P-toluenesulfonic Acid Research Articles

A practical protocol for large-scale copper-mediated radioiodination of organoboronic precursors: Radiosynthesis of [123 I]KX-1 for Auger radiotherapy.

Nucleophilic copper-mediated radioiodination (CMRI) of organoboronic precursors with radioiodides is a promising method of radioiodination. The previously reported CMRI has demonstrated its great potential and scope of labeling for the radiosynthesis of radioiodine-labeled compounds. However, the reported protocols (using a small amount/volume of radioactivity) are practically not reproducible in large-scale CMRI, in which the radioactivity was usually provided in a bulk alkaline solution. A large amount of water and a strong base are incompatible with CMRI. To overcome these issues in large-scale CMRI, we have developed a simple protocol for large-scale CMRI. The bulk water was removed under a flow of inert gas at 110°C, and the strong base (i.e., NaOH) was neutralized with an acid, pyridinium p-toluenesulfonate or p-toluenesulfonic acid. In the model reactions of [123 I]KX-1, a PARP-1 radioligand for Auger radiotherapy, radiochemical conversions were significantly improved after neutralization of the base, and the addition of additional acids was tolerated and favorable for the reactions. Using this protocol, [123 I]KX-1 was radiosynthesized from 20 mCi (0.74 GBq) of [123 I]iodide in high radiochemical yields, high radiochemical purity, and high molar activity. This protocol should be applicable to the radiosynthesis of other compounds with radioiodine via CMRI.

Blue Electrophosphorescence from Iridium(III) Phosphors Bearing Asymmetric Di-N-aryl 6-(trifluoromethyl)-2H-imidazo[4,5-b]pyridin-2-ylidene Chelates.

Efficient blue phosphors remain a formidable challenge for organic light-emitting diodes (OLEDs). To circumvent this obstacle, a series of Ir(III)-based carbene complexes bearing asymmetric di-N-aryl 6-(trifluoromethyl)-2H-imidazo[4,5-b]pyridin-2-ylidene chelates, namely, f-ct6a‒c, are synthesized, and their structures and photophysical properties are comprehensively investigated. Moreover, these emitters can undergo interconversion in refluxing 1,2,4-trichlorobenzene, catalyzed by a mixture of sodium acetate (NaOAc) and p-toluenesulfonic acid monohydrate (TsOH·H2O) without decomposition. All Ir(III) complexes present good photoluminescence quantum yield (ΦPL = 83-88%) with peak maximum (max.) at 443-452nm and narrowed full width at half maximum (FWHM = 66-73nm). Among all the fabricated OLED devices, f-ct6b delivers a max. external quantum efficiency (EQE) of 23.4% and Commission Internationale de L'Eclairage CIEx , y coordinates of (0.14, 0.12), whereas the hyper-OLED device based on f-ct6a and 5H,9H,11H,15H-[1,4] benzazaborino [2,3,4-kl][1,4]benzazaborino[4',3',2':4,5][1,4]benzazaborino[3,2-b]phenazaborine-7,13-diamine, N7,N7,N13,N13,5,9,11,15-octaphenyl (ν-DABNA) exhibits max. EQE of 26.2% and CIEx , y of (0.12, 0.13). Finally, the corresponding tandem OLED with f-ct6b as dopant gives a max. luminance of over 10000 cd m-2 and max. EQE of 42.1%, confirming their candidacies for making true-blue OLEDs.

Solvometallurgical recycling of spent LiNixCoyMnzO2 (NCM) cathode material using ternary choline chloride-ethylene glycol-p-toluenesulfonic acid deep eutectic solvent

In recent years, recycling lithium-ion batteries (LIBs) has become imperative considering their growing demand will soon lead to massive disposal of spent LIBs which causes critical environmental problems. In this study, solvometallurgy using deep eutectic solvents (DESs) is used to efficiently recover valuable metals from spent LIBs. The potential of different types of DES (binary and ternary) to leach LIB samples is evaluated. Initial leaching tests demonstrate that p-toluenesulfonic acid (PTSA) -based DES results in high metal extraction at 100 °C with 10 g/L pulp density and 72 h residence time. Cyclic voltammetry indicates a high current density of PTSA, a strong leaching agent in the DES structure. A ternary DES containing choline chloride, ethylene glycol, and p-toluenesulfonic acid (ChCl-EG-PTSA) show better performance as a leachant than other DESs. The formation of hydrogen bonds between p-toluenesulfonic acid-based DES components is examined by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. This study provides a new ternary DES for solvometallurgical recycling of LIBs while considering principles for sustainable development.

