Philosophy

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

World University root node

Analytical Chemistry (Skill Enhancement Course)

Abstract: In the present work, a simple and cost-effective precipitation approach was carried out to fabricate CuO nano-needle and its electrochemical performance was evaluated in a redox-mediated electrolyte (2 M KOH and 0.3 M K3Fe(CN)6). A high specific capacitance of 2519 F/g was recorded at a specific current of 8 A/g. However, the electrode suffered from poor rate capability as the specific capacitance was rapidly decreased to 100 and 1 F/g when the specific current was increased to 30 and 50 A/g, respectively. The CuO nanoparticles were further modified with MnO2 by a hydrothermal method and the resulting CuO–MnO2 (CMO6) electrode delivered a high specific capacitance of 539 F/g even at very high specific current of 50 A/g. The as-synthesized electrode materials were structurally and morphologically characterized using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performances of the CuO and MnO2–CuO composites have been examined in detail. Graphic abstract: Synopsis Modification of pristine CuO nano-needles with MnO2 nanosheets improved the electrochemical performance of the material. The composite was able to deliver a high specific capacitance of 539 F/g even at very high specific current of 50 A/g.[Figure not available: see fulltext.].

Fulltext

Journal of Materials Science

A high-performance pseudocapacitive electrode based on CuO–MnO2 composite in redox-mediated electrolyte

In the present work, a discrete dinuclear cadmium(II) complex Cd2($\mu$−H2L)($\mu$−OH)Cl2⋅H2O (1) and a dinuclear zinc(II) based 1D chain complex ({Zn2(L')(O2CCH3)}ClO4⋅3H2O)n (2) (where H3L = 2,6-bis{2-(2-hydroxyethylamino)ethylimino}methyl-4-methylphenol and H2L′ = bis-oxazoline (BOX) ligand), have been synthesized and characterized by single-crystal X-ray crystallography. The Cd2+ ions in the first case showed straight cut incorporation of metal ions within the ligand pockets. In case of zinc(II), the coordination induced oxazolidine ring formation resulted in macrocyclic ligand formation having two adjacent coordination pockets. In complex 2, the acetate ion acts as an O,O linker and joins the Zn2 nodes bound within the newly formed macrocyclic ligand bearing bis-oxazolidine rings to form 1D polymeric chain at the end. The H3L was next screened for its efficacy as selective fluorescence sensor for Mg2+ ions in aqueous MeOH medium. Steady state absorption and emission behaviour of H3L, 1 and 2 have been investigated. Time resolved fluorescence properties of H3L and the complexes 1 and 2 have been examined and their lifetimes have been determined in 0.038–0.257 ns range. The cell viability in presence of H3L makes it a suitable candidate for application in live cell imaging studies.

Polyhedron

Exploration of varying coordination reactivity of Schiff base H3L toward CdII, ZnII and MgII: Hydroxido-bridged dimer, acetato-directed chain and live cell-imaging

IOP Conference Series: Materials Science and Engineering

Sunlight mediated photocatalytic reduction of aqueous Cr(Vl) using metal hexacyanoferrate (M = Mn, Ni, Cu and Zn)

ACS Applied Bio Materials

Smart Metal–Organic Frameworks for Biotechnological Applications: A Mini-Review

A systematic one-step one-pot multicomponent reaction of Co(ClO4)2{\textperiodcentered}6H2O, H3L (2,6-bis((2-(2-hydroxyethylamino)ethylimino)methyl)-4-methylphenol) and readily available carboxylate salts (RCO2Na; R = CH3, C2H5) resulted in the two structurally novel coordination aggregates [CoIICoIII4L2($\mu$1,3-O2CCH3)2($\mu$-OH)2](ClO4)4{\textperiodcentered}4H2O (1) and [CoIICoIII4L2($\mu$1,3-O2CC2H5)2($\mu$-OH)($\mu$-OMe)](ClO4)4{\textperiodcentered}5H2O (2). At room temperature, reactions of H3L in MeOH with cobalt(II) perchlorate salts led to coassembly of initially formed ligand-bound {CoII2} fragments following aerial oxidation of metal centers and bridging by in situ generated hydroxido/alkoxido groups and added carboxylate anions. Available alkoxido arms of the initially formed {L($\mu$1,3-O2CCH3)($\mu$-OH/OMe)Co2}+ fragments were utilized to trap a central CoII ion during the formation of [Co5] aggregates. In the solid state, both complexes have been characterized by X-ray crystallography, variable-temperature magnetic measurements and theoretical studies. Both 1 and 2 show field-induced slow magnetic relaxation that arises from the single pseudo-Td CoII ion present. The structural distortion leads to an easy-axis magnetic anisotropy (D = -31.31 cm-1 for 1 and -21.88 cm-1 for 2) and a small but non-negligible transverse component (E/D = 0.11 for 1 and 0.08 for 2). The theoretical studies also reveal how the O-Co-O bond angles and the interplanar angles control D and E values in 1 and 2. The presence of two diamagnetic {Co2($\mu$-L)} hosts controls the distortion of the central {CoO4} unit, highlighting a strategy to control single-ion magnetic anisotropy by trapping single ions within a diamagnetic coordination environment.

