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

We report herein, the usage of N,O-bis(trimethylsilyl) acetamide (BSA) and dicyclohexyl carbodimide (DCC) as two new catalysts for three component condensation of an aldehyde, ethyl acetoacetate and urea/thiourea under solvent free conditions at 100 degrees C to afford the corresponding 3,4-dihydropyrimidine-2-(1H)-ones/thiones (DHPMs) in good to excellent yields. A comparative study of these two catalysts was made and presented. (C) 2012 Production and hosting by Elsevier B.V. on behalf of King Saud University.

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ARABIAN JOURNAL OF CHEMISTRY

Solvent free synthesis of 3,4-dihydropyrimidine-2-(1H)-ones/thiones catalyzed by N,O-bis(trimethylsilyl)acetamide and dicyclohexyl carbodimide

Coordination-driven self-assembly of dinuclear half-sandwich p-cymene ruthenium(II) complexes [Ru2(μ-η4-C2O4)(CH3OH)2(η6-p-cymene)2](O3SCF3)2 (1a) and [Ru2(μ-η4-C6H2O4)(CH3OH)2(η6-p-cymene)2](O3SCF3)2 (1b) separately with imidazole-based tritopic donors (L1-L2) in methanol yielded a series of hexanuclear [3+2] trigonal prismatic cages (2-5), respectively [L1 = 1,3,5-tris(imidazole-1-yl)benzene; L2 = 4,4′,4″-tris(imidazole-1-yl)triphenylamine]. All the self-assembled cages 2-5 were characterized by various spectroscopic techniques (multinuclear NMR, Infra-red and ESI-MS) and their sizes, shapes were obtained through geometry optimization using molecular mechanics universal force field (MMUFF) computation. Despite the possibility due to the free rotation of donor sites of imidazole ligands, of two different atropoisomeric prismatic cages (C3h or Cs) and polymeric product, the self-selection of single (C3h) conformational isomeric cages as the only product is a noteworthy observation. © 2015 Elsevier B.V. All rights reserved.

Inorganica Chimica Acta

Template-free coordination-driven self-assembly of discrete hexanuclear prismatic cages employing half-sandwich octahedral RuII2 acceptors and triimidazole donors

The structural determination and manipulation of bottle-brush polymers, a class of polymers with serially grafted side-chains, is challenging due to the interplay of side-chain and backbone interactions over various length scales. The present work performs a detailed analysis, using molecular dynamics simulation techniques, to unravel these interactions by probing the distinct rod to a flexible real-chain with self-avoiding walk (SAW) type crossover in the backbone static structure factor. This analysis elucidates the deviation from flexible chain behavior, while also providing a quantitative measure of persistence length, lp. Significantly, the results identify a trend in lp which is consistent with the debated theoretical prediction of lp Ns 15/8, where Ns is the number of monomers in each side-chain of the bottle-brush polymer. (Figure presented.). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Macromolecular Theory and Simulations

Scaling Laws of Bottle-Brush Polymers in Dilute Solutions

In this study, a simple TAMRA (tetramethyl-6-carboxyrhodamine) quenching-based aptasensing platform was designed for the detection of aflatoxin B1 (AFB1). Here, we compared the analytical performance of two aptamer sequences: seqA and seqB. The AFB1 detection was based on the interactions of FAM (carboxyfluorescein)-labeled aptamer with TAMRA-labeled DNA complementary strand in the presence and absence of target analyte. Under optimized experimental conditions, TAMRA-labeled strand quenched the fluorescence response of FAM-labeled aptamer due to the noncovalent interaction between the two DNA strands. The binding of AFB1 induced the complex formation and weakened the interaction between FAM-labeled aptamer and TAMRA-labeled complementary strand, resulting in the fluorescence recovery. By using this principle concept, an assay was constructed for the detection of AFB1. The method exhibited good sensitivity, good selectivity with a limit of detection of 0.2 ng ml−1, and a wide linear range from 0.25 to 32 ng ml−1. For real sample application, the aptasensors were tested in beer and wine samples, with good recovery rates obtained for AFB1 detection. © 2016 Elsevier Inc.