Synthesis of 1-[Aryl(Selenoacetamido)Methyl]-2-Naphthol Derivatives via a Three-Component Condensation

I report a simple and efficient one-pot route for the synthesis of 1-[aryl(selenoacetamido)methyl]-2-naphthol derivatives from the condensation of 2-naphthol, an aryl aldehydes and selenoacetamide in the presence of catalytic amounts of p-toluenesulfonic acid (p-TSA) under reflux conditions. This new protocol offers advantages such as mild reaction conditions, short reaction time, easy work-up, and use of an inexpensive and nontoxic catalyst and good yields.

Fractionation of poplar wood with different acid hydrotropes: Lignin dissolution behavior and mechanism evaluation

Acid hydrotropes was considered a green medium for efficient wood fractionation at mild conditions. This study reported a comparative study on the dissolution of lignin in different acid hydrotropes, including p-toluenesulfonic acid (p-TsOH), 4-hydroxybenzenesulfonic acid (4-HSA), 5-sulfosalicylic acid (5-SSA), and maleic acid (MA). Under identical treatment conditions (80 °C, 60 min, and 70 % acid concentration), the removal of wood lignin varied significantly among four acid hydrotropes, 4-HSA exhibited the highest removal rate at 88.0 %, followed by p-TsOH at 81.2 %, 5-SSA at 51.1 %, and MA at 26.2 %. The molecular mechanism of the lignin dissolution was analyzed by quantum chemistry (QC) calculation and molecular dynamics (MD) simulation. The higher absorb free energy (E(absorb)) of the 4-HSA and veratrylglycerol-β-guaiacyl ether (VG) complex (E(absorb) = 17.97 kcal/mol), and the p-TsOH and VG complex (E(absorb) = 17.16 kcal/mol) contributed to a higher efficiency of lignin dissolution. Under the same level of lignin removal (~ 60 %), the four acid hydrotropes showed variations in the β-O-4 content of the extracted lignin: 4-HSA (3.1 %) < 5-SSA (10.4 %) < p-TsOH (15.9 %) < MA (63.7 %). The acidity and critical aggregation concentrations of acid hydrotropes were found to influence the content of β-O-4 bonds in the extracted lignin.

Postprocessing of solution-cast polyaniline for enhanced electrochemical properties

Commercially available solutions of polyaniline (PANI) stabilized with dinonylnaphthalene sulfonic acid (DNNSA) offer a convenient means of forming PANI films via solution casting that are of interest for energy storage and other electrochemical applications. Here, we study the electrochemical charge storage properties of 200–400 nm thick PANI films cast from PANI-DNNSA solutions before and after postprocessing steps. As-cast PANI-DNNSA films exhibit a specific capacitance of <20 F/g at a 50 mV/s sweep rate, which increases to >300 F/g after p-toluene sulfonic acid:butanol (pTSA:BuOH) and dibromopropane (PrBr2) treatments. Crosslinked PANI also exhibits a 25% improvement in capacity retention over un-crosslinked PANI after 500 charge/discharge cycles. The capacity, energy, and power of postprocessed PANI films is examined in a symmetric coin cell device, and the utility of soluble PANI is demonstrated by coating planar and porous substrates using spin coating, drop casting, and dip coating techniques. These studies inform the use of PANI-DNNSA to fabricate high-capacity electrochemical devices.

A ternary eutectic solvent for cellulose nanocrystal production: exploring the recyclability and pre-pilot scale-up.