Inorganic Chemistry

Trapping of a Pseudotetrahedral CoIIO4 Core in Mixed-Valence Mixed-Geometry [Co5] Coordination Aggregates: Synthetic Marvel, Structures and Magnetism

IIT, Kharagpur

Studies on Multinuclear Coordination Aggregates of 3d Metal Ions Maintained by Phenolate Ligands

Two flexible, branched and sterically constrained di- and tripodal side arms around a phenol backbone were utilized in ligands H3L1 and H5L2 to isolate {Mn6} and {Mn3} coordination aggregates. 2,6-Bis{(1-hydroxy-2-methylpropan-2-ylimino)methyl}-4-methylphenol (H3L1) gave trinuclear complex [Mn3($\mu$-H2L1)2($\mu$1,3-O2CCH3)4(CH3OH)2](ClO4)2{\textperiodcentered}4CH3OH (1), whereas 2,6-bis[{1-hydroxy-2-(hydroxymethyl)butan-2-ylimino}methyl]-4-methylphenol (H5L2) provided hexanuclear complex [Mn6($\mu$4-H2L2)2($\mu$-HL3)2($\mu$3-OH)2($\mu$1,3-O2CC2H5)4](ClO4)2{\textperiodcentered}2H2O (2). Binding of acetates and coordination of {H2L1}- provided a linear MnIIIMnIIMnIII arrangement in 1. A MnIII6 fused diadamantane-type assembly was obtained in 2 from propionate bridges, coordination of {H2L2}3- and in situ generated {HL3}2-. The magnetic characterization of 1 and 2 revealed the properties dominated by intramolecular anti-ferromagnetic exchange interactions and this was confirmed using density functional theory calculations. Complex 1 exhibited field-induced slow magnetic relaxation at 2 K due to the axial anisotropy of MnIII centers. Both the complexes show effective solvent-dependent catechol oxidation toward 3,5-di-tert-butylcatechol in air. The catechol oxidation abilities are comparable from two complexes of different nuclearity and structure.

Dangling and Hydrolyzed Ligand Arms in [Mn3] and [Mn6] Coordination Assemblies: Synthesis, Characterization and Functional Activity

We demonstrate a straightforward process for the synthesis and fabrication of a hybrid-type asymmetric supercapacitor (ASC) by combining Mn3O4 nanoparticle-supported multi-wall carbon nanotube (Mn3O4@MWCNT) composite as positive and reduced graphene oxide (rGO) as negative electrodes. A controlled hydrothermal synthesis of Mn3O4 in the presence of MWCNT resulted in a well-distributed Mn3O4 nanoparticles on the MWCNT backbone in the Mn3O4@MWCNT composite. The structure and morphology of the as-prepared materials have been investigated by x-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller analysis and x-ray photoelectron spectroscopy measurements. The electrochemical characterizations were carried out in terms of cyclic voltammetry, galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy analysis. The constructed ASC with 1 M KOH-supporting electrolyte was able to provide high-specificity capacitance of 173.36 F/g at 2 mV/s scan rate and high-energy density of 26.8 Wh/kg accompanied by high cycle stability with 79.3% capacitance retention over 3000 GCD cycles.

Journal of Electronic Materials

A Novel Asymmetric Supercapacitor Designed with Mn3O4@Multi-wall Carbon Nanotube Nanocomposite and Reduced Graphene Oxide Electrodes

Four different carboxylato bridges have been efficiently utilized for growth of three tetranuclear nickel(II) complexes [Ni4($\mu$3-H2L)2($\mu$3-OH)2($\mu$1,3-CH3CO2)2](ClO4)2 (1), [Ni4($\mu$3-H2L)2($\mu$3-OH)2($\mu$1,3-C2H5CO2)2](ClO4)2{\textperiodcentered}1/2H2O (2) and [Ni4($\mu$3-H2L)2($\mu$3-OH)2($\mu$1,3-O2C-C6H4-pNO2)2](ClO4)(p-NO2-C6H4-CO2){\textperiodcentered}DMF{\textperiodcentered}5H2O (3) and one dinuclear nickel(II)-based chain complex {[Ni2($\mu$-H2L)($\mu$1,3-O2CCH2Ph)2(H2O)](ClO4){\textperiodcentered}1/2(CH3OH)}n (4). These were obtained via the reaction of Ni(ClO4)2{\textperiodcentered}6H2O with H3L [2,6-bis((2-(2-hydroxyethylamino)ethylimino)methyl)-4-methylphenol] and RCO2Na (R = CH3,C2H5, p-NO2C6H4 and PhCH2). This family of complexes is developed from {Ni2($\mu$-H2L)}3+ fragments following self-aggregation. The complexes were characterized by X-ray crystallography and magnetic measurements. The changes from acetate, propionate and p-nitrobenzoate to phenylacetate groups resulted in two different types of coordination aggregation. These compounds are new examples of [Ni4] and [Ni2]n complexes where organization of the building motifs are guided by the type of the carboxylate groups responsible for in-situ generation and utilization of HO- bridges with alteration in the aggregation process within the same ligand environment. Studies on the magnetic behavior of the compounds reveal that the exchange coupling within 1-4 is predominantly antiferromagnetic in nature.