Agata Białońska

Novel organic–inorganic hybrid ferroelectric: bis(imidazolium) pentachloroantimonate(III), (C3N2H5)2SbCl5

Electric permittivity, reaching ca. 4800 units at Tc, of the first haloantimonate(III) ferroelectric with R2MX5 composition characterized by unprecedented SbCl5 chains of cis-connected octahedra results from the mixed ‘order–disorder’ and ‘displacive’ mechanism of the phase transition.

Structure and ferroelectric properties of [C3N2H5]5[Bi2Br11]

A ferroelectric crystal [C3N2H5]5[Bi2Br11] has been synthesized and structurally characterized at 170 and 100 K. The crystal structure consists of discrete corner-sharing bioctahedra [Bi2Br11]5− and highly disordered imidazolium cations. The room temperature crystal structure has been determined as monoclinic, space group, P 21/n with: a = 9.257(2) A, b = 15.157(3) A, c = 13.865(3) A and β = 97.73(3)°. The crystal undergoes two solid–solid phase transitions: at 355 K of first-order and at 155 K of second-order type. The later transition takes place between monoclinic phases: . The dielectric and pyroelectric measurements allow us to characterize the low temperature phase III as ferroelectric with the Curie temperature at 155 K. The saturated spontaneous polarization of the order of 2.6 × 10−3 C m−2 was measured along the a-axis (130 K). The ferroelectric phase transition mechanism at 155 K is due to the dynamics of three of five nonequivalent imidazolium cations.

Microbial Baeyer-Villiger oxidation of steroidal ketones using Beauveria bassiana: Presence of an 11α-hydroxyl group essential to generation of D-homo lactones.

This paper demonstrates for the first time transformation of a series of 17-oxo steroidal substrates (epiandrosterone, dehydroepiandrosterone, androstenedione) by the most frequently used whole cell biocatalyst, Beauveria bassiana, to 11α-hydroxy-17a-oxa-d-homo-androst-17-one products, in the following sequence of reactions: 11α-hydroxylation and subsequent Baeyer-Villiger oxidation to a ring-D lactone. 11α-Hydroxyprogesterone, the product of the first stage of the progesterone metabolism, was further converted along two routes: hydroxylation to 6β,11α-dihydroxyprogesterone or 17β-acetyl chain degradation leading to 11α-hydroxytestosterone, the main metabolite of the substrate. Part of 11α-hydroxytestosterone underwent a rare reduction to 11α-hydroxy-5β-dihydrotestosterone. The experiments have demonstrated that the Baeyer-Villiger monooxygenase produced by the strain catalyzes solely oxidation of C-20 or C-17 ketones with 11α-hydroxyl group. 17-Oxo steroids, beside the 11α-hydroxylation and Baeyer-Villiger oxidation, also underwent reduction to 17β-alcohols; activity of 17β-hydroxysteroid dehydrogenase (17β-HSD) has significant impact on the amount of the formed ring-D δ-lactone.

When in the presence of the strong hydrogen bonds, the weak hydrogen bonds gain an importance

The crystal structures of brucinium hydrogen N-benzoyl-D-aspartate tetrahydrate (1), brucinium N-benzoyl-D-asparaginate trihydrate (2), brucinium N-tert-butoxycarbonyl-L-alaninate 2-propanol solvate hydrate (3) and brucinium N-tert-butoxycarbonyl-L-prolinate ethanol solvate hydrate (4) were determined. In all crystals under investigation, the brucinium cations form corrugated layers with anions and solvent molecules between them. Our investigations concerning the nature of the brucine layers show that such self-assemblies provide optimally appropriate surfaces for interactions in the hydrophilic environment from which the crystals of brucinium salts were usually grown. In an effort to obtain the most appropriate surfaces, weak hydrogen bonds gain in importance. This suggestion seems to be confirmed by the presence of the same pattern of the weak hydrogen bonds that one can observe in many crystals containing brucine (molecular/ionic).

A New Family of Spin-Crossover Complexes Based on a FeII(Tetrazolyl)4(MeCN)2-Type Core

A bitopic ligand 2-hydroxy-1-(tetrazol-1-yl)-3-(tetrazol-2-yl)propane (12pbtzOH) was synthesized and reacted with Fe(ClO4)(2).6H2O, giving a 1D coordination polymer {[Fe(12pbtzOH)2(CH3CN)2](ClO4)(2).2CH3CN} infinity that exhibits a high-spin to low-spin transition (T1/2(downward arrow)=T1/2(upward arrow) congruent with 104 K). This is an unprecedented example of an iron(II) complex containing Fe(tetrazolyl) 4(MeCN)2 cores.

