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.

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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

Pure and Nd3+-doped tin oxide (SnO2) nanoparticles have been prepared by the sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM, energydispersive spectroscopy and UV-visible spectroscopy. The XRD patterns of all the samples are identified as tetragonal rutile-type SnO2 phase which is further confirmed by TEM analysis. Neodymium doping introduces band gap narrowing in the prepared samples and enhances their absorption towards the visible-light region. The photocatalytic activity of all the samples was evaluated by monitoring the degradation of methylene blue solution under day light illumination and it was found that the photocatalytic activity significantly increases for the samples calcined at 600 than 400 °C, which is due to the effective charge separation of photogenerated electron-hole pairs. The efficiency of photocatalysts was found to be related to neodymium doping percentage and calcination temperature. © 2016 Indian Academy of Sciences.

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Fulltext

Bulletin of Materials Science

Band gap narrowing and photocatalytic studies of Nd3+ ion-doped SnO2 nanoparticles using solar energy

Intermolecular dissociation energies D0(S0) of the supersonic jet-cooled complexes of 1-naphthol (1NpOH) with cyclopentane, cyclohexane, and cycloheptane were determined to within &lt;0.5% using the stimulated-emission pumping resonant two-photon ionization method. The ground state D0(S0) values are bracketed as 20.23±0.07 kJ/mol for 1NpOH⋅cyclopentane, 20.34±0.04 kJ/mol for 1NpOH⋅cyclohexane, and 22.07±0.10 kJ/mol for two isomers of 1NpOH⋅cycloheptane. Upon S0→S1 excitation of the 1-naphthol chromophore, the dissociation energies of the 1NpOH⋅cycloalkane complexes increase from 0.1% to 3%. Three dispersion-corrected density functional theory (DFT) methods predict that the cycloalkane moieties are dispersively bound to the naphthol face via London-type interactions, similar to the “face” isomer of the 1-naphthol⋅cyclopropane complex [S. Maity et al., J. Chem. Phys. 145, 164304 (2016)]. The experimental and calculated D0(S0) values of the cyclohexane and cyclopentane complexes are practically identical, although the polarizability of cyclohexane is ∼20% larger than that of cyclopentane. Investigation of the calculated pairwise atomic contributions to the D2 dispersion energy reveals that this is due to subtle details of the binding geometries of the cycloalkanes relative to the 1-naphthol ring. The B97-D3 DFT method predicts dissociation energies within about ±1% of experiment, including the cyclopropane face complex. The B3LYP-D3 and ωB97X-D calculated dissociation energies are 7-9 and 13-20% higher than the experimental D0(S0) values. Without dispersion correction, all the complexes are calculated to be unbound. © 2016 Author(s).

Journal of Chemical Physics

Intermolecular dissociation energies of dispersively bound 1-naphthol⋅cycloalkane complexes

Trifluoroacetic acid promoted unprecedented domino reaction for the synthesis of diverse indanes starting from simple cinnamic acid esters is described. Their formation can be explained via acid triggered decarboxylation of cinnamic acid esters and subsequent inter/intramolecular cyclization. Overall process involves in the intramolecular cleavage of two σ-bonds (C-O and C-C) and inter/intramolecular construction of two/one C-C σ-bond(s). Significantly, this protocol was successful without the aid of any metal salts. © 2016 American Chemical Society.

Journal of Organic Chemistry

Metal-Free Domino One-Pot Decarboxylative Cyclization of Cinnamic Acid Esters: Synthesis of Functionalized Indanes

New 4,4’-bis(N-vinyl-imidazole-selone)-1,1’-biphenyl was derived from 4,4’-bis(N-vinyl-imidazolium chloride)-1,1’-biphenyl or 4,4’-bis(N-vinyl-imidazolium tetrafluoroborate)-1,1’-biphenyl or 4,4’-bis(N-vinyl-imidazolium hexafluorophosphate)-1,1’-biphenyl in good yield. Subsequently, the bis{4,4’-bis(N-vinyl-imidazole-selenide)-1,1’-biphenyl} tetra tetrafluoroborate was isolated from 4,4’-bis(N-vinyl-imidazole-selone)-1,1’-biphenyl using copper(II) tetrafluoroborate hexahydrate as an oxidizing agent. These new compounds were characterized by elemental analysis, FT-IR, multinuclear NMR and UV-vis studies. In addition, 4,4’-bis(N-vinyl-imidazolium chloride)-1,1’-biphenyl, 4,4’-bis(N-vinyl-imidazolium tetrafluoroborate)-1,1’-biphenyl and [bis{4,4’-bis(N-vinyl-imidazole-selenide)-1,1’-biphenyl} tetra tetrafluoroborate] were characterized by single crystal X-ray diffraction technique. The tetra cationic selenide salt represents the first structurally characterized 32 membered diselenide containing macrocyclic ring. The charge of tetra cationic selenide salt is balanced by four BF4 - ions. The macrocyclic ring is in chair configuration. In solid packing, tetra cationic selenide salt shows an extensive C−H⋅⋅⋅F hydrogen bonding interactions between C-H and BF4 - moieties. Besides, the thermal stability of diselenide containing macrocyclic ring was compared with bis imidazole selone. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