Analytical Biochemistry

Tetramethyl-6-carboxyrhodamine quenching-based aptasensing platform for aflatoxin B1: Analytical performance comparison of two aptamers

Trinuclear complexes of group 6, 8 and 9 transition metals with a (μ3-BH) ligand [(μ3-BH)(Cp*Rh)2(μ-CO)M′(CO)5], 3 and 4 (3: M′=Mo; 4: M′=W) and 5–8, [(Cp*Ru)3(μ3-CO)2(μ3-BH)(μ3-E)(μ-H){M′(CO)3}] (5: M′=Cr, E=CO; 6: M′=Mo, E=CO; 7: M′=Mo, E=BH; 8: M′=W, E=CO), have been synthesized from the reaction between nido-[(Cp*M)2B3H7] (nido-1: M=Rh; nido-2: M=RuH, Cp*=η5-C5Me5) and [M′(CO)5⋅thf] (M′=Mo and W). Compounds 3 and 4 are isoelectronic and isostructural with [(μ3-BH)(Cp*Co)2(μ-CO)M′(CO)5], (M′=Cr, Mo and W) and [(μ3-BH)(Cp*Co)2(μ-CO)(μ-H)2M′′H(CO)3], (M′′=Mn and Re). All compounds are composed of a bridging borylene ligand (B−H) that is effectively stabilized by a trinuclear framework. In contrast, the reaction of nido-1 with [Cr(CO)5⋅thf] gave [(Cp*Rh)2Cr(CO)3(μ-CO)(μ3-BH)(B2H4)] (9). The geometry of 9 can be viewed as a condensed polyhedron composed of [Rh2Cr(μ3-BH)] and [Rh2CrB2], a tetrahedral and a square pyramidal geometry, respectively. The bonding of 9 can be considered by using the polyhedral fusion formalism of Mingos. All compounds have been characterized by using different spectroscopic studies and the molecular structures were determined by using single-crystal X-ray diffraction analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Chemistry–A European Journal

New trinuclear complexes of group 6, 8 and 9 metals with a triply bridging borylene ligand

Objectives. Laryngeal mask airway (LMA) is an important alternative to endotracheal intubation for all professional voice users undergoing surgery. However, dysphonia is a known complication of LMA Proseal (PLMA) use. The i-gel airway (IGA) provides adequate airway seal without the need for an inflatable cuff. Hence, it helps to minimize the risk of tissue compression. This study compares effect of PLMA and IGA on voice at 24th hour after anesthesia. Design. This is a double-blind randomized clinical trial. Methods. Ninety anesthesiologists class 1 adults scheduled for surgeries lasting up to 60-120 minutes were included in the study. Participants were randomly allocated to group PLMA (n = 43) and group IGA (n = 43). Cuff pressure was monitored and maintained at just seal pressure in group PLMA. Voice was evaluated using perceptive and acoustic analysis (jitter, shimmer, and harmonics-to-noise ratio {[}HNR]) preoperatively and at 24th hour after anesthesia. Voice of patients with pharyngolaryngeal complaints was categorized into rough, breathy, asthenic, strain, or normal pattern. Results. Acoustic parameters jitter, shimmer, and HNR deteriorated significantly in both group PLMA and IGA albeit the change being comparable. Incidence of pharyngolaryngeal complaints was similar in both the groups. A total of 10\% patients in group PLMA and 12.5\% in group IGA developed breathy voice significant deterioration in all acoustic variables at 24th postoperative hour, but differences were not significant between group PLMA and group IGA. Conclusions. PLMA and IGA both produce comparable and significant deterioration in acoustic variables at 24th hour after short duration general anesthesia.

JOURNAL OF VOICE

Supraglottic Airway Devices and Effect on Voice-Comparison of LMA Proseal and i-gel: Double-Blind Randomized Clinical Trial

Design of new multifunctional nanocatalysts is a hot area of research that aims to introduce multiple types of active sites on a single nanocatalyst. Multifunctional nanocatalysts are useful to carry out a multi-step reaction requiring same or different active sites in a single pot. Such catalysts must possess the active sites at spatially distinct locations to avoid neutralization but yet remain active independently or through cooperative actions. The necessity of nanostructuring the active sites have emerged as the key point in a successful design of the catalysts. The review covers the progress in this area of research done in the last five years. It includes the classification of catalysts based on active sites and structure of active sites at the nanoscale. The review covers exhaustively with 250+ references and ample examples to present the concept succinctly. The review covers the evolution of multifunctional catalysts from the perspective of materials chemistry. © 2015 Elsevier B.V.

