English Language and Literature

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

A new Ni(ii) complex [NiL] (complex1) of an asymmetrically di-condensed N2O3donor Schiff base ligand,N-salicylidene-N′-3-methoxysalicylidene-1,3-propanediamine (H2L), has been synthesized and utilized for the synthesis of three heterometallic complexes, [(NiL)2Mn(NCS)2(CH3OH)2]·CH3OH (2) [(NiL)2Mn(N(CN)2)2(CH3OH)2]·CH3OH (3) and [(NiL)2Mn2(N3)2(μ1,1-N3)2(CH3OH)2] (4). Single crystal X-ray diffraction analyses show that complexes2and3have linear trinuclear structures where two tridentate O3donor (NiL) units are coordinated to the central octahedral Mn(ii) centre, whereas complex4has a centrosymmetric tetranuclear structure where two binuclear (NiL)Mn units are linkedviatwo phenoxido and two μ1,1-N3bridges. Among the heterometallic complexes (2-4), only4is active towards the catalytic oxidation of 3,5-di-tert-butylcatechol to the corresponding quinone. The turnover number for the aerobic oxidation of 3,5-DTBC is 935 h−1. ESI-mass spectra have been recorded to scrutinize the mechanistic pathway of this catalytic reaction. Variable temperature magnetic susceptibility measurements suggest that complexes2-4are antiferromagnetically coupled with coupling constants (J) of −4.84 and −5.23 cm−1for complexes2and3, respectively andJ1= −2.20 cm−1,J2= 1.13 cm−1andJ3= −1.12 cm−1for complex4. DFT calculations have been used to rationalize the magnetic super-exchange in complexes2-4, by computing the theoretical coupling constants and analyzing the spin density plots. © The Royal Society of Chemistry 2021.

World University root node

Chemistry

Dalton Transactions

Synthesis of Ni(ii)-Mn(ii) complexes using a new mononuclear Ni(ii) complex of an unsymmetrical N2O3donor ligand: structures, magnetic properties and catalytic oxidase activity

Organic fluorescent semiconducting nanomaterials have gained widespread research interest owing to their potential applications in the arena of high-tech devices. We designed two pyrazaacene-based compounds, their stacked system, and the role of gluing interactions to fabricate nanomaterials, and determined the prospective band gaps utilizing the density functional theory calculation. The two pyrazaacene derivatives containing complementary amide linkages (-CONH and -NHCO) were efficiently synthesized. The synthesized compounds are highly soluble in common organic solvents as well as highly fluorescent and photostable. The heterocycles and their mixture displayed efficient solvent dependent fluorescence in the visible region of the solar spectrum. Notably, the compounds were associated through complementary NH•••O = C type hydrogen bonding, π-π stacking, and hydrophobic interactions, and thereby afforded nanomaterials with a low band gap. Fascinatingly, the fabricated stacked nanomaterial system exhibited resistive switching behavior, leading to the fabrication of an efficient write-once-read-many-times memory device of crossbar structure. © 2020 IOP Publishing Ltd.

Electronic Science

Nanotechnology

Complementary amide-based donor-acceptor with unique nano-scale aggregation, fluorescence, and band gap-lowering properties: A WORM memory device

The strategic design and synthesis of two isomeric CuII complexes, [CuLA] and [CuLB], of asymmetrically dicondensed N2O3-donor Schiff-base ligands (where H2LA and H2LB are N-salicylidene-N′-3-methoxysalicylidenepropane-1,2-diamine and N-3-methoxysalicylidene-N′-salicylidenepropane-1,2-diamine, respectively) have been accomplished via a convenient CuII template method. These two complexes have been used as metalloligands for the synthesis of three pairs of Cu-Ln isomeric complexes [CuL(μ-NO3)Ln(NO3)2(H2O)]·CH3CN (for complexes 1A-3A, L = LA, and for complexes 1B-3B, L = LB and Ln = Gd, Tb, and Dy, respectively), all of which have been characterized structurally. In all six isomorphous and isostructural complexes, the decacoordinated LnIII centers and pentacoordinated CuII centers possess sphenocorona and square-pyramidal geometries, respectively. The isomeric pair of Cu-Gd compounds shows field-induced slow relaxation of magnetization, although they present the typical isotropic behavior of GdIII complexes, indicating that slow relaxation is not due to the usual energy barrier originating from the magnetic anisotropy. The isostructural derivatives with the ion-anisotropic lanthanides TbIII and DyIII do not show slow magnetic relaxation with or without a direct-current bias field, demonstrating that the magnetic response of the isotropic system CuII-GdIII occurs through different mechanisms than the rest of the Ln cations. © 2020 American Chemical Society.

