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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. [ABSTRACT FROM AUTHOR]

Although the biochemical composition and biological properties of the volatile fraction of the halophyte sea fennel (Crithmum maritimum L.) have been largely described, little is known about its polar constituents and bioactivities. Here, a hydromethanolic extract of Crithmum maritimum (L.) leaves was fractionated, and the fractions were evaluated in vitro for antioxidant (using DPPH, ABTS, and FRAP bioassays), anti-inflammatory (inhibition of NO production in RAW 264.7 macrophages), antidiabetic (alpha-glucosidase inhibition), neuroprotective (inhibition of acetylcholinesterase), and skin-protective (tyrosinase and melanogenesis inhibitions) activities. Polar fractions of the extract were rich in phenolics and, correlatively, displayed a strong antioxidant power. Moreover, fractions eluted with MeOH20 and MeOH80 exhibited a marked inhibition of alpha-glucosidase (IC50 = 0.02 and 0.04 mg/mL, respectively), MeOH60 fractions showed a strong capacity to reduce NO production in macrophages (IC50 = 6.4 μg/mL), and MeOH80 and MeOH100 fractions had strong anti-tyrosinase activities (630 mgKAE/gDW). NMR analyses revealed the predominance of chlorogenic acid in MeOH20 fractions, 3,5-dicaffeoylquinic acid in MeOH40 fractions, and 3-O-rutinoside, 3-O-glucoside, 3-O-galactoside, and 3-O-robinobioside derivatives of quercetin in MeOH60 fractions. These compounds likely account for the strong antidiabetic, antioxidant, and anti-inflammatory properties of sea-fennel polar extract, respectively. Overall, our results make sea fennel a valuable source of medicinal or nutraceutical agents to prevent diabetes, inflammation processes, and oxidative damage. [ABSTRACT FROM AUTHOR]

Pyrazolones derivatives are known for their pharmaceutical and therapeutic activities. In this regard, some new pyrazolone derivatives have been synthesized using cyclocondensation, nucleophilic substitution, and alkylation reactions. Their corresponding structures were elucidated using X-ray diffraction and NMR spectroscopic techniques. The experimental spectral data were compared with the predicted ones obtained at the B3LYP/6-311++G(d,p) level of theory. Geometrical parameters and chemical shifts are relatively well reproduced with correlation coefficients higher than 90%. The intercontacts in crystal units were investigated by the analysis of their corresponding Hirshfeld surfaces and fingerprint maps, which reveal that the major contacts are found for H...H intercontacts. Finally, the inhibition efficiency of the novel pyrazolone derivatives as SARS-CoV-2 Mpro is estimated by determining their binding affinities into the binding site of SARS-CoV-2 Mpro. The docking results reveal that the current pyrazolone derivatives may act as potent inhibitors of SARS-CoV-2 Mpro and that their inhibition efficiency may be strongly influenced by the substituted functional groups of pyrazolone moiety. Synthesis of new 4-Substituted Pyrazolone derivatives Good correlations are obtained between the spectra and X-ray data with the predicted ones. Hirshfeld surface analysis is used to analyze intermolecular interaction. 3D molecular structure is characterized using x-Ray and spectroscopic techniques. Interactions for of the newly synthesized compounds 2b, 3b, 3a, and 4 docked SARS-CoV-2 Mpro/PDB: 6LU7-A chain protein. [ABSTRACT FROM AUTHOR]

The Silres H62C methyl-phenyl-vinyl-hydrogen polysiloxane is a promising candidate as a SiC precursor for 3D printing based on photopolymerization reaction. An in-depth nuclear magnetic resonance spectroscopy analysis allowed us to determine its structure and quantify its functional groups. The polysiloxane was found to have a highly branched ladder-like structure, with 21.9, 31.4 and 46.7% of mono-, di- and tri-functional silicon atoms. The polysiloxane cross-links from 180 °C using hydrosilylation between silyl groups (8.4% of the total functional groups) and vinyl groups (12.0%) and contains a non-negligible ethoxy content (2.4%), allowing cross-linking through a hydrolyze/condensation mechanism. After converting the polymer into ceramic and thus releasing mainly hydrogen and methane, the ceramic yield was 72.5%. An X-ray diffraction analysis on the cross-linked and pyrolyzed polysiloxane showed that the ceramic is amorphous at temperatures up to 1200 °C and starts to crystallize from 1200 °C, leading into 3C-SiC carbon-rich ceramic at 1700 °C in an argon atmosphere.

