K. Subrahmanya Bhat

SYNTHESIS OF SOME NEW 1,2,4-TRIAZOLO[3,4-b]-THIADIAZOLE DERIVATIVES AS POSSIBLE ANTICANCER AGENTS

3-Substituted-4-amino-5-mercapto-1,2,4-triazoles are versatile synthons for constructing various biologically active heterocycles. Their cyclization with carboxylic acids gives fused five-membered derivatives, whereas with α-bromoketones gives a six-membered heterocycle. In this article we report the synthesis of a series of 1,2,4-triazolo[3,4-b]thiadiazoles 5 starting from 4-amino-3-substituted-5-mercapto-1,2,4-triazoles 3 and fluorobenzoic acids 4 using phosphorous oxychloride as cyclizing agent. Fourteen of the newly synthesized compounds were screened for anticancer properties. Four among them showed in vitro anticancer activity.

NOVEL THREE COMPONENT SYNTHESIS OF 1,2,4-TRIAZOLO[3,4-b]THIAZOLES AND THEIR ANTIMICROBIAL ACTIVITY

1,2,4-Triazolo[3,4-b]thiazole derivatives 5a–j have been synthesized by novel multi-component reaction of 2,4-dichloro-5-fluorophenacyl bromide (1), thiosemicarbazide (2), and aromatic carboxylic acids (4) using phosphorous oxychloride as the cyclizing agent. This reaction protocol is simple, efficient, and requires shorter reaction times in comparison to the conventional multi-step synthesis. The products were identified to be same by an alternate synthesis. All the compounds were screened for their antimicrobial activity against some of bacterial and fungal strains.

Indirect Complexometric Determination of' Palladium(II) Using Sodium Nitrite as a Selective Masking Reagent

A selective complexometric method is described for the determination of palladium, sodium nitrite being used as masking reagent. Palladium(II) in a given sample solution is initially cornplexed with an excess of EDTA and the surplus EDTA is titrated with zinc sulfate solution at pH 4.5–5.5 (acetic acid-sodium acetate buffer), using xylenol orange as indicator. An excess of sodium nitrite is then added, the mixture is shaken well and the EDTA released from the Pd-EDTA complex is titrated with a standard zinc sulfate solution. Results are obtained for 2.5–27.5 mg of Pd with relative errors ⩽0.5% and standard deviations ⩽0.05 mg. The interferences of various ions are studied. The method is applied for the determination of palladium(II) in alloys and complexes.

Synthesis of some new fluorine containing thiadiazolotriazinones as potential antibacterial agents

2,4-dichloro-5-fluorophenyl, 4-fluoro-3-(Phenoxy)phenyl, 4-fluorophen-yl groups are known pharmacophores and can be used in the synthesis of new biologically active molecules. Therefore, 4-amino-6-arylmethyl-3-mercapto-1,2,4-triazin5(4H)-ones 1 are condensed with 3-phenoxy-4-fluoro-benzoic acid, 2,4-dichloro-5-fluorobenzoic acid, and 4-fluorobenzoic acid 2 to give 7-substituted-3-arylmethyl-4H-1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones 3 . Phosphorous oxychloride was used as cyclizing agent. All the newly synthesized compounds 3a-l was screened for their antibacterial activities. Most of them showed promising activity in the range of 10 w g/mL concentrations.

Complexometric determination of copper(II) in ores, alloys and complexes using 2-mercaptoethanol as indirect masking reagent

A complexo-titrimetric method for the determination of copper(II) in the presence of other metal ions is described, based on the selective masking ability of 2-mercaptoethanol towards copper(II). Copper and other ions in a given sample solution are initially complexed with an excess of EDTA and the surplus EDTA is titrated with zinc sulfate solution at pH 5.0–6.0 (hexamine), using xylenol orange as indicator. A known excess of 2-mercaptoethanol solution (10%) is then added, the mixture is shaken well and the released EDTA from the Cu-EDTA complex is titrated against standard zinc sulfate solution. The interferences of various ions are studied and the method is applied to the determination of copper in its ores, alloys and complexes. Reproducible and accurate results are obtained for 2.5–40 mg of Cu with relative errors ⩽ 0.4% and standard deviations ⩽ 0.04 mg.

Polymer matrix-natural fiber composites: An overview

Abstract The study of polymer matrix composites had become an important topic for academic and industrial research. The current thrust for materials which are environmental friendly and biodegradable made researchers to focus on alternate options to synthetic materials. One major area of research in this direction is in the area composites of polymers with natural fibers. These composites exhibit moderate to good mechanical properties. This overview briefs about the use of polymers for different natural fiber composites. This review is expected to provide a general overview for the materials selection for the design of composite materials with improved properties.

Physicochemical Studies on Thienyl Chalcone Derivative for Nonlinear Optical Application

Single crystals of 1-(5-chlorothiophen-2-yl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one (CTTMP) having nonlinear optical property have been grown by slow evaporation technique. The functional groups were identified by FT-IR and NMR techniques. The mechanical property of the crystals was studied using Vickers microhardness tester and the load dependence hardness was observed. The material is dimensionally stable up to 112°C. The dielectric properties of the crystals were determined using semiconductor characterization system. The optical limiting behavior of the crystal was studied using Z-scan technique.

Characterization of natural cellulosic fiber from bark of Albizia amara

ABSTRACT The present investigation aimed to understand the physicochemical properties of new natural fiber extracted from Albizia amara (AA) bark. The chemical composition and structural, thermal, and tensile properties of AA fibers (AAFs) were investigated. The results indicated that AAF had crystallinity index of 63.78%, cellulose of 64.54 wt%, hemicellulose of 14.32 wt%, lignin of 15.61 wt%, and low density of 1043 kg/m3. Thermogravimetric analysis shows that AAFs were thermally stable up to 330.6°C and the functional groups of the AAFs were identified by Fourier transform infrared analysis. The AAFs exhibited tensile strength of 640 ± 13.4 MPa with strain rate of 1.57 ± 0.04%. This investigation reveals that AAFs could be a suitable material as reinforce agent in natural fiber–polymer composites for different applications.

Pyrazoline derivatives as possible corrosion inhibitors for mild steel in acidic media: A combined experimental and theoretical approach

Abstract Various experimental and theoretical methods have been employed to study the effectiveness of two pyrazoline derivatives namely, 2-(4-(5-(p-tolyl)-4,5-dihydro-1H-pyrazol-3-yl)phenoxy)acetic acid (P1) and 2-(4-(5-(4-nitrophenyl)-4,5-dihydro-1H-pyrazol-3-yl)phenoxy)acetic acid (P2) as corrosion inhibitors for mild steel in 1.0 M HCl at 303 K. The inhibitors show high inhibition efficiency and their adsorption on mild steel surface was found to obey Langmuir adsorption isotherm. Potentiodynamic polarization results revealed that both compounds behaved as mixed-type inhibitors. The results from electrochemical impedance spectroscopy studies reveal an increase in polarization resistance. Density Functional Theory calculations and molecular dynamic simulations were used to give basic insights into the action mode of inhibitors as well as to substantiate the experimental results. The surface morphology of the mild steel surface was examined using Scanning Electron Microscopy and Atomic Force Microscopy.