Deep eutectic solvents (DES) formed using choline chloride (ChCl), p-toluenesulfonic acid (pTSA) of stoichiometry ChCl: pTSA (1:1) and (1:2), and its ternary eutectic mixtures with phosphoric acid (PA) 85% as an additive (ChCl: pTSA: PA) were evaluated for cellulose nanocrystal (CNC) isolation. Initially, the hydrolytic efficiency to produce CNC of each DES was compared before and after adding phosphoric acid by Hammett acidity parameters and the Gutmann acceptor number. Moreover, different DES molar ratios and reaction time were studied at 80°C for CNC optimization. The nanomaterial characteristics were analyzed by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The ternary eutectic mixture ChCl: pTSA: PA molar ratio (1:1:1.35) was chosen as a suitable recyclable ternary system at the laboratory scale. A CNC yield of about 80% was obtained from the hydrolysis of commercial cellulose in five cycles of recovery, but it dropped to 35% in pre-pilot scaling. However, no variation in the average size of the resulting CNC was observed (132 ± 50nm x 23 ± 4nm), which presented high thermal stability (Tmax 362°C) and high crystallinity of about 80% after 3h of reaction time.

Synthesis of Imidazo[1,2-a]pyridine-Fused 1,3-Benzodiazepine Derivatives with Anticancer Activity via a One-Pot Cascade GBB-3CR/Pd(II)-Catalyzed Azide-Isocyanide Coupling/Cyclization Process.

A new one-pot synthesis of imidazo[1,2-a]pyridine-fused 1,3-benzodiazepine derivatives via a sequential GBB-3CR/Pd(II)-catalyzed azide-isocyanide coupling/cyclization process was developed. The Groebke-Blackburn-Bienaymé three-component reactions (GBB-3CR) of 2-aminopyridine, 2-azidobenzaldehydes, and isocyanides in the presence of a catalytic amount of p-toluenesulfonic acid gave azide intermediates without separation. The reaction was followed by using another molecule of isocyanides to produce imidazo[1,2-a]pyridine-fused 1,3-benzodiazepine derivatives in good yields by the Pd(II)-catalyzed azide-isocyanide coupling/cyclization reaction. The synthetic approach produces novel nitrogen-fused polycyclic heterocycles under mild reaction conditions. The preliminary biological evaluation demonstrated that compound 6a inhibited glioma cells efficiently, suggesting potentially broad applications of the approach for synthesis and medicinal chemistry.

Cationic β-Scission of C-H and C--C Bonds for Selective Dimerization and Subsequent Sulfur-Free RAFT Polymerization of α-Methylstyrene and Isobutylene.

A series of exo-olefin compounds ((CH3)2C(PhY)-CH2C(=CH2)PhY) were prepared by selective cationic dimerization of α-methylstyrene (αMS) derivatives (CH2=C(CH3)PhY) with p-toluenesulfonic acid (TsOH) via β-C-H scision. They were subsequently used as reversible chain transfer agents for sulfur-free cationic RAFT polymerization of αMS via β-C-C scission in the presence of Lewis acid catalysts such as SnCl4. In particular, exo-olefin compounds with electron-donating substituents, such as a 4-MeO group (Y) on the aromatic ring, worked as efficient cationic RAFT agents for αMS to produce poly(αMS) with controlled molecular weights and exo-olefin terminals. Other exo-olefin compounds (R-CH2C(=CH2)(4-MeOPh)) with various R groups were prepared by different methods to examine the effects of R groups on the cationic RAFT polymerization. A sulfur-free cationic RAFT polymerization also proceeded for isobutylene (IB) with the exo-olefin αMS dimer ((CH3)2C(Ph)-CH2C(=CH2)Ph). Furthermore, telechelic poly(IB) with exo-olefins at both terminals was obtained with a bifunctional RAFT agent containing two exo-olefins. Finally, block copolymers of αMS and MMA were prepared via mechanistic transformation from cationic to radical RAFT polymerization using exo-olefin terminals containing 4-MeOPh groups as common sulfur-free RAFT groups for both cationic and radical polymerizations.

Synthesis and Characterization of Functionalized Polylactides Containing Acetal Units.