The usage of laccases is a sustainable and environmentally friendly approach to modifying the Kraft lignin structure for use in certain applications. However, the inherent structure of Kraft lignin, as well as that resulting from laccase modification, still presents challenges for fundamental comprehension and successful lignin valorization. In this study, bacterial and fungal laccases were employed to modify eucalypt Kraft lignin. To evaluate the type and range of the chemical and structural changes of laccase-treated lignins, different NMR techniques, including solution 1H and 2D NMR (heteronuclear single quantum correlation (HSQC)), and solid-state 13C NMR, were applied. Size exclusion chromatography and infrared spectroscopy were also used. Interestingly, HSQC analysis showed substantial changes in the oxygenated aliphatic region of lignins, showing an almost complete absence of signals corresponding to side-chains due to laccase depolymerization. Simultaneously, a significant loss of aromatic signals was observed by HSQC and 1H NMR, which was attributed to a deprotonation of the lignin benzenic rings due to polymerization/condensation by laccase reactions. Then, condensed structures, such as α-5′, 5-5′, and 4-O-5′, were detected by HSQC and 13C NMR, supporting the increment in molecular weight, as well as the phenolic content reduction determined in lignins. [ABSTRACT FROM AUTHOR]

The Silres H62C methyl-phenyl-vinyl-hydrogen polysiloxane is a promising candidate as a SiC precursor for 3D printing based on photopolymerization reaction. An in-depth nuclear magnetic resonance spectroscopy analysis allowed us to determine its structure and quantify its functional groups. The polysiloxane was found to have a highly branched ladder-like structure, with 21.9, 31.4 and 46.7% of mono-, di- and tri-functional silicon atoms. The polysiloxane cross-links from 180 °C using hydrosilylation between silyl groups (8.4% of the total functional groups) and vinyl groups (12.0%) and contains a non-negligible ethoxy content (2.4%), allowing cross-linking through a hydrolyze/condensation mechanism. After converting the polymer into ceramic and thus releasing mainly hydrogen and methane, the ceramic yield was 72.5%. An X-ray diffraction analysis on the cross-linked and pyrolyzed polysiloxane showed that the ceramic is amorphous at temperatures up to 1200 °C and starts to crystallize from 1200 °C, leading into 3C-SiC carbon-rich ceramic at 1700 °C in an argon atmosphere. [ABSTRACT FROM AUTHOR]

A novel, straightforward, and environmentally friendly direct coupling procedure to immobilize carbohydrates on solid supports is presented. A characterization study showed that all amino groups on solid supports participated in the linkage with a carbohydrate unit, implicating that the surface load can be easily adjusted by tuning the amination coverage of the surface. Most importantly, the integrity of the cyclic conformation of the linked sugar unit was demonstrated, a feature that is critical for most of the possible applications of carbohydrate-functionalized surfaces. Furthermore, carbohydrate-immobilized submicron particles synthesized by the direct coupling method, on which lectin profiling experiments were conducted, validated the successfulness of our simplistic approach. [ABSTRACT FROM AUTHOR]

Chemical modification in surface of cellulose nanofibrils CNFs (20 nm) from an endemic and non-significant value-added, Argentine bamboo, was developed. The modification in the CNFs was carried out with three simple routes using a low molecular weight polylactic acid synthesized in our laboratory (PLA1). The first step comprises of protection of the hydroxyl groups of PLA1 through a benzoylation (PLA1Bz). The next step consisted of the activation of carboxyl groups using thionyl chloride and the last reaction was the grafting of the modified PLA onto the CNFs (PLA1Bz-g-CNF). The covalently functionalization is confirmed by spectroscopically techniques as well as PLA1Bz-g-CNFs were characterized by thermal analyses. The PLA1Bz-g-CNFs were taken up such as nanocharges to improve properties of compatibilization and changing surface properties in films based on PLA. The comparison between the films with PLA1Bz-g-CNFs with respect to the physic mixture of the components (PLA1Bz/CNF), shows an improvement in the thermal, mechanical, and surface properties of the material, particularly when 5% of PLA1Bz-g-CNFs was added. The dispersive (γS D) component of film is increased in 36.1 mN/m respect to 29.3 mN/m from the films obtained with the physic mixture nanofibrils without modification and a plasticizing effect was noticed in the final material. • Chemical grafting with short PLA on CNF was used to obtain better compatibility between the hydrophobic PLA matrix and CNFs. • Nanofibrils modified showed an improved thermal stability than unmodified nanofibrils. • Modified CNFs added into the PLA matrix films, reduced the polar contributions of the nanofibrils in the films. • Low molecular weight PLA chains grafted onto the nanofiber surface inhibit the nucleating effect, thus crystallinity in films. • Plasticizing effect in PLA films with the addition of modified nanofibers was noticed in the mechanical properties. [ABSTRACT FROM AUTHOR]

The present work investigates synthesis and characterization of two organoplatinum(II) complexes comprising various isocyanide ligands with general formula of [PtR'2(CNR)2] (R' = p-tolyl, R = 2-chloro-6-methylphenyl (1) and 2-naphtyl (2)). The resulting complexes were characterized by multinuclear (1H, 13C, 195Pt) NMR spectroscopy by assistance of two dimensional (HH COSY and HSQC) NMR technique. Besides, HH-NOESY (Nuclear Overhauser Effect Spectroscopy) technique was employed to provide more accurate 1HNMR assignments. In order to have a better structural vision for the complexes, the structures were optimized by DFT (Density Functional Theory) method in CH2Cl2 solution. The molecular docking studies were performed for complexes 1 and 2 while it revealed the specific binding site, binding mode and the best orientation of the complexes to DNA.

