Vapor phase acylation of phenol over Hβ, CeHβ and SO42-/ZrO2a

Phenol acylation on Hβ, CeHβ and SO₄ ^2-/ZrO₂ using acetic acid and acetic anhydride as acylating agents is compared in the temperature range 250-400°C. Acetic acid formed phenyl acetate (PA) and o-hydroxy acetophenone (o-HAP) and acetic anhydride formed p-hydroxyacetophenone (p-HAP ) along with PA and o-HAP. The formation of o-HAP and p-HAP, the products of C-acylation of phenol using acetic acid is proposed by studying phenyl acetate conversion on Hb, CeHβ and SO₄ ^2-/ZrO₂. Our studies show that for phenol acylation the most suitable acid site is available on CeHβ. This revised version was published online in June 2006 with corrections to the Cover Date.     

Banerjeeet al’s characterization theorem in thermohaline convection and its magnetorotatory extensions

The paper mathematically establishes that magnetorotatory thermohaline convection of the Veronis [7] type cannot manifest itself as oscillatory motions of growing amplitude in an initially bottom heavy configuration if the thermohaline Rayleigh numberR _s, the Lewis number τ, the thermal Prandtl number σ, the magnetic Prandtl number σ₁, the Chandrasekhar numberQ and the Taylor numberT satisfy the inequality \(R_s 4\pi ^4 \left[ {1 + \frac{\tau }{{\sigma \pi ^2 }}\left\{ {\pi ^2 - \left( {O\sigma _1 + \frac{T}{{\pi ^2 }}} \right)} \right\}} \right]\) when both the boundary surfaces are rigid thus achieving magnetorotatory extension of an important characterization theorem of Banerjeeet al (1992) on the corresponding hydrodynamic problem. A similar characterization theorem is mathematically established in the context of the magnetorotatory thermohaline convection of the Stern (1960) type.     

Movement of Phosphamidon in Soil Columns

Abstract

Adsorption and movement of phosphamidon, a systemic non-ionic insecticide, was studied using two different types of Indian soil, clay loam and silt loam, of alluvial origin. Equilibrium adsorption coefficient, K, values determined by batch slurry technique were in the order: clay loam>silt loam. The distribution coefficient, K_d , for both soils in batch adsorption as well as in columns was also calculated. The phosphamidon movement measured in soil columns during water infiltration was in the order: silt loam > clay loam. This order was anticipated from the K and K_d values. A larger amount of water was needed for leaching the phosphamidon to 60 inches in clay loam than in silt loam soil.     

Ceric ammonium nitrate/acetic anhydride: A tunable system for the O-acetylation and mononitration of diversely protected carbohydrates

Esterification of a wide range of partially protected carbohydrate derivatives was achieved using acetic anhydride and a catalytic amount of ceric ammonium nitrate (CAN). Compatibility with the commonly used protecting groups was demonstrated, with the esterified products being furnished in good yields. Apart from affording the O-acetylated products, their mononitrated counterparts were also produced depending upon the reactivity of the starting material. Decreasing the molar equivalents of CAN afforded the O-acetylated products exclusively, while increasing it favored the mononitrated derivatives.     

Ferrocene‐substituted bis(ethynyl)anthracene compounds as anticancer agents

Three compounds ( 1 – 3 ) were synthesized, where ethynylferrocene is substituted at different positions of anthracene and anthraquinone, and their biological properties were investigated. Compounds 1 – 3 were characterized using NMR and mass spectroscopies and confirmed by their single‐crystal X‐ray structure. They were also characterized from electronic and photophysical properties. All three crystal structures were optimized using density functional theory calculations. The presence of C–H???π interactions in 1 – 3 leads to the formation of two‐ and three‐dimensional networks. The bioactivity of 1 – 3 was expressed by molecular docking with various cancerous proteins, which participated in progression of cancer. Compound 2 displayed the best interaction with cancer‐related Aurora A protein in terms of both binding energy (?10.61 kcal mol^?1) as well as inhibition constant (16.74 nM). The molecular docking result also coincides with cytotoxicity on cancer cell lines (A375, HeLa) and DNA/protein binding affinity.     

