Synthesis,characterization, and biological screening of metal complexes of novel sulfonamide derivatives: Experimental and theoretical analysis of sulfonamide crystal

This study reports the synthesis of sulfonamide-derived Schiff bases as ligands L ¹ and L ² as well as their transition metal complexes [VO(IV), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II)]. The Schiff bases (4-{E-[(2-hydroxy-3-methoxyphenyl)methylidene]amino}benzene-1-sulfonamide ( L ¹ ) and 4-{[(2-hydroxy-3-methoxyphenyl)methylidene]amino}-N-(5-methyl-1,2-oxazol-3-yl)benzene-1-sulfonamide ( L ² ) were synthesized by the condensation reaction of 4-aminobenzene-1-sulfonamide and 4-amino-N-(3-methyl-2,3-dihydro-1,2-oxazol-5-yl)benzene-1-sulfonamide with 2-hydroxy-3-methoxybenzaldehyde in an equimolar ratio. Sulfonamide core ligands behaved as bidentate ligands and coordinated with transition metals via nitrogen of azomethine and the oxygen of the hydroxyl group. Ligand L ¹ was recovered in its crystalline form and was analyzed by single-crystal X-ray diffraction technique which held monoclinic crystal system with space group (P2₁/c). The structures of the ligands L ¹ and L ² and their transition metal complexes were established by their physical (melting point, color, yields, solubility, magnetic susceptibility, and conductance measurements), spectral (UV–visible [UV–Vis], Fourier transform infrared spectroscopy, ¹H NMR, ¹³C NMR, and mass analysis), and analytical (CHN analysis) techniques. Furthermore, computational analysis (vibrational bands, frontier molecular orbitals (FMOs), and natural bonding orbitals [NBOs]) were performed for ligands through density functional theory utilizing B3LYP/6-311+G(d,p) level and UV–Vis analysis was carried out by time-dependent density functional theory. Theoretical spectroscopic data were in line with the experimental spectroscopic data. NBO analysis confirmed the extraordinary stability of the ligands in their conjugative interactions. Global reactivity parameters computed from the FMO energies indicated the ligands were bioactive by nature. These procedures ensured the charge transfer phenomenon for the ligands and reasonable relevance was established with experimental results. The synthesized compounds were screened for antimicrobial activities against bacterial (Streptococcus aureus, Bacillus subtilis, Eshcheria coli, and Klebsiella pneomoniae) species and fungal (Aspergillus niger and Aspergillus flavous) strains. A further assay was designed for screening of their antioxidant activities (2,2-diphenyl-1-picrylhydrazine radical scavenging activity, total phenolic contents, and total iron reducing power) and enzyme inhibition properties (amylase, protease, acetylcholinesterase, and butyrylcholinesterase). The substantial results of these activities proved the ligands and their transition metal complexes to be bioactive in their nature.     

Exceptionally Plastic/Elastic Organic Crystals of a Naphthalidenimine-Boron Complex Show Flexible Optical Waveguide Properties

The design of molecular compounds that exhibit flexibility is an emerging area of research. Although a fair amount of success has been achieved in the design of plastic or elastic crystals, realizing multidimensional plastic and elastic bending remains challenging. We report herein a naphthalidenimine–boron complex that showed size-dependent dual mechanical bending behavior whereas its parent Schiff base was brittle. Detailed crystallographic and spectroscopic analysis revealed the importance of boron in imparting the interesting mechanical properties. Furthermore, the luminescence of the molecule was turned-on subsequent to boron complexation, thereby allowing it to be explored for multimode optical waveguide applications. Our in-depth study of the size-dependent plastic and elastic bending of the crystals thus provides important insights in molecular engineering and could act as a platform for the development of future smart flexible materials for optoelectronic applications.     