A camphor-derived sulfonimine with a conjugated carbonyl group, oxoimine 1 (O2SNC10H13O), reacts with amino acids (glycine, L-alanine, L-phenylalanine, L-leucine) to form a compound O2SNC10H13NC10H14NSO2 (2) which was characterized by spectroscopic means (MS and NMR) and supported by DFT calculations. The product, a single diastereoisomer, contains two oxoimine units connected by a –N= bridge, and thus has a structural analogy to the colored product Ruhemann´s purple obtained by the ninhydrin reaction with amino acids. A plausible reaction mechanism that involves zwitterions, a Strecker degradation of an intermediate imine and water-catalyzed tautomerizations was developed by means of DFT calculations on potential transition states.

In this study, lignin with fine structures and facile enzymatic saccharifying residue were successively dissociated based on the lignin-first biomass deconstruction strategy. In the lignin-first process, aldehyde-protected lignin fractions were firstly isolated by acid-catalyzed dioxane extraction in the presence of formaldehyde (FA) and acetaldehyde (AA) and then analyzed by advanced nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The optimized hydrogenolysis of the extracted lignin (LFA and LAA) resulted in a high yield (42.57% and 33.00%) of lignin monomers with high product selectivity (mainly 2,6-dimethoxy-4-propylphenol) (39.93% and 46.61%). Moreover, the cellulose-rich residues were saccharified into fermentable glucose for bioethanol production. The glucose yield of the substrate (RAA) reached to 75.12%, which was significantly higher than that (15.4%) of the substrate (RFA). In short, the lignin-first biomass deconstruction by adding AA is a promising and sustainable process for producing value-added products (energy and fine chemicals) from lignocellulosic biomass.

ABSTRACT Dioscorea pentaphylla L., a wild tuber is used both as food and medicines among different ethnic groups of Similipal Biosphere Reserve, India. Tubers are used against skin infections. In order to establish and confirm tribal claims, methanol extract was subjected to fractionation. The active fraction (DP1) was subsequently used for further purification and NMR (Nuclear magnetic resonance) characterization. The phytochemical analysis revealed the presence of saponin groups. The antibacterial activity of DP1 was done against selected bacterial strains (Salmonella typhi, Shigella flexneri, Streptococcus pyogenes, Streptococcus mutans and Vibrio cholerae) using DD (disc diffusion), AWD (agar well diffusion) and broth dilution assay. The activity was compared with antibiotics Penicillin and Kanamycin. It was observed that DP1 showed significant inhibitory activity against the tested bacteria. The characterization of DP1 through NMR analysis and presence of proton in carbon position at C-3, C-19, C-18, C-21 and C-27 was same as the known compound “Diosgenin”. Therefore, isolated compound was confirmed to be Diosgenin. The study for the first time showed that, diosgenin present in D. pentaphylla tuber was responsible for antibacterial and antioxidant potential. Present study highlights the importance of Dioscorea species as sources of diverse secondary metabolites for the isolation of active compound(s).

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Dendrimers are nanostructured 'architectural motifs' with a well‐tailored polymeric structure, symmetric tree‐like shape and the presence of several functional groups and inner cavities, and are of eminent interest in many biomedical applications such as drug delivery, gene transfection and imaging. In the work reported, reliable protocols for the synthesis of polyester‐based, hydrolysable, amphiphilic polycationic dendrimers were developed. A C‐18 hydrocarbon chain provided by a biocompatible fatty acid, stearic acid, and second‐ and third‐generation dendrons based on 2,2‐bis(hydroxymethyl)propionic acid were built on 2,2‐bis(hydroxymethyl)propanol and pentaerythritol as core molecules. αN‐BOC‐ω'N‐(NO2)‐l‐arginine alone, mixed with αN,ϵN‐di‐BOC‐l‐lysine or also with N,N′‐dimethylglycine and αN‐BOC‐methylglycine were successfully bound to the prepared polyester neutral scaffolds and, after the removal of protecting groups, five cationic dendrimers were obtained. Their structure was confirmed using NMR analysis and experimental molecular weight. Their buffer capacity, comparable to that of polyethyleneimines, was optimal, high viability percentage values were obtained from cytotoxicity assays and zeta potential and mean particle size were in the desired ranges. The synthesized nanostructured compounds that harmonize a multifunctional polycationic shell, a biodegradable uncharged polyester matrix and a C‐18 hydrophobic portion helpful for an improved hydrophilic–lipophilic balance in their structure embody all the fundamental features to be suitable for biomedical applications. © 2018 Society of Chemical Industry Five amphiphilic polyester‐based dendrimers modified at the periphery with positively charged amino acids endowed with very low level of cytotoxicity and properties suitable for biomedical applications were synthetized and characterized. [ABSTRACT FROM AUTHOR]

