Facile microwave-assisted synthesis of cyclic amidinium salts

The cyclization of N,N'-dialkyl or diaryl ethane-1,2-diamines or propane-1,3-diamines with inorganic ammonium salts and orthoesters proceeds briskly under microwave irradiation to afford the corresponding imidazolinium or tetrahydropyrimidinium salts. The transformation is highly versatile and tolerates a wide range of substituents and counterions. It could be scaled from 1 to 50 mmol without any difficulty. Because the workup is equally rapid and straightforward, this experimental procedure provides fast and convenient access to an important class of heterocyclic compounds that have found numerous applications as N-heterocyclic carbene precursors, organocatalysts, and ionic liquids.     

Modeling the growth and branching of plants: A simple rod-based model

A rod-based model for plant growth and branching is developed in this paper. Specifically, Euler's theory of the elastica is modified to accommodate growth and remodeling. In addition, branching is characterized using a configuration force and evolution equations are postulated for the flexural stiffness and intrinsic curvature. The theory is illustrated with examples of multiple static equilibria of a branched plant and the remodeling and tip growth of a plant stem under gravitational loading.     

Iron,cobalt and nickel violurate complexes

Summary The Fe^II, Fe^III, Co^II, Co^III and Ni^II violurates have been synthesised and their electronic spectra (in Nujol mulls and dimethyl formamide), i.r. spectra, magnetic properties, molar conductivity, differential thermal analysis (d.t.a.), thermogravimetric analysis (t.g.a.), elemental analysis, m.p., specific gravity and solubility have been recorded. The structures of the complexes have been inferred from magnetic and spectral data.     

Feature of catalysis on bimetallic alloys Zr with V,Mo, and Fe in the reaction of methanol oxidation

Catalytic behaviors of bimetallic catalysts-alloys of zirconium with vanadium, molybdenum, and iron was investigated in the oxidative dehydrogenation of methanol. The conditions for the formation of the catalyst’s active surface were revealed. The conversion of methanol into formaldehyde, dimethyl ether, and dimethoxymethane on bimetallic catalysts was studied. The characterization of catalysts was performed by XRD, XPS, and SEM. It was shown that the activity of samples increases after О₂ + Н₂ treatment and was associated with segregation of the active components of alloys (V, Mo) on the surface of catalysts and realization of their optimal oxidation state under catalysis conditions.     

Design,synthesis and bioactivity of chalcones and its analogues

The Vernohia anthelmintica L.'s extract is one of the most popular Uygur medicines used for vitiligo. It is believed that the chalcone compounds of the plant play an important role in the treatment since they may activate tyrosinase and improve melanin production. In this study, twenty-one chalcones and nine analogues were synthesized in view of three different components of chalcone(A, B ring and a,b-unsaturated carbonyl). After biological evaluation of their activity on tyrosinase in cell-free systems,the result showed that most compounds(except polyhydroxy chalcones) possess activator effect on the tyrosinase, especially for 13a–15a, 20 a and 1b, which bearing a comparable activity to the positive control8-MOP. SAR of these tyrosinase activator was summed up for the first time as well. Finally, compound 13 a was found to increase melanin contents and tyrosinase activity 1.75 and 1.3 fold, respectively, compared with that of untreated murine B16 cells at the concentration of 40 mg/m L.     

Synthesis and Bioactivity of New Chalcone Derivatives as Potential Tyrosinase Activator Based on the Click Chemistry

A new series of (E)‐1‐(4‐((1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)methoxy)phenyl)‐3‐phenylprop‐2‐en‐1‐one 1a (4‐((1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl) methoxy)phenyl)‐1‐phenylprop‐2‐en‐1‐one 1b – 15b were designed, synthesized based on click chemistry, and biologically evaluated for their activity on tyrosinase. The result showed that most of prepared compounds 1a – 15a have potent activating effect on tyrosinase, especially for 3a , 8a – 10a and 14a – 15a . Among them, compounds 10a and 14a demonstrated the best activity with EC₅₀=1.71 and 5.60 µmol·L^?1 respectively, even better than the positive control 8‐MOP (EC₅₀=14.8 µmol·L^?1). Conversely, compounds 3b , 5b – 6b , 9b – 10b , and 15b induced enzymatic inhibition on tyrosinase.     

Electrocatalytic Determination of the antibiotic Levofloxacin using modified carbon paste electrode with a poly-murexide thin film voltammetrically

In this work, a simple, cheap, sensitive, and selective modified carbon paste electrode is proposed for the electroanalytical determination of Levofloxacin (LEVO), the drug used to treat pneumonia caused by coronavirus. The electrochemical polymerization method was applied to create a thin poly-murexide film (POMUR) on the bare carbon paste electrode (BCPE) surface to enhance its electrocatalytic activity. The peak current response of LEVO obtained by POMUR/CPE was increased by 14.2 μA compared to BCPE. Scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques were employed to characterize BCPE and POMUR/CPE. Under the optimal experimental circumstances, the prepared sensor was capable of determining LEVO with a low limit of detection (LOD) of 7.18 nM (S/N = 3) for a linear dynamic range of 25 – 1 × 10³ nM utilizing differential pulse voltammetry (DPV). Moreover, the practical applicability of POMUR/CPE for determining LEVO in pharmaceutical formulations and biological samples (human serum) demonstrated high sensitivity and selectivity with a recovery of 95.08 – 100.5 %.     