Microstructure and magnetic characterization of the Sm-CoMn co-substituted SrCaM hexagonal ferrites

A series of Sm-CoMn substituted hexagonal ferrites with chemical composition of Sr_0.85-xCa_0.15Sm_xFe_12-y(Co_0.5Mn_0.5)_yO₁₉ (0.00?≤?x?≤?0.60, (0.00?≤?y?≤?0.50) were synthesized by the solid-state reaction method. Microstructure and magnetic properties of the hexaferrites have been investigated by the X-ray diffraction, field emission scanning electron microscopy and a permanent magnetic measuring system. A single magnetoplumbite phase is exhibited in the hexaferrites with the substitutiom of Sm (0.00?≤?x?≤?0.12) and CoMn (0.00?≤?y?≤?0.10) contents. For the hexaferrites containing Sm (x?≥?0.24) and CoMn (y?≥?0.20), impurity phases are observed in the structure. The FESEM micrographs exhibit that the hexaferrites with different Sm-CoMn contents have formed hexagonal structures and the grain size of the hexaferrites remains unchanged with increasing Sm-CoMn content. The remanence (B_r), H_k/H_cj ratios, and maximum energy product [(BH)_max] decrease with increasing Sm-CoMn content (0.00?≤?x?≤?0.60, (0.00?≤?y?≤?0.50). Instrinsic coercivity (H_cj) and magnetic induction coercivity (H_cb) increase with increasing Sm-CoMn content (0.00?≤?x?≤?0.12, 0.00?≤?y?≤?0.10), and then decrease with increasing Sm-CoMn content (0.12?≤?x?≤?0.36, 0.10?≤?y?≤?0.30), while for the hexaferrites with Sm (x?≥?0.36) and CoMn (y?≥?0.30), with increasing Sm-CoMn content, H_cj increases and H_cb decreases.     

Preparation of highly efficient Al-doped ZnO photocatalyst by combustion synthesis

Novel Al-doped ZnO (AZO) photocatalysts with different Al concentrations (0.5–6.0 mol%) were prepared through a facile combustion method and followed by calcination at 500 °C for 3 h. The obtained nanopowders were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) combined with EDX, transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy and photoluminescence spectroscopy. The XRD patterns of AZO nanopowders were assigned to wurtzite structure of ZnO with the smallest crystallite size about 11 nm consistent with the results from TEM. The doping of Al in ZnO crystal structure successfully suppressed the growth of ZnO nanoparticles confirmed by XRD patterns. The absorption spectra analysis showed that the optical band gap energy (E_g) for the AZO nanopowders were in the range of 3.12–3.21 eV and decreased with increasing of Al dopant. The photocatalytic activities of the samples were evaluated by photocatalytic degradation of methyl orange under visible light (λ ≥ 420 nm) and sunlight irradiation. The results showed that the AZO photocatalyst doped with 4.0 mol% Al exhibited five times enhanced photocatalytic activity compared to pure ZnO. The enhanced photocatalytic activity could be attributed to extended visible light absorption, inhibition of the electron–hole pair's recombination and enhanced adsorptivity of MO dye molecule on the surface of AZO nanopowders.     

Dynamics of Random One-Dimensional ±J Systems

Finite chains of a two-state random Potts spin model with periodic boundary conditions are studied within Glauber dynamics. The spin exchange is assumed random with frustration between ferro and antiferromagnetic values (±J). Time-dependent fluctuations are induced by periodic temperature oscillations. Master type differential equations for spin correlation functions are solved within linear response theory. The spectrum of relaxation times are calculated at different temperatures. The ±J Potts glass chains undergo a zero temperature phase transition. The barriers against inversion of the spin chain take only two values; 0 and 2|J|. The temperature behaviour of specific heat is characterized by rounded peaks. The frequency dependence displays two plateaus for the real part of specific heat and two corresponding peaks for the imaginary part. The dynamic specific heat is not affected by the longest relaxing mode like susceptibility. The time separation of the modes is demonstrated by the Cole-Cole plots.     

