ODOUR SENSOR BASED SOLUTION FOR THE SANITARY PROBLEM FACED BY ELDERLY PEOPLE AND KINDERGARTEN CHILDREN

ABSTRACT Old age people and kindergarten children face health problems mainly due to deficiencies in sanitation. So a complete wireless health monitoring system which continuously monitors some of the vital body parameters such as body temperature, heart pulse rate, motion sensor and odour sensor can be designed. Our paper deals with the detection of ammonia (NH3) and hydrogen sulphide (H2S) using an odour sensor or a gas sensor

Structurally simple dipodalazo linked salicylaldimine as colorimetric sensor for F⁻ and AcO⁻ ion recognition

1541-1547A dipodal N,Nʹ-bis[4-(benzeneazo)salicylaldehyde)-o-phenylenediamine (receptor 1) has been synthesized and characterized using IR, 1H and 13C NMR and mass spectroscopic techniques. The anion recognition properties of receptor 1 is investigated using colorimetric, UV-Vis and fluorescence spectroscopic techniques which shows remarkable color and optical changes for only F− and AcO− ions over other anions such as Cl−, Br−, H2PO4− and OH−. In presence of F− and AcO− ions, slight yellow colored solution of receptor 1 is turned into intense yellow color. Also, addition of F− and AcO− ions to receptor 1 induces the simultaneous decrease and increase in the intensity of absorption band at 345 nm and 455 nm. Further 1H NMR titration experiment reveals that F− ion deprotonates the phenolic OH present in receptor 1 resulting in the formation of HF2− complex. Receptor 1 showed binding constant values of 7.44×103 and 5.78×103 respectively, and detection limit in the concentration of subnanomolar and micromolar level towards F− and AcO− ions. Finally, receptor 1 has been utilized for the detection of fluoride present in tooth paste and mouthwash in aqueous phase

Effect of Microwaves in the Chiral Switching Asymmetric Michael Reaction †

† This paper is dedicated to Prof H.C. Brown, a pioneer in Physical Organic Chemistry and Asymmetric Synthesis on the occasion of his 90th birthday *Author to whom correspondence should be addressed

Novel Chiral Switching Ligands for Enantioselective Asymmetric Reductions of Prochiral Ketones

Abstract: The newly developed chiral ligands 1 and 4 show opposite enantioselectivity in the asymmetric reduction of prochiral ketones resulting in the production of either enantiomer depending on the metal complex with high enantiomeric excess

Effect of substituents on enantioselectivity in chiral oxazaborolidine mediated asymmetric ketone reduction reaction

1157-1164Various new chiral ligands have been synthesized by the condensation of different esters of l-Valine with different substituted salicylaldehydes in order to find the most effective catalyst for the enantioselctive ketone reduction. Chiral amine synthesized from l-Valine methyl ester and 5-chloro salicylaldehyde is found to catalyse the enantioselective reduction of prochiral ketone with high yield (99%) and enantiomeric excess (91%) with 20 mol% of the catalyst using borane dimethylsulphide as a stoichiometric reducutant. Different subsituted prochiral ketones have also been reduced in high yield upto 90% and the corresponding secondary alcohols are formed with good enantiomeric excess upto 99%. The mechanism of this reduction can be very well explained by considering a plausible mechanism for the CBS catalyst

Synthesis of novel chiral auxiliaries

1666-1669A simple and easy route for the preparation of the higher homologue of oxazaborolidine namely dihydrooxazaborin has been reported. Also, the preparations of new bicyclic oxazaborolidines are reported

Analysis and Review of Tin Oxide-Based Chemoresistive Gas Sensor

Different type of mechanisms of gas sensing, various factors that affect the mechanisms, ways to improve the gas sensitivity, state of the art of fabrication techniques and materials used are reviewed. The work also discusses a novel type of gas sensor derived based on the reviewed mechanisms and materials. The development of semiconductor-based gas sensors using tin oxide which is simple to implement, low cost and offering good stability and sensitivity is discussed

Tin Oxide Film Deposition and Characterization for a Chemoresistive Gas Sensor

The proposed work studies the synthesis, structural, and sensitivity of tin oxide films deposited by sputtering for a gas sensor. This includes an analysis of a tin oxide film doped with noble metal palladium. Gas sensitivity of the deposited layer is analysed as per the deposition parameters such as the thickness of the film, substrate temperature, argon-oxygen ratio of the sputtering environment, and duration and doping metal weight percentage into the tin oxide films and the results obtained are explained