Determination of catechin and epicatechin in the peel of apple varieties resistant and non-resistant to apple scab

Catechin and epicatechin were analysed in the peel of six apple cultivars (three resistant and three non-resistant to apple scab). Two methods of analytical sample preparation following extraction were tested: solid phase extraction and column separation with Sephadex LH-20 coupled to a differential refractometric detector. Prior to GC and GC-MS analyses, these compounds were silylized. This permitted co-injection with standards and the comparison of retention values and mass spectra with those recorded for standards. The content of catechin and epicatechin in apple peel is discussed in relation to the resistance of apple trees to scab.     

Modeling of diffusive transport of benzoic acid through a liquid membrane

A model of diffusive transport of benzoic acid through a liquid membrane (LM) separating two aqueous solutions, based on diffusion layers and the assumption of a steady state, has been developed and tested using experimental results. It has been found that a model with the apparent partition coefficient dependent on the concentration is able to describe the time dependence of acid concentration in LM with and without a maximum on that dependence. The quality of the model fit with the single apparent diffusion coefficient of benzoic acid is the same as the one which takes into account the diffusion of benzoic acid in different forms (undissociated and dissociated form in aqueous phase, monomer and dimer in organic phase); however, in the second case, the model becomes overparameterized. Assuming that the partition and diffusion coefficients are constant, the diffusion layer model corresponds to the model of reversible consecutive reactions. Analytical solution for such case is given. Apart from the partition equilibrium, also kinetics of partitioning was considered. It was shown that in some basic situations both cases yield identical results.     

Structure and atropisomerisation of new diastereomeric gossypol Schiff bases with (R)-(+)-2-amino-3-benzyloxy-1-propanol studied by NMR,ECD and DFT methods

Gossypol Schiff base with (R)-(+)-2-amino-3-benzyloxy-1-propanol 1 was synthesised and resolved by HPLC method into diastereomers to study their atropisomerisation process. The spectroscopic analysis performed by one- and two-dimensional NMR, UV–vis and FT-IR methods indicated that the compound exists in solution as an enamine-oxo tautomer. The ECD measurements and TD-DFT calculations allowed us to unambiguously determine the configuration about the axially chiral biaryl moiety of 1. The conditions of the atropisomerisation processes of diastereopure gossypol Schiff bases (S_AX,R)-1 and (R_AX,R)-1 were determined on the basis of ECD and NMR measurements. Exposure of the diastereomers of 1 to sunlight and to the light at λ = 254 nm significantly accelerated the atropisomerisation when compared to its rate in the dark.     

A ruthenium(II) hydride carbonyl complex with 4-phenylpyrimidine as co-ligand

The reaction of [RuHCl(CO)(PPh₃)₃] with 4-phenylpyrimidine gave a new ruthenium(II) complex, namely [RuHCl(CO)(PPh₃)₂(pyrim-4-Ph)]. The complex has been studied by IR and UV?Cvis spectroscopy and by X-ray crystallography. The molecular orbitals of the complex have been calculated by density functional theory. The spin-allowed singlet?Csinglet electronic transitions of the complex have been calculated by time-dependent DFT, and the UV?Cvis spectrum of the compound has been discussed on this basis. The emission properties of the complex were also studied.     

Corrigendum to “Convexity and concavity constants in Lorentz and Marcinkiewicz spaces” [J. Math. Anal. Appl. 343 (2008) 337-351]

In this note we state the accurate formulas of convexity and concavity constants in Lorentz spaces, correcting the formulas from Kamińska and Parrish (2008) [2].     

Ionic liquids with herbicidal anions

Ionic liquids with herbicidal anions (named herbicidal ionic liquids—HILs) were synthesized and characterized. The combination of two active chemicals as the [cation][anion] form in a single moiety reduced the number of additional chemicals required per application. HILs ([cation][MCPA]) exhibited higher biological activity than currently used salts of MCPA, and involved pesticides of a multidirectional activity ([plant growth regulator][MCPA]). Acute toxicity of HILs could be controlled by appropriate selection of cation type. These salts had chemical and thermal stability, and showed substantially lower water solubility than starting herbicides, thus reducing soil and groundwater mobility.     

Investigation of InSb(1 1 0) and InSb(1 1 1) surfaces by means of target current (VLEED) spectroscopy and LEED

In this paper, we present experimental results of target current (TCS) and LEED investigation of well-oriented InSb(1 1 0) and InSb(1 1 1)-A and InSb(1 1 1)-B crystals. TCS results are interpreted in terms of very low electron diffraction (VLEED) and empty band signatures. To examine to which extent the TCS spectra reflect the bulk or surface electronic properties of InSb(1 1 0), thin layers of indium have been evaporated and the corresponding spectrum changes have been investigated.     

General route to the total synthesis of sempervirine analogues containing modified E rings, potential cytostatics

Sempervirine analogues 13a–c with different E rings have been obtained via inverse electron demand Diels–Alder reactions of 5-acetyl-3-(methylsulfanyl)-1,2,4-triazine with cyclic enamines (formation of D and E rings) followed by Fischer indole synthesis under microwave irradiation on solid support (formation of A and B rings) and subsequent annulation of indole derivatives 10a–c via a directed metallation route (formation of C rings).     

Correlation between the surface free energy of modified and non-modified glasses with controlled porosity and their sorption properties

Summary Contact angles for water and diiodomethane drops were measured on the surface of thermally and chemically (by Carbowax 20M bonding) modified porous glasses and on the surface of naphthalene, diphenyl and anthracene. Using the obtained results to a modified Young equation, dispersion and nondispersion components of the surface free energy of these glasses and organic substances were calculated. The work of adhesion (W_A) for benzene, naphthalene, diphenyl, anthracene, nitrobenzene was estimated and correlated with the capacity factors, (k′) of these substances. On the basis of experimental and calculated data it can be stated that the thermal treatment of porous glasses increases, their hydrophobicity but the Carbowax layer causes hydrophilicity. There is a linear relationship between k′ and W_A which can be helpful for predicting retention data of chromatographed substances on the base of surface free energy which can be calculated from contact angle measurements.