Phthalic Anhydride Research Articles

Synthesis, Characterization, and Biological Evaluation of Gabapentinoid Hybrids with Isoindole-1,3(2H)-Dione Moiety as Potential Antioxidant, Antimicrobial, and Anticancer Agents

Purpose. To synthesize new isoindole-1,3(2H)-dione derivatives by molecular hybridization of gabapentin and pregabalin with phthalic anhydride derivatives and to evaluate their biological activity as promising antioxidant, antimicrobial, and anticancer agents. Method. Molecular hybridization was successfully achieved by two procedures; synthesized compounds were characterized using analytical and spectral methods. The free radical scavenging properties of synthesized compounds were evaluated using the DPPH method. The antibacterial activity of synthesized compounds and parent compounds was evaluated against two microbial Gram-positive and Gram-negative strains by the well diffusion method. Furthermore, we have studied the effect of compounds on proliferation, cell cycle, and cell death in two human cancer cell lines (Caco-2 and HCT-116). Results. Compounds 1, 3, and 4 exhibited a good free radical scavenging effect, and compound 3 is the most effective with IC50 value of 2.525 μmol/mL. All compounds showed antibacterial activity against Escherichia coli and Staphylococcus aureus related to concentration, while parent drugs did not exhibit any antibacterial effect. Compounds 1 and 2 showed a good zone of inhibition against E. coli at micromolar concentrations, and they are more effective than Gentamicin Sulfate. Treatment with the studied compounds suppresses proliferation, arrests progress throughout the cell cycle, and induces apoptosis in Caco-2 and HCT-116 cancer cells. Compound 2 is highly effective against Caco-2 cells and more effective than thalidomide, with IC50 value less than 1 μmol/L. Conclusion. Our results showed that molecular hybridization of gabapentin and pregabalin in the isoindole-1,3(2H)-dione moiety results in promising anticancer and antimicrobial molecules. Results of this preliminary study show that halogenation of the isoindole-1,3(2H)-dione moiety improves antimicrobial and anticancer activity and that tetra-brominated derivatives are comparable to or more effective than related tetra-chlorinated derivatives.

Polyester-Based Coatings with a Metal Organic Framework: An Experimental Study for Corrosion Protection

Polyester coatings containing metal-organic framework (MOF) corrosion inhibitors were studied for their ability to protect carbon steel. The polyester coating was synthesized in the laboratory using microwave (MW) radiation to polycondense soy fatty acids, phthalic anhydride, and pentaerythritol-type polyols. The incorporation of these inhibitors into the polyester coating altered the behavior of the carbon steel, resulting in enhanced corrosion protection compared with uncoated carbon steel and polyester alone. Polyester with a 49% oil content, prepared using fatty acids from soybeans, phthalic anhydride, and pentaerythritol synthesized under microwave irradiation, and with a content of 3 mM Mg(GLY), exhibited a notable enhancement in the anticorrosive properties of the alkyd coating. The inhibition mechanism of corrosion was investigated through electrochemical impedance spectroscopy analysis.

Bio-based alkyd urethane formulations: Advancing sustainable agriculture and environmental protection through slow-controlled release of NPK fertilizers

Global population growth and climate change demand sustainable food production through integrated soil fertility management. However, the use of inorganic fertilizers contributes to environmental issues, making controlled-release fertilizers a promising solution for sustained, eco-friendly crop nourishment. In this study, we present the development of Polyalkyd-urethan (PAUs) formulations based on alkyd resin to serve as coating films for NPK (Nitrogen-Phosphorus-Potassium) granules, creating Slow-Controlled Release Fertilizers (SCRF). Firstly, we thoroughly investigated the synthesis and characterization of alkyd resins from rapeseed oil and a mixture of phthalic and maleic anhydride. These alkyds were then reacted with Hexamethylene di-isocyanate (HMDI) to produce polyalkyd-urethane (PAU) films. The films were characterized using various methods including SEM, FTIR, DSC, TGA, contact angle, water uptake, and mechanical tests. The developed PAUs formulations were applied as coating films for NPK granules, and the release of Phosphorus (P), Nitrogen (N), and Potassium (K) nutrients in water was investigated following EN 13266 standards. The coated fertilizers displayed cohesive films on the NPK granules, and those coated with 6% polyalkyd-urethane formulation prepared with 100% phthalic anhydride exhibited excellent slow-release properties. After three months of incubation in water, these granules achieved a nutrient release percentage of 92.28%, 86.14%, and 82.34% for N, P, and K, respectively. Furthermore, the coated films significantly improved the hardness of the NPK granules, reaching a maximum value of 10.75 Kgf, representing a 300% improvement compared to uncoated NPK granules. These experimental results underscore the dual advantages of the biobased polyalkyd-urethane formulations, enhancing both the physical quality of fertilizers and control over nutrient release, offering economic and environmental benefits.

