-UHPC) often faces the issues of high volume shrinkage and easy cracking. Using barium alumino-silicate-based ceramic as aggregate in concrete is a promising solution for its internal curing effect and excellent radiopacity. In this study, a barium alumino-silicate-based ceramsite (BASC) was developed using bauxite, coal gangue, and barite. The effects of boric anhydride (2 %, 5 %, 8 %), barite powder dosages (20 %, 40 %, 60 %, 80 %), and sintering temperature (1260°C, 1280°C, 1300°C, 1320°C) on the apparent density, compressive strength, and water absorption of the ceramsite were investigated. The microstructure and reaction mechanism of the BASC were analyzed using TG-DSC, XRD, SEM-EDS, and low-field NMR techniques. The results showed that the addition of barite increases the apparent density of ceramsite but decreases its strength. The ceramsite with 60 % barite calcined at 1320°C has a density of 3120 kg/m3, water adsorption of 11.19 %, and a cylinder compressive strength of 11.2 MPa. The prepared BASC ceramsite exhibits a highly connected pore structure and good water retention capacity at this temperature. The ceramsite has many closely packed celsian and corundum crystallites, which give it good mechanical strength. Finally, the gamma-ray attenuation and autogenous shrinkage of UHPC prepared with this ceramsite was tested. The linear attenuation coefficient of the BASC-UHPC is 0.176 cm−1, comparable to UHPC prepared with lead glass. The BASC replacement for quartz sand reduces the 28d autogenous shrinkage of UHPC by 55.0 %. The research results can guide the application of BAS-based ceramsite in radiation-shielding ultra-high performance concrete.

Study on durability of concrete under alternating positive and negative temperature curing in plateau area

In order to investigate the durability of concrete under alternating curing from −20℃ to 20℃, different antifreeze (JB-1 type/HD-type) and different dosages (1.5 wt%/2 wt%) were chosen to carry out the study. This study used a variety of tests such as rapid freeze-thaw test, freeze-thaw-sulfate coupling test, dry and wet cycle test, electrical flux test, and drying shrinkage test, combined with NMR techniques, to comprehensively evaluate the properties and pore structure of the concrete. The results show that adding antifreeze can optimize concrete durability and pore structure under alternating curing from −20°C to 20°C. This study showed that 1.5 wt% was the optimal dose to maximize the improvement of concrete durability. Comparative analysis revealed that JB-1 type antifreeze is superior to HD-type antifreeze in enhancing the frost resistance, the freeze-thaw-sulfate coupling resistance, and the chloride ion permeation resistance of concrete, which is manifested in the relative dynamic modulus of elasticity increase of 1.5 %, compressive strength increase of 1.5 MPa, mass loss decrease of 0.12 % and electric flux decrease of 86 C. In-depth investigation reveals that the JB-1 type antifreeze agent promotes the generation of C-S-H gel by accelerating the hydration process of concrete, fills and shrinks the micropores of concrete, reduces the porosity, and improves the microstructure. However, over-addition has a reverse effect, which enhances the content of tiny bubbles and leads to a 2.4 % decrease in the relative dynamic modulus of elasticity of concrete. Meanwhile, the increase in porosity leads to an increase in the electrical flux of concrete by 151 C and shrinkage by 17.2 μm.

Structural and Property Characterizations of Dual-Responsive Core-Shell Tecto Dendrimers for Tumor Penetration and Gene Delivery Applications.

