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Shiv Nadar University

(SoNS) School of Natural Sciences

The artemisinin resistance has posed a serious threat against malaria elimination lately. Past few years have seen important development of several peroxide based medicinal compounds and their derivatives such as trioxanes and tetraoxanes. Here, we report a rapid, one-pot method for synthesizing a new series of N-sulfonylpiperidine dispiro-1,2,4,5-tetraoxane analogs with diverse substitution on the tetraoxane ring i.e., various substituted alkyl and aryl sulfonyl chlorides, as well as cyclic, acyclic and aryl substituted ketones. All the synthesized tetraoxanes were characterized by spectroscopic (1H NMR,13C NMR), and spectrometric (High-resolution mass spectrometry) techniques and quantify by High Performance Liquid Chromatography (HPLC) analysis. The structure of compound 19 was confirmed by single crystal XRD. From the overall preliminary in vitro data, analogs 14, 16, 19, 20, 24, 41, and 44 exhibited potential IC50 values in the nanomolar range between 4.7 ± 0.3 to 12.9 ± 1.1 nM against P. falciparum (Pf3D7) strains of human malaria parasite. Furthermore, these selective analogs were evaluated in vivo for their antimalarial potential against P. berghei and results revealed that analogue 24 rapidly kills the infected cell at asexual erythrocytic stage, with activity comparable to positive control chloroquine. © 2022 Elsevier Masson SAS

World University root node

Life Sciences

European Journal of Medicinal Chemistry

N-sulfonylpiperidinedispiro-1,2,4,5-tetraoxanes exhibit potent in vitro antiplasmodial activity and in vivo efficacy in mice infected with P. berghei ANKA

Memristors are one of the fastest developing electronic devices in the field of data storage and brain inspired neural computing. As a two terminal device, memristors are numerously utilized as resistive random access memories (RRAM) and energy efficient artificial synapses. Herein, the fabrication of perovskite-type rubidium lead chloride quantum dots (RPCQDs) is reported as a functional layer in a memristive system. The device, Al/RPCQDs/indium doped tin oxide (ITO), exhibits a cycling-induced decrease in SET voltage, where Al and ITO work as a top and bottom electrode respectively. However, time dependent self-recovery to the pristine state is observed in the Al/RPCQDs/ITO device. In contrast, the self-rejuvenation is suppressed when a buffer capped conducting polymer (BCCP) is incorporated on the ITO layer to make a Al/RPCQDs/BCCP/ITO structure. This customized device structure successfully retains the reproducible bipolar switching behavior without severe deviation in operating voltages, which helps in studying reliable memristive properties. In addition, the Al/RPCQDs/BCCP/ITO memristive device also demonstrates some essential synaptic functions such as pair-pulse facilitation, long-term potentiation, and long-term depression. © 2022 Wiley-VCH GmbH.

Physics

Advanced Electronic Materials

Influence of Nanoscale Charge Trapping Layer on the Memory and Synaptic Characteristics of a Novel Rubidium Lead Chloride Quantum Dot Based Memristor

Nanostructures of layered 2D materials have been proven one of the significant recent trends for visible-light-driven photocatalysis because of their unique morphology, effective optical adsorption, and rich active sites. Herein, we synthesized ultrathin-layered MoS2 nanoflowers and nanosheets with rich active sites by using a facile hydrothermal technique. The photocatalytic performance of the as-synthesized MoS2 nanoflowers (NF) and nanosheets (NS) were investigated for the photodegradation of MB (methylene blue), MG (malachite Green), and RhB (rhodamine B) dye under visible light irradiations. Ultrathin-layered nanoflowers showed faster degradation (96% in 150 min) in RhB under visible light irradiation, probably due to a large number of active sites and high available surface area. The kinetic study demonstrated that the first-order kinetic model best explained the process of photodegradation. The MoS2 nanoflowers catalysts has similar catalytic performance after four consecutive cyclic performances, demonstrating their good stability. The results showed that the MoS2 nanoflowers have outstanding visible-light-driven photocatalytic activity and could be an effective catalyst for industrial wastewater treatment. © 2022 American Chemical Society. All rights reserved.

