Reactions of α‐diazoketones with indolinone imines: Synthesis of new 1,3,3‐triaryl‐1′‐methylspiro[azetidine‐2,3′‐indoline]‐2′,4‐diones

The paper describes the synthesis of new 1,3,3‐triary‐1′‐methylspiro[azetidine‐2,3′‐indoline]‐2′,4‐diones from reaction of the 2‐diazo‐1,2‐diarylethanones with 3‐arylimino‐1‐methyl‐2‐indolinones. The compounds have been characterized by satisfactory analytical and spectral (IR, ¹H NMR and ¹³C NMR) data. The diarylketenes, generated in situ from thermal decomposition of the 2‐diazo‐1,2‐diarylethanones, react with azomethine linkage in preference to carbonyl group leading to the formation of products.     

Chemoselective Reaction of Benzoylisothiocyanates with Hydroxyl Group of Salicylamide: a New and Convenient Entry Into 2-Aryl-4H-benzo[e][1,3]oxazin-4-ones

Abstract

The reactions of benzoylisothiocyanates with salicylamide in pyridine-xylene solution occurs chemoselectively at the hydroxyl group of the salicylamide to afford the corresponding O-benzoyl derivatives. The latter products, on prolonged heating in pyridine-xylene solution, undergo cyclodehydration to give 2-aryl-4H-benzo[e][1,3]oxazin-4-ones in good yields. These compounds could also be synthesized by a direct one-pot reaction of benzoylisothiocyanates with salicylamide by slow addition of benzoylisothiocyanates into a solution of salicylamide in xylene-pyridine solution under reflux. The products have been characterized on the basis of satisfactory analytical and spectral data.     

Antifungal activity and isomerization of octadecyl p-coumarates from Ipomoea carnea subsp. fistulosa

Bioassay monitored HPLC assisted isolation and purification of the chief antifungal fraction of the leaves of Ipomoea carnea subsp. fistulosa (Convulvulaceae) were achieved using Colletotrichum gloeosporioides and Cladosporium cucumerinum as test organisms. The activity of the purified fraction was further confirmed by the dose dependent inhibition of the spore germination of Alternaria alternata and A. porri. The active fraction was identified as a mixture of (E)-octadecyl p-coumarate and (Z)-octadecyl p-coumarate. The two isomers were detected on an HPLC column with substantially different retention times, but once eluted from the column, one form was partly converted to the other in daylight. Conclusive evidence for the structures and their isomerization were obtained from the HPLC behavior, IR, UV, HRESIMS, CIMS and and NMR spectral data. Important 1H NMR and 13C NMR signals could be separately assigned for the isomers using 2D NMR techniques.     

Computation of emission characteristics of Ar–Fe arc plasma column during the synthesis of nano particles of Fe-oxides

The article reports the results of the computationally determined radiative emission characteristics of a transferred arc argon plasma source used in plasma-assisted nano particles synthesis of Fe-oxides. A thermodynamic code uses a spectroscopic database to compute internal partition functions and densities of various charged states in argon–iron vapor plasma system during the synthesis of Fe-oxides. The net amount of radiation emitted by the plasma at different axial positions along the column has been monitored by optical emission spectroscopy. It was also used to determine the amount of metal vapors mixing inside the plasma column during the synthesis process. The net emission coefficient estimated along a certain line of sight shows an effective increase even for a small inclusion of Fe vapors (0.11%) inside the column. It has been noticed that the radiations emitted by the plasma inside the reactor chamber might also be one of the factors, controlling the crystalline phase of Fe-oxide particles.     