Core-shell tecto dendrimers (CSTDs) with excellent physicochemical properties and good tumor penetration and gene transfection efficiency have been demonstrated to have the potential to replace high-generation dendrimers in biomedical applications. However, their characterization and related biological properties of CSTDs for enhanced tumor penetration and gene delivery still lack in-depth investigation. Herein, three types of dual-responsive CSTDs are designed for thorough physicochemical characterization and investigation of their tumor penetration and gene delivery efficiency. Three types of CSTDs are prepared through phenylborate ester bonds of phenylboronic acid (PBA)-decorated generation 5 (G5) poly(amidoamine) (PAMAM) dendrimers as cores and monose (galactose, glucose, or mannose)-conjugated G3 PAMAM dendrimers as shells and thoroughly characterized via NMR and other techniques. It is shown that the produced CSTDs display strong correlation signals between the PBA and monose protons, similar hydrodynamic diameters, and dual reactive oxygen species- and pH-responsivenesses. The dual-responsive CSTDs are proven to have structure-dependent tumor penetration property and gene delivery efficiency in terms of small interference RNA for gene silencing and plasmid DNA for gene editing, thus revealing a great potential for different biomedical applications.

Synthesis of palm oil-based bio-polyol by thiol-ene reaction: Preliminary study of its potential as cationic waterborne polyurethane for coating application

Thailand has the world's third-largest planting area for oil palm. Palm oil can be chemically modified to obtain bio-polyol instead of petroleum-based polyol. In this research, a new bio-polyol based on modified palm oil (MPO) was successfully synthesized by thiol-ene click reaction using Darocur1173 as a photoinitator. The molar ratios 2-Mercaptoethanol (ME) to carbon‑carbon double bonds for MPO synthesis was studied. The kinetics of the thiol-ene click reaction was investigated by monitoring with 1H NMR technique. The chemical structure of MPO was confirmed by 1HNMR and FTIR spectroscopy. In addition, the average molecular weight (Mn) of a series of MPO was determined by GPC. The influence of N-methyl diethanolamine (NMDEA) content as an internal emulsifier on cationic waterborne polyurethane (cWPU) was investigated. The resulting cWPU based on MPO showed well-dispersed particles with a shelf life of >6 months and the zeta potential increased with increasing NMDEA content ranging from 5.6 % to 9.6 %wt. Moreover, the plywood with cWPU coatings had a shiny gloss surface, with increasing NMDEA content. The cWPU coating with NMDEA content lower than 7.6 %wt protected the plywood surface against QUV accelerated weathering for 48 h without cracking the cWPU film. The cWPU showed a high gloss value, decreased contact angle, and increased water absorption behavior. The hydrophilicity of cWPU film increased with increasing NMDEA content. Also, increasing the NMDEA content led to a higher ratio of hard segment to soft segment in the PU chain which improved the tensile strength and thermal stability. These results demonstrated an efficient synthesis procedure which offers an opportunity to use palm oil as bio-polyol to develop green cWPU that can be used as a binder in coating applications.

Utilization of 13C NMR Carbon Shifts for the Attribution of Diastereomers in Methyl-Substituted Cyclohexanes.

In this report, we address the challenge of assigning diastereomers for methyl cyclohexanes, particularly those with quaternary centers, which remains nontrivial despite modern NMR techniques. By utilizing a HSQC NMR experiment to identify methyl-carbons coupled with a simple conformational analysis, we identified an effective and quite general method for assigning stereochemistry, even in cases where diastereomeric mixtures are inseparable.

Phytochemical profiling and therapeutic potential of Baliospermum montanum: A promising inhibitor of COX-2/15-LOX enzymes and NO production in LPS-stimulated RAW 264.7 macrophages