Parametric Study of Nonplanar Dust Acoustic Solitons in Two‐Dimensional Superthermal Dusty Plasmas

The nonlinear properties of two dimensional low‐frequency electrostatic excitations of charged dust particles (or defects) are studied in a collisionless, unmagnetized dusty plasma. A fully ionized three‐component model plasma consisting of kappa distributed electrons, Maxwellian ions, and negatively charged massive dust grains is considered. In this regard, the well known reductive perturbation technique is used to the hydrodynamical equations and the Poisson equation, obtaining the cylindrical Kadomtsev–Petviashvili (CKP) equation. A parametric investigation indicates that the structural characteristics of these nonlinear excitations (width, amplitude) are significantly affected by the plasma nonthermality as well as by the relevant plasma parameters, such as dust concentration and dust temperature. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Appraisal of radioactivity and associated radiation hazards in sand samples of four rivers of Punjab province, Pakistan

Natural and anthropogenic radioactivity of sand and water samples collected from the four big rivers of Punjab province, Pakistan, was measured using a high-purity germanium detector coupled with a high resolution multichannel analyser. The average concentration of the naturally occurring radionuclides (226)Ra, (232)Th and (40)K in all the sand samples from the rivers Jhelum, Chenab, Ravi and Indus was found to be 22±0.6, 36±1 and 287±10 Bq kg (-1), respectively, while the concentration of the anthropogenic radionuclide (137)Cs was found to be below the minimum detectable activity, i.e. ~1.2 Bq?kg (-1). All the sand samples have Ra(eq) concentrations lower than the limit of 370 Bq kg (-1). Indoor (H (in)) and outdoor (H (out)) radiation hazard indices were calculated for the samples to assess the radiation hazards arising due to the use of this sand in construction, and were found to be less than unity in the study area. Calculated values of the absorbed dose rate were less than the typical world average value of 59 nGy h (-1), and the annual effective dose rate was also less than the typical world value of 70 μSv, except in the Indus river, in which it is slightly higher then the world average. Results show that the measured values are comparable with other global radioactivity measurements. None of the studied riverbeds was considered a radiological hazard, and their sand can be safely used in construction.     

Additive preservers of Drazin invertible operators with bounded index

Let B(X) be the algebra of all bounded linear operators on an infinite-dimensional complex or real Banach space X. Given an integer n ≥ 1, we show that an additive surjective map Φ on B(X)preserves Drazin invertible operators of index non-greater than n in both directions if and only if Φ is either of the form Φ(T) = αATA~(-1) or of the form Φ(T) = αBT~*B~(-1) where α is a non-zero scalar,A:X → X and B:X~*→ X are two bounded invertible linear or conjugate linear operators.     

QbD approached comparison of reaction mechanism in microwave synthesized gold nanoparticles and their superior catalytic role against hazardous nirto‐dye

Microwave irradiation (MI) process characteristically enables extremely rapid “in‐core” heating of dipoles and ions, in comparison to conventional thermal (conductance) process of heat transfer. During the process of nanoparticles synthesis, MI both modulates functionality behaviors as well as dynamic of reaction in favorable direction. So, MI providing a facile, favorable and alternative approach during nanoparticles synthesis nanoparticles with enhanced catalytic performances. Although, conventionally used reducing and capping reagents of synthetic origin, are usually environmentally hazardous and toxic for living organism. But, in absence of suitable capping agent; stability, shelf life and catalytic activity of metallic nanoparticles adversely affected. However, polymeric templates which emerged as suitable choice of agent for both reducing and capping purposes; bearing additional advantages in terms of catalyst free one step green synthesis process with high degree of biosafety and efficiency. Another aspect of current works was to understand role of process variables in growth mechanism and catalytic performances of microwave processed metallic nanoparticles, as well as comparison of these parameters with conventional heating method. However, due to poor prediction ability with previously published architect OFAT (One factor at a time) design with these nanoparticles as well as random selection of process variables with their different levels, such comparison couldn't be possible. Hence, using gum Ghatti (Anogeissus latifolia) as a model bio‐template and under simulated reaction conditions; architect of QbD design systems were integrated in microwave processed nanoparticles to establish mechanistic role these variables. Furthermore, in comparison to conventional heating; we reported well validated mathematical modeling of process variables on characteristic of nanoparticles as well as synthesized gold nanoparticles of desired and identical dimensions, in both thermal and microwave‐based processes. Interestingly, despite of identical dimension, MI processed gold nanoparticles bearing higher efficiency (kinetic rate) against remediation of hazardous nitro dye (4‐nitrophenol), into safer amino (4‐aminophenol) analogues.