Raksh Vir Jasra

Montmorillonite as a drug delivery system: Intercalation and in vitro release of timolol maleate

The need for safe, therapeutically effective, and patient-compliant drug delivery systems continuously leads researchers to design novel tools and strategies. Clay minerals play a very crucial role in modulating drug delivery. This work examines the advantageous effect of clay mineral as drug carrier for timolol maleate (TM), a nonselective beta-adrenergic blocking agent. The intercalation of TM into the interlayer of montmorillonite (MMT) at different pH and initial concentration is demonstrated. MMT-TM hybrid was characterized by X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), and thermal analysis (TG-DTA). TM was successfully intercalated into the interlayer of MMT, and in vitro release properties of the intercalated TM have been investigated in simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 7.4) at 37+/-0.5 degrees C. Controlled release of TM from MMT-TM hybrid has been observed during in vitro release experiments.

Nanoclays for polymer nanocomposites, paints, inks, greases and cosmetics formulations, drug delivery vehicle and waste water treatment

An overview of nanoclays or organically modified layered silicates (organoclays) is presented with emphasis placed on the use of nanoclays as the reinforcement phase in polymer matrices for preparation of polymer/layered silicates nanocomposites, rheological modifier for paints, inks and greases, drug delivery vehicle for controlled release of therapeutic agents, and nanoclays for industrial waste water as well as potable water treatment to make further step into green environment. A little amount of nanoclay can alter the entire properties of polymers, paints, inks and greases to a great extent by dispersing 1nm thick layered silicate throughout the matrices. The flexibility of interlayer spacing of layered silicates accommodates therapeutic agents which can later on be released to damaged cell. Because the release of drugs in drug-intercalated layered materials is controllable, these new materials have a great potential as a delivery host in the pharmaceutical field. The problem of clean water can be solved by treating industrial and municipal waste water with organoclays in combination with other sorbents like activated carbon and alum. Organoclays have proven to be superior to any other water treatment technology in applications where the water to be treated contains substantial amounts of oil and grease or humic acid.

PHOTOCATALYTIC DEGRADATION OF DYES AND ORGANIC CONTAMINANTS IN WATER USING NANOCRYSTALLINE ANATASE AND RUTILE TIO2

Abstract Nanocrystalline TiO2 was synthesized by controlled hydrolysis of titanium tetraisopropoxide. The anatase phase was converted to rutile phase by thermal treatment at 1023 K for 11 h. The catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier-transform infrared absorption spectrophotometry (FT-IR) and N2 adsorption (BET) at 77 K. This study compare the photocatalytic activity of the anatase and rutile phases of nanocrystalline TiO2 for the degradation of acetophenone, nitrobenzene, methylene blue and malachite green present in aqueous solutions. The initial rate of degradation was calculated to compare the photocatalytic activity of anatase and rutile nanocrystalline TiO2 for the degradation of different substances under ultraviolet light irradiation. The higher photocatalytic activity was obtained in anatase phase TiO2 for the degradation of all substances as compared with rutile phase. It is concluded that the higher photocatalytic activity in anatase TiO2 is due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst.

Enantioselective epoxidation of non-functionalised alkenes using a urea–hydrogen peroxide oxidant and a dimeric homochiral Mn(III)-Schiff base complex catalyst

Abstract The catalytic enantioselective epoxidation of chromenes, indene and styrene using a urea–hydrogen peroxide adduct as an oxidising agent and the novel dimeric homochiral Mn(III)-Schiff base catalyst 1 has been investigated in the presence of carboxylate salts and nitrogen and oxygen coordinating co-catalysts. Conversions of more than 99% were obtained with all alkenes except styrene. Absolute chiral induction, as determined by 1 H NMR using the chiral shift reagent (+)-Eu(hfc) 3 , was obtained in the case of nitro- and cyanochromene. The catalyst could be re-used for up to five cycles with some loss of activity due to degradation of the catalyst under epoxidation condition with retention of e.e.s.