Diphosphine Compounds,Part III: UV/Visible Spectroscopy and Novel Routes to Functionalized Diphosphine-M(CO)6 Complexes (M = W,Mo, or Cr)

Reaction of coordinated (diphenylphosphino)methane and ketones or aldehydes have been characterized by ³¹P{H¹}-NMR, ¹H{³¹P}-NMR, and UV/vis spectroscopy in dichloromethane. Group VI metals hexacarbonyl [M(CO)₆ where M = Cr, Mo, and W] reacted with (diphenylphosphino)methane, [(Ph₂P)₂CH₂], to give [(OC)₄M{(Ph₂P)₂CH₂}] depending upon the reaction conditions. Condensation of [(CO)₄M{(Ph₂P)₂CH₂}] with different ketones or aldehydes forms [(CO)₄M{(Ph₂P)₂C = CR₁R₂}]. Complexes of the types [(OC)₄M{(Ph₂P)₂C = CR₁R₂}] reacted with hydrazine in a Michael addition to give [(CO)₄M{(Ph₂P)₂CHC(R₁R₂)NHNH₂}](1.3a–e), which condensed with different ketones and aldehydes to give complex of the type [(CO)₄M{(Ph₂P)₂CHC(R₁R₂)NHN = C(R₃)] (1.4a–e). The structures of the complexes are discussed on the basis of elemental analysis (EA), IR,¹H-NMR, ³¹P-NMR spectroscopic data, and FAB mass spectra. The UV/vis spectra show two absorption bands with the low energy band moving to lower energy with increasing substitution on the (diphenylphosphino) methane (dppm) (a bathochromic effect).     

Simulations of kinetic electrostatic electron nonlinear (KEEN) waves with variable velocity resolution grids and high-order time-splitting

KEEN waves are non-stationary, nonlinear, self-organized asymptotic states in Vlasov plasmas. They lie outside the precepts of linear theory or perturbative analysis, unlike electron plasma waves or ion acoustic waves. Steady state, nonlinear constructs such as BGK modes also do not apply. The range in velocity that is strongly perturbed by KEEN waves depends on the amplitude and duration of the ponderomotive force generated by two crossing laser beams, for instance, used to drive them. Smaller amplitude drives manage to devolve into multiple highly-localized vorticlets, after the drive is turned off, and may eventually succeed to coalesce into KEEN waves. Fragmentation once the drive stops, and potential eventual remerger, is a hallmark of the weakly driven cases. A fully formed (more strongly driven) KEEN wave has one dominant vortical core. But it also involves fine scale complex dynamics due to shedding and merging of smaller vortical structures with the main one. Shedding and merging of vorticlets are involved in either case, but at different rates and with different relative importance. The narrow velocity range in which one must maintain sufficient resolution in the weakly driven cases, challenges fixed velocity grid numerical schemes. What is needed is the capability of resolving locally in velocity while maintaining a coarse grid outside the highly perturbed region of phase space. We here report on a new Semi-Lagrangian Vlasov-Poisson solver based on conservative non-uniform cubic splines in velocity that tackles this problem head on. An additional feature of our approach is the use of a new high-order time-splitting scheme which allows much longer simulations per computational effort. This is needed for low amplitude runs. There, global coherent structures take a long time to set up, such as KEEN waves, if they do so at all. The new code’s performance is compared to uniform grid simulations and the advantages are quantified. The birth pains associated with weakly driven KEEN waves are captured in these simulations. Canonical KEEN waves with ample drive are also treated using these advanced techniques. They will allow the efficient simulation of KEEN waves in multiple dimensions, which will be tackled next, as well as generalizations to Vlasov-Maxwell codes. These are essential for pursuing the impact of KEEN waves in high energy density plasmas and in inertial confinement fusion applications. More generally, one needs a fully-adaptive grid-in-phase-space method which could handle all small vorticlet dynamics whether pealing off or remerging. Such fully adaptive grids would have to be computed sparsely in order to be viable. This two-velocity grid method is a concrete and fruitful step in that direction.     

DIPHOSPHINE COMPOUNDS: PART I. NOVEL BIOLOGICALLY ACTIVE 1,1′bis-AND/OR 1,2-cis-(DIPHENYLPHOSPHINO-)ETHENE AND THEIR COMPLEXES [M(CO)n{Ph2P(CHn)nPPh2}] & [Cu(Cl)2{Ph2P(CHn)nPPh2}], (M = W,Mo, Crn = 1,2….n)

Interaction of [Ph₂PC(═CH₂)PPh₂] (A)^1–3 and/or [Ph₂P (CH═CH) PPh₂](B) ligands in different molar ratio with hexacarbonyl metals M(CO)₆ gives [M(CO) _n Ph₂PC(═CH₂)PPh₂] and/or [M(CO) _n Ph₂P (CH═CH)PPh₂ where M═ Cr, Mo or W, n = 2 and/or 4]. The carbon diphosphine complexes of type (A) which form four heteromemebered rings and/or type (B) form five heteromembered rings which reacts (addition reaction) with some different amines (methyl amine, dimethyl amine), phenyl hydrazine and/or some of amino acids (glycine, alanine, aspartic acid, serene). The structures of A and/or B complexes and their amino derivatives have been characterized by using elemental analysis, IR spectra, ¹HNMR,¹H-³¹P-NMR, and mass spectra. Ligands and their complexes were screened in vitro to investigate the biological activities (antibacterial and antifungi). Interestingly, complexes are having strong and remarkable activities increases than the free ligands.