Mixed convection flow over a vertical wedge embedded in a highly porous medium

 The steady mixed convection flow over a vertical wedge with a magnetic field embedded in a porous medium has been investigated. The effects of the permeability of the medium, surface mass transfer and viscous dissipation on the flow and temperature fields have been included in the analysis. The coupled nonlinear partial differential equations governing the flow field have been solved numerically using the Keller box method. The skin friction and heat transfer are found to increase with the parameters characterizing the permeability of the medium, buoyancy force, magnetic field and pressure gradient. However the effect of the permeability and magnetic field on the heat transfer is very small. The heat transfer increases with the Prandtl number, but the skin friction decreases. The buoyancy force which assists the forced convection flow causes an overshoot in the velocity profiles. Both the skin friction and heat transfer increase with suction and the effect of injection is just the reverse. Received on 21 May 1999     

Applicability of Reddish-Orange Light Emitting Samarium (III) Complexes for Biomedical and Multifunctional Optoelectronic Devices

Six crimson samarium (III) complexes based on β-ketone carboxylic acid and ancillary ligands were synthesized by adopting the grinding technique. All synthesized complexes were investigated via elemental analysis, infrared, UV–Vis, NMR, TG/DTG and photoluminescence studies. Optical properties of these photostimulated samarium (III) complexes exhibit reddish-orange luminescence due to ⁴G_5/2?→?⁶H_7/2 electronic transition at 606 nm of samarium (III) ions. Further, energy bandgap, color purity, CIE color coordinates, CCT and quantum yield of all complexes were determined accurately. Replacement of water molecules by ancillary ligands enriched these complexes (S2-S6) with decay time, quantum yield, luminescence, energy bandgap and biological properties than parent complex (S1). Interestingly, these efficient properties of complexes may find their applications in optoelectronics and lighting systems. In addition to these, the antioxidant and antimicrobial assays were also investigated to explore the applications in biological assays.

     

Structural Insights into Peptides Bound to the Surface of Silica Nanopores

The structure and surface functionalization of biologically relevant silica-based hybrid materials was investigated by 2D solid-state NMR techniques combined with dynamic nuclear polarization (DNP). This approach was applied to a model system of mesoporous silica, which was modified through in-pore grafting of small peptides by solid-phase peptide synthesis (SPPS). To prove the covalent binding of the peptides on the surface, DNP-enhanced solid-state NMR was used for the detection of ¹⁵N NMR signals in natural abundance. DNP-enhanced heterocorrelation experiments with frequency switched Lee–Goldburg homonuclear proton decoupling (¹H–¹³C and ¹H–¹⁵N CP MAS FSLG HETCOR) were performed to verify the primary structure and configuration of the synthesized peptides. ¹H FSLG spectra and ¹H-²⁹Si FSLG HETCOR correlation spectra were recorded to investigate the orientation of the amino acid residues with respect to the silica surface. The combination of these NMR techniques provides detailed insights into the structure of amino acid functionalized hybrid compounds and allows for the understanding for each synthesis step during the in-pore SPPS.     

Palladium acetate assisted synthesis of five-membered N-polyheterocycles

Abstract

The metal-assisted synthesis of heterocyclic compounds is known to be one of the extremely developing as well as significant concepts of organic chemistry. Because of their expensive, complex working of the instrument and difficult procedures, the methodologies used earlier for the heterocycle synthesis were less amicable to the researchers. The Pd(OAc)₂-mediated cyclic reactions have been recognized to be very effective for both the stereoselective as well as regioselective formation of the 5-membered N-bearing heterocyclic compounds. The different uses of palladium acetate, as a catalyst in the formation of 5-membered N-containing polyheterocycles, are covered in this review article.