Adsorption of phenol, cresol isomers and benzyl alcohol from aqueous solution on activated carbon at 278, 298 and 323 K

Adsorption of phenol, o-, m-, p-cresol and benzyl alcohol has been measured from their aqueous solutions on activated carbon at 278, 298 and 323 K in their complete solubility range. An anomalous temperature dependence of adsorption of these compounds has been observed. Desorption measurements at 278 K show that the adsorption is not reversible in the lower concentration range. This behaviour, as well as the anomalous temperature dependence, has been attributed to chemical transformations which the adsorbed species undergo on the activated carbon surface.

Chiral Mn(III) salen complex-catalyzed enantioselective epoxidation of nonfunctionalized alkenes using urea–H2O2 adduct as oxidant

AbstractEnantioselective epoxidation of chromenes, indene, and styrene mediated by manganese salen complexes 1a–b, 2a–b (1 mol%) as catalystswith urea–H 2 O 2 adduct as an oxidant is observed to give excellent epoxide yield ( > 99%) in 0.5–4 h with enantiomeric excess (ee) in therange 56–99% except for styrene in which case 23–39% ee was obtained in 20 h. Even with a catalyst loading of 0.4 mol%, the system worksefficiently with retention of enantioselectivity, albeit with an increase in reaction time. Kinetic investigations of a representative substrate,indene, with these catalysts indicated a kinetic profile having first-order dependence with respect to the concentrations of the catalyst andoxidant and independent of-initial concentration of the substrate. Based on kinetic, catalytic and experimental evidence, the mechanism ofthe epoxidation reaction is suggested.  2003 Elsevier Inc. All rights reserved. Keywords: Enantioselective; Chiral; Manganese; Nonfunctionalized alkenes; Catalysis; Urea–H

Dimeric chiral Mn(III) Schiff base complex-catalysed enantioselective epoxidation of non-functionalised alkenes

Abstract Dimeric chiral Mn(III) Schiff base complex 1 has been investigated as a catalyst for enantioselective epoxidation of chromenes, indene and styrene with an objective to explore its efficiency and recycling capability. Excellent conversions were obtained with all alkenes. More than 99% chiral induction, as determined by 1 H NMR using the chiral shift reagent Eu(hfc) 3 , was obtained in the case of electron deficient chromenes, viz. nitro and cyano chromene.

Sorption of water in aluminophosphate molecular sieve AlPO4-5

The water sorption isotherm over AlPO4-5, in which a low sorption capacity in the initial region followed by a steep rise in sorption is observed, is different from those obtained for polar molecules, namely acetonitrile, ammonia and methanol. An attempt has been made to explain the water sorption behaviour on the basis of a condensation phenomenon using the structural characteristics of AlPO4-5.

Facile Synthesis of Oxatricyclic Systems with Various Ring Sizes and Substituents

Abstract A series of α-diazo carbonyl compounds having cyclopentanone, cyclohexanone and substituted cyclohexanone units with different tether lengths have been synthesized using diazomethane solution or methanesulphonyl azide. The above synthesized α-diazo carbonyl compounds with rhodium(II) acetate dimer furnish cyclic five- or six-ring carbonyl ylide dipoles, which undergo facile 1,3-dipolar cycloaddition with different dipolarophiles to furnish the substituted and functionalized oxatricyclic systems having various ring sizes. Two X-ray crystallographic analyses of compounds 8b and 15a are reported to firmly establish the stereochemistry of the cycloadducts.

Hydrogenation of alkenes and aromatic hydrocarbons using water-soluble RuCl2(TPPTS)3 in aqueous medium

Abstract Water-soluble ruthenium complex RuCl 2 (TPPTS) 3 have been used for the catalytic hydrogenation of unsaturated hydrocarbons, namely, 1-hexene, 1-heptene, styrene, cyclooctadiene, cyclooctene and benzene. Hydrogenation reactions were carried out under mild conditions. Optimum conditions for hydrogenation was evaluated and all substrate were studied at optimum conditions. The catalytic hydrogenation performances have been compared for aliphatic and aromatic hydrocarbons analogues. Results shows aliphatic hydrogenation occurs more easily compared to aromatic hydrogenation. Effect of addition of zinc chloride to aqueous solution on the hydrogenation of benzene showed that at some critical concentration of zinc chloride, partial hydrogenation of benzene to cyclohexene occurs.