Synthesis and Antibacterial Activity of N,N-Diethylamide Bearing Benzenesulfonamide Derivatives

Sulfonamides are known to represent a class of medicinally important compounds which are extensively used as antibacterial agents. Hence, a series of new N,N-diethyl amide bearing sulfonamides (2a-k) were synthesized via amidation of easily prepared benzenesulfonamide precursors (1a-k). The chemical structures of all synthesized compounds were substantiated using spectroscopic means such as IR, Mass spectra and 1H-NMR as well as analytical data. The antimicrobial activity of these compounds along with streptomycin, was investigated on Escherichia coli and Staphylococcus aureus. The results showed that this skeletal framework exhibited marked potency as antibacterial agents. The most active antibacterial agent against both targeted organisms was N,Ndiethyl-1-(phenylsulfonyl) piperidine-2-carboxamide (2b)

Room Temperature Synthesis and Antibacterial Activity of New Sulfonamides Containing N,N -Diethyl-Substituted AmidoMoieties

Sulfonamide drugs which have brought about an antibiotic revolution in medicine are associated with a wide range of biological activities. We have synthesized a series of α-tolylsulfonamide, 1–11 and their substituted N,N-diethyl-2-(phenylmethylsulfonamido) alkanamide derivatives, 12–22 in improved and excellent yields in aqueous medium at room temperature through highly economical synthetic routes. The chemical structures of the synthesized compounds 1–22 were confirmed by analytical and spectral data such as IR, 1H- and 13C-NMR, andmass spectra. The in vitro antibacterial activity of these compounds along with standard clinical reference, streptomycin, was investigated on two key targeted organisms. It was observed that 1-(benzylsulfonyl) pyrrolidine-2-carboxylic acid, 2 emerged as the most active compound against Staphylococcus aureus at MIC value of 1.8 μg/mL while 4-(3-(diethylamino)-3-oxo-2-(phenylmethyl sulfonamido) propyl)phenyl phenylmethanesulfonate, 22 was the most active sulfonamide scaffold on Escherichia coli at MIC value of 12.5 μg/mL

Emergent charge density wave featuring quasi-one-dimensional chains in Ta-intercalated bilayer 2HH-TaS2_{2} with coexisting superconductivity

Recently, intercalation emerges as an effective way to manipulate ground-state properties and enrich quantum phase diagrams of layered transition metal dichalcogenides (TMDCs). In this work, we focus on fully Ta-intercalated bilayer 2$H$-TaS$_{2}$ with a stoichiometry of Ta$_{3}$S$_{4}$, which has recently been experimentally synthesized. Based on first-principles calculations, we computationally show the suppression of an intrinsic $3\times3$ charge-density wave (CDW) in the TaS$_{2}$ layer, and the emergence of a $2\times1$ CDW in intercalated Ta layer. The formation of the CDW in Ta$_{3}$S$_{4}$ is triggered by strong electron-phonon coupling (EPC) between the $d$-like orbitals of intercalated Ta atoms via the imaginary phonon modes at M point. A 2$\times$1 CDW structure is identified, featuring quasi-one-dimensional Ta chains, attributable to the competition between the CDW displacements associated with potential CDW vectors ($\boldsymbol{q}_{\text{CDW}}$s). Superconductivity is found to coexist with the 2$\times$1 CDW in Ta$_{3}$S$_{4}$, with an estimated superconducting transition temperature ($T_{\mathrm{c}}$) of 3.0 K, slightly higher than that of bilayer TaS$_{2}$. The Ta$_{3}$S$_{4}$ structures of non-CDW, 2$\times$1 CDW, and $2\times$2 CDW can be switched by strain. Our work enriches the phase diagram of TaS$_{2}$, offers a candidate material for studying the interplay between CDW and superconductivity, and highlights intercalation as an effective way to tune the physical properties of layered materials.Comment: 7 pages, 5 figures. Published as a Letter in PR

Distinct fingerprints of charge density waves and electronic standing waves in ZrTe3_3

Experimental signatures of charge density waves (CDW) in high-temperature superconductors have evoked much recent interest, yet an alternative interpretation has been theoretically raised based on electronic standing waves resulting from quasiparticles scattering off impurities or defects, also known as Friedel oscillations (FO). Indeed the two phenomena are similar and related, posing a challenge to their experimental differentiation. Here we report a resonant X-ray diffraction study of ZrTe$_3$, a model CDW material. Near the CDW transition, we observe two independent diffraction signatures that arise concomitantly, only to become clearly separated in momentum while developing very different correlation lengths in the well-ordered state. Anomalously slow dynamics of mesoscopic ordered nanoregions are further found near the transition temperature, in spite of the expected strong thermal fluctuations. These observations reveal that a spatially-modulated CDW phase emerges out of a uniform electronic fluid via a process that is promoted by self-amplifying FO, and identify a viable experimental route to distinguish CDW and FO.Comment: 6 pages, 4 figures; supplementary information available upon reques

Ising Superconductivity and Quantum Phase Transition in Macro-Size Monolayer NbSe2

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have a range of unique physics properties and could be used in the development of electronics, photonics, spintronics and quantum computing devices. The mechanical exfoliation technique of micro-size TMD flakes has attracted particular interest due to its simplicity and cost effectiveness. However, for most applications, large area and high quality films are preferred. Furthermore, when the thickness of crystalline films is down to the 2D limit (monolayer), exotic properties can be expected due to the quantum confinement and symmetry breaking. In this paper, we have successfully prepared macro-size atomically flat monolayer NbSe2 films on bilayer graphene terminated surface of 6H-SiC(0001) substrates by molecular beam epitaxy (MBE) method. The films exhibit an onset superconducting critical transition temperature above 6 K, 2 times higher than that of mechanical exfoliated NbSe2 flakes. Simultaneously, the transport measurements at high magnetic fields reveal that the parallel characteristic field Bc// is at least 4.5 times higher than the paramagnetic limiting field, consistent with Zeeman-protected Ising superconductivity mechanism. Besides, by ultralow temperature electrical transport measurements, the monolayer NbSe2 film shows the signature of quantum Griffiths singularity when approaching the zero-temperature quantum critical point