Asymmetric Schmidt reaction of hydroxyalkyl azides with ketones

An asymmetric equivalent of the Schmidt reaction permits stereocontrol in ring expansions of symmetrical cyclohexanones. The procedure involves the reaction of chiral 1,2- and 1,3-hydroxyalkyl azides with ketones under acid catalysis; the initial reaction affords an iminium ether that can be subsequently opened with base. A systematic study of this reaction is reported, in which ketone substrates, chiral hydroxyalkyl azides, and reaction conditions are varied. Selectivities as high as ca. 98:2 are possible for the synthesis of substituted caprolactams, with up to 1,7-stereoselection involved in the overall process. The fact that either possible migrating carbon is electronically identical provides an unusual opportunity to study a ring-expansion reaction controlled entirely by stereoelectronic factors. The mechanism of the reaction and the source of its stereoselectivity are also discussed.     

Synthesis,Antimicrobial, and Brine Shrimps Lethality Assays of 3,3‐Diaryl‐4‐(1‐methyl‐1H‐indol‐3‐yl)azetidin‐2‐ones

The paper describes the synthesis, characterization data, and biological activity (antibacterial, antifungal, and brine shrimps lethality) of new azetidin‐2‐ones. The compounds have been synthesized by the reaction of diarylketenes, generated in situ from thermal decomposition of the 2‐diazo‐1,2‐diarylethanones, with N‐(1‐methyl‐1H‐indol‐3‐yl)methyleneamines. The compounds have been characterized by elemental analysis and spectral (IR, ¹H and ¹³C NMR, and MS) data. The paper also reports the results of antibacterial, antifungal, and brine shrimps lethality assays of these compounds. Some of the compounds exhibited significant biological activity.     

Crystallization and Characterization of Calcium Phosphates: Brushite and Monetite

Spherulitic monetite (CaHPO₄) and brushite (CaHPO₄ · H₂O) of different morphologies which have close resemblance to those found in pathological joints, stones and dental calculi were crystallized in silica gel under acidic conditions. These crystals were characterized by x-ray powder diffraction, fourier transform infra-red, and thermogravimetric analyses. The molar ratios (Ca/P) were calculated from ICP analysis and found to be in agreement with the theoretical stoichiometric molar ratio. The microstructure of the spherulitic monetite crystals have been studied using scanning electron microscopy.     

On the steady laminar flow in a curved pipe of varying elliptic cross-section

The fully developed steady flow of a fluid through a curved tube with elliptic cross-section is studied, the cross-sectional area varying slowly with longitudinal distance. Using a perturbation scheme in terms of two small parameters (geometric parameter and curvature parameter), complete analytical solutions are obtained to the first order. The effects of constriction combined with constant curvature of the centre line are discussed. The phenomenon of secondary flow, shear stress and the increased impedance (due to the constriction) are calculated. The possibility of the application of the results to various engineering problems and physiological flows is indicated.     

Partitioning a graph into monochromatic connected subgraphs

We show that every -edge-colored graph on vertices with minimum degree at least can be partitioned into two monochromatic connected subgraphs, provided is sufficiently large. This minimum degree condition is tight and the result proves a conjecture of Bal and DeBiasio. We also make progress on another conjecture of Bal and DeBiasio on covering graphs with large minimum degree with monochromatic components of distinct colors.     

Near-infrared quantum dots for deep tissue imaging

Developments in nanotechnology have paved the way for the early detection, treatment, and prevention of several tumors which affect mankind. In the past few years, near-infrared (NIR) fluorescence imaging techniques have emerged that enable the in vivo imaging of physiological, metabolic, and molecular function. The NIR window, also known as the diagnostic window (700–900 nm), can be explored for sensitive detection techniques. Nanoparticles, particularly semiconductor quantum dots (QDs), can be utilized for the purpose of optical imaging. These semiconductor QDs possess novel electronic, optical, magnetic, and structural properties which are quite different from those of bulk materials. NIR QDs with these unique properties can be utilized as contrast agents for optical imaging, particularly for deep tissue imaging. Deep tissue imaging provides more information about the pathological status of the disease, which makes the treatment more effective and efficient. In this review we highlight the importance of NIR QDs as probes for optical imaging. We describe the different types of NIR QDs, their synthesis, and their application for deep tissue imaging along with recently developed self-illuminating NIR QDs.