Conjugated Carbonyl Groups Research Articles

Water‐Soluble, Spin‐Cast‐Based Crystalline Poly(Methacrylic Acid) Film as a Reversible Li‐Ion Battery Anode

Poly(methyl methacrylate) (PMMA) polymer anodes are proposed as potential reversible anode materials for lithium‐ion batteries (LIBs) owing to their simple thin‐film formation process and cost‐effectiveness. Nevertheless, challenges such as the use of toxic aprotic solvents and the irreversible consumption of Li ions during the initial cycle need to be addressed to improve their performance. Herein, a water‐soluble poly(methacrylic acid) (PMAA) polymer processed using a simple spin‐casting method as a reversible LIB anode is presented. Unlike the PMMA anode, the conjugated carbonyl groups of the crystalline PMAA polymer readily form a chain backbone during ex situ thermal annealing, demonstrating a reversible capacity. The mechanism underlying the superior electrochemical characteristics of the PMAA anode is revealed using grazing incidence X‐ray diffraction and theoretical calculations. In particular, the highly crystalline cyclic anhydride PMAA polymer induced by thermal annealing shows enhanced interactions between Li ions and CO groups during operation, resulting in improved electrochemical properties. The resulting crystalline cyclic anhydride PMAA anode achieves a capacity of ≈427.7 mAh g−1 and retains a reversible specific capacity of 156 mAh g−1 after 500 cycles, indicating that it is a promising polymeric anode for next‐generation LIBs.

Oxygen concentration regulated the efficient liquefaction of vulcanized natural rubber

Oxidative liquefaction represents a promising avenue for the homogeneous and high-value utilization of waste tire rubber. Given that truck tires predominantly comprise natural rubber (NR), this study investigated the efficient liquefaction of vulcanized NR regulated by oxygen concentration. Remarkably, the liquefaction of vulcanized NR was realized with an oxygen concentration of 75 % at 200 °C within 3 min. FTIR spectroscopy showed that carbonyl, ether and sulphoxide groups were produced during the liquification of NR vulcanizates. Oxygen concentration significantly affected the oxidative efficiency of both the main chains and crosslinks, with a more pronounced effect observed on the main chains. Nevertheless, the similar molecular weights and polydispersity indices across various degraded products suggested a selective oxidative cleavage of the NR backbone. Furthermore, online ATR-FTIR was used to monitor the dynamic changes of NR's molecular structure to elucidate the oxidative degradation mechanism. The oxidative cleavage of NR main chain primarily occurred at the C-C bonds connected with allyl groups, producing oxidized products enriched with conjugated carbonyl groups. Alternatively, the main chain scission may also occur due to the electronic rearrangement effect of the C=C bond and produce saturated carbonyl groups. Oxygen concentration modulated the degradation efficiency of vulcanized NR, which provided an efficient strategy for the upcycling of NR-based waste tires.

The Structural and Thermal Characteristics of Musa paradisiaca L. Lignin for Carbon Footprint Reduction Applications

The need for the use of suitable natural alternative materials to oil-derived carbon-based materials, largely because of carbon IV oxide emissions and the attendant global health and environmental impact, has led to the discovery of lignin, a biomass-derived material, as a precursor for carbon fibre (CF) manufacture and as a reinforcement for biologically derived polymers like polylactide (PLA) with a variety of biomedical and industrial applications. This study investigated the thermal, structural, and compositional properties of lignin extracted from the pseudostem of Musa paradisiaca L. (the plantain tree). Dried and milled plantain pseudostem was pretreated using diethyl ether. Lignin was extracted from the untreated and pretreated pseudostem samples using 5M HCl for 1 h at 200 °C and 250 °C (acid hydrolysis). The results revealed that lignin obtained from pretreated pseudostem at 200 °C and 250 °C possesses superior thermal stability, as shown by the thermogram, with a DTGmax of 429.97 °C and 442.62 °C in contrast to 397.22 °C and 382.53 °C for lignin from untreated pseudostem due to the removal of volatile impurities and unwanted constituents after pretreatment. The FTIR spectrum of the extracted lignin samples shows similar absorption bands, like 1703.4 cm−1 (C=O–conjugated carbonyl group), 1606–1602 cm−1 (C=C stretching–aromatic compounds, benzene ring), 1315 cm−1 (C-O stretching–syringyl units), and 1200.2 cm−1 (C-H stretching, guaiacyl units), with the pretreated biomass having higher transmittance (%) values, indicating increased purity after pretreatment. The results presented above showed that lignin has been successfully extracted and can serve as a potential precursor for the production of carbon fibre, thereby reducing dependence on fossil-fuel-based precursors, with a reduction in carbon dioxide emission pollution.