Inorganic Chemistry

Family of Isomeric CuII-LnIII(Ln = Gd, Tb, and Dy) Complexes Presenting Field-Induced Slow Relaxation of Magnetization only for the Members Containing GdIII

N-Heterocyclic carbene-catalyzed tandem Stetter-aldol reaction of phthalaldehyde and α,β-unsaturated ketimines has been developed to afford functionalized naphthalen-1(2H)-one derivatives as the formal [4+2] annulation product. Interestingly, the reaction of aldimines led to the formation of isoquinoline derivatives instead of the expected indanone derivatives as a [4+1] annulation product. ©

Organic Letters

NHC-Mediated Stetter-Aldol and Imino-Stetter-Aldol Domino Cyclization to Naphthalen-1(2 H)-ones and Isoquinolines

Discovery of new smart luminescent nanomaterials from small organic molecules possessing multiple useful properties is advantageous yet challenging. Self-assembling peptide-based molecules, which contained halogen-substituted (Cl, Br, and I) bithiophene chromophores, were developed to achieve organic luminescent nanomaterials. The dipeptide-based bithiophenes were fabricated to unidirectional nanofibers, and their novel applications were explored. The peptide analogues formed efficient luminescent organogelation, which displayed aggregation-induced emission. Further, the building blocks, 3,5′-dihalo-2,2′-bithiophene-5-carboxaldehydes, formed luminescent nanomaterials with aggregation-induced emission properties. Notably, the luminescence properties of the building blocks were exploited to sense the lethal cyanide ion, organic solvent, and moisture. The insight about the noncovalent interactions through NMR, solid-state X-ray crystallography, and Hirshfeld surface analyses revealed the existence of the halogen bonding of type C-I···O for 3,5′-diiodo-2,2′-bithiophene-5-carboxaldehyde for the self-aggregation process. Copyright © 2020 American Chemical Society.

ACS Applied Nano Materials

Halogen-Bonded Bithiophene-Based Nanofibers for Luminescent Sensing

Two mononuclear uranyl complexes, [UO2L1] (1) and [UO2L2]⋅0.5 CH3CN⋅0.25 CH3OH (2), have been synthesized from two multidentate N3O4 donor ligands, N,N′-bis(5-methoxysalicylidene)diethylenetriamine (H2L1) and N,N′-bis(3-methoxysalicylidene)diethylenetriamine (H2L2), respectively, and have been structurally characterized. Both complexes 1 and 2 showed a reversible UVI/UV couple at −1.571 and −1.519 V, respectively, in cyclic voltammetry. The reduction potential of the UVI/UV couple shifted towards more positive potential on addition of Li+, Na+, K+, and Ag+ metal ions to acetonitrile solutions of complex 2, and the resulting potential was correlated with the Lewis acidity of the metal ions and was also justified by theoretical DFT calculations. No such shift in reduction potential was observed for complex 1. All four bimetallic products, [UO2L2Li0.5](ClO4)0.5 (3), [UO2L2Na(ClO4)]2 (4), [UO2L2Ag(NO3)(H2O)] (5), and [(UO2L2)2K(H2O)2]PF6 (6), formed on addition of the Li+, Na+, Ag+, and K+ metal ions, respectively, to acetonitrile solutions of complex 2, were isolated in the solid state and structurally characterized by single-crystal X-ray diffraction. In all the species, the inner N3O2 donor set of the ligand encompasses the equatorial plane of the uranyl ion and the outer open compartment with O2O′2 donor sites hosts the second metal ion. © 2019 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim

Chemistry - A European Journal

The Effect of Guest Metal Ions on the Reduction Potentials of Uranium(VI) Complexes: Experimental and Theoretical Investigations

A Cu(ii) complex [CuL] of an asymmetrically di-condensed N2O2 donor Schiff base ligand, N-α-methylsalicylidene-N′-salicylidene-1,3-propanediamine (H2L) has been employed towards the synthesis of four heterometallic complexes, [(CuL)2Zn(N(CN)2)2] (1) [(CuL)2Cd(N(CN)2)2] (2), [(CuL)2Zn(SCN)2]·CH3CN (3) and [(CuL)2Cd(SCN)(H2O)]·ClO4 (4). All four complexes are found to be discrete bent trinuclear where two [CuL] units are coordinated to the central metal ion (Zn/Cd) via phenoxido oxygen atoms. In addition to two double phenoxido bridges, two monodentate dicyanamide ions in 1 and 2, two N-bonded thiocyanate in 3 and one S-bonded thiocyanate and one water molecule in 4 complete the hexa-coordination around the central metal ions. Recurrent π(arene)⋯π(chelate ring) stacked motifs were detected in the solid state of all complexes that have been studied by means of DFT calculations, rationalized using molecular electrostatic potential (MEP) surface calculations and characterized using the noncovalent interaction plot (NCIplot). The data presented herein show that the π(arene)⋯π(chelate ring) stacking interactions in complexes 1-4 are strong and relevant for determining their crystal packing. © 2020 The Royal Society of Chemistry.

