Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

In the present work, we have designed and synthesized a thermally stable catalyst based on functionalized benzimidazolium perchlorate ionic liquid and tested its efficacy towards metal free and solvent free transamidation of amides and amines. The ionic liquid comprising the perchlorate ion has shown remarkably better activity than those which contain other anions and accordingly a plausible mechanism for the catalytic activity is arrived. The developed catalytic system has shown excellent activity towards the transamidation of alicyclic and aromatic amines with acetamide, benzamide and p-nitrobenzamide under mild conditions. Furthermore, the transamidation of nicotinamide with benzylamine in presence of the ionic liquid catalyst was found to occur with very good yields and thus provides a facile route for the synthesis of pharmaceutically significant compounds. The catalyst has exhibited very good thermal stability upto 203 °C and very good recyclability upto 5 runs without significant loss in its activity. © 2015 Elsevier B.V. All rights reserved.

VIT Unitversity

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Applied Catalysis A: General

Designing of thermally stable amide functionalized benzimidazolium perchlorate ionic liquid for transamidation of primary carboxamides

Herein, we report our attempt to covalently immobilize toluidine blue with 3-aminopropyltrimethoxysilane and develop a simple amperometric sensor for the determination of hydrogen peroxide. The immobilization of TB to the silane matrix was effected using glutaraldehyde as the cross-linker. The mediator immobilized silane was spin coated as a thin film on a graphite rod to get the modified electrode. The modified electrode was characterized using cyclic voltammetry and its applicability as a sensor was probed for the determination of H2O2. H2O2. reduction was observed at a reduced potential of -0.33 V and a linear relation was obtained for H2O2. in the concentration range of 4.04 × 10-6M to 2.81 × 10-3 M with a detection limit of 1.62 × 10-6M and a correlation coefficient of 0.9996. Amperometric studies have revealed a rapid response at the modified electrode for H2O2. determinations under dynamic conditions. © 2015 Scientific Publishers. All Rights Reserved.

World University root node

Journal of the Indian Chemical Society

Covalently immobilized toluidine blue/sol-gel film electrode for the amperometric determination of hydrogen peroxide

Herein, we report the synthesis of a new series of amide functionalized dicationic benzimidazolium based ionic liquids (DBimILs) and appraised their efficacy towards perceptive esterification of carboxylic acids with alkyl/allyl/aryl halides in presence of triethylamine. The amide groups present in this new series of DBimILs are expected to form hydrogen bonding with the carboxylic acids and this could facilitate the esterification reactions under mild conditions devoid of any added catalyst or organic solvent. The plausible mechanism for the enhanced catalytic activity in presence of this new series of ILs has been proposed. The corresponding alkyl/allyl/aryl esters isolated from this reaction were of high purity after simple extraction, which wipe out the necessity for further purification. This protocol addresses clean methodology and the efficient recyclability as well as reusability of the catalyst. © 2014 Elsevier B.V.

Facile esterification of carboxylic acid using amide functionalized benzimidazolium dicationic ionic liquids

Metal based anticancer drugs have demonstrated their crucial role in preventing all types of cancers whereas their effectiveness is selective with respect to the cancer cells rather than the normal cells. Recently metal N-heterocyclic carbenes have established their selective performance for cancer cells excluding normal healthy cells based on which they are widely utilised for targeting cancer cells specifically which leads to cell death or cell growth inhibition. This is mainly due to their ionic character which helps them to localise in cancer cells with the help of enhanced expression of Organic Cation Transporters (OCT). Also their unique mechanism of action involving DNA binding, less recognizable by DNA repair machinery, mitochondria targeting gives them a new area for anticancer drug development. This review summarises the medicinal as well as pharmacological approach to the anticancer properties of metal NHC complexes. © 2014 Published by Elsevier Masson SAS.

European Journal of Medicinal Chemistry

Recent developments of metal N-heterocyclic carbenes as anticancer agents

The determination of hydrogen peroxide at a new Neutral Red carbon paste electrode is reported in this work. The phenazine dye, neutral red which is electrochemically active has been used as the mediator and has been rendered leak free for the development of sensor by covalently immobilizing neutral red to the functionalized graphite powder which was then made into a carbon paste electrode. The sensor demonstrated good sensitivity towards hydrogen peroxide and the linear response range spanned from 1.91 × 10-5 M to 6.60 × 10-3 M of H2O2 with a detection limit of 1.15 × 10-5 M. The developed hydrogen peroxide sensor had excellent stability and reproducibility.

International Journal of ChemTech Research

Carbon paste electrode based on neutral red functionalized graphite as an amperometric sensor for hydrogen peroxide

An electrochemical sensor using thionin as a mediator for hydrogen peroxide determination is described. The mediator was covalently immobilized with 3-aminopropyltrimethoxy silane (APTMOS) which is also used as the sol-gel precursor. The covalent immobilization of thionin to sol-gel matrix was achieved through glutaraldehyde cross-linking. This sol-gel matrix was coated as a thin film over the graphite rod and characterized using cyclic voltammetry. The performance of the modified electrode was examined on various supporting electrolytes, scan rates and pHs. The modified electrode showed good electrocatalytic activity towards the reduction of hydrogen peroxide at a reduced overpotential. The catalytic current is linear with hydrogen peroxide concentration ranging from 3.82 × 10-6 M to 4.07 × 10-3 M with a detection limit of 1.53 × 10-6 M and a correlation coefficient of 0.9951. Due to the covalent cross-linking of the mediator, the sensor showed a constant and reproducible response for more than 2 months. © 2007 Elsevier B.V. All rights reserved.