Regio- and stereoselective nucleophilic addition reactions of Swaminathan ketone and its methylated analog using organometallic reagents

Herein, we report the regio- and stereoselective nucleophilic addition reactions of Swaminathan ketone 2a and its methylated analog 2b, both of which contain a 6–7 fused carbocyclic enedione moiety. Nucleophilic additions to 2 using generic organometallic reagents, such as Grignard and organolithium reagents, preferentially occurs at the conjugated carbonyl group to afford a range of tert-alcohols with high stereoselectivity. The selectivity observed with 2 was notable when compared to that observed with Wieland–Miescher ketone 1a bearing a decalin framework. A variety of substituents, such as alkyl, alkenyl, alkynyl and aryl groups, can be introduced into 2 using this method. Exceptionally, the allylation reaction of 2 occurred at both the conjugated and non-conjugated carbonyl groups, but this regioselectivity problem was solved using organocopper reagents.

Copper(II)-flavonolate complexes of 2N ligands as functional models for quercetin 2,4-dioxygenase enzymes: The role of axially coordinated water and ligand substitution on dioxygenase activity

Three new copper(II)-flavonolate complexes of the type [Cu(L)(fla)(ClO4)] 1–3, where L is the 2N ligand N-(pyridin-2-ylmethyl)aniline (L1), 2,6-dimethyl-N-(pyridin-2-ylmethyl)aniline (L2) and 2,6-diisopropyl-N-(pyridin-2-ylmethyl)aniline (L3), and H(fla) is 3-hydroxyflavonone, have been isolated as functional models for Cu(II)-containing quercetin 2,4-dioxygenase (2,4-QueD). Single crystal X-ray structure of 3 contains a CuN2O2Oʹ chromophore with a slightly distorted square pyramidal geometry (TBDSP, τ = 0.03). The pyridyl N1 and the tertiary amine N2 nitrogens of the 2N ligand occupy the two corners of the basal plane. The O1 (enolate) and the carbonyl O2 atoms of deprotonated 3-hydroxyflavanone (fla−) occupy the remaining corners while the O3 of perchlorate anion (ClO4−) occupies the axial position at a longer distance. The molecular structures of the complexes 1–3, their aquated species [Cu(L)(fla)(H2O)]+1a–3a and the square planar species [Cu(L)(fla)]+1c–3c have been computed by using DFT method. While 1–3 contain axially coordinated perchlorate 1a–3a contain axially coordinated water molecule with a slightly distorted square pyramidal geometry (CuN2O2Oʹ) with varying trigonality (τ, 0.03–0.05). The significantly high g|| (2.305) and low A|| (150 × 10−4 cm−1) values observed for 1–3 are consistent with π–back bonding of Cu(II) with the conjugated carbonyl group of coordinated fla− and are typical of type-II copper enzymes. The electrochemical reduction of CuII to CuI and oxidation of fla− occur upon dissociation of axially coordinated water molecule in 1a–3a formed in DMF solution to give 1c–3c. Upon exposure to dioxygen, all the Cu(II)-flavonolate adducts undergo oxygenative degradation in DMF solution, as seen from the disappearance of the LMCT band at 430 nm at 80 °C to produce CO and the corresponding acids. The rate of dioxygenation, kO2, of the complexes decrease in the order, 1 (3.31 ± 0.53) > 3 (2.59 ± 0.36) > 2 (1.52 ± 0.13 × 10−1 M−1 s−1), due to electron-donating substituents on the primary ligand.

