Synthesis of Novel 1,2,3-Triazole-dihydro[3,2-c]chromenones as Acetylcholinesterase Inhibitors

A novel series of 1,2,3-triazole-dihydro[3,2-c]chromenone derivatives were synthesized through an efficient three-step reaction starting from 4-hydroxybenzaldehyde. All the newly synthesized compounds were characterized by infrared and NMR spectroscopy as well as elemental analysis and evaluated for their acetylcholinesterase inhibitory activity.     

Synthesis and evaluation of antiproliferative activity of substituted N-(9-oxo-9H-xanthen-4-yl)benzenesulfonamides

Several novel N-(9-oxo-9H-xanthen-4-yl)benzenesulfonamide derivatives were prepared as potential antiproliferative agents. The in vitro antiproliferative activity of the synthesized compounds was investigated against a panel of tumor cell lines including breast cancer cell lines (MDA-MB-231, T-47D) and neuroblastoma cell line (SK-N-MC) using MTT colorimetric assay. Etoposide, a well-known anticancer drug, was used as a positive standard drug. Among synthesized compounds, 4-methoxy-N-(9-oxo-9H-xanthen-4-yl)benzenesulfonamide (5i) showed the highest antiproliferative activity against MDA-MB-231, T-47D, and SK-N-MC cells. Furthermore, pentafluoro derivatives 5a and 6a exhibited higher antiproliferative activity than doxorubicin against human leukemia cell line (CCRF-CEM) and breast adenocarcinoma (MDA-MB-468) cells. Structure–activity relationship studies revealed that xanthone benzenesulfonamide hybrid compounds can be used for the development of new lead anticancer agents.     

Synthesis of cyano-2,3-dihydropyrrolo[1,2-<Emphasis Type="Italic">f</Emphasis>]phenanthridine derivatives via a domino-Knoevenagel-cyclization

Abstract  

In a new multicomponent reaction phenanthridine reacts with isocyanides and malonitrile in the presence of benzaldehyde derivatives to produce 2-aryl-3-(alkyl- or arylimino)-2,3-dihydropyrrolo[1,2-f]phenanthridine-1,1(12b H)-dicarbonitrile in a simple, mild, and efficient protocol in excellent yields.     

Hierarchically Organized Silica–Titania Monoliths Prepared under Purely Aqueous Conditions

Hierarchically organized silica–titania monoliths were synthesized under purely aqueous conditions by applying a new ethylene glycol‐modified single‐source precursor, such as 3‐[3‐{tris(2‐hydroxyethoxy)silyl}propyl]acetylacetone coordinated to a titanium center. The influence of the silicon‐ and titanium‐containing single‐source precursor, the novel glycolated organofunctional silane, and the addition of tetrakis(2‐hydroxyethyl)orthosilicate on the formation of the final porous network was investigated by SEM, TEM, nitrogen sorption, and SAXS/WAXS. In situ SAXS measurements were performed to obtain insight into the development of the mesoporous network during sol–gel transition. IR‐ATR, UV/Vis, XPS, and XAFS measurements showed that up to a Si/Ti ratio of 35:1, well‐dispersed titanium centers in a macro‐/mesoporous SiO₂ network with a specific surface area of up to 582 m² g^?1 were obtained. An increase in Ti content resulted in a decrease in specific surface area and a loss of the cellular character of the macroporous network. With a 1:1 Si/Ti ratio, silica–titania powders with circa 100 m² g^?1 and anatase domains within the SiO₂ matrix were obtained.     

One‐Pot Synthesis of Sulfonamides and Sulfonyl Azides from Thiols using Chloramine‐T

A convenient synthesis of sulfonamides and sulfonyl azides from thiols is described. In situ preparation of sulfonyl chlorides from thiols was accomplished by oxidation with chloramine‐T (=N‐chlorotosylamide=N‐chloro‐4‐methylbenzenesulfonamide), tetrabutylammonium chloride (Bu₄NCl), and H₂O. The sulfonyl chlorides were then further allowed to react with excess amine or NaN₃ in the same pot.     