Sensors and Actuators, B: Chemical

Electrochemical sensor for H2O2 based on thionin immobilized 3-aminopropyltrimethoxy silane derived sol-gel thin film electrode

An organically modified sol-gel electrode using 3-aminopropyltrimethoxy silane for covalent immobilization of a redox mediator namely toluidine blue has been reported. Cyclic voltammetric characterization of the modified electrode in the potential range of 0.2 V to - 0.6 V exhibited stable voltammetric behavior in aqueous supporting electrolyte with a formal potential of -0.265 V vs. SCE, corresponding to immobilized toluidine blue. The electrocatalytic activity of the modified electrode when tested towards nitrite ion exhibited a favorable response with the electrocatalytic reduction of nitrite occurring at a reduced potential of -0.34 V. A good linear working range from 2.94 × 10-6 M to 2.11 × 10-3 M with a detection limit of 1.76 × 10-6 M and quantification limit of 5.87 × 10 -6 M was obtained for nitrite determination. The stable and quick response (4 s) of the modified electrode towards nitrite under hydrodynamic conditions shows the feasibility of using the present sensor in flow systems. Significant improvements in the operational stability by overcoming the leachability problem and repeatability with a relative standard deviation of 1.8% of the TB thin film sensor have been obtained by the strategy of immobilization of the mediator in the sol-gel matrix. © 2007 Wiley-VCH Verlag GmbH &amp; Co. KGaA.

Electroanalysis

Electrocatalytic reduction of nitrite ion on a toluidine blue sol-gel thin film electrode derived from 3-aminopropyl trimethoxy silane

Sol-gel technique has been used for the covalent immobilization of the water-soluble mediator, thionin to construct a bulk modified, leak free composite electrode. This renewable composite electrode provides stable immobilization matrix for thionin via glutaraldehyde crosslinking. In the electrode composition the sol-gel precursor 3-aminopropyltrimethoxy silane serves as the host for immobilization of thionin, thereby preventing its leakage. An additional precursor methyl trimethoxy silane endows hydrophobicity and limits the wetting section of the modified electrode. Cyclic voltammetric characterization of the modified electrode in the potential range of 0.2 to -0.6 V exhibited stable redox peaks with a formal potential of -0.273 V, corresponding to immobilized thionin. This chemically modified electrode exhibits good electrocatalytic activity for the reduction of H2O2 at a lower potential of -0.35 V. The reduction current of the modified electrode increases linearly in the range of 3.44 × 10-6 M to 3.07 × 10-3 M H2O2 with a detection limit of 1.38 × 10-6 M. The stable and quick response (5 s) during chronoamperometry shows the potential application of the modified electrode for flow system analysis. The low potential operation (-0.35 V) favoured selective determination of H2O2. The composite electrode exhibits distinct advantages of polishing in the event of surface fouling as well as simple preparation, good chemical and mechanical stability, economical and remarkable long-term stability (more than 1 year). The applicability of the present sensor for H2O2 determination proposes a method for the detection of other biologically significant analytes. © 2007 Elsevier B.V. All rights reserved.

Biosensors and Bioelectronics

Surface renewable sol-gel composite electrode derived from 3-aminopropyl trimethoxy silane with covalently immobilized thionin

A carbon composite amperometric hydrogen peroxide sensor has been developed using a sol-gel technique. Toluidine blue (TB), which acts as the redox mediator, was covalently immobilized via glutaraldehyde crosslinking with an organically modified silane, namely 3-aminopropyltrimethoxysilane (APTMOS). Methyltrimethoxysilane (MTMOS) was used as the additional monomer; this controls the hydrophobicity of the electrode surface, thus limiting the wettability. The immobilization of TB within the sol-gel matrix was confirmed with FTIR studies. The sol-gel mixture containing TB immobilized in APTMOS and MTMOS was mixed with graphite powder in order to prepare the carbon composite electrode. The electrode was characterized using voltammetric techniques and its electrocatalytic activity for the reduction of hydrogen peroxide was also studied. The carbon composite electrode has the advantage of sensing H 2O2 at a lower potential and with a higher sensitivity, and interferences due to ascorbic acid, uric acid and acetaminophen were greatly minimized. The linear range for the determination of H2O2 extends from 5.37∈×∈10-6 to 6. 15∈×∈10-3 M, with a correlation coefficient of 0.9981. The detection limit was found to be 2.15∈×∈10 -6 M. The covalent immobilization of TB effectively prevents the leakage of the water-soluble mediator during measurements. The modified electrode, aside from electrocatalyzing the reduction of H2O 2, exhibits distinct advantages in terms of surface renewal in the event of surface fouling, as well as simple preparation, good chemical and mechanical stability, and good reproducibility. [Figure not available: see fulltext.]. © Springer-Verlag 2007.

Analytical and Bioanalytical Chemistry

Amperometric hydrogen peroxide sensor based on a sol-gel-derived ceramic carbon composite electrode with toluidine blue covalently immobilized using 3-aminopropyltrimethoxysilane