Department of Chemistry

Indian Institute of Technology Hyderabad (IITH) is a premier institute of science and technology established in 2008. IITH has been consistently ranked in the&nbsp;<a href="https://iith.ac.in/reports/" rel="noopener noreferrer">top 10 institutes</a>&nbsp;in India for Engineering&nbsp;<a href="https://www.nirfindia.org/2021/EngineeringRanking.html" rel="noopener noreferrer" target="_blank">according to NIRF</a>&nbsp;making it one of the most coveted schools for science and technology in the country.

IITH offers&nbsp;<a href="https://iith.ac.in/academics/under-graduate/">undergraduate programs</a>&nbsp;in all the classical engineering disciplines, applied sciences, design, as well as several modern interdisciplinary areas. Students are given a flexibility to explore a broad set of areas, and potentially pursue a minor or double major in a discipline that is not their own. Students who wish to seek a deeper understanding of their own discipline are strongly encouraged to get involved in cutting-edge research with the help of a faculty to mentor them, and earn an Honors in their own field.

The very foundation of IIT Hyderabad is based on&nbsp;<a href="https://iith.ac.in/research/">research and innovation</a>. The vibrant research culture is evident from the number of patents and publications that IITH produces consistently every year. IITH offers&nbsp;<a href="https://iith.ac.in/academics/programmes-offered/">graduate programs</a>&nbsp;at both a masters, and a doctoral level, in several diverse areas. There are separate programs for technology, design, science, and liberal arts. The&nbsp;<a href="https://iith.ac.in/academics/post-graduate/">MTech program</a>&nbsp;is offered in various modes and durations to cater to the ever-growing need of postgraduate level professionals in the country.

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IITH creates a unique holistic ecosystem for education that offers interactive learning, a very flexible academic structure, cutting-edge research, strong industry collaboration, and entrepreneurship. This is an environment which enables students and faculty to translate their dreams into realities.

IIT Hyderabad

O3-type NaNi0.5Mn0.3Co0.2O2 based positive electrode materials are very promising for sodium-ion batteries. However, the irreversible phase transition due to structural deformation leads to sluggish kinetics, rapid capacity fade, and low C-rate performance, limiting its wide practical applications. The partial substitution of Co3+ (0.545 Å) by Al3+ (0.535 Å) ions in the transition-metal layer in NaNi0.5Mn0.3Co0.2-xAlxO2 (0.01 ≤ x ≤ 0.02) is an effective strategy to address the issue of structural deformation and thus to improve the electrochemical performance of NaNi0.5Mn0.3Co0.2O2 cathode. Solution combustion synthesis of NaNi0.5Mn0.3Co0.2-xAlxO2 (x = 0.01, 0.02) shows O3-type structure of NaNi0.5Mn0.3Co0.2−xAlxO2 material with the space group of R3¯m. The composition with an overall x = 0.02 Al doping delivers an initial 120 mAh g−1 capacity at a 0.1 C rate. It retains 90 % capacity even after 200 cycles than the other stoichiometric aluminum substitution, x = 0.01 (77 %). Moreover, the NaNi0.5Mn0.3Co0.18Al0.02O2 shows a good capacity of ~ 83 mAh g−1 even at a high C-rate of 5 C, almost 70 % of the initial capacity at the 0.1 C rate. The Al-substitute NaNi0.5Mn0.3Co0.2−xAlxO2 cathode's electrochemical performance is attributed to the enhancement in the structural stability of the sodium layered transition metal oxide after the partial substitution of Co3+ by Al3+ ion. Finally, the practical sodium-ion full cells are realized using a hard carbon-based anode and NaNi0.5Mn0.3Co0.18Al0.02O2 cathode, showing 91 % capacity retention at the end of 100th cycles with an OCV of 3.5 V. © 2022 Elsevier B.V.

