Synthese von Tetracyanoniccolat-clathraten mit Benzol Kurze Mitteilung

Zusammenfassung Durch Ersetzung des Cadmiums im Clathrat Cden[Ni(CN)₄]·2C₆H₆ wurden drei Verbindungen des TypsM(en) _m[Ni(CN)₄]·nC₆H₆ (M ²⁺=Ni, Cu, Zn;m=2–3;n=0.14–0.28) hergestellt und charakterisiert.

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Synthesis of ethylendiamine-(metal II)-tetracyanoniccolate dibenzene clathrate compounds

Replacing cadmium ion in Cden[Ni(CN)₄]·2C₆H₆ clathrate compound three compounds ofM(en) _m[Ni(CN)₄]·nC₆H₆ type (M ²⁺=Ni, Cu, Zn;m=2–3;n=0.14–0.28) were prepared and characterized.

     

Synthesis and Evaluation of Antioxidant Properties of 2-Substituted Quinazolin-4(3H)-ones

Quinazolinones represent an important scaffold in medicinal chemistry with diverse biological activities. Here, two series of 2-substituted quinazolin-4(3H)-ones were synthesized and evaluated for their antioxidant properties using three different methods, namely DPPH, ABTS and TEAC_CUPRAC, to obtain key information about the structure–antioxidant activity relationships of a diverse set of substituents at position 2 of the main quinazolinone scaffold. Regarding the antioxidant activity, ABTS and TEAC_CUPRAC assays were more sensitive and gave more reliable results than the DPPH assay. To obtain antioxidant activity of 2-phenylquinazolin-4(3H)-one, the presence of at least one hydroxyl group in addition to the methoxy substituent or the second hydroxyl on the phenyl ring in the ortho or para positions is required. An additional ethylene linker between quinazolinone ring and phenolic substituent, present in the second series (compounds 25a and 25b), leads to increased antioxidant activity. Furthermore, in addition to antioxidant activity, the derivatives with two hydroxyl groups in the ortho position on the phenyl ring exhibited metal-chelating properties. Our study represents a successful use of three different antioxidant activity evaluation methods to define 2-(2,3-dihydroxyphenyl)quinazolin-4(3H)-one 21e as a potent antioxidant with promising metal-chelating properties.     

Mechanochemistry for Energy Materials: Impact of High-Energy Milling on Chemical,Electric and Thermal Transport Properties of Chalcopyrite CuFeS2 Nanoparticles

Chalcopyrite CuFeS₂, a semiconductor with applications in chemical sector and energy conversion engineering, was synthetized in a planetary mill from elemental precursors. The synthesis is environmentally friendly, waste-free and inexpensive. The synthesized nano-powders were characterized by XRD, SEM, EDX, BET and UV/Vis techniques, tests of chemical reactivity and, namely, thermoelectric performance of sintered ceramics followed. The crystallite size of ∼13 nm and the strain of ∼17 were calculated for CuFeS₂ powders milled for 60, 120, 180 and 240 min, respectively. The evolution of characteristic band gaps, Eg, and the rate constant of leaching, k, of nano-powders are corroborated by the universal evolution of the parameter S_BET/X (S_BET-specific surface area, X-crystallinity) introduced for complex characterization of mechanochemically activated solids in various fields such as chemical engineering and/or energy conversion. The focus on non-doped semiconducting CuFeS₂ enabled to assess the role of impurities, which critically and often negatively influence the thermoelectric properties.     

Concise synthesis of 22-hydroxyacuminatine, cytotoxic camptothecinoid from Camptotheca acuminata, by pyridone benzannulation

A short, efficient synthesis of 22-hydroxyacuminatine, starting from a readily accessible hydroxy pyridone, is presented; key steps include a Heck coupling with methyl pentadienoate, a flash vacuum pyrolytic cyclization, and a Friedl?nder condensation.     