IntroductionBaliospermum montanum (BM) is traditionally used to treat various ailments such as inflammation, rheumatoid arthritis, pain, etc. The root part of BM is well documented for its anti-inflammatory activity. However, the present study evaluates the multitargeted anti-inflammatory activity of the less explored BM leaf part. This is the first study investigating the COX-2, 15-LOX dual inhibiting potential and NO production inhibition of BM leaf extracts, fractions and compounds. MethodsThe BM leaf's water, ethanol, and hydroethanolic extracts were evaluated for anti-inflammatory activity by assessing the inhibition of COX-2, 15-LOX, and NO production. Additionally, the antioxidant potential of the extracts was determined through DPPH, ABTS, and FRAP assays. The most active ethanol extract was fractionated into 12 fractions and tested for anti-inflammatory, antioxidant, phenol and flavonoid content. Compounds were isolated from the most active fractions and identified using NMR techniques. The isolated compounds were checked for their anti-inflammatory activity. In addition, HPLC analysis of ethanol extract, fractions, and isolated compounds was carried out. ResultsThe ethanol extract exhibited higher inhibition of COX-2, 15-LOX enzymes and NO production (IC50 35.75 ± 1.95 μg/mL) in LPS-treated RAW 264.7 cells. It also showed higher antioxidant activity. Following the fractionation of the ethanol extract using different solvents, only the ethyl acetate fractions demonstrated inhibition of COX-2, 15-LOX enzymes, and NO production. The ethyl acetate and acetone fractions are excellent sources of antioxidants, phenolic and flavonoid compounds. An effort to find the active principles from these ethyl acetate fractions resulted in the isolation and identification of four potent anti-inflammatory agents, namely, (-)-epiafzelechin, afzelechin-(4α→8)-afzelechin, afzelechin-(4α→8)-epiafzelechin and β-sitosterol-d-glycoside. The first three compounds were reported for the first time from this plant and afzelechin-(4α→8)-afzelechin was found to be a potent inhibitor of the COX-2/15 LOX enzyme as well as NO production (IC50 = 5.9 ± 1.09 µM). ConclusionBased on these findings, we conclude that ethanol extract, fractions, and isolated compounds exert anti-inflammatory activity through multiple therapeutic mechanisms. The present study scientifically supports the traditional use of plant BM for treating inflammation and other related disorders.

Digital light processing 3D printing of polymerizable ionic liquids towards carbon capture applications

This study presents new 3D printable materials based on ad-hoc synthesized photocurable imidazolium ionic liquids (ILs) with bis(trifluoromethanesulfonyl)imide (NTf2)− as counterion and two different alkyl chain's structures at the cation, with enhanced CO2 capture properties. The molecular structure of the synthesized ILs was confirmed through NMR technique and a polymerization study was carried out, by means of photorheological tests and FT-IR analyses, on formulations containing a crosslinking monomer (PEGDA). The study confirmed the good reactivity of the formulations that makes them suitable for digital light processing (DLP) 3D printing technique. Simple membranes were then tested through high pressure CO2 uptake analysis to estimate their capture efficiency, comparing the results with the standard room temperature ionic liquid (RTIL) counterpart, and evidencing an increase of CO2 absorption regardless the pressure applied. At last, complex gyroid-like structures incorporating the synthesized ILs were successfully 3D printed, showing the remarkable ability of these materials to be processed with 3D printing technology while maintaining the great CO2 capture performances of ionic liquids. This preliminary work paves the way for the implementation of “ad-hoc” designs to create filters or devices to enhance the CO2 capture.

RGB-algorithm whiteness appraisal approach for quantitative determination of clopidogrel and aspirin in presence of salicylic acid as a degradation product based on proton NMR technique