Synthesis, spectroscopic, DFT calculations, biological activity, SAR, and molecular docking studies of novel bioactive pyridine derivatives

Enaminonitrile pyridine derivative was used as a precursor for preparation of fourteen heterocyclic compounds using both conventional thermal and microwave techniques. Diverse organic reagents, such as chloroacetyl chloride, acetic anhydride, chloroacetic acid, carbon disulfide, p-toluene sulfonyl chloride, maleic anhydride, phthalic anhydride, were used. The chemical formulae and structures of isolated derivatives were obtained using different analytical and spectroscopic techniques such as IR, 1H-, 13C-NMR as well as mass spectrometry. The spectroscopic analyses revealed diverse structure arrangements for the products. Molecular structure optimization of certain compounds were performed by the density functional theory (DFT/B3LYP) method and the basis set 6–31 G with double zeta plus polarization (d,p). The antimicrobial inhibition and the antioxidant activity of the reported compounds were screened. Compounds 5, 6, 11 and 13 exhibited the highest antibacterial inhibition, while compound 8 gave the highest scavenging activity (IC50 43.39 µg/ml) against the DPPH radical. Structure–activity relationship of the reported compounds were correlated with the data of antibacterial and the antioxidant activity. The global reactivity descriptors were also correlated with the biological properties of compounds. The molecular docking studies of reported compounds were investigated, and the analysis showed that the docked compounds have highly negative values for the functional binding scores. The binding interaction was found to be correlated with the substituent fragments of the compounds.

Synthesis of cellulose graft cyclic anhydride and epoxide alternating copolyesters in a DBU/ DMSO/CO2 solvent system

A series of cellulose grafted alternating cyclic anhydride (CA) and epoxide (EPO) copolyesters (cell-g-P(CA-alt-EPO)) have been prepared in the novel DBU/DMSO/CO2 cellulose solvent system. The DBU acted both as a reagent for cellulose dissolution and as a catalyst for ring-opening copolymerization (ROCOP) of cellulose with EPO and CA. The structural features and thermal performances of cell-g-P(CA-alt-EPO) were characterized via MALDI-TOF, FT-IR NMR, TGA, DSC and XPS. Perfectly alternating sequence distributions and controlled molecular weights of a series of cell-g-P(CA-alt-EPO) were easily achieved by a variation of the CA or EPO. The cell-g-P(CA-alt-EPO) also had satisfactory UV-absorbing properties and cellulose grafted phthalic anhydride and glycidyltrimethylammonium chloride exhibited outstanding antibacterial behavior. Antibacterial activity against Escherichia coli and Staphylococcus aureus were 96.7% and 99.4% respectively. Thus, cell-g-P(CA-alt-EPO) with good solubility, melt processability, UV absorption and antibacterial properties have potential applications in UV-shielding and antibacterial agent fields.