World University root node

Journal of Alloys and Compounds

Enhanced electrochemical performance of O3-type NaNi0.5Mn0.3Co0.2O2 cathodes for sodium-ion batteries via Al-doping

Pentadentate electron rich MePBITA ligand in [RuII(MePBITA)(NO)]n+ (n = 3, 2 and MePBITA = 1-(6-(1-methyl-1H-benzo[d]imidazol-2-yl)pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine) permits the isolation of both the redox states of nitrosyls with Enemark–Feltham notation {RuNO}6 and {RuNO}7. The nitrosyl derivative [RuII(MePBITA)(NO)](ClO4)3: [4](ClO4)3 was synthesized by stepwise synthetic manner from the chloro precursor [RuII(MePBITA)(Cl)](PF6): [1](PF6), via the acetonitrile derivative [RuII(MePBITA)(CH3CN)](PF6)2: [2](PF6)2 followed by nitro complex [RuII(MePBITA)(NO2)](PF6): [3](PF6). All the complexes were fully characterized by different analytical and spectroscopic techniques. Single crystal X-ray structures of the complexes [1](PF6), [2](PF6)2, [3](PF6), and [4](ClO4)3 were profitably determined for understanding the molecular integrity. Ru−NO stretching frequency observed at 1931 cm−1 for [4](ClO4)3 suggests a moderately electrophilic character of NO. The huge shift in νNO frequency, Δν (solid) = 325 cm−1 was observed by reducing [4](ClO4)3 to [4](ClO4)2. The conversion of [3]+ from [4]3+ was examined both electrochemically and spectrophotometrically with the addition of 0.5 M NaOH solution. Rate constants of the first order photorelease (kNO) have been found to be 8.99 × 10−3 min−1; half-life (t1/2) = 77 min and 3.84 × 10−2 min−1; half-life (t1/2) = 18 min for [4]3+ and [4]2+, respectively with visible Xenon light (200 W) source. The photo liberated NO has been scavenged by biologically relevant target protein reduced myoglobin as Mb−NO adduct. Photoactivation of [4]3+ and [4]2+ by visible light induces significant cytotoxicity in prostate cancer cell lines; VCaP (IC50 29.74 and 4.42 µM) and 22Rv1 (IC50 29.96 and 6.88 µM), and lung cancer cell line; A549 (IC50 2.24 and 0.12 µM). Collectively our results pave the way for the development of metallodrugs as potential therapeutics for a variety of cancers. Additionally, our results also demonstrate how ligand modification could enhance the photolability of metal nitrosyl, adding a new dimension for future efficient photoactive metal nitrosyl design. © 2022 Elsevier B.V.

Department of Biotechnology

Journal of Molecular Structure

Photolability of NO in ruthenium nitrosyls with pentadentate ligand induces exceptional cytotoxicity towards VCaP, 22Rv1 and A549 cancer cells under therapeutic condition

As a low-price and luxuriant C1 sustainable resource, CO2 has the privilege of synthesizing hydrogen carriers and valuable chemicals. However, expensive metallic and organic catalysts are often indispensable for going on wheels of the relevant reaction processes. In this work, a protophilic solvent-impelled quasi-catalytic system was developed for efficient synthesis of formic acid and various N-formamides with high yields of 76–94% via reductive CO2 functionalization under mild reaction conditions (50 °C). Direct activation of the liquid hydrosilane toward the reduction of CO2 enabled by DMSO with optimum basicity/protophilicity is the predominant reaction route among the examined interaction models, while carbonic acid potentially derived from excessive CO2 and residual water inhibits the reaction, as explicitly disclosed by theoretical calculations and isotope labeling experiments. In addition, the in situ formed O-formyl species is conductive to the cascade CO2 reduction steps, which remarkably facilitated the overall quasi-catalytic upgrading process. © 2022 Elsevier Ltd

Fuel

Protophilic solvent-impelled quasi-catalytic CO2 valorization to formic acid and N-formamides

Herein, we report a novel and unexpected metal-free oxygenation of 2,3-diphenyl-1-indenones, under an oxygen atmosphere (air), to either 2,3-epoxy-2,3-diphenyl-1-indenone or 2-hydroxy-2,3-diphenyl-1-indanone, depending on the conditions. Several bioactive epoxy indenones and one-pot α-hydroxy indanones (α-acyloin) were synthesized from 2,3-diaryl dihydroindanone and 2,3-diarylindenone, respectively. A plausible reaction mechanism is also proposed, where oxygenation would take place at the α-position and further proton abstraction from the β-position leads to epoxy indenone derivatives. A one-pot cis-hydroxy indanone protocol is also achieved directly from biaryl indenone via reduction, epimerization, and oxygenation. The synthesized compounds were evaluated for inhibitory activity against the DNA repair protein AlkB. Among the screened (17 tested) compounds, one epoxide derivative was found to be a specific inhibitor of AlkB enzyme function. © 2022 The Royal Society of Chemistry.