Langmuir

Edge Rich Ultrathin Layered MoS2Nanostructures for Superior Visible Light Photocatalytic Activity

MoS2 based materials are considered the most reliable alternative catalysts for the hydrogen evolution reaction (HER), where engineering of active sites has emerged as an acceptable approach to tune their HER activity. In this approach, the dispersion of bulk MoS2 in the aqueous phase was increased with a surfactant (sodium dodecyl sulfate), which reduced the exfoliation time and enhanced the exfoliation ability to produce layered MoS2 nanosheets. During the hydrothermal treatment, the nanosheets were further scissored into small nanocrystals. Nanocrystals have attractive properties with stable dispersion and high-water solubility. Our method provides a scalable, eco-friendly, easy, and low-cost strategy for designing other HER catalysts. Such ultra-small MoS2 nanocrystals with rich Mo vacancies were used as catalysts for HER, which showed excellent electrocatalytic activity with a low overpotential (95 mV) and small Tafel slope (41 mV/dec) in 0.5M H2SO4 electrolyte. The design and synthesis of the HER catalyst in this work presents a promising path for preparing active and stable electrocatalysts to replace costly metal-based catalysts for hydrogen production. © 2022 Author(s).

Fulltext

AIP Advances

A simple two-step strategy to synthesize defect-rich MoS2nanocrystals for enhanced electrochemical hydrogen evolution

Herein, two donor-acceptor conjugated polymers based on dithieno[3,2-b:2′,3′-d]thiophene (DTT) and thiophene-flanked diketopyrrolopyrrole (DPP) or furan-flanked DPP, namely PDPPT-DTT and PDPPF-DTT were synthesised, characterised and evaluated for their electrical performance in transistor devices for comparison. The influence of the heteroatoms (thiophene and furan) flanked DPP on their thermal, optical, electronic structure and charge carrier transport properties were investigated. The absorption spectra of polymer PDPPT-DTT are broader and red-shifted (26-30 nm) compared with that of polymer PDPPF-DTT, indicating the resonance energy of thiophene is greater than furan, which may allow for different electron localization and result in the difference of optical properties. In addition, energy levels of polymers were slightly affected by the aromatic remote end-groups (thiophene to furan) in DPP-based molecule. Hole transport properties of copolymers were investigated by fabricating the field-effect transistors in the bottom gate top contact (BGTC) configurations for three different self-assembled monolayers (SAMs)/gate dielectric interfaces and different annealing temperatures of polymeric active layer. The BGTC organic thin film transistor (OFET) devices having PDPPT-DTT and PDPPF-DTT thin film annealed at 200 °C exhibit the hole mobility of 0.18 and 0.20 cm2 V−1 s−1, respectively. The OFET devices with trichloro(octyl)silane SAM, fabricated and characterized in ambient environment (temperature ∼25 °C, humidity ∼50%), were found to retain 90% of their performance up to 1000 h. © 2022 IOP Publishing Ltd.

Flexible and Printed Electronics

Bottom gate top contact organic transistors using thiophene and furan flanked diketopyrrolopyrrole polymers and its comparative study

Sustainable polybenzoxazines sourced from renewable feedstock has emerged as an area of interest due to the inherent presence of a high number of reactive and additional functionalities. Plants are a rich source of flavan-3-ol viz., catechin (CAT) with four phenolic-OH and one aliphatic secondary-OH that can be a viable substitute to petro-phenols. In this current work, a biobased benzoxazine monomer, viz. CAT-fa, is synthesized using CAT and carbohydrate sourced furfurylamine (fa). Interestingly, an unexpected tris-oxazine (instead of tetra-oxazine) benzoxazine monomer is obtained. The unreacted phenolic-OH is involved in intramolecular H-bonding with the neighboring oxazine ring. Upon heat treatment, H-bonded hydroxyl groups become free and initiate ring-opening polymerization reaction at a low temperature of ≈125 °C exhibiting the latent catalyst effect. The ring-opening polymerization of the monomer and the thermal stability of polybenzoxazine are analyzed by differential scanning calorimetry, thermal gravimetric analysis, rheometry, and Fourier transform infrared spectroscopy. The polymerization reaction is proposed to proceed by the ring-opening reaction by cleavage at the oxygen of the pyran ring and O─CH2-N bond in oxazine ring to generate multiple polar functionalities to enable extensive H-bonding interactions. This work supports the potential of catechin as a green synthon to form sustainable polymers to employ H-bonding interactions and latent-catalytic potential. © 2022 Wiley-VCH GmbH.