CrystEngComm

Recurrent π(arene)⋯π(chelate ring) motifs in four trinuclear CuII2MII(M = Cd/Zn) complexes derived from an unsymmetrical N2O2donor ligand: Structural and theoretical investigations

Two new Cd(ii) complexes, [Cd4L2(NO3)2(μ1,1-N3)2(CH3OH)2] (1) and {[Cd2L(IPA)]2·(CH3OH)}n (2), have been synthesized by using a multidentate Schiff base ligand H2L (N,N′-bis(3-methoxysalicylidene)-diethylenetriamine) and two bridging co-ligands azide and isophthalic acid (IPA), respectively. Single crystal structure analysis shows that complex 1 has a tetranuclear structure whereas complex 2 forms a 1D polymer. The photoswitching behavior of both complexes has been measured under 1 Sun illumination. A significant enhancement of frequency ∼65 Hz was observed for complex 2, but for complex 1 no such enhancement was detected. To gain a detailed understanding about the charge transport mechanism of the complexes, the effective carrier mobility, transit time, carrier concentration and diffusion length have been estimated considering Schottky Barrier Diode (SBD) characteristics. The charge transport properties of complex 2 were found to be superior to complex 1. Complex 2 showed increased conductivity from 5.4 × 10-8 S cm-1 to 135 × 10-8 S cm-1 in the presence of light. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

New Journal of Chemistry

Tetra- And poly-nuclear Cd(ii) complexes of an N3O4Schiff base ligand: Crystal structures, electrical conductivity and photoswitching properties

All optical multiband radio transceiver is designed using Polarization Modulators. Polarization Modulators have been gaining popularity in recent times as the device is free from bias drift problem that is commonly noticed in Mach Zhender intensity modulator. Two continuous wave (CW) optical frequencies separated by 26.25 GHz are selected from optical frequency comb generator designed using two parallel polarization modulators. Two subcarrier multiplexed (SCM) signal is modulated on a comb frequency using a polarization modulator. The SCM modulated optical signal and another CW optical comb separated by 26.25 GHz are fed to a remote radio access unit (RAU) via a single mode fibre. The two signals are heterodyned in a photo detector at a remote RAU producing multi radios at 27.25 GHz and 28.75 GHz in 5G New Radio frequency band of n258 (24.25–27.5 GHz) and n257 (26.5–29.5 GHz). In the receiver part of the transceiver, the received 5G signals are modulated by a Polarization Modulator with a CW optical comb frequency and the resultant optical sidebands along with the carrier are fed to the baseband unit (BBU) at the central office via a return fiber. At the BBU the signals are heterodyned in a photo-detector with a CW comb frequency to produce the down converted baseband output at the BBU. The proposed transceiver scheme is analysed and simulation is carried out inOptisystem16® platform. BER performance of the received signal with various laser powers show that the scheme is practically implementable. In particular BER of 10−6 is obtained at the photodetector output in the transmitted (downlink) signal and returned link (uplink) signal at 2.25 dBm laser power. Two tone IMD analysis of the transmitted signal provides input and output third order intercept point at 52 dBm and 32 dBm respectively. Spurious free dynamic range (SFDR) between fundamental and 3rd order intermodulation distortion product obtained is 85 dB.Hz2/3 considering a noise floor of − 140 dBc/Hz. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

Radio Physics and Electronics

Optical and Quantum Electronics

Design and analysis of all optical RF transceiver using polarization modulators

Adsorption of organic pollutants, toxic metal ions, and removal of harmful bacteria can give us clean and pure drinkable water from wastewater resources. Respective magnetite nanoparticles (MNPs) were synthesized using a cheaper and greener way in an open-air environment with the use of crude latex of Jatropha curcas (JC) and leaf extract of Cinnamomum tamala (CT). Characterization of MNPs had been performed by dynamic light scattering (DLS), Ultraviolet-visible (UV-vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, powdered X-ray diffraction (XRD), and field emission scanning electron microscope (FE-SEM). The size ranges of the synthesized MNPs were observed in between 20–42 nm for JC-Fe3 O4 and within 26–35 nm for CT-Fe3 O4 by FE-SEM images. The effect of synthesized magnetic nanoparticles in wastewater treatment (bacterial portion), dye adsorption, toxic metal removal as well as antibacterial, antioxidant, and cytotoxic activities were studied. This purification will lead to an increase in the resources of pure drinking water in the future. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.