On the importance of multiphase photolysis of organic nitrates on their global atmospheric removal

Abstract. Organic nitrates (RONO2) are secondary compounds, and their fate is related to the transport and removal of NOx in the atmosphere. While previous research studies have focused on the reactivity of these molecules in the gas phase, their reactivity in condensed phases remains poorly explored despite their ubiquitous presence in submicron aerosols. This work investigated for the first time the aqueous-phase photolysis-rate constants and quantum yields of four RONO2 (isopropyl nitrate, isobutyl nitrate, α-nitrooxyacetone, and 1-nitrooxy-2-propanol). Our results showed much lower photolysis-rate constants for these RONO2 in the aqueous phase than in the gas phase. From alkyl nitrates to polyfunctional RONO2, no significant increase of their aqueous-phase photolysis-rate constants was observed, even for RONO2 with conjugated carbonyl groups, in contrast with the corresponding gas-phase photolysis reactions. Using these new results, extrapolated to other alkyl and polyfunctional RONO2, in combination with estimates for the other atmospheric sinks (hydrolysis, gas-phase photolysis, aqueous- and gas-phase ⚫OH oxidation, dry and wet deposition), multiphase atmospheric lifetimes were calculated for 45 atmospherically relevant RONO2 along with the relative importance of each sink. Their lifetimes range from a few minutes to several hours depending on the RONO2 chemical structure and its water solubility. In general, multiphase atmospheric lifetimes are lengthened when RONO2 partition to the aqueous phase, especially for conjugated carbonyl nitrates for which lifetimes can increase by up to 100 %. Furthermore, our results show that aqueous-phase ⚫OH oxidation is a major sink for water-soluble RONO2 (KH>105 M atm−1) ranging from 50 % to 70 % of their total sink at high liquid water content (LWC) (0.35 g m−3). These results highlight the importance of investigating the aqueous-phase RONO2 reactivity to understand how it affects their ability to transport air pollution.

Cost‐Effective Vat Orange 3‐Derived Organic Cathodes for Electrochemical Energy Storage

AbstractOrganic compounds are desirable alternatives for sustainable lithium‐ion battery electrodes. Vat orange 3 (VO3, 4,10‐dibromoanthanthrone) is a highly cost‐effective organic dye containing two conjugated carbonyl groups, which can reversibly accept two electrons. The skeleton also contains two bromine atoms, which allows easy incorporation of the anthanthrone unit into polymers through simple reactions. In this work, we report the preparation of organic cathodes derived from the low‐costVO3dye for lithium‐organic batteries (LOBs). The results show that polymericVO3‐based materials exhibit remarkably high cyclability and rate performance, because of their effective suppression of dissolution. In particular, the sulfide polymer poly(anthanthrone sulfide) (PATS) shows an initial large‐current (0.2 A g−1) discharge capacity of 133 mAh g−1at a potential near 2.4 V. The capacity reaches a maximum capacity of 147 mAh g−1after 24 cycles and is maintained at 132 mAh g−1after 300 cycles. Moreover, a full battery cell with the structure:PATScathode||graphite anode, further delivers an impressive electrochemical performance with an energy density up to 237 Wh kg−1along with an output voltage of 2.3 V. The present study initiates the use ofVO3‐based organics, which show promising potential for future application in LOBs on a large scale.