Concise Synthesis,Conformational Study,and Aroma Properties of Carba-Homologues of Helvetolide and Serenolide

We have designed, prepared, and evaluated a set of racemic (un)saturated carba-homologues of prominent musks Helvetolide and Serenolide. The short synthesis employs commercially available Artemone and/or Herbac, that are transformed in three steps to the target compounds. Their qualitative olfactory analysis revealed that incorporation of methylene bridge into the backbone chain of parent compounds completely erases the original musk scent and such new derivatives exhibit a pleasant and often intense sweet(ish) aroma of fruit with floral and herbal aspects. The results of computational modelling suggest that previously postulated horseshoe shape conformation might be necessary but not sufficient prerequisite for musk-scented compounds. Thus, we offer an alternative hypothesis based on the structural differences between metallocomplexes of Helvetolide and/or Serenolide vs. their (un)saturated carba-homologues with zinc-atom as a model for the putative metal-binding site in human olfactory receptors.     

Ternary MIn2S4 (M = Mn,Fe, Co,Ni) Thiospinels – Crystal Structure and Thermoelectric Properties

A combined structural, magnetic and thermoelectric study of polycrystalline ternary MIn₂S₄ (M = Mn, Fe, Co, Ni) thiospinels is presented. All compounds crystallize with MgAl₂O₄-type structure. Rietveld refinement analysis confirmed that the preferred crystallographic position of transition metal element changes from mainly tetrahedral 8a for Mn to exclusively octahedral 16d for Ni (i.e. increase of the inversion parameter). Magnetic susceptibility measurements revealed M-elements to possess 2+ oxidation state in MIn₂S₄. All these compounds order antiferromagnetically with Néel temperatures T_N ranging from 5–13 K. The studied thiospinels are n-type semiconductors with large values of electrical resistivity ρ > 0.6 Ω · m at room temperature. An increase of the inversion parameter leads to a reduction of the determined activation energies, as well as to a more disorder-like behavior of thermal conductivity. The highest thermoelectric Figure of merit ZT was observed for MIn₂S₄ with M = Fe, Ni, which adopt inverse spinel structure.     

Conformationally tailored N-[(2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl)carbonyl]proline templates as molecular tools for the design of peptidomimetics. Design and synthesis of fibrinogen receptor antagonists

The proline peptide bond was shown by 2D proton NMR studies to exist exclusively in the trans conformation in benzyl (2S)-1-[[(2S)-2-methyl-6-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl]-2-pyrrolidinecarboxylate [(S,S)-11], benzyl (2S)-1-[[(2S)-2-methyl-7-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl]-2-pyrrolidinecarboxylate [(S,S)-9], and in the corresponding 6-amino and 7-amino carboxylic acids (S,S)-3 and (S,S)-4. On the other hand, the diastereomers (R,S)-11 and (R,S)-9 containing an (R)[2-methyl-6/7-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl moiety, and the diastereoisomers (R,S)-3 and (R,S)-4 incorporating an (R)[6/7-amino-2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl moiety were found to exist as equilibria of trans(63-83%) and cis(17-37%) isomers. These conformationally defined templates were applied in the construction of RGD mimetics possessing antagonistic activity at the platelet fibrinogen receptor.     

A Simple Synthesis of Polyfunctionalized 4‐Aminopyrazolidin‐3‐ones as ‘Aza‐deoxa’ Analogs of D‐Cycloserine

A simple five‐step synthesis of fully substituted (4RS,5RS)‐4‐aminopyrazolidin‐3‐ones as analogs of D ‐cycloserine was developed. It comprises a two‐step preparation of 5‐substituted (4RS,5RS)‐4‐(benzyloxycarbonylamino)pyrazolidin‐3‐ones, reductive alkylation at N(1), alkylation of the amidic N(2) with alkyl halides, and simultaneous hydrogenolytic deprotection/reductive alkylation of the primary NH₂ group. The synthesis enables an easy stepwise functionalization of the pyrazolidin‐3‐one core with only two types of common reagents, aldehydes (or ketones) and alkyl halides. The structures of products were elucidated by NMR spectroscopy and X‐ray diffraction.