Simple optical determination of silver ion in aqueous solutions using benzo crown-ether modified gold nanoparticles

We describe a method for the modification of gold nanoparticles (Au-NPs) with benzo-15-crown-5 that led to the development of a colorimetric assay for Ag(I) ion. The brown color of a solution of the modified Au-NPs turns to purple on addition of Ag(I) ion. The ratio of the UV–vis absorption at 600 nm and 525 nm is proportional to the concentration of Ag(I) ions in the range from 20 to 950 nM, and the detection limit is 12.5 nM. Other metal ions do not interfere if present in up to millimolar concentrations. The method enables a rapid determination of Ag(I) in lake and drinking water and is amenable to bare-eye readout.

Synthesis of Oxazolo[5,4‐d][1,2,4]triazolo[4,3‐a]pyrimidines as a New Class of Heterocyclic Compounds

Several new derivatives of oxazolo[5,4‐d]pyrimidine ( 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h ) have been synthesized through the reaction of 2,4‐dichloro‐6‐methyl‐5‐nitropyrimidine ( 2 ) with aryl carboxylic acids in refluxing POCl₃. Further treatment of compounds ( 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h ) with hydrazine hydrate gave the hydrazine derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h ) that were subsequently cyclized into a novel heterocyclic system, oxazolo[5,4‐d][1,2,4]triazolo[4,3‐a]pyrimidine ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m , 5n , 5o , 5p ) and ( 7a , 7b , 7c , 7d ) on treatment with triethylorthoesters or carbondisulfide and alkylhalides, respectively.     

Bioinspired synthesis,characterization and antifungal activity of enzyme-mediated gold nanoparticles using a fungal oxidoreductase

The development of efficient cell-free systems of nanoparticle synthesis using microbial enzymes is a growing field of biological and green chemistry for the supportable improvement in nano-biotechnology. In the present study, we established a cell-free system for producing gold nanoparticles (AuNPs) using a fungal oxidoreductase named sulfite oxidoreductase purified to homogeneity from Fusarium oxysporum. The enzyme was purified by ultrafiltration followed by anion exchange chromatography on DEAE Sephadex A-50 gel, and its molecular weight was determined by gel filtration chromatography on Sephacryl S-300 gel. The purified enzyme had a molecular weight of 346 kDa. It was composed of three subunits of 176, 94 and 76 kDa. Purified enzyme was successfully used for production of gold nanoparticles in a cell-free system. Synthesized gold nanoparticles showed the highest absorbance at 520 nm wavelength as shown by UV–visible spectroscopy. They were spherical in shape with an average size of 20 nm as determined by scanning and transmission electron microscopy and dynamic light scattering. Assessment of the antifungal properties of synthesized nanoparticles by disk diffusion method indicated a potent growth inhibitory activity against all tested human pathogenic yeasts and molds by inhibition zones ranged from 10 to 18 mm. Taken together, our enzymatically established method of nanoparticle synthesis using a purified sulfite oxidoreductase of F. oxysporum can be considered as an efficient tool for generating harmless bioactive gold nanoparticles with potential applications in biology, medicine and industry.     

Pt–NiO–Al2O3/G derived from graphene-supported layered double hydroxide as efficient catalyst for p-nitrophenol reduction

Research on Chemical Intermediates - The present work reports the synthesis of a Pt-modified NiO–Al2O3 nanocomposite derived from graphene-supported layered double hydroxide (Pt–NiO/G)...     

H2 adsorption on Ag‐nanocluster/single‐walled carbon nanotube composites: A molecular dynamics study on the effects of nanocluster size,diameter, and chirality of nanotube

The H₂ physisorption on Ag_N (with N = 32, 108, 256, 500, and 864)/carbon nanotube (CNT; in armchair and zigzag structures with diameters between 0.54 and 2.98 nm) composites were studied by molecular dynamic simulation to investigate the effect of nanocluster size, diameter, and chirality of nanotube on the adsorption phenomena. The calculations indicate that the effects of nanocluster properties are more important than those of the nanotube, in such a way that increase of nanocluster size, decreases the H₂ adsorption. Also, the diameter and chirality of CNTs have considerable influence on the adsorption phenomena. As the diameter of nanotube is increased, the amount of adsorption is decreased. Moreover, H₂ molecules have more tendencies to those nanoclusters located on the armchair nanotubes than the zigzag ones. Another important result is the reversibility of H₂ adsorption on these materials in which the structure of composite in vacuum and after reduction of H₂ pressure to zero, is not changed, considerably. © 2015 Wiley Periodicals, Inc.