ChemistrySelect

Facile Access to Diselenide Containing Macrocyclic Ring from Diselone

Recent trends in research have gained an orientation toward developing efficient strategies using innocuous reagents. The earlier reported transition-metal-catalyzed carbonylations involved either toxic carbon monoxide (CO) gas as carbonylating agent or functional-group-assisted ortho sp2 C-H activation (i.e., ortho acylation) or carbonylation by activation of the carbonyl group (i.e., via the formation of enamines). Contradicting these methods, here we describe an environmentally benign process, [Pd]-catalyzed direct carbonylation starting from simple and commercially available iodo arenes and aldehydes, for the synthesis of a wide variety of ketones. Moreover, this method comprises direct coupling of iodoarenes with aldehydes without activation of the carbonyl and also without directing group assistance. Significantly, the strategy was successfully applied to the synthesis n-butylphthalide and pitofenone. © 2016 American Chemical Society.

Palladium-Catalyzed Environmentally Benign Acylation

This work reports hydrodeoxygenation of dibenzofuran into bicyclic hydrocarbons over Cu-Ni catalysts supported on TiO2, ZrO2 and CeO2. The supported Cu-Ni catalysts were synthesized using a wet-impregnation method and calcined and reduced at 500 °C in accordance with TGA, DSC, and H2-TPR results. The catalyst properties were systematically examined using Raman, XRD, SEM, EDX and XPS techniques. XRD and Raman studies reveal the existence of cubic phase CeO2, monoclinic ZrO2, anatase TiO2, and cubic NiO in the synthesized catalysts. H2-TPR results show the simultaneous reduction of Cu2+ to Cu0 and Ni2+ to Ni0, forming bimetallic Cu-Ni alloy. Among the supports, a high dispersion of Cu-Ni particles was found on the CeO2 support, as evidenced by SEM studies. The reduced catalysts were investigated for hydrodeoxygenation of dibenzofuran at 250, 260 and 270 °C at 100 H2 bar for 6 h. The results show that the conversion of dibenzofuran increases with the increase of temperature: at 250 and 260 °C CuNi/TiO2 catalyst showed higher dibenzofuran conversions of 96% and 99% than the NiCu/CeO2 catalyst with relatively low conversions of 89% and 98%, respectively. In contrast, low conversions of 63% and 68% were found for the CuNi/ZrO2 catalyst under identical reaction conditions. In the case of selectivity to hydrocarbons, NiCu/TiO2 catalyst showed excellent selectivity to bicyclohexyl compared with that of NiCu/CeO2 and NiCu/ZrO2 catalysts at 260 °C. However, in terms of selectivity to bicyclohexyl-1-ene, NiCu/CeO2 catalyst showed the highest selectivity at 250 °C, while NiCu/ZrO2 catalyst exhibited the highest selectivity at 260 and 270 °C. © 2016 Elsevier Ltd. All rights reserved.

Fuel

Hydrodeoxygenation of dibenzofuran to bicyclic hydrocarbons using bimetallic Cu-Ni catalysts supported on metal oxides

Abstract: This work demonstrates that MoOx/CeO2–ZrO2 solid acid acts as a promising catalyst in the solvent-free oxidative-coupling of benzylamine into dibenzylimine with O2 as the oxidant. The benzylamine conversions were found to be ~27, 51, 74, and 99 % for CeO2, CeO2–ZrO2, MoOx/CeO2, and MoOx/CeO2–ZrO2 catalysts, respectively. The MoOx/CeO2–ZrO2 catalyst also efficiently converts various substituted- and secondary-benzylamines under solvent-free conditions with O2 resulting in moderate to excellent yields. Remarkably, a high selectivity of ~99.6–99.9 % towards the dibenzylimine product was found for all reaction conditions. The outstanding performance of MoOx/CeO2–ZrO2 catalyst was attributed to high specific surface area, improved structural defects, and superior acid properties. Graphical Abstract: [Figure not available: see fulltext.] The MoOx/CeO2–ZrO2 catalyst show an outstanding performance in the oxidation of benzylamine and its derivatives, which is attributed to abundant acidic sites, large number of oxygen vacancies, and superior BET surface area. © 2015, Springer Science+Business Media Dordrecht.