Abstract: L‐arginine is often used to decorate several scaffolds in order to obtain biomedical devices with increased efficiency and reduced toxicity, so nitrogen atoms need protection for example with BOC group. It has recently been reported that following three protocols which assured the achievement of the widely described (E)‐αN,ωN,ω’N‐Tri‐BOC‐arginine as pure isoform, additional four isoforms were obtained. As a rational consequence, further investigations about their reactivity were performed and in this work the results that showed as it is influenced by BOC location, isoforms structure and double bond position and geometry were reported. Only one isoform, i. e. rotamer E, shown appreciable reactivity highlighting that only the procedure which provides it is actually valid. From rotamer E, two new first generation arginine dendrons were prepared. These fragments, exploitable for decorating dendrimer, polymer or lipid scaffolds are very appealing for preparing synthetic arginine materials potentially suitable for biomedical application. Their spectral characterization as well as that of three other unreported isolated compounds were also provided. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) cryoporometry is a non-invasive method for determining the pore size distributions of materials such as porous silica. Cryoporometry has several advantages over other porometric techniques. It is able to measure the melting process in a series of discrete steps, whereas transient heat flow techniques, such as differential scanning calorimetry (DSC), have a minimum rate of measurement, and, secondly, NMR cryoporometry can analyze pore shapes with any geometry, where nitrogen porosimetry is complicated for samples with spherical pores with narrow necks. However, one key drawback of the method is that, for any one liquid observed in any one material, there is a lack of consensus in the two parameters, k c and 2 s l , used to convert experimental NMR melting point depression data into a pore size distribution. By considering two decades worth of literature data, values for both were obtained for water in porous silica supports, in particular an estimate of a non-freezing layer between the solid ice and the inner surface of the pore. These values were used to produce pore size distributions for three silica materials, SBA-15 and KIT-6, both with cylindrical pores but possessing different structures, and SBA-16, which has spherical pores. This represents the first time KIT-6 has been characterized by the NMR method. Furthermore, this work demonstrates a general method for obtaining values for k c and 2 s l which can be applied to any liquid for which suitable literature data is available. [ABSTRACT FROM AUTHOR]

A porous anode composed of β-PbO2 was electrochemically deposited onto a carbon cloth substrate (e.g., CC/β-PbO2) aiming for the electrochemical ozone production (EOP) in electrolyte-free water using a solid polymer electrolyte (SPE) filter-press reactor. Scanning electron microscopy (SEM) images revealed the presence of a three-dimensional oxide structure necessary to obtain a fluid-permeable anode. X-ray analysis showed the predominance of the β-PbO2 phase. The maximum current efficiency for the EOP was 9.5% with an ozone production rate of 1.40 g h−1. Using a constant ozone production rate of 0.5 g h−1, the oxidative degradation of paracetamol (PCT) dissolved in water was accomplished as a function of the PCT concentration (20, 30, and 50 mg L−1) and the pH (acid, natural (without adjustment), and alkaline). The UV-Vis spectrophotometric analysis showed that the degradation process is more pronounced in alkaline media with a strong reduction in the electrical energy per order (EEO). A reduction of the chemical oxygen demand (COD) of up to 80% was observed. A linear correlation between data referring to COD and HPLC measurements with the UV absorbance measured at 243 nm (UV243) was verified indicating that these different techniques can be complementary to each other. The nuclear magnetic resonance (NMR) study of the ozonation by-products revealed that the oxidation of PCT occurred through the rupture of the aromatic ring. The major part of phenol’s ring was oxidized to CO32− while no reaction occurs in the acetamide group of paracetamol during the ozonation reaction. [ABSTRACT FROM AUTHOR]

l-arginine is often covalently linked to vectors for gene or drug delivery as a means of increasing their transfection activity and reducing toxicity. This strategy relies on the protection of basic nitrogen atoms, for example, by employing the tert-butoxycarbonyl group. Our aim in the present work was to prepare the widely described αN,ωN,ω′N-tris(tert-butyloxycarbonyl)-l-arginine as a single isomer in high yield and with high levels of purity for use in the esterification of dendrimers with several peripheral hydroxyl groups. Following three reported protocols which assured this goal, we observed the unexpected formation of four additional isomers. Using the first procedure, αN,ωN,ω′N-tris(tert-butyloxycarbonyl)-l-arginine was never obtained. The second procedure delivered the desired compound as a mixture of geometric isomers (E/Z), while the third protocol led to a single isomer in high yield and purity, but with an unreported symmetrical structure. Since Boc protection is transient, this discovery would seem to be of little interest, but preliminary results from an ongoing investigation of the behavior of each of the isomers obtained in the esterification reactions of interest has shown that their reactivity depends on their structure. Although this research is ongoing, here we report a detailed description of these unexpected results, along with an NMR investigation focusing on the double-bond geometry and position which enabled confirmation of the structures. [ABSTRACT FROM AUTHOR]