A rapid, precise, and selective spectroscopic method based on the quantitative proton nuclear magnetic resonance (1H-qNMR) was developed to estimate aspirin and clopidogrel in their pharmaceutical dosages for the first time. The evolved method was utilized to estimate both drugs in presence of the aspirin degradation product, salicylic acid. Moreover, aspirin and clopidogrel were subjected to various stress conditions such as acid hydrolysis, alkali hydrolysis, water hydrolysis, H2O2 oxidation, and photodecomposition for studying the stability of both compounds under these stress conditions. The 1H-qNMR analyses of the analytes of interest were conducted using the internal standard phloroglucinol and the solvent dimethyl sulfoxide-d6. The NMR spectra showed a quantitative doublet of doublets (dd) signal of aspirin at 7.945 ppm, a doublet signal of clopidogrel at 6.875 ppm, and a dd signal of salicylic acid at 7.810 ppm. The internal standard phloroglucinol exhibited a singlet signal at 5.690 ppm. The results demonstrated the linearity (r2 > 0.999), accuracy, precision (RSD < 2.0 %), stability, selectivity, and specificity of the evolved method. Linearity was confirmed in the ranges of 0.05–3.0 mg/mL for aspirin, 0.15–10.0 mg/mL for clopidogrel, and 0.1–5.0 mg/mL for salicylic acid. The evolved method was efficiently applied to analyse aspirin and clopidogrel in their dosages with high %recovery. Moreover, The RGB algorithm technique was used to evaluate the whiteness profile of the suggested method; the findings confirmed the sustainability of the evolved method, which employed an ecological solvent, followed a simple and straightforward procedure, and avoided any pretreatment or labelling stages for the samples. All the aforementioned advantages gave the technique the privilege.

Oxidation product of 5-methyltetrahydrofolate: Structure elucidation, synthesis, and biological safety evaluation

Impurity control is essential as impurities can diminish the biological activity, increase the toxicity, and affect the clinical efficacy of drugs. This study elucidated the structure of (4-((4aS,7R)-2-amino-10-methyl-4-oxo-3,6,7,8-tetrahydro-4a,7-epiminopyrimido[4,5-b][1,4]diazepin-5(4H)-yl)benzoyl)-l-glutamic acid (JK12A), an oxidative impurity of 5-methyltetrahydrofolic acid (5-mTHF), using NMR and HRMS techniques. The biological safety of JK12A was assessed using a zebrafish assay, evaluating its impact on genes critical for cardiac development through qRT-PCR analysis. The findings demonstrated that JK12A adversely influenced the growth of zebrafish embryos and altered both the heart rate and survival rate in a dose-dependent manner. Additionally, the expression levels of cardiac development-related genes (has2, hand2, mef2a, and nkx2.5) exhibited significant changes upon exposure to various concentrations of JK12A at different time points.

Identification and characterization of the rat in-vivo and in-vitro metabolites of tazemetostat using LC-QTOF-MS

In drug discovery, metabolite profiling unveils biotransformation pathways and potential toxicant formation, guiding selection of candidates with optimal pharmacokinetics and safety profiles. Tazemetostat (TAZ) is employed in treating locally advanced or metastatic epithelioid sarcoma. Identification of drug metabolites are of significant importance in improving safety, efficacy and reduced toxicity of drugs. The current study aimed to investigate the comprehensive metabolic fate of TAZ using different in vivo (rat) and in vitro (RLM, HLM, HS9) models. For in vivo studies, drug was orally administered to Sprague–Dawley rats with subsequent analysis of plasma, feces and urine samples. A total of 21 new metabolites were detected across various matrices and were separated on Phenomenex kinetex C18 (2.5 μm; 150 × 4.6 mm) column using acetonitrile and 0.1% formic acid in water as mobile phase. LC-QTOF-MS/MS and NMR techniques were employed to identify and characterize the metabolites from extracted samples. The major metabolic routes found in biotransformation of TAZ were hydroxylation, N-dealkylation, N-oxidation, hydrogenation, hydrolysis and N-acetylation. In silico toxicity revealed potential immunotoxicity for TAZ and few of its metabolites. This research article is the first time to discuss the complete metabolite profiling including identification and characterization of TAZ metabolites as well as its biotransformation mechanism.

Coal-Based Branched Vicinal Diol Ethoxylates Versus Guerbet Alcohol Ethoxylates: Role of Tertiary Hydroxyl Groups.