Conversion of waste PET into triazines-incorporated polyols and flame-retardant polyurethane foams

Preparation of flame retardant rigid polyurethane foams (RPUFs) from sustainable material sources like recycled polyethylene terephthalate (rPET) remains a challenge due to the difficulty in controlling the synthesis of polyols with flame retardant functionalities. Here, we propose a method for converting rPET into a polyester-amide-ether oligools incorporated flame retardant triazine-ring through the partial codepolymerization of rPET by 1,3,5-tris(hydroxymethyl isocyanurate (THMI), ethanolamine, and diethylene glycol, followed by linking oligools into polyols with phthalic anhydride. THMI was synthesized through nucleophilic additions of formaldehyde with isocyanuric acid. The codepolymerization and linking were carried out using a one-pot method. Single-factor experiments were implemented to optimize the process parameters such as reacting temperature and time. The L9 (43) orthogonal experiments were employed to systematically investigate the influence of the dosages of four raw materials on the performance of the synthesized polyols. Based on the range analysis of acid value, hydroxyl value, and viscosity of the synthesized polyols, the optimized polyol was synthesized as a candidate for preparing flame retardant RPUFs. Results demonstrated that the obtained RPUF derived from the optimized polyol could achieve a limiting oxygen index (LOI) value of 30.3% when mixed with phosphorous-containing flame-retardant DCPP, meeting the national standard of combustible stage B1.The high flame retardancy RPUF obtained from an rPET-based polyol with a triazine ring represents a novel and practical method of preparation, providing new insights into the optimization of synthesis parameters across multiple factors and levels.

Synthesis, Molecular Docking Studies, and In vitro Anticancer Evaluation of Novel Tolfenamic Acid Derivatives

Background: Accumulating experimental evidence has demonstrated that tolfenamic acid (TA) has anticancer activity. TA has been shown to modulate the expression of several cancer-related genes involved in apoptosis and cell cycle arrest, as well as metastasis and angiogenesis. Objective: The current study was carried out to evaluate the anticancer activities of eight newly synthesized TA derivatives by conducting in silico molecular docking studies and in vitro biological evaluations to validate their VEGFR-2 tyrosine kinase inhibitory activities. Methods: The novel TA derivatives (3A–F–5) were obtained by reacting TA hydrazide with substituted aldehydes, phthalic anhydride, and succinic anhydride, respectively. Spectroscopic techniques were used to characterize the target molecules. Docking studies were performed to determine the binding patterns to the potential molecular target VEGFR-2, and these were compared with the results of the in vitro VEGFR-2 tyrosine kinase (TK) inhibition assay. Results: Our findings indicate that the newly synthesized compounds are cytotoxic, with compound 4 being the most potent. Additionally, all compounds inhibited VEGFR-2 TK activity, the EC50 value of compound 4 was nearly identical to that of the conventional VEGFR TK inhibitor sorafenib. SAR studies revealed that the presence of an aryl or a heteroaryl fragment attached to the hydrophilic linker (as found in compound 4) is crucial to the anticancer activity. Conclusion: The outcomes suggest that the isoindoline derivative (compound 4) is a good candidate for further investigation. The docking results provide evidence for a correlation between the experimental and predicted VEGFR-2 TK inhibitory activity. Moreover, ADMET studies indicate that all ligands have good pharmacokinetic properties.

Synthesis of N-Propargyl Pyrrolylamides and Theoretical Study of Pyrrolylimide Reduction by NaBH4

AbstractThis study is divided into two parts: experimental and theoretical. In the experimental part, N-propargyl-substituted pyrrolylamide derivatives are synthesized in five steps starting from pyrrole. The main features of this procedure are (i) the synthesis of 2- and 3-nitropyrrole, (ii) the introduction of a propargyl group on the nitrogen atom of the pyrrole, (iii) coupling of various substituents with the alkyne functionality by the Sonogashira reaction, (iv) synthesis of pyrrolylimides by a tin-catalyzed reaction with phthalic anhydride, and, finally, (v) reduction of pyrrolylimides with sodium borohydride (NaBH4) in the presence of water. The theoretical part concerns the reduction mechanism of the pyrrolylimide by NaBH4. The hybrid functional B3LYP in density functional theory is used to determine and discuss the energetics of the compounds.

