Novel plastoquinone analogs containing benzocaine and its analogs: structure‐based design,synthesis, and structural characterization

Introducing new biologically active organic molecules or their analogs into the pharmaceutically important molecules significantly enables the discovery and development of the medicines that improve the health of patients. Chemical synthesis has a key role in pharmaceutical research and development, aiming to design and build molecules with the essential biological activity needed in drugs. For that reason, herein, three series of novel PQ analogs (the nonhalogenated (PQ1-6) and the halogenated PQ analogs (BrPQ1-6 and ClPQ1-6)) containing benzocaine and its analogs were designed and synthesized starting from the commercially available dimethylhydroquinone (1) with benzocaine and its analogs. The structures of all synthesized analogs were characterized by using spectroscopic methods. The in vitro antibacterial and antifungal activities were evaluated for the PQ analogs.

     

Centri-voltammetric study with amberlite XAD-7 resin as a carrier system

Centri-voltammetry is a novel method, which allows combining the advantages of centrifugation and voltammetry. The method offers a practical way for application of coprecipitation in trace analysis allowing direct voltammetric scan hence prevents the loss of the analyte, which usually is the case for other preconcentration techniques. The performance of the method was successfully tested using trace amounts of Pb²⁺ ions in aqueous solution in a vessel specially designed to be compatible to both centrifugation and voltammetry. XAD-7 resin was used as the carrier material and the parameters related to the carrier material and medium characteristics as well as the centrifugation settings were investigated. The sensitivity of the method was found comparable to that of stripping techniques and the detection limit for lead ions was calculated as 5.2 × 10⁻⁹ M with mercury coated gold sphere electrode. The precision of the method depends on the configuration of the working electrode and better reproducibility was obtained with mercury coated plate electrodes (R.S.D. 3.3%, n = 6).     

Application of Solid Sampling for the Determination of Total Fluorine in Fish and Seafood by High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry

Total fluorine concentrations in some fish species and seafood such as mussels, squid (calamary), and shrimp were determined using the molecular absorption of calcium monofluoride (CaF) generated in a graphite furnace using a high-resolution continuum source atomic absorption spectrometer and direct solid sampling. The fish fillets and seafood were dried at 110°C, minced finely, put on the platform using masses less than 1.2?mg, and introduced to the graphite furnace with 20?µg of calcium by a solid sampling accessory. The effects of CaF wavelength, graphite furnace program, amount of sample introduced to the furnace, the use of modifier on the determination of fluorine were investigated and optimized. The absolute limit of detection and characteristic mass of the method were 0.28 and 0.14?ng of fluorine, respectively. By applying the optimized parameters, the concentrations of fluorine in various fish species and seafood were determined.     

Axially phenoxy-derivative disubstituted phthalocyanine: synthesis,characterization and photophysical properties

Research on Chemical Intermediates - We report the highly soluble axially disubstituted 4-(methoxymethyl) phenol silicon (IV) (1) phthalocyanine which was synthesized by the reaction of silicon...     

Effects of hydrogen bonding on the monolayer properties of amphiphilic double-decker-shaped polyhedral silsesquioxanes

"Core-corona" type amphiphiles, which comprise double-decker-shaped POSSs (DDSQs) as the core and two or four di(ethylene glycol) (DEG) units as the coronae, have recently been reported to form a stable monolayer at the air-water interface. In this paper, another core-corona amphiphile, 2DEGNH-DDSQ, which has a urethane group at the end of the coronae, was synthesized to elucidate the effects of hydrogen bonding on monolayer properties. The surface pressure-area isotherm and Brewster angle microscopy revealed that 2DEGNH-DDSQ initially formed rodlike assemblies. They subsequently coalescence to form a uniform monolayer with compression. Actually, 2DEGNH-DDSQs are well ordered in the rodlike assembly because of the strong hydrogen bonds among the urethane groups, as confirmed by FT-IR spectra. Although the monolayer was not transferred onto a solid substrate, mixing of 2DEGNH-DDSQ with 2DEG-DDSQ, which has already been reported to form a liquidlike monolayer, overcame this problem. The 1:1 molar mixture of 2DEGNH-DDSQ and 2DEG-DDSQ forms a uniform liquidlike monolayer. The mixed monolayer was transferred onto a solid substrate as a Z-type Langmuir-Blodgett film. Atomic force microscopic (AFM) images of the mixed-bilayer film showed a uniform surface with root-mean-square surface roughness of 0.21 nm. The intermolecular hydrogen bonds between the urethane groups in 2DEGNH-DDSQ and the hydroxyl groups in 2DEG-DDSQ improve the monolayer properties, which enable successful transfer of the LB film.     

