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  • 5 Reads
Synthesis and characterization of iminophosphorane palladacycles

Recently research on palladacycles has come upon new findings employing tetradentate [C,N:C,N] ligands derived from Schiff bases . The related iminophosphoranes are also adequate ligands for the synthesis of palladacycles. Thus, the chemistry of iminophosphoranes seeks new compounds with reactivity and / or relevant structural characteristics which could be similar to the imine palladium complexes.

Herein we report on the synthesis and characterization of bisiminophosphoranes as potential tetradentate ligands. Treatment of the latter with palladium acetate gives tetranuclear structures with two ligand moieties linked by acetate-bridging ligands. The addition of ddpm (4 equivalents) provides doubly metallated structures where the phosphine acts as a bidentate chelating ligand.

  • Open access
  • 9 Reads
In-situ preparation of three types of metal nanoparticles-polyacrylonitrile nanofibers (M NPs-PAN NFs, M=Pt, Au, and Ag) using electrospinning technique assisted with ultrasound irradiation

In recently years, the many alluring methods to prepare the inorganic-organic hybrid nanomaterials have garnered great interest. The in-situ growth phenomenon is the most straightforward way to from these compounds with multiply dimensions. Here in, we demonstrate the in-situ synthesis of noble metal nanoparticles-polyacrylonitrile nanofibers (M NPs-PAN NFs) using electrospinning route. Synthesis includes two main paths in the presence of DMF. In the first path, the M NPs were prepared from the precursor solution using in-situ reduction route in the presence of ultrasound irradiation and DMF (as solvent and weak reducing agent) at 60 °C for 9 min. The mechanism of our second path exhibited that the polymer matrix solution (PAN/DMF) acts as an appropriate host solution for the MNPs, due to possessing high contents of effectiveness groups. These groups not only anchor NM NPs tightly in PAN fibers via dipole-induced dipole interactions but also they stabilize metal nanoparticles by good bonding interaction with their surface atoms. After preparing all nanofibers, TEM images revealed that both M NPs and their related nanofibers have particular and unique shape without agglomerated particles with different sizes. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) with SEM-mapping images, and Fourier-transform infrared (FT-IR) were also applied to verify the formation all samples. In this report, we tried to present a preparative synthesis strategy to preparation of nanofibers.

  • Open access
  • 5 Reads
Asymmetric iodoetherification of isosorbide-derived glycals: A regio- and stereoselective access to a variety of O‑substituted isosorbide derivatives

Isosorbide is a competitive starting material for various valuable derivatives by functionalization and/or substitution since it is a renewable and carbon neutral material that is produced on an industrial scale from sorbitol. A set of O‑alkyl‑ or O‑arylated beta‑iodo ethers has been synthesized from isosorbide. The key step was the iodoetherification of isosorbide-derived glycals with a variety of oxygenated nucleophiles in the presence of N‑iodosuccinimide. trans‑Iodo ethers and acetate were obtained in good yields and the removal of iodide affords isosorbide derivatives. The usefulness of this new approach is illustrated by the synthesis of a surfactant having a dimer of isosorbide as hydrophilic group and by the preparation of a structurally unusual bicyclic anhydro carbohydrate.

  • Open access
  • 15 Reads
BODIPY (meso-phenyl-meso) dimer as a photovoltaic material

Derivatives of boron-dipyrromethene (BODIPY) constitute an important class of chromophores. The BODIPY dyes can be applied in an extensive variety of applications, such as cellular imaging, photodynamic therapy, drug-delivery or organic photovoltaics. BODIPYs are also excellent compounds to be applied as electron-donor materials in organic photovoltaic cells as they have a strong absorption in the visible spectra region, a photochemical and chemical stability, good solubility and a general suitable HOMO/LUMO frontier orbital energy levels.

Following our own work on the use of BODIPYs as photovoltaic materials, in this communication we present the synthesis and characterization of a meso-meso BODIPY dimer. This BODIPY dimer has all the main properties to work efficiently as electron-donor material since it exhibits strong absorbance in the visible spectrum, good solubility and suitable HOMO and LUMO energy orbitals to work as donor material in the bulky heterojunction BODIPY/PCBM layer, based solar cells.