New functionalized lactide copolymers containing acetal units were prepared for the first time in a controlled manner that enabled the regulation of the number of reactive groups introduced into the polyester chain. The presence of functional groups in the copolymer backbone provided chemical modification sites, and the nature of the acetal unit affected the material degradability. First, paraformaldehyde was reacted with selected diols containing reactive pendant groups (3-allyloxypropane-1,2-diol and 3-chloropropane-1,2-diol), which was catalyzed by p-toluenesulfonic acid, to synthesize new cyclic acetals with different functionalities (allyl- or chloro-). In addition, using butane-1,4-diol, a nonfunctionalized seven-membered cyclic acetal (dioxepane) was obtained for comparative studies. In the next step, the prepared cyclic acetals were used for cationic copolymerization with lactide in the presence of glycol as an initiator and triflic acid as a catalyst. Different temperatures (-15, 2, and 30 °C) and copolymerization times (24, 48, 72, and 192 h) were investigated to produce copolyesters with variable contents of acetal units in the range of 5-27%. The copolymers' structure and molar masses were carefully investigated using 1H, 13C NMR, 2D NMR, and size-exclusion chromatography. Moreover, the ability of functionalized copolymers to perform post modifications was also proven by the reaction with sodium azide and propanethiol. Finally, we speculate that structurally diverse groups can be attached to the copolyester chain, fine-tuning the on-demand properties, which could rapidly expand the library of polylactide-based materials.

Preparation of spherical porous carbon from lignin-derived phenolic resin and its application in supercapacitor electrodes

Lignin is the most abundant aromatic biomass resource in nature and is the main by-product of paper industry and biorefinery industry, which has the characteristics of abundant source, renewable and low cost. Deep eutectic solvents (DES) are a nascent environmentally friendly solvent option that is gaining traction. DES composed of p-toluenesulfonic acid and choline chloride is used for batch treatment of alkaline lignin, and the bio-oil obtained is ternary polymerized with formaldehyde and phenol to obtain lignin phenolic resin. The porous carbon material is produced through a two-step carbonization process, utilizing phenolic resin derived from lignin as the primary source of carbon. The morphology and composition of the carbon were analyzed by SEM, TEM, XRD, TGA, XPS and Raman spectroscopy, the specific surface area and pore size distribution were analyzed by BET. The results showed that the specific surface area of the lignin-based phenolic resin was significantly higher than that of the pure phenolic resin carbon, and the porous carbon material that was acquired demonstrated a specific surface area of as much as 1026 m2/g. In the three-electrode system, the specific capacitance of DLPFC can reach 245.8 F/g (0.25 A/g), with a very small decrease in the value of specific capacitance at 10,000 cycles, with a retention of 97.62% (10 A/g). The porous carbon demonstrated a specific capacitance of 112.4 F/g at a current density of 0.5 A/g, and the capacitance retention rate could still reach 98.8% after 5000 charge/discharge cycles, with high cycling stability (in the two-electrode system). The prepared symmetrical supercapacitors exhibited high energy density and power density of 3.9 Wh/kg and 125.0 W/kg. The results suggest a new idea of high value-added application of lignin phenolic resin for high-performance supercapacitor electrodes.

Synthesis and characterization of acidic deep eutectic solvents based on p-Toluenesulfonic acid

There is growing interest in identifying suitable, less hazardous deep eutectic solvent (DES) alternatives for conventional solvents and catalysts, particularly acid catalysts which can be volatile and highly corrosive. In this study, novel acidic DESs based on mixtures of either tetrabutylammonium hydrogensulfate (TBAHS) (DES1) or tetraphenylphosphonium bromide (TPPB) (DES2) with p-toluenesulfonic acid monohydrate (PTSAM) are prepared. The properties of these DESs were investigated using multiple analytical techniques, including density, viscosity, conductivity and diffusion measurements. DES1 formed a room-temperature liquid, whereas DES2 melted at 337 K at its eutectic point. Hammett acidity studies revealed that both the DESs show super acidity (H0DES1 = -2.91 and H0DES2 = -1.89) even when present in relatively dilute (40 mM) aqueous solutions. Conductivity measurements established that both DESs show good ionicity at elevated temperatures based on a Walden plot, although DES2 displayed reduced ionicity close to its melting point. Equilibrium structural arrangements for these DESs are proposed based on findings, with the formation of a complex hydrogen-bonded anion and isolated cation. These DESs are proposed as potential replacements for ionic liquids, and existing acid catalysts in acid catalyzed reactions.

