Synthesis and characterization of biocompatible poly (L-lactide) using zinc (II) salen complex

Abstract

A biocompatible zinc (II) complex based on a tetradentate N,N,O,O-type salen ligand was synthesized, characterized and used for the solvent-free ring-opening polymerization (ROP) of L-lactide in bulk at 180?°C to prepare high molecular weight poly(L-lactide) (M_n : 82,600?Da; M_w : 140,000?Da; PDI: 1.70). Poly(L-lactide) (PLLA) was characterized using FTIR, ¹H NMR, ¹³C NMR, GPC, TGA, DSC, WAXD, and MALDI-ToF. Kinetic measurement was carried out and first-order behavior to monomer was observed. The k _app was found as 6?±?0.001?×?10^?4?s^?1. The biocompatibility of the PLLA was confirmed by in vitro cytotoxicity against NIH/3T3 fibroblast cell line and can be used in biomedical applications.     

Synthesis of 2-(Triazolyl,Oxadiazolyl, and Pyrazolyl) Substituted 1,5-Benzothiazepin-S,S-Dioxide Derivatives of Potential Medicinal Interest

Abstract

The synthetic potential of 2,3,4,5-tetrahydrobenzo[b] [1,5]thiazepine-1,1,4-trione-2-carbohydrazide (5) which resulted from ethyl-4-oxo-2,3,4,5-tetrahydrobenzo[b] [1,5]thiazepine-2-carboxylate (3), on its oxidation with H₂O₂/AcOH followed by treatment with NH₂NH₂.H₂O, was exploited to provide an access to 2-triazolo, 2-oxadiazolo, and 2-pyrazolo substituted derivatives of 1,5-benzothiazepin-4-oxo-1,1-dioxides (6–10), respectively.     

Applications of Dithioacetals in Ester Synthesis

The α-oxoketene dithioacetals are simple synthetic intermediates widely utilized and implicated for the synthesis of a variety of heterocyclic compounds other than alicyclic and aromatic compounds. They act as 1,3-electrophilic three-carbon synthons. The α-oxoketene dithioacetal of pyrazolone derivatives can be efficiently converted through a base-catalyzed alcoholysis into the corresponding ester in a single one-step reaction with good yield of pure products. In this article, we summarize recent direct conversion of α-oxoketene dithioacetals to highly desirable esters. The overall process is an example of intramolecular rearrangement of bonds. Characterization and identification of all synthesized compounds were assigned through ¹H NMR and mass spectroscopy.     

Synthesis and Characterization of Some Heteroaromatic Derivatives of 3‐But‐2‐enoyl‐chromen‐2‐one and Their Potential as Anti‐inflammatory Agents

A novel series of chromen‐2‐ones containing pyrazole, isoxazole, oxazine, and thiazine substitutions have been synthesized by reacting 3‐[3‐(4‐chloro‐phenyl)‐acryloyl]‐chromen‐2‐one and 3‐[3‐(3‐methoxy‐phenyl)‐acryloyl]‐chromen‐2‐one with various cyclizing agents such as hydrazine, phenylhydrazine, urea, and thiourea. The structures of all the synthesized compounds were confirmed by the use of IR, ¹H‐NMR, mass spectroscopy, and elemental analysis data. All the newly synthesized compounds were evaluated for their anti‐inflammatory activity at a dose of 100 mg/kg body weight in carrageenan‐induced rat paw edema model. The entire series of the compounds exhibited moderate to good anti‐inflammatory activity, with the percentage inhibition of edema formation ranging from 39.99 to 63.15 against the reference drug ibuprofen (100 mg/kg) that showed 78.96% inhibition at the third hour. Compounds 3a , 3c , and 3d showed good inhibitory activity, whereas compounds 3b , 3e , 3f , and 3j showed moderate inhibitory activity at the third hour.     

Total Stereospecific Synthesis of (3E,7Z)-Tetradecadienyl Acetate,the Major Sex Pheromone Component of the Potato Pest Symmetrischema tangolias

Chemistry of Natural Compounds - (3E,7Z)-Tetradecadienyl acetate, the major sex pheromone component of the potato pest Symmetrischema tangolias (Gyen), was stereoselectively synthesized from the...     

Channelled Porous TiO2 Synthesized with a Water‐in‐Oil Microemulsion

Porous titanium dioxide synthesized with a bicontinuous surfactant template is a promising method that leads to a high active surface area electrode. The template used is based on a water/isooctane/dioctyl sodium sulfosuccinate salt together with lecithin. Several parameters were varied during the synthesis to understand and optimize channel formation mechanisms. The material is patterned in stacked conical channels, widening towards the centre of the grains. The active surface area increased by 116 % when the concentration of alkoxide precursors was decreased and increased by 241 % when the template formation temperature was decreased to 10 °C. Increasing the oil phase viscosity tends to widen the pore aperture, thus decreasing the overall active surface area. Changing the phase proportions alters the microemulsion integrity and disrupts channel formation.     

