β-D-galactopyranoside Seco-phytoporphyrin from Atropa Belladonna and Solanum Tuberosum Yellow Leaves Determined by Nuclear Magnetic Resonance

The study described the isolation of β-D-galactopyranoside seco-phytoporphyrin from Atropa belladonna and Solanum tuberosum yellow leaves. Column chromatography was applied for its isolation. The UV-Vis, mass spectrometry and NMR spectroscopy were used for the structure confirmation. The results demonstrate that the two plants that the same chlorophyll catabolite structure.

Synthesis and Characterization of Trimethylolpropane Based Esters as Green Biolubricant Basestock

Bio-based lubricant is crucial to be developed considering the toxicity risk, climate change, energy security, and green-environmental approach. In this work, trioleate trimethylolpropane (TOTMP) (1) was synthesized through the esterification between trimethylolpropane (TMP) and oleic acid (OA) using a sulfuric acid catalyst. TOTMP was chemically modified to produce hyperbranched nonaoleate trimethylolpropane (NOTMP) (4). TOTMP was first epoxidized to epoxidized trioleate trimethylolpropane (ETOTMP) (2) followed by ring-opening reaction to produce trihydroxyhexaoleate trimethylolpropane (THHOTMP) (3). Lastly, THHOTMP was further esterified with OA to produce hyperbranched biolubricant NOTMP. Chemical structure confirmation of each product was performed by using Fourier transformation infrared (FTIR), proton, and carbon nuclear magnetic resonance (1H and 13C NMR). The physicochemical analysis showed that the oxidative stability of NOTMP was at 172°C, pour point at -34°C, flash point at 320°C, and viscosity index at 237. The tribology analysis showed good wear protection with a minimal decrease in the friction coefficient (µ). Furthermore, rheology analysis showed that all synthesized compounds had been classified as Newtonian fluids. Therefore all the branched esters' bio lubricant products were successfully produced with improved lubricity properties, which are plausible for bio lubricants for both tropical and temperate countries.

New total synthesis and structure confirmation of putative (+)-hyacinthacine C3 and (+)-5-epi-hyacinthacine C3

A second total synthesis of (+)-hyacinthacine C3 is reported. As a result, structure of the first synthetically prepared alkaloid is proved to be correct, clearly confirming the inconsistency with the stereochemistry assigned to the natural sample.

Study on Thermal and Flame Retardant Properties of Phosphorus-containing Polyimides

The present study aimed to design macromolecular architectures having imide core in the main chain and bearing two 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide heterocycles in the side chain of each structural units as a synergetic two components key factor to induce attractive flame retardant properties in the resulted materials. The synthesis pathway consisted in the classical polycondensation reaction strategy using a phosphorus-containing diamine synthesized in the laboratory and three commercial dianhydrides co-monomers. The chemical structure confirmation of the phosphorus-containing polyimides has been performed by means of FTIR and NMR spectroscopy. The thermal stability of the products was introspected through TGA analysis. The char yields measured at 900oC ranged between 35% and 54%. Using these parameters limiting oxygen index values were theoretically calculated. Also, the microscale combustion calorimetry measurements have been conducted, in order to investigate the combustion mechanism of the synthesized phosphorus-containing polyimides.

Natural products as inspiration for the development of bacterial antibiofilm agents

Synthetic and medicinal chemistry are important tools in the development of more potent, more accessible, or more pharmacologically favorable derivatives of anti-biofilm natural products, in addition to facilitating structure confirmation and understanding of mechanistic pathways.

Unequivocal structure confirmation of a breitfussin analog by anisotropic NMR measurements

Structural features of proton-deficient heteroaromatic natural products, such as the breitfussins, can severely complicate their characterization by NMR spectroscopy.

Synthesis and biological evaluation of suffrutines A, B and their N-fused analogues

The synthesis, structure confirmation, stability and isomerization features of suffrutines A, B and their N-fused analogues were reported. Biological tests showed that the introduction of nitrogen atom might be beneficial to the anticancer activity.