Herein, the polyphenolic content in extracts of Ruppia cirrhosa (Petagna) Grande and Ruppia maritima L.was fully characterized for the first time. High amounts of the main compound chicoric acid (CA) (<30.2 ± 4.3 mg/g) were found in both Ruppia species. In addition, eight flavonoids, namely the 3-O-glucopyranosides and 3-O-galactopyranosides, as well as malonylated 3-O-glycosides of quercetin and isorhamnetin, were isolated and identified. The antioxidant activity of Ruppia cirrhosa extracts and isolated compounds was investigated spectrophotometrically by a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. IC50 values were 31.8-175.7 µg/mL for Ruppia cirrhosa extracts and 12.1-88.4 µg/mL for isolated flavonoids. Both individual and total phenolic and flavonoid content were quantified in crude extracts using analytical HPLC. The relative high amount of total flavonoids ranged from 5.9 to 14.7 mg/g in both species, with concentrations of individual flavonoids ranging from 0.4 to 2.9 mg/g dry weight. The content of chicoric acid was twofold more in Ruppia maritima than in Ruppia cirrhosa. Seasonal variation of the quantitative content in Ruppia cirrhosa was examined. Total flavonoid content ranged from 8.4 mg/g in October to 14.7 mg/g in August, whereas the highest concentration of chicoric acid was observed in March (29.2 mg/g). [ABSTRACT FROM AUTHOR]

Novel allyl cobalt complexes, i.e., (η³-C4H7)(η4-C4H6)Co(PCyPh2) (1), (η³-C4H7)(η4-C4H6)Co(PMePh2) (2) and (η³-C5H9)(η4-C5H8)Co(PMePh2) (3), were synthesized by reacting CoCl2(PRPh2)2 (R = methyl, cyclohexyl) with 1,3-butadiene or isoprene in presence of metallic zinc. The complexes were fully characterized by Nuclear Magnetic Resonance (NMR) spectroscopy (¹H and 2D experiments); in case of 1, single crystals, suitable for X-ray analysis, were obtained and the molecular structure was determined. The allyl cobalt phosphine complexes alone gave highly crystalline 1,2 polymers from 1,2-propadiene, but they did not polymerize 1,3-dienes. Nevertheless, in the presence of a stoichiometric amount of methylaluminoxane (MAO), they were able to polymerize 1,3-butadiene and substituted 1,3-butadienes such as isoprene, (E)-1,3-pentadiene, (E)-1,3-hexadiene, and (E)-3-methyl-1,3-pentadiene. Specifically, 1/MAO gave predominantly syndiotactic 1,2 polymers from 1,3-butadiene and terminally substituted 1,3-butadienes (e.g., 1,3-pentadiene and 1,3-hexadiene), but it was practically not active in the polymerization of internally substituted 1,3-butadienes (e.g., isoprene and 3-methyl-1,3-pentadiene); 2/MAO and 3/MAO exhibited instead an opposite behavior, giving predominantly isotactic 1,2 polymers from 3-methyl-1,3-pentadiene, and showing very low activity in the polymerization of 1,3-butadiene, 1,3-pentadiene and 1,3-hexadiene. The results obtained are interesting from the mechanistic point of view, and some hypotheses to explain this particular behavior were formulated. [ABSTRACT FROM AUTHOR]

The comparative study on the pyrolysis of two Polypropylene samples, with a similar high isotactic character but quite distinct molecular weights, reveals a significant difference in their thermal performances. The detailed qualitative analysis of the parameters, which are expected to govern the thermal degradation, leads to reasonably assume a main role of the molecular weight in their relative early stabilities. Furthermore, the correlation found between the sharp initial build-up of the E act and the selective cleavage of isotactic stereosequences in both samples, suggests the relevance of the stereoregular length into the energy required for chain scission. [ABSTRACT FROM AUTHOR]

