Synthesis of Symmetrical Acetophenone Azine Derivatives as Colorimetric and Fluorescent Cyanide Chemosensors

Cyanide is a highly toxic anion and poison to the environment. Therefore, fast, effective, and efficient analysis methods to detect cyanide are needed. Herein, symmetrical chemosensor of 2’-hydroxy acetophenone azine (1) and 2’,4’-dihydroxy acetophenone azine (2) has been synthesized tested as colorimetric and fluorescent cyanide chemosensor. The azines were produced from the condensation of acetophenone derivatives with hydrazine hydrate in ethanol under reflux or ultrasonic irradiation methods. Colorimetric and fluorescent chemosensor tests showed selectivity to acetate and cyanide anions in DMSO. The limit of detection (LOD) for colorimetric measurement of cyanide anion was 9.68×10–4 M for compound (1) and 9.63×10–5 M for compound (2), while the fluorescent method showed 15.90×10–4 M for compound (1) and 8.95×10–5 M for compound (2), respectively. In addition, test paper-strips containing sensor 2 indicated noticeable results for 'naked eye' detection of cyanide in an aqueous medium.

Zn-Nx sites on N-doped carbon for aerobic oxidative cleavage and esterification of C(CO)-C bonds

Selective cleavage of C-C bonds is very important in organic chemistry, but remains challenging because of their inert chemical nature. Herein, we report that Zn/NC-X catalysts, in which Zn2+ coordinate with N species on microporous N-doped carbon (NC) and X denotes the pyrolysis temperature, can effectively catalyze aerobic oxidative cleavage of C(CO)-C bonds and quantitatively convert acetophenone to methyl benzoate with a yield of 99% at 100 °C. The Zn/NC-950 can be applied for a wide scope of acetophenone derivatives as well as more challenging alkyl ketones. Detail mechanistic investigations reveal that the catalytic performance of Zn/NC-950 can be attributed to the coordination between Zn2+ and N species to change the electronic state of the metal, synergetic effect of the Zn single sites with their surrounding N atoms, as well as the microporous structure with the high surface area and structural defects of the NC.

Green Chemistry Approaches To The Synthesis Of Flavonoids

: In nature, flavonoids constitute a relatively diverse family of aromatic molecules such as flavones, flavonols, flavanones, isoflavone, chalcones, and their derivatives. Natural and synthetic flavonoids have reported diverse biological activity including antimycobacterial, antimicrobial, antiproliferative, antiarrhythmic, antiviral, antihypertensive, antioxidant, and anti-inflammatory. Flavonoids have garnered much attention as potential targets for nutraceuticals and pharmaceuticals. The recent development of ‘‘Green Chemistry’’ has enabled us to manipulate biosynthetic pathways to generate a library of synthetic flavonoids and to diminish the hazards for human health and environmental pollution from conventional methods. This paper presents an exhaustive review of the green synthesis of flavonoids. Green chemistry is the need of the day; hence chalcones can be synthesized in an eco-friendly manner without using solvents. The chalcone synthesis involves the solvent-free solid-state trituration between acetophenone derivatives and substituted benzaldehydes in the presence of NaOH/KOH as a base (Claisen-Schmidt reaction). Using these chalcone derivatives, synthesis of flavonoids can be done. In the pharmaceutical arena, economical bulk production of different types of flavonoids has been successfully established by green chemistry techniques.

Design of Iridium N-Heterocyclic Carbene Amino Acid Catalysts for Asymmetric Transfer Hydrogenation of Aryl Ketones

A series of chiral complexes of the form Ir(NHC)2(aa)(H)(X) (NHC = N-heterocyclic carbene, aa = chelated amino acid, X = halide) was synthesized by oxidative addition of -amino acids to iridium(I) bis-NHC compounds and screened for asymmetric transfer hydrogenation of ketones. Following optimization of the reaction conditions, NHC, and amino acid ligands, high enantioselectivity was achieved when employing the Ir(IMe)2(l-Pro)(H)(I) catalyst (IMe = 1,3-dimethylimidazol-2-ylidene), which asymmetrically reduces a range of acetophenone derivatives in up to 95% enantiomeric excess.

Design of Iridium N-Heterocyclic Carbene Amino Acid Catalysts for Asymmetric Transfer Hydrogenation of Ketones

A series of chiral complexes of the form Ir(NHC)2(aa)(H)(X) (NHC = N-heterocyclic carbene, aa = chelated amino acid, X = halide) was synthesized by oxidative addition of -amino acids to iridium(I) bis-NHC compounds and screened for asymmetric transfer hydrogenation of ketones. Following optimization of the reaction conditions, NHC, and amino acid ligands, high enantioselectivity was achieved when employing the Ir(IMe)2(l-Pro)(H)(I) catalyst (IMe = 1,3-dimethylimidazol-2-ylidene), which asymmetrically reduces a range of acetophenone derivatives in up to 95% enantiomeric excess.

Synthesis and antibacterial activity of new chalcones bearing an imidazo[1,2-a]pyridine moiety

Aim and Objective: Herein, A series of new imidazo[1,2-a]pyridine-chalcone derivatives 3a-m were designed and synthesized to find new class of antibacterial agents. These compounds were prepared by the aldol condensation of 2-phenylimidazo[1,2-a]pyridine-3-carbaldehyde 2a-b with acetophenone derivatives and other aromatic acetyls. High reaction yields have been obtained in a short reaction time, through applying this multi-step pathway. Materials and Methods: In vitro antibacterial activities of the synthesized imidazo[1,2-a]pyridine-chalcones were measured against S. aureus, B. subtilis and E. coli with MIC values of 32 -128 μg/mL. Finally, essential structural analyses such as CHN and NMR spectroscopies were used to identify the synthesized chalcones based on imidazo[1,2-a]pyridine derivatives. Results: The results showed that most of the products presented moderate to good antibacterial activities. Compounds 3b, 3d, 3g, 3l and 3m revealed obvious potency against S. aureus, B. subtilis and E. coli with MIC values of 32 μg/mL and 64 μg/mL, which were better when compared with other chalcones. Conclusion: The synthesized antibacterial compounds were obtained with appealing advantages such as high purity, simple pathway, good to excellent yields, inexpensive and easy availability of materials as well as good activities against bacteria. So in this work, new class of antibacterial chalcones based on imidazo[1,2-a]pyridine have been reported.