Polyimide-reinforced solid polymer electrolyte with outstanding lithium transferability for durable Li metal batteries

Solid polymer electrolytes drastically enhance the operational safety of Li metal battery by eliminating the flammable liquid electrolyte, but still suffer from low ionic conductivity and inferior thermostability. Herein, we tack this issue by strengthening the polyvinylidene fluoride matrix with lithiophilic polyimide. The actively conjugated carbonyl groups in polyimide polymer backbone with Li+-conductivity feature accelerate the ion conduction, accordingly improving the ionic conductivity up to 4.1 × 10−4 S cm−1. With the polyimide solid electrolyte, lithium symmetrical battery shows a stable operation without obvious dendrite growth over 300 h at 0.17 mA cm−2, effectively uniformizing the Li+ deposition at the electrolyte/anode interface. The LiFePO4 cell based on the polyimide electrolyte delivers a high discharge capacity of 126 mAh g−1 at 25 °C with a capacity retention of 86% after 500 cycles at 0.15 mA cm−2. In addition, polyimide chain with high thermostability owns affinity to polyvinylidene fluoride with an adsorption energy of 0.1 eV, giving rise to 35% enhancement in mechanical strength and 68% reduction in thermal shrinkage at 300 °C as compared with pure polyvinylidene fluoride electrolyte. This design allows a promising route for enhancing the safety operation of polymer electrolyte and promoting ionic transfer by reconstructing the polymer architecture.

Oxo-Carotenoids as Efficient Superoxide Radical Scavengers.

Oxo-carotenoids containing conjugated carbonyl groups in their chains were designed to be more efficient superoxide radical scavengers than natural carotenoids, β-carotene and canthaxanthin. A practical chain-extension method for polyene dials (e.g., crocetin dial) was also proposed based on Horner–Wadsworth–Emmons olefination. Double aldol condensation between polyene dials and acetophenones with ring substituents produced oxo-carotenoids with substituted benzene rings. The antioxidant activity of oxo-carotenoids was measured using DPPH (radical) and ABTS (cationic radical) scavenging assays and compared with the analysis with the superoxide (anionic radical) probe. An effective conjugation length by carbon–carbon double bonds is important to provide superior antioxidant activity for oxo-carotenoids, regardless of the type of radical probe used in the assay. Increasing electron density is favorable to strong antioxidant activity in DPPH, and the phenol group is favored in ABTS, whereas electron deficient oxo-carotenoids are very potent in the superoxide radical assay. All oxo-carotenoids exhibited 105~151% better superoxide radical scavenging activity compared to beta-carotene (100%), whereas 38~155% in DPPH and 16~96% in ABTS radical scavenging activities were observed.

A dynamic intercalation mechanism in pre-intercalation carbon nanosheets for capacitive deionization cells

Given that carbon-based electrodes suffer from poor long-term stabilities and limited desalination capacity, the optimized charge storage mechanism used for improving desalination performance remains requisite. In this work, the KC-pre-intercalated carbon nanosheets (PCNs) with abundant conjugated carbonyl groups were designed via a one-step smelting method for the first time as a novel intercalation electrode in the symmetric capacitive deionization. Interestingly, below 500 mg/L, the physical electrical double-layer mechanism is mainly influential. Benefitting from the proposed dynamic intercalation mechanism, a remarkable ion removal capacity of 1.65 g g−1 and impressive cyclability of 300 cycles (97.96%) were observed in the high salt concentrations (>1000 mg/L) and simulated seawater system rather than pure NaCl solution. The ultrahigh adsorption capacity and prominent cycling stability make the PCNs-based device rank top three among these of all the symmetric CDI systems reported in the literatures so far. The Na+ ions are intercalated in the enlarged interlayer spacing without a host structure deformation, thus offering a high ion removal rate (2.04 mg g−1 min−1) and a low energy consumption (0.28 Wh g−1). Our work exemplifies the importance of engineering conjugated carbonyl groups and pre-intercalated structure to capacitive deionization for brine.

