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

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Cancer Research 80 (16 Supplement)

SIRT5 inhibition causes increased oxidative stress and impairs tumor progression and metastasis

Precise control over the monomeric sequence on natural sequence-defined polymers (SDPs) leads to their structural diversity and functions. However, absolute control over the monomeric sequence on a synthetic polymer remains a challenging process. Herein, we describe a support-free, protection-deprotection-free, cost-effective, and fast iterative strategy for multigram production of a new class of SDP with a unique functional group, dithiocarbamate, a potential group for material and biomedical applications. The strategy is based on a unique monomer, named as amine-hydroxyl monomer, and a three-component reaction between the monomer, CS2, and terminal chloro group of the growing chain. The fast strategy allows us to synthesize a 5-mer sequence-defined oligomer in 6 h. For a proof of concept, a range of aliphatic and aromatic groups have been incorporated at different sequences in the sequence-defined oligomer. This SDP platform has further been advanced by two ways: (i) multiple approaches for postsynthetic modification of SDP and (ii) increasing the chain length in a single step. © 2020 American Chemical Society.

Macromolecules

Sequence-Defined Dithiocarbamate Oligomers via a Scalable, Support-free, Iterative Strategy

The solvothermal synthesis and structural characterization of two new supramolecular coordination polymers featuring a unique V-shaped ligand bis-[N-(3-pyridyl)methyl)]-9,18-methano-1,8-naphthalimide-[b,f][1,5]diazocine (TBNap), are reported. The ligand TBNap was synthesized as a racemic mixture and the molecular structure was analyzed crystallographically. TBNap showed a positive solvatochromism effect which was further supported by DFT calculations illustrating the D-π-A type fluorophore effects within the ligand structures. TBNap was further employed as a potential fluorescence probe for the discriminative sensing of structurally assorted antibiotics. A strong fluorescence quenching and preferential binding affinity were realized for nitro-containing antibiotics, i.e., Furazolidone, Nitrofurantoin and Nitrofurazone. The solvothermal reaction of TBNap with Cd(OAc)2‧2H2O afforded a one-dimensional coordination polymer (TB-CP-1, poly-[Cd(TBNap)(OAc)2]). Similarly, reaction between TBNap and CdCl2.4H2O in DMF-C2H5OH rendered a 4,4’-2D coordination sheet (TB-CP-2, poly-[CdCl2(TBNap)]·DMF). The extended polymeric structures are further propagated into 3D supramolecular network through multiple face-to-face π-π interaction. © 2021 Informa UK Limited, trading as Taylor & Francis Group.

Fulltext

Supramolecular Chemistry

Synthesis, structural characterization, antibiotics sensing and coordination chemistry of a fluorescent 4-amino-1,8-naphthalimide Tröger’s base supramolecular scaffold

The full control of site selectivity in C-H activation is paramount for the programmed late-stage functionalization of structurally complex structures. During the past decade, directing groups have revolutionized molecular synthesis in terms of ortho-selective C-H activation. In sharp contrast, a selectivity switch that guides the typical ortho- to remote meta-C-H activation has thus far proven elusive. Herein, we describe the realization of such a concept for a robust selectivity control in ruthenium catalysis. The distal C-H transformation was guided by key mechanistic insights into the mild, synergistic action of carboxylates and phosphines in ruthenium(II) catalysis. Our findings allowed remote selectivity in broadly effective late-stage diversification of structurally complex drugs and natural product molecules, tolerating sensitive fluorescent dyes, drugs, lipids, peptides, nucleosides, and carbohydrates. Copyright © 2019 American Chemical Society.

ACS Catalysis

Late-stage diversification by selectivity switch in meta-c-h activation: Evidence for singlet stabilization

Ambient temperature ruthenium-catalyzed C−H arylations were accomplished by visible light without additional photocatalysts. The robustness of the ruthenium-catalyzed C−H functionalization protocol was reflected by a broad range of sensitive functional groups and synthetically useful pyrazoles, triazoles and sensitive nucleosides and nucleotides, as well as multifold C−H functionalizations. Biscyclometalated ruthenium complexes were identified as the key intermediates in the photoredox ruthenium catalysis by detailed computational and experimental mechanistic analysis. Calculations suggested that the in situ formed photoactive ruthenium species preferably underwent an inner-sphere electron transfer. © 2020 The Authors. Published by Wiley-VCH GmbH

Angewandte Chemie - International Edition

Photo-Induced Ruthenium-Catalyzed C−H Arylations at Ambient Temperature

A catalyst-free, direct electrochemical synthesis of synthetically challenging medium-sized lactams through C-C bond cleavage has been developed. In contrast to previous typical amidyl radical cyclization, this electrosynthetic approach enabled step-economical ring expansion through a unique remote amidyl migration under mild, metal- and external-oxidant-free conditions in a simple undivided cell. The strategy features unparalleled broad substrate scope with all ring sizes of (hetero)aryl-fused 8-11-membered rings and hetero atom-tethered rings, high yields, and good functional group tolerance. Our experimental and computational findings provided strong support for a SET-based reaction manifold. This journal is © The Royal Society of Chemistry.