Organic and Biomolecular Chemistry

Solvent controlled synthesis of 2,3-diarylepoxy indenones and α-hydroxy diarylindanones and their evaluation as inhibitors of DNA alkylation repair

We present here an efficient method for the hydroboration of organic nitriles, carboxylic esters, and carboxamides with pinacolborane (HBpin) using an alkali metal catalyst, neosilyllithium (LiCH2SiMe3), in neat reaction conditions. The reactions were accomplished with efficient catalytic reactivity and demonstrated by neosilyllithium at room temperature, in solvent-free condition, to afford a high yield of the corresponding N-boryl amines, boryl ethers, and amine hydrochlorides. The protocol for the catalytic reaction presented in this paper is simple and efficient, with diverse substrate scope for nitriles, carboxylic esters, and carboxamides showing excellent functional group tolerance. DLPNO-CCSD(T) calculations were also performed, showing that the hydroboration of nitriles catalyzed by neosilyllithium occurs through the pre-coordination of the nitrile at Lewis acid lithium followed by hydride migration from the B–H entity. © 2022 Elsevier Ltd

Polyhedron

Hydroboration of nitriles, esters, and amides catalyzed by simple neosilyllithium

Cooperative supramolecular polymerization is important for the synthesis of functional supramolecular homo and block-copolymers of π-systems. Current strategies indicate the need of strong hydrogen bonding (H-bonding) and/or dipolar interactions in the π-systems to achieve cooperativity. In sharp contrast, here we report the cooperative supramolecular polymerization in alkyl chain substituted perylene diimides (alkyl PDIs) driven by dispersive interactions with molecular level understanding. Moreover, alkyl PDIs follow cooperative mechanism with cooperativity similar to the strong H-bonded π-systems (σ ∼10−5) despite the lack of strong H-bonding and dipolar interactions. Computer simulations show that this surprising phenomenon in alkyl PDIs is driven by the efficient dispersive interactions among the alkyl chains and π-cores due to their zigzag arrangement in the supramolecular polymer. Importantly, alkyl PDIs display cooperative supramolecular polymerization in both polar and non-polar solvents which is difficult for H-bonded/dipolar π-systems thus highlighting the advantages of dispersive interactions. © 2022 Wiley-VCH GmbH.

Chemistry - An Asian Journal

Cooperative Supramolecular Polymerization Guided by Dispersive Interactions

We investigate ion-probe interactions within the molecular liquid, examine dynamics, and interpret the vibrational spectral dynamics of the mixtures of ionic liquid, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIm][NTf2] with the probes of varying alkyl chain length – HOD, methanol-d4, ethanol-d6. Structural analysis depicts pronounced interactions of the oxygen atom of HOD with the corresponding anionic oxygen site rather than the hydrogen atom located at the two-position of the imidazolium ring. Our computed frequency distribution for each of the probes in IL exhibits similarity with the experimental linear FT-IR spectrum. We further performed the orientational anisotropy calculations; the ion reorientation plays a significant role in determining the transport properties in ILs. The results of rotational anisotropy of the O-D bond vector reflect the hydrogen bond length-scale fluctuations and collective reorientation associated with the complete structural reorganization of the probe modes. Our findings in this study agree well with the earlier experimental and simulation studies. © 2022 Elsevier B.V.