Chemistry

Macromolecular Chemistry and Physics

Catechin and Furfurylamine Derived Biobased Benzoxazine with Latent-Catalyst Effect

We study the spectral properties of and spectral crossovers between different random matrix ensembles [Poissonian, Gaussian orthogonal ensemble (GOE), Gaussian unitary ensemble (GUE)] in correlated spin-chain systems, in the presence of random magnetic fields, and the scalar spin-chirality term, competing with the usual isotropic and time-reversal invariant Heisenberg term. We have investigated these crossovers in the context of the level-spacing distribution and the level-spacing ratio distribution. We use random matrix theory (RMT) analytical results to fit the observed Poissonian-to-GOE and GOE-to-GUE crossovers, and examine the relationship between the RMT crossover parameter λ and scaled physical parameters of the spin-chain systems in terms of a scaling exponent. We find that the crossover behavior exhibits universality, in the sense that, it becomes independent of lattice size in the large Hamiltonian matrix dimension limit. Moreover, the scaling exponent obtained from such a finite size scaling analysis, seems to be quite robust and independent of the type of crossover considered or the specific spectral correlation measure used. © 2022 American Physical Society.

Physical Review B

Spectral crossovers and universality in quantum spin chains coupled to random fields

CePdAl is a prototypical frustrated Kondo lattice with partial long-range order (LRO) at TN=2.7 K. Previous bulk experiments under hydrostatic pressure found signatures for a quantum critical regime that extends from pc≈0.9 GPa, where LRO disappears, up to ∼1.7 GPa. We employed extensive muon spin relaxation and rotation experiments under pressure. The continuous and complete suppression of LRO at pc is confirmed. Above TN(p) and beyond pc, an additional crossover scale T∗(p) characterizes the change from pure to stretched exponential relaxation in zero field. Remarkably, T∗(p) agrees with previously determined signatures of entropy accumulation above LRO. This coincidence microscopically evidences fluctuating frustrated spins at T≤T∗ with spin-liquid behavior. Power-law divergences of the temperature and longitudinal field dependences of the relaxation rate, with time-field scaling, at pressures between pc and 1.7 GPa characterize this regime as quantum critical. © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by the Max Planck Society.

Spin-liquid signatures in the quantum critical regime of pressurized CePdAl

A new series of (co)polycarbonates bearing pendent azido groups was synthesized by polycondensation of varying molar proportions of 4, 4’-(5-azidopentane-2, 2-diyl) diphenol and bisphenol-A with triphosgene. The chemical structures, compositions and random nature of (co)polycarbonates were confirmed by NMR spectroscopy. Inherent viscosities and number-average molecular weights of (co)polycarbonates were in the range 0.63–0.77 dL g−1 and 35,400–43,400 g mol−1, respectively indicating the formation of reasonably high molecular weight polymers. (Co)polycarbonates could be cast into tough, transparent and flexible films from chloroform solutions. (Co)polycarbonates were further characterized using IR spectroscopy, XRD, TGA and DSC. The thermal crosslinking of (co)polycarbonates bearing pendant azido groups was studied by DSC analysis. Independently, (co)polycarbonates bearing pendant azido groups were exposed to UV irradiation at wavelength of 254 nm and decomposition reaction of azido groups was monitored by FT-IR spectroscopy. The complete decomposition of azido groups was observed with exposure time of 30 min. The formed cross-linked (co)polycarbonates exhibited improved % char yield values compared to parent (co)polycarbonates. The measurement of mechanical properties of representative crosslinked (co)polycarbonates indicated increase in tensile strength and Young's modulus and decrease in % elongation compared to corresponding parent linear (co)polycarbonates. © 2022 Wiley-VCH GmbH.

ChemistrySelect

Synthesis, Characterization and UV-Crosslinking of Aromatic (Co)polycarbonates Bearing Pendant Azido Groups

This article presents the effects of an imidazolium-based ionic liquid (IL) on the thermodynamics and in-plane viscoelastic properties of model membranes of anionic phospholipids. The negative Zeta potential of multilamellar vesicles of 14 carbon lipid 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DMPG) is observed to reduce due to the presence of few mole % of an IL 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). The effect was found to be stronger on enhancing the chain length of the lipid. The surface pressure–area isotherms of lipid monolayer formed at air–water interface are modified by the IL reducing the effective area per molecule. Further, the equilibrium elasticity of the film is altered depending upon the thermodynamic phase of the lipids. While the presence of the IL in the DMPG lipid makes it ordered in the gel phase by reducing the entropy, the effect is opposite in the fluid phase. The in-plane viscoelastic parameters of the lipid film is quantified by dilation rheology using the oscillatory barriers of a Langmuir trough. Even though the low chain lipid DMPG does not show any effect of IL on its storage and loss moduli, the longer chain lipids exhibit a prominent effect in the liquid extended (LE) phase. Further, the dynamic response of the lipid film is found to be distinctly different in the liquid condensed (LC) phase from that of the LE phase. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.