Efficient decontamination of RO concentrate in a sonochemical zero-valent iron/persulfate Fenton-like system: The molecule-size preferred degradation of dissolved organic matters

Interference of real dissolved organic matters (DOMs) in advanced oxidation processes (AOPs) treatment of pharmaceuticals in reverse osmosis concentrates (ROC) has rarely reported. In this study, an ultrasound/zero valent iron/persulfate (US/ZVI/PS) system has been developed to degrade typical antibiotic sulfadiazine in the presence of co-existing ROC DOMs. It was found that common inorganic anions slightly affected the removal of SD, while fulvic acid (FA) and humic acid (HA) would bring medium to strong inhibition. 3D-EEM results evidenced the degradation of DOMs attributed to their competition for the oxidative radicals, suggesting the selective attack liable to larger molecular sizes. Intensive hydroxylation of HA and cleavage of C-C in FA molecule would occur respectively, where benzene ring, carbonyl or conjugated carbonyl group in DOMs would be destructed with oxidation of the nitrogen-containing functional groups. Scaled-up dosages of the agents could achieve efficient decomposition of all the three DOMs in a SD-spiked pristine ROC and all macromolecular structures were transformed into small molecules, suggesting the US/ZVI/PS system would be an good option for treating practical ROCs.

Porphyrin-based conjugated microporous polymers with dual active sites as anode materials for lithium-organic batteries

Conjugated microporous polymers have been regarded as ideal electrode materials for green lithium-ion batteries (LIBs) considering their advantages such as insolubility, adjustable structure and porosity. Herein, we synthesize porphyrin-based CMPs (Co-PCMPs) with dual active sites composed of metal-N4 conjugated macrocycle and conjugated carbonyl groups through the condensation polymerization. In view of the rational design and unique organic skeleton, when used as the anode material for LIBs, Co-PCMPs show a high capacity (700 mAh g −1 at 0.05 A g −1 ) and excellent rate capability (400 mAh g −1 at 1.0 A g −1 ). Meanwhile, theoretical calculations are used to further study the lithium storage mechanism of Co-PCMPs as the anode material for LIBs. In addition, a full cell is also assembled by using LiCoO 2 as the cathode material and Co-PCMPs as the anode material, which also shows a high capacity (212 mAh g −1 at 0.05 A g −1 ) and good rate capability (116 mAh g −1 at 0.2 A g −1 ), implying the possibility of practical applications of this type of conjugated microporous polymers. We synthesize porphyrin-based conjugated microporous polymers with dual active sites composed of metal-N4 conjugated macrocycle and conjugated carbonyl groups through the condensation polymerization, which could be served as anode materials to a full cell of lithium ion batteries. • Porphyrin-based conjugated microporous polymers were prepared by condensation reaction. • The polymers with dual active sites were used as anode materials for lithium ion batteries. • Full cell is also assembled to show the possibility of practical applications of these polymers.

In Situ Polymerized and Imidized Si@Polyimide Microcapsules with Flexible Solid‐Electrolyte Interphase and Enhanced Electrochemical Activity for Li‐Storage

AbstractA novel in situ polymerization and imidization method is adopted to synthesize Si‐based microcapsule materials with polyimide shell. As a mechanically stable polymer, polyimide microcapsule shell can effectively alleviate the volume effect of silicon nanoparticles during alloying/de‐alloying reactions, stabilize the electrode construction, suppress the serious side reactions of electrolyte components on silicon anode surface, and help to form a flexible, homogeneous and low‐resistance solid electrolyte interphase (SEI). In addition, the conjugated carbonyl groups of polyimide make it Li+‐conductive and electrochemically active, thus increasing the electrochemical activity of silicon anode. The as‐prepared Si@polyimide microcapsules manifest high initial coulombic efficiency of 91.1 %, high initial discharge capacity of 2798.7 mA h g−1 at 210 mA g−1 (0.05 C), good rate behavior with a capacity of 1954 mA h g−1 at 10 C current rate, and considerably improved cycling performance preserving a capacity of 1239.9 mA h g−1 at 4.2 A g−1 (1 C) after 300 cycles.

