A solvent-free synthesis of 1,2,3,5-tetrasubstituted pyrroles from enaminones and α-haloketones

A simple synthesis of 1,2,3,5-tetrasubstituted pyrrole derivatives from the reaction of enaminone withα-haloketones,under solvent-free conditions,is described.     

Synthesis of Monospiro‐2‐amino‐4H‐pyran Derivatives Catalyzed by Propane‐1‐sulfonic Acid‐Modified Magnetic Hydroxyapatite Nanoparticles

Various monospiro‐2‐amino‐4H‐pyran derivatives have been synthesized in high yields (via three‐component coupling of ninhydrin or different isatins with malononitrile and 1,3‐dicarbonyl compounds) in the presence of catalytic amount of propane‐1‐sulfonic acid‐modified magnetic hydroxyapatite nanoparticles in H₂O. Due to easy magnetic removal of nanocatalyst and applying of H₂O as solvent, this protocol enhanced product purity, and promised economic as well as environmental benefits, exemplifying a waste‐free chemistry. More importantly, the catalyst could be easily recycled for more than five times without loss of activity.     

Studies on Phosphonium Ylides,XXIV: Reactions of Phosphorus Ylides with 1,2,3,4-Tetrahydro1-Naphthylidene-Malononitrile

1,2,3,4-tetrahydro-1-naphthylidene-malononitrile (1) reacts with carbethoxymethylene and carbmethoxymethylene- triphenylphosphoranes (2a, 2b) to give the new phospho-ranylidenecyclopentaylidene products (4a, 4b, and 5), respectively. The treatment of (1) with phosphorus ylide 2c afforded the new phosphonium ylide 6. Moreover, the application of reagent (2d) on (1) renders compound 7. On the other hand, when N-phenyliminotriphenylphosphorane (3) reacts with (1), the corresponding adduct (8) was obtained together with triphenylphosphine. Mechanisms accounting for the formation of new products are discussed, and probable structures of products are presented based on analytical and spectroscopic data.     

Comparison of Pulsed and Continuous Wave Diode Laser at 940 nm on the Viability and Migration of Gingival Fibroblasts

Gingival fibroblasts have critical roles in oral wound healing. Photobiomodulation (PBM) has been shown to promote mucosal healing and is now recommended for managing oncotherapy-associated oral mucositis. This study examined the effects of the emission mode of a 940 nm diode laser on the viability and migration of human gingival fibroblasts. Cells were cultured in a routine growth media and treated with PBM (average power 0.1 W cm⁻², average fluence 3 J cm⁻², every 12 h for six sessions) in one continuous wave and two pulsing settings with 20% and 50% duty cycles. Cell viability was assessed using MTT, and digital imaging quantified cell migration. After 48 and 72 h, all treatment groups had significantly higher viability (n = 6, P < 0.05) compared with the control. The highest viability was seen in the pulsed (20% duty cycle) group at the 72-h time point. PBM improved fibroblast migration in all PBM-treated groups, but differences were not statistically significant (n = 2, P > 0.05). PBM treatments can promote cell viability in both continuous and pulsed modes. Further studies are needed to elucidate the optimal setting for PBM-evoked responses for its rationalized use in promoting specific phases of oral wound healing.     

Synthesis and characterization of a novel magnetic nano‐palladium Schiff base complex: application in cross‐coupling reactions

A novel and task‐specific nano‐magnetic Schiff base ligand with phosphate spacer using 2‐aminoethyl dihydrogen phosphate instead of usual coating agents, i.e. tetraethoxysilane and 3‐aminopropyltriethoxysilane, for coating of nano‐magnetic Fe₃O₄ is introduced. The nano‐magnetic Schiff base ligand with phosphate spacer as a novel catalyst was synthesized and fully characterized using infrared spectroscopy, X‐ray diffraction, scanning and transmission electron microscopies, thermogravimetry, derivative thermogravimetry, vibrating sample magnetometry, atomic force microscopy, X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray spectroscopy. The resulting task‐specific nano‐magnetic Schiff base ligand with phosphate spacer was successfully employed as a magnetite Pd nanoparticle‐supported catalyst for Sonogashira and Mizoroki–Heck C–C coupling reactions. To the best of our knowledge, this is the first report of the synthesis and applications of magnetic nanoparticles of Fe₃O₄@O₂PO₂(CH₂)₂NH₂ as a suitable spacer for the preparation of a designable Schiff base ligand and its corresponding Pd complex. So the present work can open up a new and promising insight in the course of rational design, synthesis and applications of various task‐specific magnetic nanoparticle complexes. Copyright © 2016 John Wiley & Sons, Ltd.     

Meglumine sulfate catalyzed solvent-free one-pot synthesis of coumarins under microwave and thermal conditions

A convenient method has been developed for the Pechmann reaction of phenols and β-keto esters catalyzed by meglumine sulfate. Solvent-free conditions, inexpensive catalyst, short reaction times, high yield, and ease of purification of the products are the advantages of this protocol. This novel catalytic system is expected to contribute to the development of more benign Pechmann condensation reactions of phenols with β-keto esters.     