Synthesis and Chemical Characterization of Alkyd Resins Using Maleic and Phthalic Anhydrides and Seed oil of Luffa aegyptiaca

The study aimed to provide sustainable alternatives to reduce industries’ over-reliance on edible vegetable oil for alkyd resin preparation as applicable in paint production. Alkyd resins were synthesized and characterized from sponge (Luffa aegyptiaca) seed oil. Condensation polymerization of monoglyceride with phthalic and maleic anhydride was carried out, and physico-chemical parameters such as drying time, total solids, viscosity, and chemical resistance were investigated following standard procedures. UV–visible, FT-IR, 1H, and 13C NMR spectroscopies were used to characterize the prepared alkyd resins. Sponge seed oil alkyd resins prepared with maleic anhydride (SPOMA) had a higher percentage yield (77.56%) than sponge seed oil prepared using phthalic anhydride (SPOPA) with 64.44%. The two alkyd resins showed a better drying time of 40 – 50 min than their commercial counterparts (70 min). This was attributed to the high degree of unsaturation of the seed oil due to the considerable proportion of linoleic acid in the seed oil. The alkyd resins were largely stable in 0.1 M HCl, 5% NaCl, and 0.1 M KOH, which caused the alkyd resins to whiten and shrink. The resins were generally soluble in xylene, kerosene, and petroleum ether. The nature of the alkyd resin can be described as nonpolar. This observation was consistent with the literature report. This study concluded that quality or industrial-grade alkyd resins could be prepared from sponge seed oil and thereby serve as a cheap and viable replacement for edible oils used in industries.

Producing polyglycerol polyester polyol for thermoplastic polyurethane application: A novel valorization of glycerol, a by-product of biodiesel production

The production of biodiesel generates glycerol as a by-product that needs valorization. Glycerol, when converted to polyglycerol, is a potential polyol for bio-based thermoplastic polyurethane (TPU) production. In this study, a novel polyglycerol polyester polyol (PPP) was developed from refined glycerol and coconut oil-based polyester polyol. Glycerol was first converted to glycerol acetate and then polymerized with coconut oil-based polyester polyol (CPP) as secondary polyol and phthalic anhydride. The resulting PPP polymerized at 220 °C and OH:COOH molar ratio of 2.5 exhibited an OH number of <100 mg KOH·g sample−1, an acid number of <10 mg KOH·g sample−1, and a molecular weight (MW) of 3697 g mol−1 meeting the polyol requirement properties for TPU (Handlin et al., 2001; Parcheta et al., 2020) [1-2]. Fourier-transform infrared (FTIR) spectroscopic characterization determined that higher reaction temperatures increase the polymerization rate and decrease the OH and acid numbers. Further, higher OH:COOH molar ratios decrease the polymerization rate and acid number, and increase the OH number. Gel permeation chromatography determined the molecular weight of PPP and suggested two distinct molecular structures which differ only in the number of moles of CPP in the structure. A differential scanning calorimetric (DSC) experiment on a sample of PPP-based polyurethane revealed that it was able to melt and remelt after 3 heating cycles which demonstrates its thermoplastic ability. The novel PPP derived from the glycerol by-product of biodiesel industries can potentially replace petroleum-derived polyols for TPU production.

Electrical Properties of Alicyclic Epoxy Resins for Application to Varnish of Rotating Machine Winding

Epoxy resins (EP) are commonly used to power apparatus due to their excellent electrical, thermal, and mechanical properties. Two types of EP resins were prepared to develop the varnishes for a rotating machine winding. A bifunctional alicyclic EP were used as an EP main resin, and an acid anhydride [mixture of hexahydro phthalic anhydride and methyl hexahydro phthalic anhydride (HHPA), or methyl nadic anhydride (NMA)] were used as a curing agent. The DC and impulse breakdown strengths of the EP‐HHPA were higher than that of EP‐NMA regardless of the applied voltage waveform and the temperature. The PDIV of the twisted pair sample coated with EP‐HHPA under the surge voltage application was also higher than that of twisted pair sample without the coating with EP resin and that with EP‐NMA. Furthermore, the transferred and/or accumulated charge amount of the EP‐HHAP on bulk and surface properties at high temperatures were superior to that of EP‐NMA. From these results, it is considered that EP‐HHPA may be preferable varnishes materials than EP‐NMA for a rotating machine winding. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Fluorinated polyimide with triphenyl pyridine structure for 5G communications: Low dielectric, highly hydrophobic, and highly transparent