Holistic lignocellulosic biorefinery approach for dual production of bioethanol and xylonic acid coupled with efficient dye removal

The complete valorization of lignocellulosic biomass (LCB) to valuable bio-products with one-step fractionation is still challenging. This study represents sustainable waste-free biorefinery routes for efficient fractionation of LCB, employing a novel pretreatment method using hydrotropic p–toluenesulfonic acid (TsOH) mixed with pentanol. The potential of LCB pretreatment using TsOH/pentanol reagent as lignin absorbent with co-production of bioethanol and xylonic acid was investigated. Biomass pretreatment at 120 °C for 40 min with 20% TsOH dosage was the optimal condition that significantly dissolved more than 88.2% of lignin and 95.1% of hemicellulose in the biphasic phase, while 95.6% of cellulose was retained in the solid phase. Further fermentation of cellulose-rich fraction using Saccharomyces cerevisiae resulted in 225 g kg−1 bioethanol yield. In addition, xylose-rich phase was converted into xylonic acid by Gluconobacter oxydans fermentation with a yield of 202 g kg−1. Importantly, the isolated lignin was altered by acid groups during sulphonation through TsOH/pentanol pretreatment, which makes lignin a potential adsorbent for cationic contaminants in wastewater. In particular, the isolated lignin achieved high adsorption capacity (300 mg/g) of methylene blue. The proposed biorefinery routes showed a high net positive energy of 3.65 MJ kg−1 dry biomass with an energy ratio of 1.70. Therefore, this study provides an innovative synergistic pretreatment using TsOH/pentanol as a promising fractionation process for efficient cascade valorization of LCB into valuable bio-products.

Optimizing Molecular Structure for Trimethylolpropane Ester-Insulating Oil: Achieving High Fluidity and Stability

Synthetic ester exhibits a unique combination of advantages, including remarkable oxidation stability similar to mineral oil, as well as high flash point and biodegradability of natural ester, which makes it a promising insulating fluid alternative for transformers. In this work, a series of medium-chain fatty acid trimethylolpropane (TMP) esters (MTE) were prepared by esterification of a mixture of TMP blended with 3 saturated medium-chain fatty acids (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> , C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sub> , and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> ). The MTEs were synthesized via a vacuum esterification method with the following optimized reaction conditions: 1 wt.% p-toluenesulfonic acid (TsOH) as catalyst, reaction temperature of 120 °C, internal air pressure of 5 kPa, and the acid:TMP molar ratio of 3.2:1. The MTEs were obtained through a rationally designed purification procedure. By characterizing the physical and electrical properties of the 9 MTEs, it is found that the viscosity of MTEs increases with increasing mean molecular weight, the pour point decreases with increasing C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sub> content, and the flash point slightly increases with inscreasing C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> content. The C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> with a relatively short carbon chain and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sub> with an odd carbon chain may be beneficial for enhancing the oxidation stability of MTEs, whereas the AC breakdown voltage of the MTEs shows a negligible correlation with the fatty acid ratios.

Combined iron (III) chloride/sodium citrate with enzymatic hydrolysis for xylo-oligosaccharides and monosaccharides production from poplar

Currently, the production of xylo-oligosaccharides (XOS) from lignocelluloses by chelating system hydrolysis has not been investigated. Herein, iron (III) chloride/sodium citrate (IC/SC) chelating system hydrolysis and xylanase hydrolysis were used to produce XOS from poplar. Then, the delignification of IC/SC-hydrolyzed poplar was performed by p-toluenesulfonic acid (p-TsOH) pretreatment to increase the accessibility of cellulase. The results demonstrated that 42.3% of XOS with an extremely low by-product (xylose/XOS = 0.11) was produced from poplar by 50 mM IC/SC hydrolysis (molar ratio of 1:1, 170 °C, 60 min) and xylanase hydrolysis. The second step IC/SC hydrolysis and xylanase hydrolysis of poplar increased the yield of XOS to 51.3%. Finally, the glucose yield of p-TsOH-pretreated poplar (60% p-TsOH, 70 °C, 30 min) was greatly increased from 37.5% to 83.8% by cellulase hydrolysis with Tween 80 addition. The novel strategy proposed in this work was feasible for XOS and monosaccharides production from poplar.

