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  • Open access
  • 39 Reads
Synthesis of cationic polymers based on porphyrins for photoinactivation of bacteria

The growing appearance of resistant microbial strains has promoted the development of viable alternatives for the eradication of infectious diseases. In this sense, photodynamic inactivation (PDI) of microorganisms has been proposed as useful therapy. Therefore, the development of new phototherapeutic agents and photoinactivation strategies are of great interest to maintain aseptic conditions in public health.

In this work, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPPF20) was synthesized from the condensation between pentafluorobenzaldehyde and pyrrole catalyzed by BF3.OEt2 in dichloromethane. Subsequent oxidation reaction with 2,3-dichloro-5,6-dicyano-p-benzoquinone afforded TPPF20 in 38% yield. This porphyrin is a versatile template to develop more elaborate photodynamic compounds. TPPF20 can be modified by nucleophilic aromatic substitution (SNAr) with the displacement of the four para-fluoro atoms. This porphyrin was metaled with Zn(II) acetate in DCM/methanol to produce the complex ZnTPPF20 in 98% yield. After that, TPPF20 and ZnTPPF20 were reacted with N,N,N′,N′-tetrakis(3-aminopropyl)-1,4-butanediamine as the dendrimeric structure by SNAr to obtain two polymers, PTPPF16 and PZnTPPF16, respectively. The reactions were carried out in N,N-dimethylformamide at room temperature for 44 h, followed by heating at 80 °C for 4 h. This approach produces the polymers in 100% conversion. The polymers were purified by precipitation in water and washing the solid with petroleum ether. The UV-visible absorption spectra of PTPPF16 and PZnTPPF16 showed the Soret and Q bands of both polymers red-shifted by about 15 nm compared to those of the corresponding monomers, TPPF20 and ZnTPPF20. Also, the polymers exhibited the two red emission bands, characteristic of porphyrins. Furthermore, these polymers were able to produce reactive oxygen species, such as singlet molecular oxygen and superoxide radical anion. Therefore, PTPPF16 and PZnTPPF16 are potential photodynamic materials to eliminate pathogens.

  • Open access
  • 90 Reads
Ultrasound Assisted Synthesis of 1,5-Disubstituted Tetrazoles Containing Propargyl or 2-Azidophenyl Moieties via Ugi-Azide Reaction

A series of ten 1,5-disubstituted-1H-tetrazoles (1,5-DS-T) were synthesized via isocyanide-based multicomponent reactions (IMCR) Ugi-azide in low to excellent yields, using propargyl amine or 2-azidobenzaldehyde as component under ultrasound irradiation (USI). 1,5-DS-T are useful heterocyclic moieties present in many bioactive compounds and drugs. Morever 1,5-DS-T are used as bidentate ligands, in coordination chemistry, metal-organic framework science, bioimaging, photo-imaging, explosives, propellants, high energy materials. The generated products can be used as synthetic platforms for subsequent post-transformations.

  • Open access
  • 43 Reads
Reaction of N-(tosylmethyl)ureas with NaCN: synthetic and mechanistic aspects

Reaction of NaCN with N-(tosylmethyl)ureas, prepared by condensation of urea with aldehydes and p-toluenesulfinic acid, has been studied. Generally, this reaction afforded the corresponding α-ureido nitriles. Some mechanistic aspects of cyanide-anion amidoalkylation with N-(tosylmethyl)ureas were discussed based on DFT calculations.

  • Open access
  • 56 Reads
A novel heterocyclic thiosemicarbazone: synthesis, characterization and preliminary sensing studies for ions

Over the past decades, the interest in the fast and sensitive recognition and detection of molecules and ions with biological and/or environmental relevance has increased. Therefore, the search of new molecules capable of coordinating these analytes is an important topic of investigation, especially those with an optical response (via colour or fluorescence changes). Thiosemicarbazones are versatile organic compounds due to their wide range of biological activities and interesting optical, electronic and redox properties. Also, they possess various binding sites, whose complexing ability can be tuned by the introduction of substituents of different electronic character.

Having this in mind, we report the synthesis of a new thiosemicarbazone derivative functionalized with a nitrogen heterocyclic moiety. The new compound was characterized by 1H and 13C NMR, UV-Vis absorption and fluorescence spectroscopies. Moreover, a preliminary chemosensory study was undertaken in acetonitrile solutions in the presence of relevant ions with biological, medicinal and environmental relevance showing that this receptor has potential application as a fluorimetric chemosensor.

  • Open access
  • 27 Reads
Cyclometallated thiosemicarbazones containing fluorine atoms: a solubility improvement

A novel set of thiosemicarbazone palladacycles is discussed. The addition of a fluorine atom to the thiosemicarbazone ligand increases not only the solubility of the ligand itself, but also that of the ensuing cyclometallated complexes.

Ligands are synthesized in acidic ethanolic solution, and then reacted with potassium tetrachloropalladate(II), to give the corresponding cyclopalladated compounds bearing a tetranuclear structure.

