Department of Chemistry

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

Treatment of [M2(μ-Cl)2(cod)2] (M=Ir and Rh) with Na[H2B(bt)2] (cod=1,5-cyclooctadiene and bt=2-mercaptobenzothiazolyl) at low temperature led to the formation of dimetallaheterocycles [(Mcod)2(bt)2], 1 and 2 (1: M=Ir and 2: M=Rh) and a borate complex [Rh(cod){κ2-S,S′-H2B(bt)2}], 3. Compounds 1 and 2 are structurally characterized metal analogues of 1,5-cyclooctadiene. Metal–metal bond distances of 3.6195(9) Å in 1 and 3.6749(9) Å in 2 are too long to consider as bonding. In an attempt to generate the Ru analogue of 1 and 2, that is [(Rucod)2(bt)2], we have carried out the reaction of [Ru(Cl)2(cod)(CH3CN)2] with Na[H2B(bt)2]. Interestingly, the reaction yielded agostic complexes [Ru(cod)L{κ3-H,S,S′-H2B(bt)2}], 4 and 5 (4: L=Cl; 5: L=C7H4NS2). One of the key differences between 4 and 5 is the presence of different ancillary ligands at the metal center. The natural bond orbital (NBO) analysis of 1 and 2 shows that there is four lone pairs of electrons on each metal center with a significant amount of d character. Furthermore, the electronic structures and the bonding of these complexes have been established on the ground of quantum-chemical calculations. All of the new compounds were characterized by IR,1H,11B,13C NMR spectroscopy and X-ray crystallographic analysis. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

World University root node

Chemistry–A European Journal

Reactivity of [M2(μ‐Cl)2(cod)2] (M=Ir, Rh) and [Ru(Cl)2(cod)(CH3CN)2] with Na[H2B(bt)2]: Formation of Agostic versus Borate Complexes

The Acceptorless Dehydrogenative Coupling (ADC) of alcohols with amines is reported using a heterogeneous Fe-catalyst. The reaction operates under mild conditions with the liberation of dihydrogen and water as the byproducts. The developed ADC strategy is simple, efficient, exhibits wide functional group tolerance and can be scaled up. The present catalytic approach possesses a dual role; acting as a catalyst as well as being magnetically separable. The sustainable reuse of a heterogeneous iron catalyst is also shown. © 2016 The Royal Society of Chemistry.

Green Chemistry

Sustainable iron-catalyzed direct imine formation by acceptorless dehydrogenative coupling of alcohols with amines

Cellular metabolites, such as acyl-CoA, can modify proteins, leading to protein posttranslational modifications (PTMs). One such PTM is lysine succinylation, which is regulated by sirtuin 5 (SIRT5). Although numerous proteins are modified by lysine succinylation, the physiological significance of lysine succinylation and SIRT5 remains elusive. Here, by profiling acyl-CoA molecules in various mouse tissues, we have discovered that different tissues have different acyl-CoA profiles and that succinyl-CoA is the most abundant acyl-CoA molecule in the heart. This interesting observation has prompted us to examine protein lysine succinylation in different mouse tissues in the presence and absence of SIRT5. Protein lysine succinylation predominantly accumulates in the heart when Sirt5 is deleted. Using proteomic studies, we have identified many cardiac proteins regulated by SIRT5. Our data suggest that ECHA, a protein involved in fatty acid oxidation, is a major enzyme that is regulated by SIRT5 and affects heart function. Sirt5 knockout (KO) mice have lower ECHA activity, increased longchain acyl-CoAs, and decreased ATP in the heart under fasting conditions. Sirt5 KO mice develop hypertrophic cardiomyopathy, as evident from the increased heart weight relative to body weight, as well as reduced shortening and ejection fractions. These findings establish that regulating heart metabolism and function is a major physiological function of lysine succinylation and SIRT5.