Chemical Physics

Vibrational spectral dynamics and ion-probe interactions of the hydrogen-bonded liquids in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

The quantitative analysis of trace water in organic solvents remains a hotspot in current research because of the importance in both industrial and laboratory scale chemistry. This study introduced a fluorescence chemosensor (L3) for the detection of trace water in dimethyl sulfoxide (DMSO). Addition of water into the DMSO solution of L3 resulted a significant fluorescence enhancement at 533 nm with a detection limit of 0.002 wt%. The fluorescence turn-on response is occurred due to the formation of aggregates of L3. Also, other possible mechanism for trace water detection by L3 in DMSO is attributed to the specific water-L3 interaction and partially to the increase in polarity of the solvent caused by an increase in water concentration. Dynamic light scattering (DLS), 1H NMR, scanning electron microscope (SEM), transmission electron microscope (TEM) and quantum mechanical studies were performed to support the water sensing by L3 in DMSO. © 2021

Fluorescent sensing of water in DMSO by 2,4-dinitrophenyl hydrazine derived Schiff base

Black phosphorus (BP) is unique among 2D materials due to its anisotropic puckered structure. It has been used as a multifunctional catalyst for various purposes. In this study, we performed first principles molecular dynamics simulations to understand the water-splitting reaction on a bi-layer BP surface. We focused on the site-specific aqueous reactivity of the buckled surface. A difference in the axis-dependent reactivity is observed owing to edge defects and exposed sites. Thus, we believe that BP edges, which significantly affect the interfacial water or organic solvent molecules, must exhibit very different edge-dependent reactivity. Experiments suggested the increasing catalytic efficiency of undisturbed BP in the order bulk, few-layered BP, and BP quantum dots. We choose three active sites to investigate the mechanistic details of the OER: the zigzag (ZZ), armchair (AC), and bulk sites. This study will provide insight into the enhanced catalytic activity when more edges are exposed as the active surface. We hope to clarify the reactive pathway in an aqueous solution supported by bi-layer BP by exploring the two different mechanisms for forming the OOH∗ complex. We explore and report two mechanisms: a simple push-pull reaction for oxygen-oxygen bond formation, the nucleophilic attack by formed OH- and an attack by a water molecule. The free energy barriers procured for mechanism 1 taking place at the zigzag, armchair, and bulk sites are 7.59 ± 0.33, 9.04 ± 0.01, and 12.80 ± 0.09 kcal mol-1, respectively. For mechanism 2 the free energy barriers are 7.62 ± 0.11, 9.15 ± 0.16, and 11.63 ± 0.11 kcal mol-1 for the ZZ, AC, and bulk sites. The interlink between both the mechanisms is established concerning the reported free energy barriers for OOH∗ formation. The ZZ site is found to lower the activation barrier for the rate-determining step, followed by the AC and bulk. © 2022 the Owner Societies.

Physical Chemistry Chemical Physics

Site dependent catalytic water dissociation on an anisotropic buckled black phosphorus surface

In this study, we explore the water oxidation process with the help of density functional theory. The formation of an oxygen-oxygen bond is crucial in the water oxidation process. Here, we report the formation of the oxygen-oxygen bond by the N5-coordinate oxoiron species with a higher oxidation state of FeIV and FeV. This bond formation is studied through the nucleophilic addition of water molecules and the transfer of the oxygen atom from meta-chloroperbenzoic acid (mCPBA). Our study reveals that the oxygen-oxygen bond formation by reacting mCPBA with FeV = O requires less activation barrier (13.7 kcal mol−1) than the other three pathways. This bond formation by the oxygen atom transfer (OAT) pathway is more favorable than that achieved by the hydrogen atom transfer (HAT) pathway. In both cases, the oxygen-oxygen bond formation occurs by interacting the σ*dz2-2pz molecular orbital of the iron-oxo intermediate with the 2px orbital of the oxygen atom. From this study, we understand that the oxygen-oxygen bond formation by FeIV O with the OAT process is also feasible (16 kcal mol−1), suggesting that FeV O may not always be required for the water oxidation process by non-heme N5-oxoiron. After the oxygen-oxygen bond formation, the release of the dioxygen molecule occurs with the addition of the water molecule. The release of dioxygen requires a barrier of 7.0 kcal mol−1. The oxygen-oxygen bond formation is found to be the rate-determining step. © 2022 The Royal Society of Chemistry.