The effect of the stereochemistry of the sulfur atom on 1H chemical shifts of the diasteromeric pair of cyclic sulfites of 4-[methoxy(4-nitrophenyl)methyl]-5-phenyl-1,3,2-dioxathiolan-2-oxide was investigated. The complete 1H and 13C NMR spectral assignment was achieved by the use of one-dimensional and two-dimensional NMR techniques in combination with X-ray data. A correlation of experimental data with theoretical calculations of chemical shift tensors using density functional theory and topological theory of atoms in molecules was made. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The degradation of polyethylene terephthalate (PET) bottles has been successfully achieved by depolymerization through glycolysis with pentaerythritol. The reaction was performed at 250°C in the presence of an organotin catalyst. The glycolyzed products were characterized by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. The existence of the chemical bond between the polyol and the PET was detected through heteronuclear multiple bond correlation spectroscopy, and the NMR signals of different species were separated according to their diffusion coefficient by diffusion-ordered spectroscopy. This method offers a rapid quantification of glycolyzed products. Furthermore, it was found that the major product was the mono-pentaerythritol ester followed by the di-pentaerythritol ester, and lastly the tri-pentaerythritol ester. [ABSTRACT FROM AUTHOR]

The use of precipitation followed by acetylation procedures and preparative TLC purification allowed a facile isolation of four carbohydrates from the methanol extract ofPinus halepensisseeds. The isolated oligosaccharides exhibited high degree of purity. They were identified as α-D-galactosyl-(1→1)-myo-inositol nonaacetate (1), α-D-glucosyl-(1→2)-β-D-fructosyl octaacetate (2), α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl undecaacetate (3), and α-D-galactosyl-(1→6)-α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl tetradecaacetate (4) and were isolated for the first time from this plant. The1H and13C NMR assignments for compounds2,3, and4were detailed herein for the first time. [ABSTRACT FROM PUBLISHER]

Herein, the polyphenolic content in extracts of Ruppia cirrhosa (Petagna) Grande and Ruppia maritima L.was fully characterized for the first time. High amounts of the main compound chicoric acid (CA) (≤30.2 ± 4.3 mg/g) were found in both Ruppia species. In addition, eight flavonoids, namely the 3-O-glucopyranosides and 3-O-galactopyranosides, as well as malonylated 3-O-glycosides of quercetin and isorhamnetin, were isolated and identified. The antioxidant activity of Ruppia cirrhosa extracts and isolated compounds was investigated spectrophotometrically by a 1,1-diphenyl-2-picrylhydrazyl (DPPH·) radical scavenging assay. IC50 values were 31.8–175.7 μg/mL for Ruppia cirrhosa extracts and 12.1–88.4 μg/mL for isolated flavonoids. Both individual and total phenolic and flavonoid content were quantified in crude extracts using analytical HPLC. The relative high amount of total flavonoids ranged from 5.9 to 14.7 mg/g in both species, with concentrations of individual flavonoids ranging from 0.4 to 2.9 mg/g dry weight. The content of chicoric acid was twofold more in Ruppia maritima than in Ruppia cirrhosa. Seasonal variation of the quantitative content in Ruppia cirrhosa was examined. Total flavonoid content ranged from 8.4 mg/g in October to 14.7 mg/g in August, whereas the highest concentration of chicoric acid was observed in March (29.2 mg/g).

[Display omitted] • The synthesis of a fluorescent steroid dimer with androstanes cores is reported. • The cores are linked through C-19 by a 1,4 bis(phenylethynyl)benzene fragment. • The detailed NMR characterization is provided. • The UV and Fluorescence spectra were recorded. • The compound showed a quantum yield of 60%. The synthesis and characterization of a dimer in which two nuclei of 3β-acetoxy-19-hydroxyandrost-5-en-17-one are linked by the fluorescent 1,4-bis(phenylethynyl)phenylene bridge attached to the oxygenated functions at positions C-19 of each steroid fragment is described. The compound was obtained in five steps and 23 % overall yield and showed a strong blue emission with a quantum yield of 0.66. [ABSTRACT FROM AUTHOR]

Two new polypropionates, named exiguapyrone ( 2 ) and exiguaone ( 3 ) along with the known haminol-1 ( 4 ) and -2 ( 5 ), have been isolated from the lipidic extract of the Mediterranean cephalaspidean mollusc Haminoea exigua . The regular propionate skeletons, structurally related to other polypropionates from the congener Haminoea fusari , have been elucidated by means of NMR techniques as natural ( 2 and 3 ) and α-/γ-pyrone methyl derivatives ( 2a and 2b ). This is a further report showing the co-occurrence of alkyl-pyridines and polypropionates in Haminoea molluscs strengthening the role of polypropionates as chemical markers among cephalaspideans. [ABSTRACT FROM AUTHOR]

Changes in chain microstructure during the pyrolysis of a high molecular weight isotactic polypropylene (iPP) have been tracked by means of FTIR, DSC and NMR techniques. For this purpose, preparative dynamic TGA experiments have been performed up to final temperatures between 200 °C and 420 °C. The evolutions of molecular weight, tacticity and both quality and content of chain-end double bonds have been analysed and correlated with the conversion-dependent Eact build-up, estimated from analytical TGA curves. The obtained results allows correlating the earliest low Eact values with the vanishing of chemical defective structures like carbonyls, as well as with the scission of some very few regular C–C bonds. The growing trend of the Eact, found from low to advanced pyrolysis stages, is associated to the collapse of the molecular weight and the decreasing of the isotacticity degree. The evolution towards shorter and more flexible chains is thought to underlie an increasingly energy demanding scission process. [ABSTRACT FROM AUTHOR]