Langmuir-Blodgett films composed of amphiphilic double-decker shaped polyhedral oligomeric silsesquioxanes

New amphiphilic polyhedral oligomeric silsesquioxanes (POSSs) were synthesized, and their monolayer behavior on a water surface and Langmuir-Blodgett (LB) film formation were studied. Two kinds of amphiphilic POSS molecules, which have two or four di(ethylene glycol) units (2OH-DDSQ and 4OH-DDSQ, respectively), were synthesized by direct hydrosilylation of di(ethylene glycol) vinyl ether with double-decker shaped polyhedral oligomeric silsesquioxanes (DDSQs). Surface pressure (π)-area (A) isotherms and Brewster angle microscope (BAM) measurements indicated that both amphiphilic DDSQs form a stable monolayer at the air-water interface. In addition, 4OH-DDSQ can be deposited on a solid substrate by the LB technique. Atomic force microscope (AFM) images of a one-layer 4OH-DDSQ film showed a homogenous uniform surface on a hydrophilic silicon substrate, whereas nanometer scale dots were formed on a hydrophobic silicon substrate. Multilayer deposition on a hydrophobic substrate resulted in an increase of dot size with increasing deposition number of layers. Moreover, homogenous multilayer films with a few voids were obtained on a hydrophilic substrate. The results indicate that 4OH-DDSQ is a good candidate for preparing hybrid nanoassemblies.     

An efficient computational method for the optimal control problem for the Burgers equation

Pointwise control of the viscous Burgers equation in one spatial dimension is studied with the objective of minimizing the distance between the final state function and target profile along with the energy of the control. An efficient computational method is proposed for solving such problems, which is based on special orthonormal functions that satisfy the associated boundary conditions. Employing these orthonormal functions as a basis of a modal expansion method, the solution space is limited to the smallest lower subspace that is sufficient to describe the original problem. Consequently, the Burgers equation is reduced to a set of a minimal number of ordinary nonlinear differential equations. Thus, by the modal expansion method, the optimal control of a distributed parameter system described by the Burgers equation is converted to the optimal control of lumped parameter dynamical systems in finite dimension. The time-variant control is approximated by a finite term of the Fourier series whose unknown coefficients and frequencies giving an optimal solution are sought, thereby converting the optimal control problem into a mathematical programming problem. The solution space obtained is based on control parameterization by using the Runge–Kutta method. The efficiency of the proposed method is examined using a numerical example for various target functions.     

Three-term asymptotic expansions for the moments of the random walk with triangular distributed interference of chance

In this study, a semi-Markovian random walk with a discrete interference of chance (X(t)) is considered and under some weak assumptions the ergodicity of this process is discussed. The exact formulas for the first four moments of ergodic distribution of the process X(t) are obtained when the random variable ζ₁, which is describing a discrete interference of chance, has a triangular distribution in the interval [s, S] with center (S + s)/2. Based on these results, the asymptotic expansions with three-term are obtained for the first four moments of the ergodic distribution of X(t), as a ≡ (S − s)/2 → ∞. Furthermore, the asymptotic expansions for the variance, skewness and kurtosis of the ergodic distribution of the process X(t) are established. Finally, by using Monte Carlo experiments it is shown that the given approximating formulas provide high accuracy even for small values of parameter a.