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  • Open access
  • 40 Reads
Synthesis of novel tryptamine-based triazoles

1,2,3 triazoles are important types of heterocyclic compounds. They find numerous applications in industry, namely as dyestuffs, fluorescent whiteners, photostabilizers of polymers, optical brightening agents, corrosion inhibitors and as photographic photoreceptors.

On the other hand, tryptamine has also great pharmacological properties, for this raison we have proposed to synthesize tryptamine-based triazoles. Several methods for synthesizing the triazole moiety are described in the literature; we have chosen a simple synthesis method.

  • Open access
  • 46 Reads
Synthesis and Structure of (2E)-3-Aryl(hetaryl)-2-[5-bromo-4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles
, , ,

Bromination of (2E)-3-aryl(hetaryl)-2-[4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles proceeds regioselectively at the C5 atom of the thiazole ring with the formation of new (2E)-3-aryl(hetaryl)-2-[5-bromo-4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles. The latter were alternatively obtained by the reaction of aldehydes,cyanothioacetamide, α-bromoketones and bromine in the presence of triethylamine in DMF. Structure of the keycompounds was confirmed using 2D NMR spectroscopy and single crystal X-ray diffraction analysis.

  • Open access
  • 61 Reads
In Situ Hemi-synthesis of new unexpected chiral chromeno-pyrimidine derivative
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A hemi-synthesis reaction of barbituric Acid with an α,β-unsaturated aldehyde using Perillaldehyde from Essential oil of Ammodaucus leucotrichus subsp leucotrichus, affording to a chromeno-pyrimidine derivative. The reaction was carried out in Water/Ethanol medium without an added catalyst. The obtained pyrimidine was identified by their spectral 1H, 13C, HMBC and HSQC 2D NMR.

  • Open access
  • 53 Reads
Design, synthesis and structural characterization of a novel asymmetric hydrazone-thiosemicarbazone ligand with the aim of obtaining interesting metallosupramolecular architectures

The asymmetric hydrazone-thiosemicarbazone ligand H2L was synthesized in two stages by means of a double condensation reaction. Firstly, one equivalent of phenyl-semicarbazide reacted with one equivalent of the dialdehyde 2,6-diformylpyridine. Afterwards, the product formed was condensed with one equivalent of phenyl-thiosemicarbazide. The potentially dianionic and pentadentate [N3SO] organic ligand H2L possesses two flexibles bidentate [NS/NO] domains separated by a pyridine spacer which could stabilize a wide variety of metal ions, giving rise to different metallosupramolecular architectures. This ligand was fully characterized by different techniques such as elemental analysis, infrared spectroscopy, mass spectrometry and 1H/13C NMR confirming that it was obtained with high purity.

  • Open access
  • 57 Reads
Synthesis and aminomethylation of 6-amino-2-(dicyanomethylene)-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile morpholinium salt
, , ,

Condensation of benzaldehyde with malononitrile and malononitrile dimer (2-aminopropene-1,1,3-tricarbonitrile) in the presence of an excess of morpholine in ethanol afforded the morpholinium salt of 6-amino-2-(dicyanomethylene)-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile. The latter, under the Mannich reaction conditions with the participation of primary amines and formaldehyde, gives 6-amino-2-(dicyanomethylene)-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile, 2-(dicyanomethylene)-6-(hydroxymethylamino)-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile or zwitterionic aminomethylation products, 6-(ammoniomethylamino)-3,5-dicyano-4-phenylpyridin-2-yl)dicyanomethanides. Structure of the obtained compounds was established using 2D NMR spectroscopy and single crystal X-ray diffraction analysis

  • Open access
  • 77 Reads
Dysprosium(III)-mediated carboxylate formation from a Schiff base

Hydrolysis of imines usually leads to the formation of aldehydes. Our research group has previously shown that DyIII can mediate the hydrolysis of Schiff bases in an unusual process to convert imines into acetaldehydes. As a continuation of this work, an uncommon new case of imine hydrolysis, leading to the formation of a carboxylate group, is presented in this communication. The conditions of the media that favour this conversion, which seems again to be mediated by the presence of DyIII , are analysed. The process leads to the formation of a dysprosium complex of formula {[Na2(DyL)2(H2O)8(Et3NH)2(DyL)2}·14H2O. Full characterization of the final product, including single X-ray studies, is reported.