ABSTRACT Copolymerization behavior of ethylene (E) and propylene (P) using ansa-dimethylsilylene(fluorenyl)(amido)dimethyltitanium complex was investigated. P was more reactive than E regardless of the chain-end monomer unit, which was very unusual in the coordination polymerization system. The terpolymerizations of E, P and norbornene (NB) or 5-ethylidene-2-norbornene (5E2N) were also performed. The each content in the E/P/NB terpolymer was independently controlled by the initial concentration of NB and E/P feed ratio. Glass transition temperature ( Tg) of the terpolymer was raised in proportion to the NB content and close to that of the corresponding NB/E random copolymer with the same NB content. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 685-691 [ABSTRACT FROM AUTHOR]

Abstract: Development of heterogeneous catalysts for the biorenewable industry requires hydrothermal degradation resistance. However, the relationship between hydrothermal stability and the immediate electronic hybridization of the carbon atoms adjacent to the sulfonic acid active group is not fully known. We systematically tested model compounds containing sulfonic acid groups linked to aromatic, alkane, or cycloalkane carbon atoms. We subjected them to hydrothermal conditions. The compounds' structural integrity was monitored with solution NMR. The aromatic-sulfonic acid compounds degraded readily, while the hydrolysis of the alkyl sulfonic acid linkages was negligible. Therefore, hydrothermally stable sulfonic-acid catalysts need sulfonic acid attached via alkyl linkers. [Copyright &y& Elsevier]

Aqueous solutions of F127 pluronic systems exhibit an interesting thermal gelation above a certain concentration. This phenomenon concerns the transition from a liquid-like behavior at low temperatures to a solid-like behavior at high temperatures, and it is due to different temperature responses from the different polymer segments, polypropylene oxide (PPO) and polyethylene oxide (PEO). Such property leads to a structural change in the self assembled macromolecule upon heating, from an isotropic micellar structure to an ordered cubic structure. These two types of assembly are clearly distinct with respect to their rheological behavior. This contribution emphasizes the rheological properties of the pluronic system in micellar and cubic phase, in combination with NMR, Dynamic Light Scattering and DSC information. The results emphasize the gelation process upon heating and a cubic phase characterized by higher storage modulus and higher A and z Weak Gel Model exponents than the micellar phase. Micellar growth upon heating was found within micellar phase. The presented data support the hypothesis that each polymer segment actively participates in the formation of the different phases: while PPO is responsible for micelle formation, PEO plays a dominating role in cubic phase formation. Finally, different stiffness between the core and the corona of the aggregates in the two phases is observed.

Highlights: [•] Pyrolysis of SW kraft lignin and pine wood were examined. [•] Various NMR and GPC were used to characterize various pyrolysis oils. [•] Fast pyrolysis improved cleavage of methoxyl, aliphatic C C and carbonyl bonds. [•] Fast pyrolysis produced more PAH from lignin. [•] Molecular weight of fast pyrolysis oils increased by ∼100%. [Copyright &y& Elsevier]

Abstract: The pyrolysis of a highly syndiotactic and high-molecular weight polypropylene (sPP) has been thoroughly studied through preparative TGA experiments, which were performed up to final temperatures between 262 °C and 427 °C. The 13C NMR characterization of the samples shows a two-stage process clearly evidenced by changes in the chain microstructure. In a first period, up to a 22% weight loss, the molecular weight collapses and only vinylidene end-capped chains are produced. In a second stage, over 22% weight loss, a wider variety of groups, including both terminal vinylen and isobutenyl functions as well as n-propyl tails, are also detected. Regardless the type, all these new species are formed at the expense of propylene units belonging to rrrr pentads. The evolution of the Eact predicted by means of analytical TGA allows us to associate the lowest Eact value found with the changes taking place during the very beginning of the process (up to a 3% weight loss), i.e. the molecular weight collapse and a some evidence of configurational stereo-specificity. As regards the further Eact build-up, it can be rationalized in terms of the ability of chains to be rolled in the most stable GGTT conformation, as it is supported by complementary FTIR and DSC characterization of the samples. [Copyright &y& Elsevier]