With the rapid development of 5G communications, the traditional interlayer dielectric material polyimide (PI) requires modification due to its intrinsically high dielectric constant (Dk), high dielectric loss (Df), and high moisture absorption, which make it difficult to meet the needs of the high-frequency communications industry. In this paper, a new strategy for the preparation of novel PI with intrinsically low Dk and Df is proposed from the perspective of molecular structure design, the modification effect of superimposing bulky triphenyl pyridine structures and strong electronegativity groups, combined with long-chain anhydride to reduce the density of the imide structure. Therefore, three bulk diamine monomers (BPAB, PBAB3F, PBAB6F) containing triphenyl pyridine structures were designed in this paper and polymerized with 4,4′-(4,4′-isopropyldiphenoxy) phthalic anhydride (BPADA) to obtain three new PIs (PI-H, PI-CF3, PI-2CF3) with different fluorine contents, focusing on the relationship between structure and properties, especially the effect of fluorine content on dielectric properties. The results of the study show that the dielectric and hygroscopic properties of PI improve with increasing fluorine content. Among them, PI-2CF3 has the best overall performance, showing low dielectric (Dk = 2.72@10 GHz & Df = 0.00233@10 GHz), high transparency (Cut-off wavelength (λ0) = 389 nm, Maximum transmittance (Tvia) = 89%) and low hygroscopicity (Water absorption (Ma) = 0.246%, Contact angle (Ca) = 111°).

Environmentally benign plant-based polymeric organogel for wastewater treatment

Designing thermally and chemically stable adsorbents with higher efficiency than traditional adsorbents for wastewater treatment from natural resources has been getting the attention of the scientific community recently. In our search for better toxic dye adsorbents, in the present investigation, we have designed polymeric organogel by interacting polyvinyl alcohol (PVA) with cellulose diacetate (CA) using phthalic anhydride (PA) as the cross-linker. Here, cellulose diacetate (CA) was synthesized from cellulose phytochemically extracted from Dalbergia sissoo bark biomass. The cross-linking of CA with PA improved the polymeric organogel's stability and its dye adsorption capability over the pristine polymeric (PVA) organogel (12 %). The structure, morphology, and thermal stability of the organogel were evaluated using various state-of-the-art analytical techniques. The polymeric organogel offers 78% (223.46 mg/g) adsorption capability for the crystal violet (cationic), 69% (181.3 mg/g) for the congo red (anionic) against the 52%, and 48% of pristine PVA-based hydrogel. Based on the findings, produced organogel might be used as an environmentally safe, thermally stable, and more effective adsorbent for removing synthetic dyes from wastewater.

High- and low-temperature resistant and intrinsically flame retardant poly(bisphthalazinone thioether sulfone ketone)s: Synthesis, structures and properties

High-performance polymers that are both high temperature resistant and soluble is significant for the development of high-tech fields. 4,4′-(Thiobis(4,1-phenylene))bis(phthalazin-1(2H)-one) (T-BDHPZ) monomer is synthesized by an efficient two-step method using inexpensive phenyl sulfide and phthalic anhydride as raw materials. A series of novel poly(bisphthalazinone thioether sulfone ketone)s (PBPTSKs) were synthesized via aromatic nucleophilic substitution polycondensation. The structures of PBPTSKs were characterized by NMR and FT-IR. These polymers have glass transition temperatures (Tgs) in the range of 302–328 ℃, and are soluble in N-methyl-2-pyrrolidone (NMP), pyridine (Py) and 1,1,2,2-tetrachloroethane (TECT), and partially soluble in N,N -dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dichloromethane (DCM), trichloromethane (TCM) and pyridine. PBPTSK films were prepared by solution casting, and the average light transmittance from 400 to 800 nm of films are all over 70%. PBPTSK boards prepared by hot press molding have outstanding mechanical properties with the tensile strength and the flexural strength of 91–102 MPa and 123–135 MPa, respectively. PBPTSK boards also exhibit excellent high- and low-temperature resistance properties at 290 and −60c, respectively. Moreover, these polymers with bisphthalazinone thioether moiety have outstanding inherent flame retardancy, which pass the V-0 level of the UL-94 test. This provides opportunities to develop high-performance polymers that are both high temperature resistant and soluble, showing great prospects in frontier applications.