  • Open access
  • 47 Reads
New methods of synthesis, structure and aminomethylation of 4-imino-2-(dicyanomethylene)-3-azaspiro[5.5]undecane1,5-dicarbonitrile
, , ,

Sequential reaction of cyclohexanone with malononitrile and 2-aminopropene-1,1,3-tricarbonitrile in potassium hydroxide or sodium ethylate in ethanol gave 4-imino-2- (dicyanomethylene) -3-azaspiro [5.5] undecane-1, 5-dicarbonitrile ... The latter reacts with primary amines and an excess of formaldehyde to form new derivatives of 2- (dicyanomethylene) -3,7-diazaspiro [bicyclo [3.3.1] non-3-ene-9,1'-cyclohexane] -1,5-dicarbonitrile. ... Contrary to the literature data, the reaction of cyclohexanone with 2-aminopropene-1,1,3-tricarbonitrile in benzene in the presence of piperidine and glacial acetic acid led to the formation of 2,4-diamino-5,6,7,8-tetrahydronaphthalene-1,3-dicarbonitrile

  • Open access
  • 58 Reads
Weak donor- strong acceptor thienopyrazine based polymers for fine tune of LUMO levels in optoelectronic applications

In the last decades researchers focused on the synthesis and design of new materials for solar cells in order to boost the power conversion efficiency (PCE). One way it is to use NIR sensitizer since more than 50% of solar radiation falls in the NIR spectral region.

One approach in order to tune the energy levels and achieve small band gap polymers or molecules is alternating donor-like (electron donating) and acceptor-like (electron withdrawing) monomer. Polymer for solar cells need to maintain a low highest occupied molecular orbital (HOMO) energy level in order to maximize the open circuit voltage (Voc) and small band gap in order to maximize the short circuit current (Jsh). Alternatig “weak donor” and “strong acceptor” will maintain a low HOMO energy level and reduce the band gap via Intramolecular Charge transfer (ICT).

Here we present the synthesis and characterization of a series of polymer based on thienopyrazine acceptor and carbazole donor. We have compared the optoelectronic properties of classic PCDTBT (poly-carbazole-dithiophene-benzothiadiazole) polymer with one where benzothiadiazole has been substituted with thienopyrazine and one where we have randomly alternate thienopyrazine and benzothiadiazole as acceptor unit, maintaining the same donor unit. The approach to alternate weak donor- strong acceptor moieties allow to obtain fine LUMO levels modulation of the materials opening the way to the design of new donor materials.

  • Open access
  • 60 Reads
Comparative study of the effect of aqueous micellar media formed by amphiphilic ionic liquids and conventional surfactants on reactions of synthetic interest.

For polar Diels-Alder (DA) reactions one of the most relevant aspects is its dependence on the reaction media so in this work the objective is to analyze the effect of aqueous micellar systems on the synthesis of compounds of biological interest. Based on the system formed by isoprene and 2-nitrofuran, the experiments were carried out in micellar media formed by amphiphilic ionic liquids (N,N-dodecylmethylimidazolium bromide) and by conventional surfactants (SDS and CTAB).

In this sense, there are few studies that involve DA reactions in micro-heterogeneous systems.

The challenge is to have the knowledge about the behavior of ILs in order to take advantage of all their potentialities in order to replace a toxic molecular solvent with ILs that allows developing a methodology framed within the concepts of Green Chemistry.

  • Open access
  • 67 Reads
SOLVATOCROMIC BEHAVIOR OF POLARITY INDICATORS IN PILs AND THEIR MIXTURES WITH MOLECULAR SOLVENTS. AUTOPROTOLYSIS AND ITS RELATION TO ACIDITY

It is interesting to know the behavior of Protic Ionic Liquids (PILs) within the binary mixture of molecular solvents since it is usual to carry out processes such as organic and inorganic synthesis, or liquid-liquid extractions in the presence of another solvent. Moreover, on certain occasions the absence of water is strictly required. In this sense, it is important to note that the addition of small amounts of IL to the molecular solvent allows a fine adjustment in its microscopic properties; obtaining "new solvent systems" with particular properties. Taking into account that solvatochromic indicators are traditionally used as microscopic descriptors to determine the molecular microscopic properties of solvents. In this sense, we look for re-evaluate the behavior of solvatochromic probes and reconsider the validity of traditional polarity scales such as ET(30), in alkylammonium-based PILs and in their mixtures with molecular solvents, taking into account now that the real composition of these PILs depends on the equilibrium of autoprotolysis.

In addition to the spectroscopic analysis developed, the characterization of the PILs and their binary mixtures was completed in terms of a change in the ∆pKa of the precursor species of a PIL. Thermal analysis was also employed to determine the acid strength's role in ions complete formation in pure PILs.

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