  • Open access
  • 17 Reads
Synthesis of polycyclic quinolines using SiO2/H2SO4 via Friedlӓnder synthetic method

An attention to the novel synthetic route for the polycyclic quinolines (3 & 5) from cyclic-diketones, cyclohexan-1,2-dione (2) / cyclohexan-1,3-dione (4) with o-aminoarylketones (1) in the presence of SiO2/H2SO4 yielded via Friedlӓnder synthetic method. The catalytic efficiency of the SiO2/H2SO4 was discussed through their utilization in the synthesis of biologically active substituted polycyclic quinoline derivatives (3 & 5) and the mechanism has been proposed. The SiO2/H2SO4 was found as a effective catalyst for the Friedlӓnder reaction and gave considerable isolated yield of the targeted products under the mild reaction condition. The synthesized polycyclic quinolines (3 & 5) were characterized through diverse analytical techniques like FT-IR, NMR spectroscopy and single crystal X-ray diffraction studies.

  • Open access
  • 11 Reads
Convenient synthesis of some new 3-(4-chloro-phenyl)-3-hydroxy-2,2-dimethyl-propionic acid methyl ester derivatives of expected Anticancer Activity

A series of 25 compounds were synthesized based on structure modification of the model methyl 3-(4-chlorophenyl)-3-hydroxy-2,2-dimethylpropanoateas potent HDACIs. Saponification and hydrazinolysis of the model ester afforded the corresponding acid and hydrazide, respectively.The model ester was transformed into corresponding trichloroacetimidate or acetate by the reaction with trichloroacetonitrile and acetic anhydride, respectively. N-alkyl-3-(4-chlorophenyl)-3-hydroxy-2,2-dimethylpropan-amides and methyl 2-[(3-(4-chlorophenyl)-3-hydroxy-2,2-dimethylpropanoyl)amino] alkanoates were obtained by the reaction ofcorresponding acid or hydrazide with amines and amino acid esters via DCC and azidecoupling methods. Methyl 3-aryl-3-(4-chlorophenyl)-2,2-dimethylpropanoates were obtainedin good yields and short reaction timefrom the corresponding trichloroacetimidate or acetate by the reaction with C-active nucleophiles in the presence of TMSOTf (0.1 eq %) via C-C bond formation.

  • Open access
  • 21 Reads
C-28 esters of triterpenoid acids bearing tris(hydroxymethyl)aminomethane: Synthesis, anticancer and antimicrobial activity.

Widespread secondary plant metabolites (betulinic, ursolic and oleanolic acids) are promising scaffolds for the discovery of new drugs. Among the many semi-synthetic derivatives of lupane triterpenoids known today, the anticancer agent, C-28 ester of betulinic acid with tris(hydroxymethyl)aminomethane (NVX-207), has been actively studied. This betulinic acid derivative, which has shown significant antitumor activity in vitro and in vivo against various malignant tumors, is a candidate drug. It is known that modification of the structure of the triterpenoid skeleton can lead to significant changes in biological properties. In this regard, we have synthesized C-28 esters of ursolic, oleanolic acids and C20-29 hydrogenated betulinic acid bearing tris(hydroxymethyl)aminomethane (TRIS), and transformed them into guanidinium salts by guanylation of the primary amino group in a branched ester fragment under the action of 1H-pyrazole-1-carboxamidine hydrochloride. The obtained compounds were tested in vitro experiments on five human cancer cell lines. The presence of TRIS-fragment in the triterpenoid conjugates markedly enhanced the cytotoxic action as compared to the parent compounds, dihydrobetulinic, ursolic and oleanolic acids, (IC50 values 2.8-7.6 mkM for Jurkat cells and 1.8-6.8 mkM for U937 cells), while the correlation between the cytotoxic activity and the chemical structure of the triterpenoid skeleton was not observed. Extended biological testing of these triterpenoids by using flow cytometry analysis showed that antitumor activity of compounds is caused by apoptotic processes and induction of cell cycle arrest in the S-phase. New triterpenoids were also tested for their antimicrobial activity against the growth of four bacterial strains (Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus (MRSA)) and two fungal strains (Candida albicans and Cryptococcus neoforman). The TRIS-dihydrobetulinic acid conjugate and its guanidinium derivative did not exhibit antimicrobial properties. The corresponding ursane and oleane-skeleton pentacyclic tritrerpenoids showed good bacteriostatic activity against methicillin-resistant S. aureus (MICs 4 and 32 mkg / mL) and excellent antifungal effect against Cryptococcus neoformans and Candida albicans (MICs 4 and 0.25 mkg / mL).