Fulltext

Proceedings of the National Academy of Sciences of the United States of America

Metabolomics-assisted proteomics identifies succinylation and SIRT5 as important regulators of cardiac function

ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY

Metabolomics-assisted proteomics identifies protein lysine succinylation and SIRT5 as important regulators of cardiac metabolism and function

Hydrogenation of CO2 to hydrocarbons is one of the crucial technologies to address the energy deficit and increasing environmental pollution. In this work, we have synthesized and systematically studied the influence of composition and nanostructure of a Fe-based, carbon-coated core–shell nanocatalyst. The synthesis method offered good control over the thickness of the carbon coating in the core–shell catalyst, which in turn controlled the chemical composition of the core. The results emphasized an optimal amount of Fe3O4, Fe5C2 in the core and partially graphitized carbon in the shell for a high catalytic activity in the conversion of CO2 at atmospheric pressure with higher selectivity to C2-C4 olefins. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

ChemNanoMat

Fine Tuning the Composition and Nanostructure of Fe-Based Core–Shell Nanocatalyst for Efficient CO2 Hydrogenation

Aflatoxin B1 (AFB1) is the most prevalent and toxic contaminant for human beings and animals among all the aflatoxins (AFs). Additionally, AFB1 is documented as a highly carcinogenic and mutagenic contaminant in the literature. Therefore, it is of vital importance to monitor AFB1 contamination to reduce its health associated risks. In the present work, we have designed a label-free electrochemical impedimetric aptasensor for aflatoxin B1 detection. Herein, we compared the analytical performances of two aptamer sequences (seqA and seqB). The detection is based on specific recognition by the aptamer covalently-bound as compact monolayer on screen printed carbon electrodes (SPCEs) via diazonium coupling reaction. The quantification of AFB1 was achieved by using electrochemical impedance spectroscopy. A dynamic quantification range from 0.125 ng mL−1 to 16 ng mL−1 was obtained with both types of aptamer sequences while the detection limits were 0.12 ng mL−1 and 0.25 ng mL−1 for seqA and seqB respectively. For real sample applications, the developed aptasensors were demonstrated in beer and wine samples, and good recovery levels in the range of 92–102% were recorded for AFB1 detection. © 2016 Elsevier B.V.

Sensors and Actuators, B: Chemical

Disposable and portable electrochemical aptasensor for label free detection of aflatoxin B1 in alcoholic beverages

A highly selective and sensitive impedimetric sensor based on molecular imprinted polymer (MIP) has been developed for the detection of 5-chloro-2,4-dinitrotoluene (5CDNT). Computational simulations were carried out for the best combinations of MIP precursors by using Hyperchem software. MIP of 5CDNT is synthesized using the optimized combinations of polymer precursors such as the functional monomer and cross-linker. Synthesized MIP and non-imprinted polymer (NIP) were characterized by Fourier transform infrared spectroscopy (FT-IR) and BET adsorption isotherm analysis. The surface area and pore volume of MIP are quite high compared to that of NIP, while the average pore diameter of MIP is lower than that of NIP. However, the synthesized MIP with high surface area and quite good pore diameter for free flow of analytes is suitable for efficient binding with the analyte 5CDNT. Binding assay studies of MIP by using UV-Visible spectroscopy showed that the molecular imprinting factor is nearly thrice to that of NIP. Carbon paste electrodes incorporated with MIP were employed as a sensor for 5CDNT by applying electrochemical impedance spectroscopy (EIS) as transduction principle. The charge transfer resistance obtained by impedimetric analysis is proportional to the concentration of 5CDNT over a wide concentration range: 10 nM to 100 μM. A linear determination range of 1.0 to 100 μM was obtained, and the low-detection-limit was found to be 0.1 μM. The MIP carbon paste electrode has shown very good selectivity towards specific recognition of 5CDNT despite the coexistence of possible interferents like 2,4-dinitrotoluene and 1,3-dinitrobenzene. The present MIP based sensor system could be used successfully for direct determination of 5CDNT. [Figure not available: see fulltext.] © 2016, Indian Academy of Sciences.