Effect of the substituents on luminescent behaviors of the salts based on 4,4′-(4-amino-4H-1,2,4-triazole-3,5-diyl)diphenol

To further exploit the new luminescent materials, three new salts containing 4-amino-1,2,4-triazole, namely, [HADO]+A– (A = BSA (1), MBA (2) and SBA (3), ADO = 4,4′-(4-amino-4H-1,2,4-triazole-3,5-diyl) diphenol, BSA = benzene sulfonic acid, MBA = p-toluene sulfonic acid, SBA = 2-hydroxybenzoic-5-sulfonic acid), have been successfully prepared by the reaction of ADO and a set of sulfonic acids, respectively. The luminescent maximal emission peaks can be found at 429, 434 and 461 nm for its salts 1–3 in the solid state at room temperature, respectively. Evidently, the order of luminescent peaks: 1<2<3, can be assigned to the substituent groups effect. Compared with the free ADO, the emission maxima of salts 1–3 are assuredly red-shifted about 27, 32 and 59 nm, respectively, suggesting that the emission bands are relevant to the intermolecular interactions. Compounds 1–3 were structurally characterized by X–ray single crystal diffraction, FT-IR spectroscopy and powder X-ray diffraction (PXRD). The results of single crystal X-ray diffraction analysis reveal that a set of hydrogen bonds of N/O/C–H⋯O could be observed. The Hirshfeld analysis indicates that the order of the C…C close contacts contribution can be observed to be 1<2<3, which can be responsible for that of the luminescent maxima. Additionally, the thermal behaviors of compounds 1–3 were investigated in detail.

The coupling effects between acid-catalyzed hydrothermal pretreatment and acidic/alkaline deep eutectic solvent extraction for wheat straw fractionation

Mild hydrothermal pretreatment (HP) integrating with solvent extraction is a promising two-step technique to enhance the overall lignin and carbohydrate output for lignocellulose fractionation. This work comparatively assessed the coupling effect between mild HP (the first step) and the emerging acidic choline chloride-natural acid or alkaline choline hydroxide based deep eutectic solvents (DES, the second step) for wheat straw fractionation. It was shown HP with 0.3% p-toluenesulfonic acid (p-TsOH) catalyst achieved a good compromise between complete hemicellulose removal (nearly 100%) and high cellulose recovery (99.2%). While choline hydroxide based DES showed better coupling effect with HP than choline chloride-natural acid DES, corresponding to 75.6 and 31.2% lignin removal respectively. It was proposed that the alkaline DES enhanced lignocellulose swelling the lignin phenolic hydroxyl groups deprotonation and thus facilitating lignin solubilization despite of its condensation at HP. Therefore, the alkaline DES resulting cellulose-rich fraction exhibited higher potential for further processing.

Production of Lignin-containing nanocellulose by FeCl3-catalyzed ternary deep eutectic solvent pretreatment system: Structural characteristics and emulsification capabilities