Research on Chemical Intermediates

Novel molybdenum–cerium based heterogeneous catalysts for efficient oxidative coupling of benzylamines under eco-friendly conditions

This work has been undertaken with the aim of designing promising noble-metal-free catalysts for efficient hydrodeoxygenation (HDO) of dibenzofuran (DBF) into fuel grade hydrocarbons. For this, various Ni/Al-SBA-15 catalysts with different Si/Al (50, 60, 70 and 80) mole ratios were synthesized and their catalytic performance was tested for HDO of DBF in a batch reactor. The catalysts were systematically characterized using XRD, N2-adsorption-desorption, Raman, H2-TPR, NH3-TPD, XRF, and FESEM techniques. The activity results showed that the HDO of DBF proceeds via hydrogenation of benzene on the Ni sites followed by cleavage of C-O bonds on the acidic sites of the catalyst to yield unsaturated hydrocarbons. Further hydrogenation of unsaturated hydrocarbons on the Ni sites gives bicyclohexane as the major product. Remarkably, a 100% DBF conversion was found for all the catalysts except for Ni/SBA-15 and Ni/Al-SBA-15(80) (Si/Al mole ratio = 80) catalysts, which showed 97.97 and 99.31%, respectively. A significant observation noticed in this study is that the incorporation of Al into Ni/SBA-15 results in an outstanding improvement in the selectivity of the bicyclohexane product. Among the catalysts tested, the Ni/Al-SBA-15(50) (Si/Al mole ratio = 50) catalyst showed the highest efficiency, with superior selectivity of ∼87% for bicyclohexane and ∼96% degree of deoxygenation at 10 MPa, 260 °C and 5 h. The obtained structure-activity results reveal the synergetic effect of Ni and support in HDO of DBF reaction: the concentration of acidic sites has a significant effect on the selectivity of the desired products. © 2016 The Royal Society of Chemistry.

RSC Advances

Promising Ni/Al-SBA-15 catalysts for hydrodeoxygenation of dibenzofuran into fuel grade hydrocarbons: Synergetic effect of Ni and Al-SBA-15 support

Sulfur composites were prepared with graphite nanoplatelets (GNPs) for the first time, wherein the GNPs served as a scaffold for tethering the nano-sulfur (nano-S) particles. Three protocols were employed: (i) an in situ route, wherein the GNPs (40 wt%) were introduced in the precursor solution of nano-S, (ii) by ex situ mixing of solid GNPs (40 wt%) with solid nano-S, and (iii) by using a combination of methods (i) and (ii). The sulfur particles are uniformly and contiguously attached to the ribbon like graphitic nanoplatelets in the nano-S/GNPs (ex situ 20 wt% + in situ 20 wt%) composite, whereas in the other two composites, the sulfur particles tend to agglomerate over different regions of the platelet fibers. A comparative study of the electrochemical performances of half-cells based on the three composites, nano-S and S revealed that the nano-S/GNPs (ex situ 20 wt% + in situ 20 wt%) composite retains 73% of its’ original capacity at the end of 100 cycles with a reversible capacity of 610 mA h gsulfur−1. The cell also showed an outstanding rate capability for the cell capacity reverted to nearly the same value, when the C-rate was ricocheted to 0.1 C after going through higher C-rates. The role of GNPs and the dependence of the method of embedding sulfur particles on GNPs demonstrate that GNPs have tremendous promise to unlock the potential of sulfur for producing cells with reproducible, stable and durable charge storage characteristics. © 2016 Elsevier B.V.

Department of Chemical Engineering

Chemical Engineering Journal

Durable Li-S batteries with nano-sulfur/graphite nanoplatelets composites

Lanthanide (Ln) fluorides are considered exceptional luminescent rigid host matrices for various optical active Ln3+ ions due to their high refractive index, high chemical stability and low phonon energy, leading to the low probability of non-radiative decay, which results in higher photoluminescence quantum yield (PLQY) (usually higher than oxide hosts). In this study, Eu3 +-activated Ln fluorides (LnF3:Eu3 +–Ln = La, Gd) are synthesized by the hydrothermal method using 1-butyl-3-methylimidazolium tertrafluoroborate [BMIBF4] and NH4F as fluorine precursors. The synthesized nanocrystals (NCs) are structurally and morphologically characterized, and their optical properties investigated using spectrofluorometry. The X-ray diffraction (XRD) patterns of Eu3 +-substituted and -unsubstituted LnF3 (prepared from a different fluorine source) are indexed based on the hexagonal and orthorhombic crystal structure, respectively. Average crystalline sizes are calculated using the Scherrer equation and it is found that the synthesized NCs have an average crystalline size of 12–35 nm. Transmission electron microscopy (TEM) images reveal that the NCs are well dispersed and nearly ellipsoid, with an average size of ~ 5 nm. Eu3 +-activated NCs show characteristic excitation and emission spectra. The emission spectra show both magnetic (5D0–7F1) and electric (5D0–7F2) dipole transition with appropriate CIE color coordinates; however, the intensity of the magnetic dipole transition is high, which is in accordance with local site symmetry. Owing to their unique size and excellent optical properties, the synthesized NCs may have potential application in the fields bio-imaging and solar concentrators. Copyright © 2016 John Wiley &amp; Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Luminescence

Europium-activated rare earth fluoride (LnF3:Eu3 +–Ln = La, Gd) nanocrystals prepared by using ionic liquid/NH4F as a fluorine source via hydrothermal synthesis