Applied Catalysis A: General

Multifunctional nanocatalysts for tandem reactions: A leap toward sustainability

A benzil-based semi-rigid dinuclear organometallic acceptor 4,4′-bis[trans-Pt(PEt3)2(NO3)(ethynyl)]benzil (bisPt-NO3) containing a Pt-ethynyl functionality was synthesized in good yield and characterized by multinuclear NMR (1H,31P, and 13C), electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray diffraction analysis of the iodide analogue bisPt-I. The stoichiometric (1:1) combination of the acceptor bisPt-NO3 separately with four different ditopic donors (L1-L4; L1 = 9-ethyl-3,6-di(1H-imidazol-1-yl)-9H-carbazole, L2 = 1,4-bis((1H-imidazol-1-yl)methyl)benzene, L3 = 1,3-bis((1H-imidazol-1-yl)methyl)benzene and L4 = 9,10-bis((1H-imidazol-1-yl) methyl)anthracene) yielded four [2 + 2] self-assembled metallacycles M1-M4 in quantitative yields, respectively. All these newly synthesized assemblies were characterized by various spectroscopic techniques (NMR, IR, ESIMS) and their sizes/shapes were predicted through geometry optimization employing the PM6 semi-empirical method. The benzil moiety was introduced in the backbone of the acceptor bisPt-NO3 due to the interesting structural feature of long carbonyl C-C bond (∼1.54 Å), which enabled us to probe the role of conformational flexibility on size and shapes of the resulting coordination ensembles. © 2015 Schweizerische Chemische Gesellschaft.

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Chimia

Self-assembly of metallamacrocycles employing a New Benzil-based organometallic bisplatinum(II) acceptor

Thermolysis of an in situ generated intermediate {[}(Cp{*}Ta)(2)(BH3)(2)Cl-2], 1 generated from the reaction of {[}Cp{*}TaCl4], (Cp{*} = eta(5)-C5Me5) and {[}LiBH4.thf], in presence of {[}Ru-3(CO)(12)] yielded pileo- {[}Cp{*}TaCl(mu-Cl)-B2H4Ru3(CO)(8)], 2 having two electrons fewer than seven pairs required for the observed square pyramidal geometry. Cluster 2 is the first example of an unsaturated cluster comprising early and late transition metals in a square pyramid core. This reaction also yielded {[}(Cp{*}Ta)(2)(B2H6)(B2H4Cl2)], 3 as a by-product. In addition, the reaction of {[}Cp{*}MoCl4] (Cp{*} = eta(5)- C5Me5) with {[}LiBH4.thf] in presence of excess {[}MeI] at mild condition led to the isolation of periodinated dimolybdatetraborane {[}(Cp{*}Mo)(2)B4H3I5], 4 that hints a possible existence of {[}(Cp{*}Mo)(2)B4H8]. After the isolation of periodinated 4, we extended this chemistry towards the late transition metallaborane {[}(Cp{*}Rh)(3)B4H4], 5 using {[}PtBr2] as brominating source. Although all the attempts to isolate perbrominated rhodaborane failed, we have isolated partially brominated rhodaborane clusters {[}(Cp{*}Rh)(3)(BH)-(BBr)(3)], 6 and {[}(Cp{*}Rh)(3)(BH)(3)(BBr)], 7. All the compounds were characterized by IR and H-1, B-11 and C-13 NMR spectroscopy in solution, and the solid-state structures of 2, 4 and 6 were established by crystallographic analysis.

PURE AND APPLIED CHEMISTRY

Chemistry of early and late transition metallaboranes: synthesis and structural characterization of periodinated dimolybdaborane {[}(Cp{*}Mo)2B4H3I5]

In an attempt to synthesize a zero valent germanium compound, we have carried out the reaction of [(Cp∗RuCO)(GeCl2)]2, 1 with potassium metal that led to the formation of a metallagermoxane [(Cp∗Ru(CO)2Ge)4(μ-O)6], 2. Compound 2 is the first example of a tetrametallagermoxane with an exo-{Cp∗Ru(CO)2} fragment. DFT calculations were used to examine the key intermediates associated with the formation of 2. © 2015 The Royal Society of Chemistry.