Phenanthriporphyrin: An Antiaromatic Aceneporphyrinoid as a Ligand for a Hypervalent Organophosphorus(V) Moiety

The incorporation of a phenanthrene moiety into a porphyrin framework results in the formation of a hybrid macrocycle—phenanthriporphyrin—merging the structural features of polycyclic aromatic hydrocarbons and porphyrins. An antiaromatic aceneporphyrinoid, adopting the trianionic {CCNN} core, is suitable for the incorporation of a phosphorus(V) center to form a hypervalent organophosphorus(V) derivative.

Biotransformations of steroid compounds by Chaetomium sp. KCH 6651

Biotransformations of steroid compounds: androstenedione, testosterone, progesterone, pregnenolone and DHEA using Chaetomium sp. 1 KCH 6651 strain as a biocatalyst were investigated. The microorganism proved capable of selective hydroxylation of the steroid substrates. Androstenedione was converted to 14alpha-hydroxyandrost-4-en-3,17-dione (in over 75% yield) and 6beta-hydroxyandrost-4-en-3,17-dione (in low yield), while testosterone underwent regioselective hydroxylation at 6beta position. Progesterone was transformed to a single product-6beta,14alpha-dihydroxypregnan-4-en-3,20-dione in high yield, whereas biotransformation of DHEA resulted in the formation of 7alpha-hydroxy derivative, which was subsequently converted to 7alpha-hydroxyandrost-4-en-3,17-dione.

Synthesis of piperitone-derived halogenated lactones and their effect on aphid probing, feeding, and settling behavior{{

Five racemic and five enantiomeric pairs of new halolactones with the p-menthane system were obtained in two or three step synthesis from racemic and optically active cis- and trans-piperitols. The key steps of the syntheses were the Claisen-Johnson rearrangement of piperitols to γ,δ-unsaturated esters and haloloctonization of γ,δ-unsaturated esters or acids. The structures of the compounds were confirmed by spectroscopic and crystallographic data. Antifeedant activity of all iodo-, bromo- and chlorolactones and racemic piperitone against Myzus persicae was examinated. The effect of these compounds on probing, feeding, and settling behavior of M. persicae in vivo was studied.

Piperitone-derived saturated lactones: synthesis and aphid behavior-modifying activity.

Two racemic and two enantiomeric pairs of new saturated lactones with the p-menthane system were obtained. The lactones were synthesized from racemic and enantiomerically enriched cis- and trans-piperitols, which were obtained from piperitone. The structures of the compounds were confirmed by spectroscopic data. The antifeedant activity of piperitone to Myzus persicae was studied, and the biological consequences of structural modifications of piperitone, that is, lactonization and chiral center configuration, were examined as well. The behavioral responses of M. persicae to piperitone and piperitone-derived saturated lactones were investigated to reveal the biological background of their deterrent activity. Piperitone appeared rather neutral or weakly deterrent to aphids. The introduction of a lactone moiety into a piperitone molecule dramatically changed its biological activity. All piperitone-derived lactones evoked negative aphid responses. However, the deterrent activity of individual compounds varied in potency, the time of expression, and the duration of the effect, depending on the spatial structure of the lactone. Lactones (1R,3S,6R)-3-isopropyl-6-methyl-9-oxabicyclo[4.3.0]nonan-8-one and trans-3-isopropyl-6-methyl-9-oxabicyclo[4.3.0]nonan-8-one showed the broadest ranges and the highest potencies and durabilities of deterrent activity to M. persicae: they acted immediately after application, caused a cessation of probing before aphids reached phloem elements, and decreased the quality of phloem sap.

Racemic resolution of N-protected alanine by strychnine and brucine versus donor/acceptor capability

The crystal structures of strychninium N-phthaloyl-D-α-alaninate 2 hydrate (1) and brucinium N-phthaloyl-L-α-alaninate 0.5 hydrate (2) were obtained as a result of racemic resolution by stereochemically related strychnine and brucine, respectively. Comparison of crystal structures of 1 and 2 with previously presented crystal structures of strychnine with N-benzoyl-L- and brucine with N-benzoyl-D-alanine points at the importance of alkaloid self-assemblies in molecular recognition. Simultaneously, various donor/acceptor capabilities of both alanine derivatives control acceptors’ access of resolving agent self-assemblies and therefore racemic resolution.