Pretreatment method is one of the key factors to improve the quality of nanocellulose (NC) production. As a green novel solvent, ternary deep eutectic solvent (TDES) plays an important role in production of lignin-containing nanocellulose (LNC), however, higher reaction temperature would limit its industrial application. Herein, a novel strategy of FeCl3-catalyzed TDES (F-TDES) pretreatment combined microfluidization was proposed to produce LNC from poplar (PopulusL.) at lower temperature (80 °C). The TDES was composed of choline chloride, lactic acid, and p-toluenesulfonic acid in a molar ratio of 2:10:1. When the optimum dose of FeCl3 in per gram TDES system was 0.15 mmol (i.e. about 3.9% based on the weight of F-TDES), ribbon-like LNCs about 28.68 nm wide and 3.46 nm thick were obtained, which were smaller than that of lignin-free nanocellulose attained from the same preparation conditions. The LNC, lignin content 18.93%, displayed good dispersion stability in water and higher cellulose I crystallinity (57.8%) and thermal stability (Tmax=376 °C). Especially, the LNC exhibited more excellent emulsification performance and emulsion stability than NC, which was closely associated with its good amphiphilicity. Within the studied LNC concentration (0.1–0.4%) and oil/water mass ratio (20:80–50:50), increasing LNC concentration and/or oil/water mass ratio was beneficial for the stability of Pickering emulsions. The findings not only provide a milder route for producing LNC from lignocellulose, but also prove LNC would have promising prospects in emulsion systems.

Click chemistry as a method for the synthesis of steroid bioconjugates of bile acids derivatives and sterols

Six steroid conjugates of bile acids and sterol derivatives have been synthesized using the click chemistry method. The azide-alkyne Huisgen cycloaddition of the propionyl ester of lithocholic, deoxycholic and cholic acid with azide derivatives of cholesterol and cholestanol gave new bile acid–sterol conjugates linked with a 1,2,3-triazole ring. Previously, sterols were converted to bromoacetate substituted derivatives by reaction with bromoacetic acid bromide in anhydrous dichloromethane. These compounds were then converted to azide derivatives using sodium azide. The propiolic esters of lithocholic, deoxycholic and cholic acids were obtained by reaction with propiolic acid in the presence of p-toluenesulfonic acid. Additionally, two of these steroids: methyl 3α-propynoyloxy-12α-acetoxy-5β-cholane-24-oate and methyl 3α-propynoyloxy-7 α,12α-diacetoxy-5β-cholane-24-oate were also obtained and characterized for the first time. All conjugates were obtained in good yields using an efficient synthesis method. The structures of all conjugates and the four substrates were confirmed by spectral (1H- and 13C NMR, FT-IR) analysis, mass spectrometry (ESI-MS), and PM5 semiempirical methods. The pharmacotherapeutic potential of the synthesized compounds was estimated based on the in silico Prediction of Activity Spectra for Substances (PASS) method. The cytotoxicity of the compounds was in vitro evaluated in a hemolytic assay using human erythrocytes as a cell model. The in silico and in vitro study results indicate that the selected compound possesses an interesting biological activity and can be considered as potential drug design agent. Additionally, molecular docking was performed for the selected conjugate.

Azomethine-Containing Pyrrolo[3,2-b]pyrrole Copolymers for Simple and Degradable Conjugated Polymers.

Conjugated polymers have received significant attention as potentially lightweight and highly tailorable alternatives to inorganic semiconductors, but their synthesis is often complex, produces toxic byproducts, and they are not typically designed to be degradable or recyclable. These drawbacks necessitate dedicated efforts to discover materials with design motifs that enable targeted and efficient degradation of conjugated polymers. In this vein, the synthetic simplicity of 1,4-dihydropyrrolo[3,2-b]pyrroles (DHPPs) is exploited to access azomethine-containing copolymers via a benign acid-catalyzed polycondensation protocol. Polymerizations involve reacting a dialdehyde-functionalized dihydropyrrolopyrrole with p-phenylenediamine as the comonomer using p-toluenesulfonic acid as a catalyst. The inherent dynamic equilibrium of the azomethine bonds subsequently enabled the degradation of the polymers in solution in the presence of acid. Degradation of the polymers is monitored via NMR, UV-vis absorbance, and fluorescence spectroscopies, and the polymers are shown to be fully degradable. Notably, while absorbance measurements reveal a continued shift to higher energies with extended exposure to acid, fluorescence measurements show a substantial increase in the fluorescence response upon degradation. Results from this study encourage the continued development of environmentally-conscious polymerizations to attain polymeric materials with useful properties while simultaneously creating polymers with structural handles for end-of-life management or/and recyclability.