Journal of Chemical Sciences

Development of highly selective electrochemical impedance sensor for detection of sub-micromolar concentrations of 5-Chloro-2,4-dinitrotoluene

Synthetic macrocycles derived from sequence-defined oligomers are a unique structural class whose ring size, sequence and structure can be tuned via precise organization of the primary sequence. Similar to peptides and other peptidomimetics, these well-defined synthetic macromolecules become pharmacologically relevant when bioactive side chains are incorporated into their primary sequence. In this article, we report the synthesis of oligothioetheramide (oligoTEA) macrocycles via a one-pot acid-catalysed cascade reaction. The versatility of the cyclization chemistry and modularity of the assembly process was demonstrated via the synthesis of >20 diverse oligoTEA macrocycles. Structural characterization via NMR spectroscopy revealed the presence of conformational isomers, which enabled the determination of local chain dynamics within the macromolecular structure. Finally, we demonstrate the biological activity of oligoTEA macrocycles designed to mimic facially amphiphilic antimicrobial peptides. The preliminary results indicate that macrocyclic oligoTEAs with just two-to-three cationic charge centres can elicit potent antibacterial activity against Gram-positive and Gram-negative bacteria. © 2016 Macmillan Publishers Limited. All rights reserved.

Nature Chemistry

Sequence-defined bioactive macrocycles via an acid-catalysed cascade reaction

Understanding the impact of tensile forces on disulfide bond cleavage is not only crucial to the breaking of cross-linkers in vulcanized materials such as strained rubber, but also to the regulation of protein activity by disulfide switches. By using ab initio simulations in the condensed phase, we investigated the response of disulfide cleavage by β-elimination to mechanical stress. We reveal that the rate-determining first step of the thermal reaction, which is the abstraction of the β-proton, is insensitive to external forces. However, forces larger than about 1 nN were found to reshape the free-energy landscape of the reaction so dramatically that a second channel is created, where the order of the reaction steps is reversed, turning β-deprotonation into a barrier-free follow-up process to C-S cleavage. This transforms a slow and force-independent process with second-order kinetics into a unimolecular reaction that is greatly accelerated by mechanical forces. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Angewandte Chemie - International Edition

Force-Induced Reversal of β-Eliminations: Stressed Disulfide Bonds in Alkaline Solution

Treatment of {[}M-2(-Cl)(2)(cod)(2)] (M=Ir and Rh) with Na{[}H2B(bt)(2)] (cod=1,5-cyclooctadiene and bt=2-mercaptobenzothiazolyl) at low temperature led to the formation of dimetallaheterocycles {[}(Mcod)(2)(bt)(2)], 1 and 2 (1: M=Ir and 2: M=Rh) and a borate complex {[}Rh(cod)\{(2)-S,S-H2B(bt)(2)\}], 3. Compounds 1 and 2 are structurally characterized metal analogues of 1,5-cyclooctadiene. Metal-metal bond distances of 3.6195(9)angstrom in 1 and 3.6749(9)angstrom in 2 are too long to consider as bonding. In an attempt to generate the Ru analogue of 1 and 2, that is {[}(Rucod)(2)(bt)(2)], we have carried out the reaction of {[}Ru(Cl)(2)(cod)(CH3CN)(2)] with Na{[}H2B(bt)(2)]. Interestingly, the reaction yielded agostic complexes {[}Ru(cod)L\{(3)-H,S,S-H2B(bt)(2)\}], 4 and 5 (4: L=Cl; 5: L=C7H4NS2). One of the key differences between 4 and 5 is the presence of different ancillary ligands at the metal center. The natural bond orbital (NBO) analysis of 1 and 2 shows that there is four lone pairs of electrons on each metal center with a significant amount of d character. Furthermore, the electronic structures and the bonding of these complexes have been established on the ground of quantum-chemical calculations. All of the new compounds were characterized by IR, H-1, B-11, (CNMR)-C-13 spectroscopy, and X-ray crystallographic analysis.

CHEMISTRY-A EUROPEAN JOURNAL

Reactivity of {[}M2(μ-Cl)2(cod)2] (M=Ir, Rh) and {[}Ru(Cl)2(cod)(CH3CN)2] with Na{[}H2B(bt)2]: Formation of Agostic versus Borate Complexes