  • Open access
  • 4 Reads
Synthesis and characterization of novel thiosemicarbazone palladacycles

Since the appearance of the term palladacycle, as coined by Trofimenko[1], one of the most salient group of such compounds is the thiosemicarbazone class.

Herein, the synthesis and characterization of several palladium cyclometallated compounds with thiosemicarbazone ligands is discussed. The ligands were synthesized by treatment of a ketone with four different thiosemicarbazides in acidified aqueous solution; after which there were conveniently treated with a palladium salt thus yielding the corresponding palladacycle. All show a tetranuclear structure with [C, N, S] coordination of the ligands to the metal centers.

[1] S. Trofimenko, Inorg. Chem., 1973, 12, 1215.

  • Open access
  • 13 Reads
Design of biologically active surfaces based on functionalized polysulfones by electrospinning

Development of a new generation of electrospun polymeric materials designed to accomplish multi-performance in a bioinspired integrated system represents an important goal of the scientific research community. The major concerns in the medical therapy by the development of a new "construct" are based on a professional designing and understanding of the origin and physicochemical properties of the polymeric materials. It is well-known that almost all tissues and organs, i.e., skin, cartilage, and bone, etc., show a kind of similarity to nanosize fibrous structures. In this context, polysulfones promise to become such generation of nanofibrous scaffolds with attractive properties associated with biomedical applications. Therefore, the homogeneous solutions of the functionalized polysulfones, with a tunable density of quaternary ammonium functional groups (PSFQ), dissolved in N,N-dimethylformamide and 2-Methoxyethanol, were processed by electrospinning to create of polymeric scaffolds that can modulate cellular behavior. By analyzing the relationship between processable solution properties and morphological aspects, the results have shown that the morphology of formed fibers, with different forms and dimensions, could be attributed to the combined effects of the polymer solutions concentration, thermodynamic quality of the used solvents, and implicitly, the cumulative effects of electrostatic interactions, hydrogen bonding or association phenomena, as well as the process parameters. Thus, by investigation of the electrospun fibers morphology, the long, uniform and continuous fibers was visualized, with a wide distribution of diameters ranging from 0.65 μm to 2.40 μm, depending on the solvent used. Additionally, the antibacterial activity of PSFQ fibers against Gram-negative and Gram-positive bacteria has indicated the potential of these scaffolds for biomedical use.

  • Open access
  • 19 Reads
Polymers of 4-Thieno[3,2-b]thiophen-3-ylbenzonitrile with Anthracene and Biphenyl: Their electronic and optoelectronic properties

Design and synthesis of conjugated organic polymers for electronic and optoelectronic applications, such as electrochromic devices (ECD), organic light emitting diodes (OLED), organic field effective transistors (OFET), lasers, photodiodes and solar cells, have an increasing momentum. Fused thiophenes, i.e. thieno[3,2-b]thiophenes (TT), have been widely accepted as important building blocks for such materials. In this work, 4-thieno[3,2-b]thiophen-3-ylbenzonitrile (TT-CN), having electron withdrawing cyano moiety, was polymerized with anthracene and biphenyl through Suzuki coupling to obtain the polymers. Electronic and optical properties of the resultant polymers were investigated. Effects of different molecular orientations of anthracene and biphenyl blocks in the polymer backbone were compared.

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