Regulation of vincamine biosynthesis and associated growth promoting effects through abiotic elicitation,cyclooxygenase inhibition,and precursor feeding of bioreactor grown Vinca minor hairy roots

Hydroxylase/acetyltransferase elicitors and cyclooxygenase inhibitor along with various precursors from primary shikimate and secoiridoid pools have been fortified to vincamine less hairy root clone of Vinca minor to determine the regulatory factors associated with vincamine biosynthesis. Growth kinetic studies revealed that acetyltransferase elicitor acetic anhydride and terpenoid precursor loganin significantly reduce the growth either supplemented alone or in combination (GI?=?140.6?±?18.5 to 246.7?±?24.3), while shikimate and tryptophan trigger biomass accumulation (GI?=?440.2?±?31.5 to 540.5?±?40.3). Loganin also downregulates total alkaloid biosynthesis. Maximum flux towards vincamine production (0.017?±?0.001 % dry wt.) was obtained when 20-day-old hairy roots were fortified with secologanin (10 mg/l) along with tryptophan (100 mg/l), naproxen (8.4 mg/l), hydrogen peroxide (20 μg/l), and acetic anhydride (32.4 mg/l). This was supported by RT PCR (qPCR) analysis where 2- and 3-fold increase in tryptophan decarboxylase (TDC; RQ?=?2.0?±?0.09) and strictosidine synthase (STR; RQ?=?3.3?±?0.36) activity, respectively, was recorded. The analysis of variance (ANOVA) for growth kinetics, total alkaloid content, and gene expression studies favored highly significant data (P?<?0.05–0.01). Above treated hairy roots were also up-scaled in a 5-l stirred-tank bioreactor where a 40-day cycle yielded 8-fold increase in fresh root mass.     

Recent development in the synthesis of pyrrolin-4-ones/pyrrolin-3-ones

Pyrrolin-4-ones/pyrrolin-3-ones and its derivatives are important heterocyclic systems which are observed in vast variety of natural products, pharmaceuticals, and biologically important compounds. Different researchers all across the world have developed different synthetic methodologies for the construction of functionalized pyrrolin-4-ones/pyrrolin-3-one scaffolds such as the transition-metal catalyzed/mediated cycloisomerizations of 1-aminoynones and dimerization of enaminones or α-diazo-β-oxoamides etc. The present review article summarizes various reports on the synthesis of various simple and functionalized pyrrolin-4-ones/pyrrolin-3-ones from 2000 onward.     

Electron Acceleration by Beating of Two Intense Cross-Focused Hollow Gaussian Laser Beams in Plasma

This paper presents propagation of two cross-focused intense hollow Gaussian laser beams(HGBs) in collisionless plasma and its effect on the generation of electron plasma wave(EPW) and electron acceleration process,when relativistic and ponderomotive nonlinearities are simultaneously operative. Nonlinear differential equations have been set up for beamwidth of laser beams, power of generated EPW, and energy gain by electrons using WKB and paraxial approximations. Numerical simulations have been carried out to investigate the effect of typical laser-plasma parameters on the focusing of laser beams in plasmas and further its effect on power of excited EPW and acceleration of electrons. It is observed that focusing of two laser beams in plasma increases for higher order of hollow Gaussian beams,which significantly enhanced the power of generated EPW and energy gain. The amplitude of EPW and energy gain by electrons is found to enhance with an increase in the intensity of laser beams and plasma density. This study will be useful to plasma beat wave accelerator and in other applications requiring multiple laser beams.     

Synthesis and photo physical properties of Au @ Ag (core @ shell) nanoparticles disperse in poly vinyl alcohol matrix

Synthesis of core @ shell (Au @ Ag) nanoparticle with varying silver composition has been carried out in aqueous poly vinyl alcohol (PVA) matrix. Core gold nanoparticle (~15 nm) has been synthesized through seed-mediated growth process. Synthesis of silver shell with increasing thickness (~1–5 nm) has been done by reducing Ag⁺ over the gold sol in the presence of mild reducing ascorbic acid. Characterization of Au @ Ag nanoparticles has been done by UV–Vis, High resolution transmission electron microscope (HRTEM) and energy dispersive X-ray (EDX) spectroscopic study. The blue shift of surface plasmon resonance (SPR) band with increasing mole fraction of silver has been interpreted due to dampening of core, i.e. Au SPR by Ag. The dependence of nonlinear optical response of spherical core @ shell nanoparticles has been investigated as a function of relative composition of each metal. Simulation of SPR extinction spectra based on quasi-static theory is done. A comparison of our experimental and the simulated extinction spectra using quasi-static theory of nanoshell suggests that our synthesized bimetallic particles have core @ shell structure rather than bimetallic alloy particles.