Cationization of different cellulosic materials was successfully accomplished using an efficient solvent-minimizing spray-technique. The obtained materials were studied and evaluated in regard to reaction efficiency and regioselectivity using 1D and H-C correlated 2D NMR experiments. The high consistencies and temperatures applied using the spray-technique resulted in reagent effective etherifications and shorter reaction times. The NMR spectra indicated that the spray-technique favors substitutions at position O-6, showing a regioselectivity of O-6 > O-2 > O-3 for softwood kraft pulp (SKP) and cotton linters. However, cationization of mercerized cellulose and dissolving pulp, using the spray-technique, demonstrated more efficient reactions compared to SKP and cotton, and a regioselectivity of O-6 ≥ O-2 > O-3. Nanocrystalline cellulose showed the lowest reactivity and a regioselectivity of O-6 ≫ O-2 > O-3. In this work we provide information on structure-property relationships and characterization methods for modified polysaccharides, together with a solvent system that is well known industrially and in line with sustainability aspects. [ABSTRACT FROM AUTHOR]

Abstract: Aiming to develop new dielectric polymers containing CN and F groups with strong dipole moments, a novel copolymer of acrylonitrile (AN) and 2,2,2-trifluoroethyl acrylate (ATRIF) was synthesized in acetonitrile by free radical process as well as the respective homopolymer (poly(ATRIF)). The copolymer’s composition and microstructure were analyzed by FTIR, 1H and 13C NMR spectroscopy and SEC. The molar incorporation of AN determined in the copolymer by NMR was 58mol%. Thermogravimetric analysis of poly(AN-co-ATRIF) copolymer showed good thermal stability comparatively to the fluorinated homopolymer. Both copolymer, poly(AN-co-ATRIF), and homopolymer, poly(ATRIF), were dielectrically characterized over a frequency range from 10−1 to 106 Hz, and in a temperature range from 223 to 393K. The dominating relaxation process detected in both materials is the α-relaxation, associated with the dynamic glass transition. A VFTH temperature dependence of the relaxation times (τ) was found for both materials, as characteristic of cooperative processes, from which the respective glass transition temperatures (T g(τ =100s)) were estimated, which differ ∼40K, the one of the copolymer being higher (307K) in accordance to the calorimetric analysis. This effect was attributed to a higher stiffness of the backbone in the copolymer originated by the inclusion of the acrylonitrile groups. Both relaxation functions have the same breath of relaxation times allowing constructing a single master curve, indicating similar non-exponential character. A less fragile behavior was found for the copolymer. This was rationalized in a more straightforward way by the free volume approach instead from a correlation between fragility and intermolecular coupling. It was found that in the copolymer the free volume increases at a lower rate with the temperature increase. It was inferred from the VFTH temperature dependence of the dc conductivity and low values of the decoupling index that ion motion is significantly influenced by the dynamics of the α-process. [Copyright &y& Elsevier]

Abstract: We report a simple and suitable method for the preparation of useful 2-trifluoromethylchromones in one step, in high yields and avoiding the use of solvents. We were able to detect the intermediate of this reaction. Furthermore a mechanism for the formation of the 7-methoxy-3-trifluoroacetyl-2-trifluoromethylchromone through the unexpected double trifluoroacetylation of 4-methoxy-2-hydroxyacetophenone followed by dehydration is also proposed. All compounds are fully identified and characterized by spectroscopic techniques. [Copyright &y& Elsevier]

Abstract: The reaction of Pt(COD)Cl2, where COD is 1,5-cyclooctadiene, with one equivalent of a diamidato-bis(phosphino) Trost ligand ((R,R)-2 = N,N′-bis(2-diphenylphosphino-1-benzoyl)-(1R,2R)-1,2-diaminocyclohexane, (R,R)-3 = N,N′-bis(2-diphenylphosphino-1-naphthoyl)-(1R,2R)-1,2-diaminocyclohexane, or (±)-4 = N,N′-bis(2-diphenylphosphino-1-benzoyl)-1,2-bis(aminobenzene)) in the presence of base afforded square planar diamidato-bis(phosphino) platinum(II) complexes (R,R)-2-Pt, (R,R)-3-Pt, (±)-4-Pt. Characterization of all complexes included the solution and solid state structure determination of each complex based on multinuclear NMR and X-ray analyses, respectively. Stability of the complexes in acid was examined on addition of HCl to (R,R)-2-Pt in chloroform and compared to the unreactive nature of the similar diamidato-bis(phosphino) complex 1-Pt (1 =1,2-bis-N-[2′-(diphenylphosphino)benzoyl]diamino-benzene) in the presence of acid. Protonation of the bound amidato nitrogen atoms of (R,R)-2-Pt was observed along with decoordination of the nitrogen atoms from the platinum(II) center producing (R,R)-2-PtCl2 in quantitative yield by NMR analysis. Confirmation of the product was made on comparison of the NMR spectra to that of authentic (R,R)-2-PtCl2 prepared on reaction of Pt(COD)Cl2 with (R,R)-2 in CH2Cl2 and characterized by single-crystal X-ray diffraction analysis and NMR spectroscopy. Results add to the knowledge of rich coordination chemistry of bis(phosphino) ligands with late transition metals, metal–amidato chemistry, and has implications in catalysis. [Copyright &y& Elsevier]