Valence bond calculations of vicinal proton coupling constants in cyclopropane

Vicinal proton couplings in cyclopropane have been calculated using Dirac-Van Vleck and variational methods in valence bond formalism. The couplings may be considered as taking place along a path comprising either three or four intervening bonds. Inclusion of all exchange integrals in the appropriate fragment models leads to a satisfactory ratio of J_cis/J_trans . In this respect valence bond results appear to be superior to those obtained using a molecular orbital approach. The present valence bond results on couplings in cyclopropane are not affected by the choice of models for bonding in cyclopropane, namely the Coulson-Moffitt model or the Walsh model.     

Effect of Grinding on the Low Temperature Photoluminescence of Certain Molecular Crystals

The wavelengths of the vibronic peaks of the low temperature photoluminescence of anthracene, phenanthrene, benzophenone and phthalic acid crystals do not change considerably, but their relative intensity changes significantly with grinding. The dislocations may change both the absorption coefficient and absorption spectra of the crystals, hence the photoluminescence emission may be affected by the grinding.     

Base Catalysed Condensation of Acetone with Uracil Derivatives: One Step Synthesis of Pyranopyrimidines

Condensation of uracil derivatives (1,3,4) with acetone in the presence of triethylamine gave pyranopyrimidines (2,5,6).     

Synthesis and characterization of stable nitrenium ion complex: 1-hydroxy-3-methyl benzotriazolium trifluromethane sulfonate

The isolation of stable carbenes of the Arduengo and Wanzlick type has prompted us to look for stable nitrenium ions of the related structural type 1-Hydroxy-3-methyl benzotriazolium trifluromethane sulfonate. Nitrenium ions are azocations with structure and survive long enough under in vitro conditions to bind with biological nucleophiles, i.e. DNA bases, and play an important role in carcinogenic processes involving the metabolism of aromatic amines. The title compound (C₁₅H₁₆F₃N₆O₅S) was isolated and crystallized in the monoclinic space group Cc with cell parameters a = 19.866(1) Å, b = 13.128(9) Å, c = 7.673(5) Å, and Z = 4. The structure has both intra- and intermolecular hydrogen bonds.     

Electrochemical detection of nitrate,nitrite and ammonium for on-site water quality monitoring

This review examines the most recent electrochemical developments for nitrate, nitrite and ammonium detection for on-site water monitoring. There remains a high demand for effective field-based detection of the dissolved inorganic nitrogen (DIN) analytes to aid in mitigating nitrogen loading. Electrochemical approaches show increasing potential to fill this role as advancements in nanotechnology continually improve analytical performance and on-site applicability. However, translating these improvements into the field still faces the resonating challenges of reaching analytical proficiency (selectivity, sensitivity, robustness, stability), practical end-user functionality, minimal matrix interferences and cost effectiveness. Herein, we elaborate on these challenges via a critical evaluation of current studies and examine how realistic the prospects of on-site nitrate, nitrite and ammonium are. We also present recommendations in addressing these gaps to conclude the review.     

Two-Dimensional Layered Metallic VSe2/SWCNTs/rGO Based Ternary Hybrid Materials for High Performance Energy Storage Applications

In this work, the ternary hybrid structure VSe₂/SWCNTs/rGO is reported for supercapacitor applications. The ternary composite exhibits a high specific capacitance of 450 F g⁻¹ in a symmetric cell configuration, with maximum energy density of 131.4 Wh kg⁻¹ and power density of 27.49 kW kg⁻¹. The ternary hybrid also shows a cyclic stability of 91 % after 5000 cycles. Extensive density functional theory (DFT) simulations on the structure as well as on the electronic properties of the binary hybrid structure VSe₂/SWCNTs and the ternary hybrid structure VSe₂/SWCNTs/rGO have been carried out. Due to a synergic effect, there are enhanced density of states near the Fermi level and higher quantum capacitance for the hybrid ternary structure compared to VSe₂/SWCNTs, leading to higher energy and power density for VSe₂/SWCNTs/rGO, supporting our experimental observation. Computed diffusion energy barrier of electrolyte ions (K⁺) predicts that ions move faster in the ternary structure, providing higher charge storage performance.     

Chemical Composition of Essential Oil from Pilea microphylla and its Antimicrobial Activity

Chemistry of Natural Compounds -     

Ru(II)‐based antineoplastic: A “wingtip” N‐heterocyclic carbene facilitates access to a new class of organometallics that are cytotoxic to common cancer cell lines

The syntheses, structures, and chemotherapeutic activities of Ag(I)‐, Au(I)‐, and Ru(II)‐complexes ligated to a novel N‐heterocyclic carbene ligand, 2‐(4‐nitrophenyl)imidazo[1,5‐a]pyridin‐2‐ylidene ( 1 ), are described. The corresponding complexes, [Ag( 1 )₂][PF₆], [Au( 1 )₂][PF₆] ( 3 ), and [Ru( 1 )(p‐cymene)Cl][PF₆] ( 4 ), were prepared using convenient transmetallation chemistry and characterized using a range of spectroscopic and analytical techniques. X‐ray crystallography revealed that complexes 2 and 3 adopted linear structures whereas 4 exhibited a prototypical “piano‐stool”‐like geometry; the structural assignments were further supported by DFT calculations. A series of in vitro studies revealed that while the aforementioned Ag(I), Au(I) and Ru(II) complexes exhibited significant cytotoxicities against the human colon adenocarcinoma (HCT 116), lung cancer (A549), and breast cancer (MCF7) cell lines, the Ru derivative was most prominent.     

All- optical phase encoded 4-to-1 phase multiplexer using four wave mixing in semiconductor optical amplifier

Optics has already showed its potency over its electronic complements in case of superfast computing and communication systems. Semiconductor optical amplifier, (SOA) with its several nonlinear properties, plays a very crucial role in the development of high-speed all-optical processor. Multiplexer and demultiplexer are the extremely important element of the processor which takes part in utilizing different actions like encoding, decoding, routing, and the different process of data conversion and generation, etc. In this paper, the authors have proposed a scheme of phase encoded all-optical phase multiplexer using four wave mixing (FWM) property of semiconductor optical amplifier. Thus, the improved tolerance against fiber-nonlinearity and higher receiver sensitivity of phase encoding method with the fast occurring processes like FWM in SOA offers higher speed in this proposed scheme of multiplexing.