Characterization of Native and Modified Fermented Smoked Cassava for Food Packaging Application

The goal of this study is to see what changes may be made to fermented smoked cassava (FSC) for use in food packaging. For 5 days, cassava was soaked in water. The fermented cassava was shaped into balls and dried at 50oC d in an oven. The fermented smoked cassava that resulted was milled. The fermented smoked cassava was subjected to chemical modification by pregelatinized phthalation. To make pregelatinized phthalated, FSC, the FSC was pre-gelatinized by heating the solution above 70°C and esterified with phthalic anhydride. The characteristics of modified and native FSC were investigated. The native FSC typical spherical form had vanished, and a fibrous-like irregular structure had replaced it, according to the results of scanning electron microscopy. After some alterations The degree of crystallinity in the native FSC has changed to amorphosity in the modified FSC, according to X-Ray Diffractometry. Thermogravimetry findings demonstrated that the native structural matrix of FSC was totally collapsed at 380oC, whereas the modified FSC structural matrix fully collapsed, leaving just residues at 700 oC. The modified fermented, smoked-dried cassava was discovered to be a promising alternative biopolymer for food packaging applications.

Bimetallic Al(III) Compounds as Catalysts for the Synthesis of Biodegradable Polyesters and Polycarbonates

AbstractEthylenediamine bridged benzoxazine proligands were synthesized by a modified Mannich condensation reaction. The reaction of the proligands with two equivalents of AlMe3 resulted in the formation of dinuclear Al(III) compounds in high yield and purity. When the ligand binds to the Al(III) center, it forms two separate six‐membered N,O‐chelates with the two Al atoms that resembles the N‐alkylated salan moiety. Each aluminum atom adopts a distorted tetrahedral geometry as revealed from the single‐crystal X‐ray diffraction studies of 1. The catalytic activity of these aluminum compounds was investigated towards the ROP of rac‐LA and ROCOP of epoxides (PO, CHO, tBuGE) and phthalic anhydride and ROCOP of CHO with CO2. These aluminum compounds showed notable catalytic activity towards the ROP and ROCOP reactions in the absence of cocatalyst.

High-Glass-Transition Polyesters Produced with Phthalic Anhydride and Epoxides by Ring-Opening Copolymerization (ROCOP).

Polyesters with a high glass transition temperature above 130 °C were obtained from limonene oxide (LO) or vinylcyclohexene oxide (VCHO) and phthalic anhydride (PA) in the presence of commercial salen-type complexes with different metals-Cr, Al, and Mn-as catalysts in combination with 4-(dimethylamino) pyridine (DMAP), bis-(triphenylphosphorydine) ammonium chloride (PPNCl), and bis-(triphenylphosphoranylidene)ammonium azide (PPNN3) as cocatalysts via alternating ring-opening copolymerization (ROCOP). The effects of the time of precontact between the catalyst and cocatalyst and the polymerization time on the productivity, molar mass (Mw), and glass transition temperature (Tg) were evaluated. The polyesters were characterized by a molar mass (Mw) of up to 14.0 kg/mol, a narrow dispersity Tg of up to 136 °C, and low (<3 mol%) polyether units. For poly(LO-alt-PA) copolymers, biodegradation tests were performed according to ISO 14851 using the respirometric biochemical oxygen demand method. Moreover, the vinyl double bond present in the poly(LO-alt-PA) copolymer chain was functionalized using three different thiols, methyl-3-mercaptopropionate, isooctyl-3-mercaptopropionate, and butyl-3-mercaptopropionate, via a click chemistry reaction. The thermal properties of poly(LO-alt-PA), poly(VCHO-alt-PA) and thiol-modified poly(LO-alt-PA) copolymers were extensively studied by DSC and TGA. Some preliminary compression molding tests were also conducted.