Green Chemistry

Catalyst-free, direct electrochemical synthesis of annulated medium-sized lactams through C-C bond cleavage

Palladium-catalyzed regioselective di- or mono-arylation of o-carboranes was achieved using weakly coordinating amides at room temperature. Therefore, a series of B(3,4)-diarylated and B(3)-monoarylated o-carboranes anchored with valuable functional groups were accessed for the first time. This strategy provided an efficient approach for the selective activation of B(3,4)-H bonds for regioselective functionalizations of o-carboranes. This journal is © The Royal Society of Chemistry.

Chemical Science

Regioselective B(3,4)-H arylation of: O -carboranes by weak amide coordination at room temperature

β-diketiminate coordinated magnesium(I) compounds, [{(ArNacnac)Mg}2] (ArNacnac = [(ArNCMe)2CH]- (Ar = 2,6-diisopropylphenyl (Dip) or mesityl (Mes)), have been utilized as reducing agents in reactions with the redox active 1,4-diazabutadiene, (ButNCH)2 (ButDAB) and 2,2′-bipyrine (bipy). These reactions led to one-electron reductions of the unsaturated substrate and formation of the highly colored radical complexes, [(ArNacnac) Mg(ButDAB.)] and [(MesNacnac)Mg(bipy.)(bipy)]. The X-ray crystal structures of the compounds reveal each to possess one singly reduced ButDAB or bipy ligand. © 2020 Yuvaraj and Jones.

Main Group Metal Chemistry

Reduction of a 1, 4-diazabutadiene and 2, 2’-bipyridine using magnesium (I) compounds

An extremely bulky, symmetrical three-coordinate magnesium(i) complex, [{(TCHPNacnac)Mg}2] (TCHPNacnac = [{(TCHP)NCMe}2CH]-, TCHP = 2,4,6-tricyclohexylphenyl) has been prepared and shown to have an extremely long Mg-Mg bond (3.021(1) Å) for such a complex. It was shown not to react with either DMAP (4-dimethylaminopyridine) or CO. Three unsymmetrical 1 : 1 DMAP adducts of less bulky Mg-Mg bonded species have been prepared, viz. [(ArNacnac)Mg-Mg(DMAP)(ArNacnac)] (ArNacnac = [(ArNCMe)2CH]- Ar = 2,6-xylyl (Xyl), mesityl (Mes) or 2,6-diethylphenyl (Dep)) and their reactivity toward CO explored. Like the previously reported bulkier complex, [(DipNacnac)Mg-Mg(DMAP)(DipNacnac)] (Dip = 2,6-diisopropylphenyl), [(DepNacnac)Mg-Mg(DMAP)(DepNacnac)] reductively trimerises CO to give a rare example of a deltate complex, [{(DepNacnac)Mg(μ-C3O3)Mg(DMAP)(DepNacnac)}2]. In contrast, the two smaller adduct complexes react with only two CO molecules, ultimately giving unusual ethenediolate complexes [{(ArNacnac)Mg{μ-OC(H)C(DMAP-H)O}Mg(ArNacnac)}2] (Ar = Xyl or Mes). DFT calculations show the latter reactions to proceed via reductive dimerizations of CO and subsequent intramolecular C-H activation of Mg-ligated DMAP by "zig-zag" [C2O2]2- fragments of reaction intermediates. Calculations also suggest that magnesium deltate complexes are kinetic products in these reactions, while the magnesium ethenediolates are thermodynamic products. This study shows that subtle changes to the bulk of the reacting 1 : 1 DMAP-magnesium(i) adduct complexes can lead to fine steric control over the products arising from their CO reductive oligomerisations. Furthermore, it is found that the more activated nature of the adduct complexes, relative to their symmetrical, three-coordinate counterparts, [{(ArNacnac)Mg}2], likely derives more from the polarisation of the Mg-Mg bonds of the former, than the elongated nature of those bonds. This journal is © The Royal Society of Chemistry.

Sterically controlled reductive oligomerisations of CO by activated magnesium (I) compounds: deltate vs. ethenediolate formation

A virtual assembly model of robotic single peg-in-hole assembly environment is developed to determine contact force using ADAMS/MATLAB Co-simulation in this work. The existing dynamic models of the insertion process are incapable of replicating the real assembly scenarios due to its complicated mathematical expressions and handling variety of dynamic parameters. In order to address this problem, a co-simulation model is proposed to study the dynamic behaviour of a planar robot in executing an assembly process. Initially, the physical robotic assembly environment with 3-R planar manipulator is built in SolidWorks and it is imported to ADAMS environment for the analysis. A Cartesian trajectory for the end-effector is given as input for executing the assembly process. Since simulation in ADAMS is executed with joint values, inverse kinematic calculations of the manipulator are employed in MATLAB environment to convert the given Cartesian descriptions into their corresponding joint descriptions. Further, the joint values are properly exchanged between these different software environments using co-simulation model to simulate the intended assembly process. Besides, the contact forces at peg end are analysed under defined lateral error condition.