Changes of lignin structure of poplar wood chips in autohydrolysis pretreatment and bleachability of chemi-thermomechanical pulp

In this work, poplar wood chips (PWCs) were subjected to autohydrolysis pretreatment with different levels of intensity, and the autohydrolyzed PWCs were used to make chemi-thermomechanical pulp (CTMP). The changes of the lignin structure of PWCs and the bleachability of the CTMP with autohydrolyzed PWCs as raw materials were both investigated. The results showed that the lignin structure changed to some extent in both CTMP pulping and the following bleaching process. The contents of conjugated carbonyl and quinone groups in the lignin structure were negatively correlated with the CTMP bleachability. Compared to the quinone groups, the conjugated carbonyl groups had a much greater impact on the bleachability. The present work would play a vital role for the application of autohydrolysis to the poplar CTMP pulping and the subsequent bleaching processes.

The evolution of microstructure of Styrene-Isoprene-Butadiene Rubber during the thermal-oxidative aging process using In-situ FTIR way

The thermal-oxidative aging of Styrene-Isoprene-Butadiene Rubber (SIBR) has been studied using transmission spectroscopy in In-situ. These In-situ FTIR imaging results have interpreted the microstructure and mechanism of SIBR in the thermal-oxidative aging process. The conjugated carbonyl group is generated in SIBR during the aging process because SIBR contains both cis 1,4-polyisoprene and 3,4-polyisoprene units. The generation rate of the conjugated carbonyl group in SIBR is significantly increased with the prolonged aging time. Moreover, due to the larger side groups in the 3,4-polyisoprene unit, it needs a higher temperature in the aging process to generate the conjugated carbonyl group. Based on the changes of methylene and -C-O bond during the aging process, the thermal-oxidative aging of SIBR has been found that the cross-linking reaction and chain scission reaction take place simultaneously, but the cross-linking reaction dominates the degradation. Compared with Solution-polymerizated-Styrene-Butadiene Rubber (SSBR) and Nd-Polyisoprene Rubber (Nd-IR), the thermal-oxidative aging rate of SIBR is between SSBR and Nd-IR in view of the changes in carbonyl group and –CO structure during the aging process.

Oil Palm Empty Bunch Compost as a Source of Humic Acid

Humic acid is a fraction of humic compounds that are part of soil organic matter. In this research, humic acid is extracted from oil palm empty fruit bunches compost. Compost is made from the process of counting the empty oil palm bunches, which are composted until the compost is cooked. The humic acid extraction process uses a strong base extraction method. The principle of humic acid extraction is to dissolve the humic compound with a base solution and then separate it by adding an acid solution (HCl solution). The extraction of humic acid from oil palm empty fruit bunches compost produced blackish-brown humic acid with a yield of 4.895%. The result showed that the main functional group content of palm oil empty fruit bunches compost humic acid was the -OH group and phenol group which had a conjugated carbonyl group and a more aliphatic humic acid structure. Quantitatively, the functional groups of humic acid functional groups each amounted to a total acidity of 7,400 cmol/kg, a carboxylic group of 520 cmol/kg, and a phenolic -OH group content of 6,880 cmol/kg. Research results show that oil palm empty fruit bunches compost can be used as a source of humic acid.

Browning of Epicatechin (EC) and Epigallocatechin (EGC) by Auto-Oxidation.

Green tea catechins are well known for their health benefits. However, these compounds can easily be oxidized, resulting in brown color formation, even in the absence of active oxidative enzymes. Browning of catechin-rich beverages, such as green tea, during their shelf life is undesired. The mechanisms of auto-oxidation of catechins and the brown products formed are still largely unknown. Therefore, we studied auto-oxidative browning of epicatechin (EC) and epigallocatechin (EGC) in model systems. Products of EC and EGC auto-oxidation were analyzed by reversed-phase ultra-high-performance liquid chromatography with photodiode array detection coupled to mass spectrometry (RP-UHPLC-PDA-MS). In the EC model system, 11 δ-type dehydrodicatechins (DhC2s) and 18 δ-type dehydrotricatechins (DhC3s) that were related to browning could be tentatively identified by their MS2 signature fragments. In the EGC model system, auto-oxidation led to the formation of 13 dihydro-indene-carboxylic acid derivatives and 2 theaflagallins that were related to browning. Based on the products formed, we propose mechanisms for the auto-oxidative browning of EC and EGC. Furthermore, our results indicate that dimers and oligomers that possess a combination of an extended conjugated system, fused rings, and carbonyl groups are responsible for the brown color formation in the absence of oxidative enzymes.