Characterization will be carried by IR, 1H NMR and 19F NMR spectroscopies.

  • Open access
  • 32 Reads
Synthesis and characterization of amine functionalized thiosemicarbazone cyclopalladated compounds.

Differences in the functional groups of the ligands can change the properties of the cyclometallated compounds and modify their suitability for various applications, such as catalysis and biomedicine.

Herein we report the synthesis and characterization of a new series of cyclometallated palladium compounds bearing an amine-functionalized thiosemicarbazone. The synthesis of the ligands was achieved by condensation of the thiosemicarbazide and aminoacetophenone. Reaction of the ligands with an appropriate metalating agent gave rise to the tetranuclear cyclometallated compounds.

The compounds were characterized by EA, 1H-NMR and IR spectroscopy.

  • Open access
  • 64 Reads
Synthesis and biological evaluation of some substituted benzimidazole derivatives

In the current research work, the title compounds 5-ethoxy- benzimidazole, were synthesized by nitration of phenacetin with concentrated nitric acid it gives N-(2-nitro-5-ethoxyphenyl) acetamide (I), which on reduction with alcohol gives 5-ethoxy-2-nitroaniline (II). Reaction of hydrazine hydrate with 5-ethoxy-2-nitroaniline produced 5-ethoxy ortho phenylene diamine (III). The substituted acids reacted with 5-ethoxy ortho phenylene diamine then yielded the corresponding 5-ethoxy-benzimidazole (IV). The identification and characterization of the synthesized compounds were carried out by Elemental analysis, melting point, Thin Layer Chromatography, FT-IR, NMR and Mass data. The synthesized compounds were evaluated for anti-tubercular activity. The test compounds were subjected to in vitro screening by the tube dilution technique employing the human virulent H37RV strain of M. tuberculosis. The test compounds IVa, IVc and IVd showed significant anti-tubercular activity against H37RV strain of Mycobacterium tuberculosis. The minimum inhibitory concentration (MIC) values were found in the range of 0.8 to 12.5 μg/ml compared with the standard drugs Isoniazid.

  • Open access
  • 60 Reads
Formulation and Evaluation of Verdant Tablets Containing Saponin-coalesced Silver Nanoparticles Got From Fenugreek Seed Extract

Presently nanoparticles are in demand due to several applications. Commercially used Metallic nanoparticles are usually comprised of synthetic chemicals. These chemicals are noxious and combustible. Current research had the objective to explore the advantages of nanoparticles using herbal material, hence we developed silver nanoparticles of aqueous extract of Trigonella foenum-graecum (Fenugreek) seeds and formulated them into tablets. Fenugreek seeds contain steroidal sapogenins and are responsible for the reduction of blood cholesterol levels, control diabetes, enhance breast milk production, digestion aid, and helps in weight loss hence prepared formulation can be recommended in all the above cases. The pre-compression parameters evaluated for formulations are bulk density, tapped density, Carr’s index Hausner's ratio, angle of repose and results are 0.16gm/cc, 0.86gm/cc, 14.16, ratio 1.13 and 32° respectively; whereas post-compression parameters are weight variation, friability, hardness, thickness, and disintegration were evaluated the results are 0.504gm, 0.2%, 3.21gm/cm2, 2.55mm, and 07min respectively.

  • Open access
  • 116 Reads
Molecular Docking study of flavonoids to block the Aryl Hydrocarbon Receptor.

Anti-HIF flavonoids have been described with antitumor activities by interfering with a presumed antioxidant mechanism through direct and indirect ways of overexpression of Hypoxia Inducible Factor (HIF-1α). The aryl hydrocarbon receptor (AhR) is a protein homologous to HIF-1α and is overexpressed in smoking patients suffering from lung and breast cancer. The interaction of thirteen flavonoids group with the AhR was evaluated by molecular docking. The AhR:ARNT model obtained by SwissModel was used for docking with the MOE 2019.01 program, as well as several servers for the determination of protein-protein interactions and alanine mutations. For the blocking of AhR:functional ARNT different interaction sites were identified. The interface between the bHLH and PAS-A domains plays a major role between the sites. The blocking capacity to AhR:ARNT for flavonoids 4´,7-dihydroxy-flavone, fisetin, luteolin, flavone, apigenin, and galangin was around 50% to 60%. None of the flavonoids evaluated bound to the PAS-B domain (AhR active site). Only flavone and fisetin were found to be active to bind to ARNT at the level of the α-helical region in the PAS-A domain of this monomeric protein. All flavonoids studied bound to AhR (with the exception of flavone) and to ARNT (except for the compounds 3,7-dihydroxy-flavone and kaempferol). The best flavonoid for blocking the formation of the AhR:ARNT heterodimer was fisetin, which is found in food sources such as strawberries, apples, and grapes, and has shown the ability to reduce pro-cancer inflammatory markers in colorectal cancer patients.

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