The Phthalic Selenoanhydride Decreases Rat Blood Pressure and Tension of Isolated Mesenteric, Femoral and Renal Arteries.

Phthalic selenoanhydride (R-Se) solved in physiological buffer releases various reactive selenium species including H2Se. It is a potential compound for Se supplementation which exerts several biological effects, but its effect on the cardiovascular system is still unknown. Therefore, herein we aimed to study how R-Se affects rat hemodynamic parameters and vasoactive properties in isolated arteries. The right jugular vein of anesthetized Wistar male rats was cannulated for IV administration of R-Se. The arterial pulse waveform (APW) was detected by cannulation of the left carotid artery, enabling the evaluation of 35 parameters. R-Se (1-2 µmol kg-1), but not phthalic anhydride or phthalic thioanhydride, transiently modulated most of the APW parameters including a decrease in systolic and diastolic blood pressure, heart rate, dP/dtmax relative level, or anacrotic/dicrotic notches, whereas systolic area, dP/dtmin delay, dP/dtd delay, anacrotic notch relative level or its delay increased. R-Se (~10-100 µmol L-1) significantly decreased the tension of precontracted mesenteric, femoral, and renal arteries, whereas it showed a moderate vasorelaxation effect on thoracic aorta isolated from normotensive Wistar rats. The results imply that R-Se acts on vascular smooth muscle cells, which might underlie the effects of R-Se on the rat hemodynamic parameters.

In Situ Redox Synthesis of Highly Stable Au/Electroactive Polyimide Composite and Its Application on 4-Nitrophenol Reduction.

In this study, we developed a series of Au/electroactive polyimide (Au/EPI-5) composite for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using NaBH4 as a reducing agent at room temperature. The electroactive polyimide (EPI-5) synthesis was performed by chemical imidization of its 4,4'-(4.4'-isopropylidene-diphenoxy) bis (phthalic anhydride) (BSAA) and amino-capped aniline pentamer (ACAP). In addition, prepare different concentrations of Au ions through the in-situ redox reaction of EPI-5 to obtain Au nanoparticles (AuNPs) and anchored on the surface of EPI-5 to form series of Au/EPI-5 composite. Using SEM and HR-TEM confirm the particle size (23-113 nm) of the reduced AuNPs increases with the increase of the concentration. Based on CV studies, the redox capability of as-prepared electroactive materials was found to show an increase trend: 1Au/EPI-5 < 3Au/EPI-5 < 5Au/EPI-5. The series of Au/EPI-5 composites showed good stability and catalytic activity for the reaction of 4-NP to 4-AP. Especially, the 5Au/EPI-5 composite shows the highest catalytic activity when applied for the reduction of 4-NP to 4-AP within 17 min. The rate constant and kinetic activity energy were calculated to be 1.1 × 10-3 s-1 and 38.9 kJ/mol, respectively. Following a reusability test repeated 10 times, the 5Au/EPI-5 composite maintained a conversion rate higher than 95%. Finally, this study elaborates the mechanism of the catalytic reduction of 4-NP to 4-AP.

Salen-like Chromium and Aluminum Complexes as Catalysts in the Copolymerization of Epoxides with Cyclic Anhydrides for the Synthesis of Polyesters.

Chromium and aluminum complexes bearing salalen ligands were explored as catalysts for the ring-opening copolymerization (ROCOP) of succinic (SA), maleic (MA), and phthalic (PA) anhydrides with several epoxides: cyclohexene oxide (CHO), propylene oxide (PO), and limonene oxide (LO). Their behavior was compared with that of traditional salen chromium complexes. A completely alternating enchainment of monomers to provide pure polyesters was achieved with all the catalysts when used in combination with 4-(dimethylamino)pyridine (DMAP) as the cocatalyst. Poly(propylene maleate-block-polyglycolide), a diblock polyester with a precise composition, was obtained by switch catalysis, in which the same catalyst was able to combine the ROCOP of propylene oxide and maleic anhydride with the ring-opening polymerization (ROP) of glycolide (GA) through a one-pot procedure, starting from an initial mixture of the three different monomers.