Branched surfactants exhibit a lower surface tension, excellent low defoaming performance, and better wetting ability compared with linear surfactants, making them promising for applications in industrial cleaning. In this study, 2-hexyl-1-decene (C8 olefin dimer), obtained from the dimerization of 1-octene, was used as the hydrophobe to synthesize branched nonionic surfactants via hydroxylation and ethoxylation. The hydroxylation of the C8 olefin dimer to synthesize 2-hexyldecane-1,2-diol (C8 BD) using H2O2 and HCOOH was investigated systematically. Under the optimal reaction conditions (H2O2/C8 olefin dimer molar ratio: 1.5, HCOOH/C8 olefin dimer molar ratio: 4.0, reaction time: 10 h, reaction temperature: 50 °C), the conversion of the C8 olefin dimer and selectivity toward C8 BD were found to reach 99.96 and 79.89%, respectively. Further, branched nonionic surfactants (C8 BDEn) were synthesized via ethoxylation of C8 BD with ethylene oxide and characterized using FTIR, LCMS, 1H NMR, and 13C NMR techniques. The presence of a tertiary hydroxyl group in C8 BD increases the reactivity of the primary hydroxyl group, leading to a narrower range of products and lower residual substrate content. The physicochemical properties and surface properties of C8 BDEn with different degrees of ethoxylation at various concentrations were investigated and compared with those of commercially available Guerbet alcohol polyoxyethylene ethers (C8 GAEO9 and C6 GAEO9). The results show that, compared with C8 GAEO9 and C6 GAEO9, C8 BDE6 displayed a higher surface activity with a lower equilibrium surface tension (27.14 mN·m-1), superior wettability with a smaller contact angle (39.2°), better emulsification performance with a longer emulsification time of 548 s, and excellent foaming properties (initial foam volume of 11.6 mL). This strategy of utilizing coal-based α-olefins for the synthesis of branched nonionic surfactants presents a route to prepare value-added fine chemicals from coal-based resources.

Dynamics of Coordinated Phosphonate Group Directly Observed by 17O-NMR in Lanthanide(iii) Complexes of a Mono(ethyl phosphonate) DOTA Analogue.

Biological phosphates can coordinate metal ions and their complexes are common in living systems. Dynamics of mutual oxygen atom exchange in the tetrahedral group in complexes has not been investigated. Here, we present a direct experimental proof of exchange ("phosphonate rotation") in model Ln(III) complexes of monophosphonate H4dota analogue which alters phosphorus atom chirality of coordinated phosphonate monoester. Combination of macrocycle-based isomerism with P-based chirality leads to several diastereoisomers. (Non)-coordinated oxygen atoms were distinguished through 17O-labelled phosphonate group and their mutual exchange was followed by various NMR techniques and DFT calculations. The process is sterically demanding and occurs through bulky bidentate (κ2-PO2)- coordination and was observed only in twisted-square antiprism (TSA) diastereoisomer of large Ln(III) ions. Its energy demands increase for smaller Ln(III) ions (298ΔG≠(exp./DFT)=51.8/52.1 and 61.0/71.5 kJ mol-1 for La(III) and Eu(III), respectively). These results are helpful in design of such complexes as MRI CA and for protein paramagnetic NMR probes. It demonstrates usefulness of 17O NMR to study solution dynamics in complexes involving phosphorus acid derivatives and it may inspire use of this method to study dynamics of phosphoric acid derivatives (as e. g. phosphorus acid-based inhibitors of metalloenzymes) in different areas of chemistry.

Elastin-Like Peptide as a Model for Disordered Proteins: Diffusion Behaviour in Self-Crowding Conditions.

Despite the current high interest, there is limited information on diffusion data for intrinsically disordered proteins (IDPs). This study investigates the effect of crowding on the diffusion behaviour of an elastin-like peptide (ELP), by combined pulse field gradient (PFG) and static field gradient (SFG) NMR techniques. We interpret our findings in terms of highly dynamic chain assemblies with weak interactions, resulting in ELP diffusion that is primarily governed by the viscous flow of the solvent. The diffusion behaviour of the peptide appears to resemble that of globular proteins rather than flexible linear polymers over a wide concentration range.