Synthesis of novel star-shaped molecules based on a 1,3,5-triazine core linked to different heterocyclic systems as novel hybrid molecules

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

A new paradigm for energy is underway demanding decarbonized energy systems. Some of them rely on emerging electrochemical devices, crucial in hydrogen technologies, including fuel cells, CO2 and water electrolysers, whose applications and performances depend on key components such as their separators/ion-exchange membranes. The most studied and already commercialized Nafion membrane shows great chemical stability, but its water content limits its high proton conduction to a limited range of operating temperatures. Here, we report the synthesis of a new series of triazinephosphonate derivatives and their use as dopants in the preparation of new modified Nafion membranes. The triazinephosphonate derivatives were prepared by substitution of chlorine atoms in cyanuric chloride. Diverse conditions were used to obtain the trisubstituted (4-hydroxyphenyl)triazinephosphonate derivatives and the (4-aminophenyl)triazinephosphonate derivatives, but with these amino counterparts, only the disubstituted compounds were obtained. The new modified Nafion membranes were prepared by casting incorporation of the synthesized 1,3,5-triazinephosphonate (TPs) derivatives. The evaluation of the proton conduction properties of the new membranes and relative humidity (RH) conditions and at 60 °C, showed that they present higher proton conductivities than the prepared Nafion membrane and similar or better proton conductivities than commercial Nafion N115, in the same experimental conditions. The Nafion-doped membrane with compound TP2 with a 1.0 wt % loading showed the highest proton conductivity with 84 mS·cm-1.

Novel hybrid thiazoles, bis-thiazoles linked to azo-sulfamethoxazole: Synthesis, docking, and antimicrobial activity

The reaction of sulfamethoxazolehydrazonoyl chloride with thiosemicarbazones, bis-thiosemicarbazones, or 4-amino-3-mercapto-1,2,4-triazole in dioxane in the presence of triethylamine as a basic catalyst at reflux resulted in the regioselective synthesis of thiazoles and bis-thiazoles linked to azo-sulfamethoxazole as novel hybrid molecules. The structures of the new compounds were confirmed using a range of spectra. Each compound's antibacterial properties were evaluated using the agar well-diffusion technique, and most of them demonstrated significant potency. In silico investigations revealed that the described compounds had strong interactions with the binding sites of MurE ligase, tyrosyl-tRNA synthetase, and dihydropteroate synthase, demonstrating inhibitory activity.

Utility of 2-Chloro-N-arylacetamide and 1,1'-(Piperazine-1,4-diyl)bis(2-chloroethanone) as Versatile Precursors for Novel Mono- and Bis[thienopyridines]

A series of novel thieno[2,3-b]pyridines linked to N-aryl carboxamides or (carbonylphenoxy)-N-(aryl)acetamides, as well as bis(thieno[2,3-b]pyridines) linked to piperazine core via methanone or carbonylphenoxyethanone units, were synthesized by treating the appropriate chloroacetyl- or bis-bromoacetyl derivatives with 2-mercaptonicotinonitrile derivatives in ethanolic sodium ethoxide at reflux. The spectral data were used to determine the compositions of novel compounds.

Novel Scaffolds Based on Bis-thiazole Connected to Quinoxaline or Thienothiophene through 2-Phenoxy-N-arylacetamide Groups as New Hybrid Molecules: Synthesis, Antibacterial Activity, and Molecular Docking Investigations

The resistance of microorganisms to antimicrobials has endangered the health of many people across the world. Overcoming the resistance problem will require the invention of molecules with a new mechanism of action so that no cross-resistance with existing therapies occurs. Because of their powerful antibacterial activity against a wide spectrum of Gram-positive and Gram-negative bacterial strains, heterocyclic compounds are appealing candidates for medicinal chemists. In this regard, as unique hybrid compounds, we synthesized a novel family of bis-thiazoles linked to quinoxaline or thienothiophene via the 2-phenoxy-N-arylacetamide moiety. The target compounds were synthesized by reacting the relevant bis(α-haloketones) with the corresponding thiosemicarbazones in EtOH at reflux with a few drops of TEA. Under comparable reaction conditions, the isomeric bis(thiazoles) were synthesized by reacting the appropriate bis(thiosemicarbazone) with the respective α-haloketones. The structures of the novel compounds were confirmed using elements and spectral data. All of the synthesized compounds were tested for antibacterial activity in vitro. With an inhibitory zone width of 12 mm, compound 12a had the same activity as the reference medication tobramycin against Staphylococcus aureus. Compound 12b showed 20 mg/mL as a minimum inhibitory concentration (MIC) against Bacillus subtilis. Some of the synthesized compounds were tested via molecular docking against two bacterial proteins (dihydrofolate reductase and tyrosyl-tRNA synthetase).

An Efficient Synthesis of Novel 4-Aryl-2-thioxo-3,4-dihydro-1H-pyrimido[1,2-a][1,3,5]triazin-6(2H)-ones and Their Antibacterial Activity

New substituted 4-aryl-8-methyl-2-thioxo-1,2,3,4-tetrahydro-6H-pyrimido[1,2-a][1,3,5]triazin-6-one 8a–b and ethyl 4-aryl-6-oxo-2-thioxo-1,3,4,6-tetrahydro-2H-pyrimido[1,2-a][1,3,5]triazine-7-carboxylate 8c–e were synthesized by the reaction of the corresponding 4-oxopyrimidin-2-ylthioureas with arylaldehydes. The formation of only one regioisomer was proven using complex spectral data and its structure was characterized. It was found that the interaction of 6-amino-4-phenyl-3,4-dihydro-1,3,5-triazine-2(1H)-thione with ethyl acetoacetate and diethyl ethoxymethylenemalonate leads to the formation of the same regioisomer. That is, changing the sequence of stages in this cascade process does not affect the structure of the final reaction product. All synthesized compounds exhibit antibacterial activity against E. coli and S. aureus cultures at a concentration (MIC) of 256 µg/mL.

Copper(II) Schiff-Base Complex Modified UiO-66-NH2(Zr) Metal-Organic Framework Catalysts for Knoevenagel Condensation-Michael Addition-Cyclization Reactions

The synthesis of five- and six-membered oxygen- and nitrogen-containing heterocycles has been regarded as the most fundamental issue in organic chemistry and chemical industry because they are used in producing high-value products. In this study, an efficient, economic, sustainable, and green protocol for multicomponent synthesis has been developed. The one-pot direct Knoevenagel condensation-Michael addition-cyclization sequences for the transformation of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin or phthalhydrazide generate the corresponding dihydropyrano[2,3-c]chromenes and 1H-pyrazolo[1,2-b]phthalazine-5,10-diones over a novel mesoporous metal-organic framework-based supported Cu(II) nanocatalyst [UiO-66@Schiff-Base-Cu(II)] under ambient conditions. Moreover, the [UiO-66@Schiff-Base-Cu(II)] complex efficiently catalyzed the selectively large-scale synthesis of the target molecules with high yield and large turnover numbers. As presented, the catalyst demonstrates excellent reusability and stability and can be recycled up to six runs without noticeable loss of activity. Moreover, ICP-AES analysis showed that no leaching of Cu complex occurred during the recycling process of the heterogeneous [UiO-66@Schiff-Base-Cu(II)] nanocatalyst.