The effect of various compatibilizers on thermal,mechanical, and morphological properties of polystyrene/polypropylene blends

The effects of various compatibilizers on thermal, mechanical and morphological properties of 50/50 polypropylene/polystyrene blends were investigated. Various compatibilizers, polystyrene-(ethylene/butylenes/ styrene) (SEBS), ethylene vinyl acetate (EVA), polystyrene-butylene rubber (SBR) and blend of compatibilizers SEBS/PP-g-MAH, EVA/PP-g-MAH, and SBR/PP-g-MAH were used. Differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, scanning electron microscopy, microhardness, and Izod impact strength were adopted. It was found that the influence of various compatibilizers was appeared on all the properties studied. The properties of the blends compatibilized with SEBS, EVA, and SBR are very distinct from those of blends compatibilized with blend of compatibilizers. Results show that compatibilized blends with the blend of compatibilizers EVA/PP-g-MAH, SBR/PP-g-MAH, and SEBS/PP-g-MAH or SBR were relatively more stable than the uncompatibilized blend and blend compatibilized with SEBS or EVA. The compatibilizer does not only reduce the interfacial tension or increase the phase interfacial adhesion between the immiscible polymers, but greatly affects the degree of crystallinity of blends.

     

Analysis of polyvinyl alcohol microbubbles in human blood plasma using capillary electrophoresis

Recently, a new type of ultrasound contrast agent that consists of air‐filled microbubbles stabilized with a shell of polyvinyl alcohol was developed. When superparamagnetic nanoparticles of iron oxide are incorporated in the polymer shell, a multimodal contrast agent can be obtained. The biodistribution and elimination pathways of the polyvinyl alcohol microbubbles are essential to investigate, which is limited with today's techniques. The aim of the present study was, therefore, to develop a method for qualitative and quantitative analysis of microbubbles in biological samples using capillary electrophoresis with ultraviolet detection. The analysis parameters were optimized to a wavelength at 260 nm and pH of the background electrolyte ranging between 11.9 and 12. Studies with high‐intensity ultrasonication degraded microbubbles in water showed that degraded products and intact microbubbles could be distinguished, thus it was possible to quantify the intact microbubbles solely. Analysis of human blood plasma spiked with either plain microbubbles or microbubbles with nanoparticles demonstrated that it is possible to separate them from biological components like proteins in these kinds of samples.     

New poly(ester amide ether amide)s from a novel flexible diamine and different diacid chlorides using TMSCl for in situ silylation

A novel flexible diamine with built-in ester, amide and ether groups named terephthalic acid bis(4-{2-[2-(2-amino ethoxy)ethoxy]ethyl carbamoyl}phenyl) ester (TABE), was synthesized via two steps. Nucleophilic reaction of 4-hydroxybenzoic acid with terephthaloyl chloride in the presence of NaOH yielded terephthaloyl bis (4-oxybenzoic) acid (TOBA). The diamine (TABE) was prepared via two direct and indirect methods. In the indirect method TOBA was converted to related diacid chloride and reacted with 1,8-diamino-3,6-dioxaoctane (DADO). Direct method was achieved through the reaction of TOBA with DADO via Yamazaki method. TOBA and TABE were fully characterized and TABE was used to prepare new poly(ester amide ether amide)s through polycondensation with different diacid chlorides in the presence of trimethylchlorosilane (TMSCl). The polymers were characterized using conventional methods and their physical properties including inherent viscosity, thermal behavior, thermal stability, crystallinity, and solubility were studied. The polymers showed good thermal stability and improved solubility.     

A study on the binding of two water-soluble tetrapyridinoporphyrazinato copper(II) complexes to DNA

Interaction of N,N′,N″,N-tetramethyltetra-2,3-pyridinoporphyrazinatocopper(II), ([Cu(2,3-tmtppa)]⁴⁺) and N,N′,N″,N-tetramethyltetra-3,4-pyridinoporphyrazinatocopper(II), ([Cu(3,4-tmtppa)]⁴⁺) with calf thymus DNA was studied in 1 mM phosphate buffer and low ionic strength (5 mM NaCl) at various temperatures by UV-visible and circular dichroism (CD) spectroscopies and viscometric method. The binding constants were determined from the changes in the visible part of porphyrazine complexes spectra using SQUAD software. The values of K have been obtained (7.9±0.4)×10⁴ and (2.2±0.1)×10⁵ M⁻¹ for [Cu(2,3-tmtppa)]⁴⁺ and [Cu(3,4-tmtppa)]⁴⁺, respectively at 27 °C. The higher affinity of 3,4-isomer of Cu complex towards DNA with respect to the 2,3-isomer was attributed to favorable external positioning of the cationic charges in former, which enables superior interaction with the DNA duplex. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were calculated by van't Hoff equation. The enthalpy and entropy changes were determined, +34.2±3.6 kJ mol⁻¹ and +207.8±12.70 J mol⁻¹ K⁻¹ for [Cu(2,3-tmtppa)]⁴⁺ and +49.7±2.1 kJ mol⁻¹ and +267.8±7.9 J mol⁻¹ K⁻¹ for [Cu(3,4-tmtppa)]⁴⁺. The existence of extensive hypochromicity, large red shift and negative CD in the visible part of [Cu(3,4-tmtppa)]⁴⁺ spectra suggested an intercalation binding mode. Analysis of the moderate hypochromicity, red shift and bisignate CD in the Q-band absorption region of [Cu(2,3-tmtppa)]⁴⁺ spectra possibly led us to the coexistence of intercalation and outside binding modes. The influence of the ionic strength on the binding parameters and binding modes was investigated. The results show that increase in ionic strength causes the decrease in the binding constants. It was also concluded that increase in ionic strength affects the binding characteristics of positively charged complexes with DNA.

The increase in DNA viscosity in the presence of Cu–tmtppa complexes is attributed to the lengthening of DNA helix due to the intercalation. This result is consistent with conclusions obtained from the spectroscopic techniques.