Remarkable Potential of Zerumbone to Generate a Library with Six Natural Product-like Skeletons by Natural Material-Related Diversity-Oriented Synthesis

Diversity-oriented synthesis (DOS) is an effective strategy for the quick creation of diverse and high three-dimensional compounds from simple starting materials. The selection of a starting material is the key to constructing useful, chemically diverse compound libraries for the development of new drugs. Here, we report a novel, general, and facile strategy for the creation of diverse compounds with high structural diversity from readily available natural products, such as zerumbone, as the synthetic starting material. Zerumbone is the major component of the essential oil from wild ginger, Zingiber zerumbet Smith. It is noteworthy that zerumbone has a powerful latent reactivity, partly because of its three double bonds, two conjugated and one isolated, and a double conjugated carbonyl group in an 11-membered ring structure. In fact, zerumbone has been shown to be a successful example of natural material-related DOS (NMRDOS). We will report that zerumbone can be converted in one chemical step from four zerumbone derivatives into rare and markedly different scaffolds by transannulation.

Selective synthesis of the two main progesterone metabolites, 3α-hydroxy-5α-pregnanolone (allopregnanolone) and 3α-hydroxypregn-4-en-20-one, and an assessment of their effect on proliferation of hormone-dependent human breast cancer cells

A directed synthesis of two progesterone metabolites, allopregnanolone and 3a-hydroxy-pregn-4-en-20-one, from Δ16-pregnanolone and progesterone, respectively, was carried out by a reduction of the carbonyl groups in positions 3 and subsequent inversion of the configuration of the resulting alcohols by the Mitsunobu reaction. The selectivity of the reduction of the conjugated carbonyl group in position 3 of progesterone with sodium borohydride in the presence of cerium(III) chloride (Luche reduction) was demonstrated. The ef ect of the obtained metabolites on the proliferation of breast cancer cells of the MCF-7 and T47D lines under normal and steroid-free conditions was studied. It is shown that the ef ect of these compounds on the proliferation depends on the presence of additional steroids in the culture medium. Metabolites exerted small cytostatic ef ects on the growth of the MCF-7 cells under standard conditions, while the transfer of the cells to a steroid-free medium weakened these cytotoxic ef ects. In the experiments with the T47D line cells, the cell growth was stimulated under both standard and steroid-free conditions. Allopregnanolone and progesterone stimulate the growth to a greater extent under steroid-free conditions than under standard ones.

Physicochemical and antifungal properties of waterborne polymer nanoparticles synthesized with caffeine

In this work, caffeine was used as a natural additive in the emulsion polymerization of methyl methacrylate with cetyltrimethylammonium bromide (CTAB) or sodium dodecyl sulfate (SDS). Mean particle size and ζ-potential of the particles, glass transition temperature, and molecular weight of polymer chains were not affected by caffeine. However, caffeine improved considerably the colloidal stability of polymer dispersions at ionic strength of 1.0 mol L−1 NaCl. Fourier transform infrared vibrational spectra in the attenuated total reflectance mode (FTIR-ATR) of PMMA synthesized with CTAB or SDS in the presence of caffeine showed shifts of caffeine bands assigned to isolated and conjugated carbonyl groups to higher wavenumbers, indicating favorable interactions. Density functional theory (DFT) calculations revealed interactions between the negatively charged sulfate and the caffeine imidazole ring and between positively charged ammonium group and the isolated carbonyl of the caffeine. Such interactions are responsible for the improved colloidal stability of polymer dispersions synthesized with caffeine. Cell viability assays showed that adding caffeine at 26 × 10−3 mol L−1 in the polymerization reaction is enough to prevent C. albicans growth in waterborne polymer dispersions.