Monatshefte Fur Chemie最新文献

A new method for determination of selected heavy metals (Cd, Pb, Cu, Zn, and Ni) in honey bee venom was developed. Heavy metals are metabolized and incorporated into bee products, including honey and honey bee venom (apitoxin). Their composition reflects contamination of "bee environment", providing information about heavy metal contamination in the neighborhood of human dwellings. Moreover, assessment of bee products contamination is relevant for medicine, as they are a tool for promising therapeutic and chemoprophylactic strategies against COVID-19 (SARS-CoV-2). Owing to the complicated matrix, the developed method consists of wet mineralization with sulfuric acid, nitric acid, under increased temperature, and pressure and subsequent repeated boiling with concentrated nitric acid. Determination of the selected metals was carried out by anodic or cathodic stripping voltammetry on two types of electrodes: pen-type hanging mercury drop electrode (HMDE) and PLA filament with carbon conductive admixture (PLA-C) for 3D printer. Contents of lead and cadmium in all analyzed bee venom samples were on the level of mg kg^-1, of nickel and copper about ten times higher, and of zinc on the level of g kg^-1. The results achieved using HMDE were recorded with average relative standard deviation (RSD) 5.4% (from 3.2% to 8.6%) and using PLA-C 11.8% (from 6.5% to 18.0%). The results achieved using both electrodes proved to be equivalent with statistical probability higher than 95%.

Graphic abstract:

Abstract: Decades of chemophobia are taking a high toll on chemistry. As current surveys suggest, people are displaying an irrational desire to live in a world without chemistry, but at the same time are unable to answer trivial chemistry questions. Constant questioning of the importance of chemistry induced by chemophobia leads to a weakening of the identity of chemists and can have negative consequences on the reproduction of chemistry. The need for the support of a positive perception of the chemical profession and an offer of positive examples for self-identification is the result. Everyday communication thus becomes the background on which the determination of the identity of the chemist takes place. The new communication strategy, which we call "heroes of chemistry", aims not only to add a much-needed human touch to chemistry communications, but also to create the conditions for strengthening the identity of the chemist.

Graphic abstract:

Abstract: The multistep synthesis of a prenylneoflavone through a sequence of the Mitsunobu reaction/Claisen rearrangement/olefin cross-metathesis reaction has been accomplished in 5% yield over six steps starting from commercially available 3-methoxyacetophenone. The sequence is shown to be compatible with a Pechmann condensation which proved to be a robust and cost-effective method for the assembling of the α-pyrone core. The results open doors to a general approach to the prenylneoflavone system starting from phenol and acetophenone derivatives.

Graphic abstract:

Abstract: A continuous flow procedure for the synthesis of methyl glycosides (Fischer glycosylation) of various monosaccharides using a heterogenous catalyst has been developed. In-depth analysis of the isomeric composition was undertaken and high consistency with corresponding results observed under microwave heating was obtained. Even in cases where addition of water was needed to achieve homogeneity-a prerequisite for the flow experiments-no detrimental effect on the conversion was found. The scalability was demonstrated on a model case (mannose) and as part of the target-oriented synthesis of d-glycero-d-manno heptose, both performed on multigram scale.

Graphical abstract:

Abstract: The new chiral PNP pincer ligand N ²,N ⁶-bis((3aR, 8aR)-2,2-dimethyl-4,4,8,8-tetraphenyltetrahydro[1,3]dioxolo[4,5-e][1,3,2]dioxaphosphepin-6-yl)pyridine-2,6-diamine (PNP-TADDOL) was synthesized in 80% isolated yield. Complexes of the type [M(PNP-TADDOL)(CO)₃] (M = Cr, Mo, and W) were prepared via a solvothermal approach. This methodology constitutes a fast, simple, and practical synthetic method to obtain complexes of that type in high isolated yields. The X-ray structure of the molybdenum complex is presented.

Graphical abstract:

Abstract: Stable radicals in organic conjugated molecules are of great interest due to their magnetic signals and broad optical absorptions. In this paper, we report on naphthalene, benzoperylene, perylene, terrylene, and quaterrylene carboximides, reduced under controlled conditions, where stable metal-free solid salts of radical anions could be obtained forming darkly colored solutions with line-rich UV/Vis/NIR spectra and exhibiting special magnetic properties. The most bathochromic shift of the absorption maxima extend from 760 until 1700 nm. Persistent paramagnetic properties of the solids were observed and temperature-dependent susceptibilities are measured.

Graphical abstract:

Abstract: A series of neutral bis- and cationic tris-carbonyl complexes of the types cis-[M(κ³ P,N,P-PNP)(CO)₂Y] and [M(κ³ P,N,P-PNP)(CO)₃]⁺ was prepared by reacting [M(CO)₅Y] (M = Mn, Re; Y = Cl or Br) with PNP pincer ligands derived from the 2,6-diaminopyridine, 2,6-dihydroxypyridine, and 2,6-lutidine scaffolds. With the most bulky ligand PNP^NH-tBu, the cationic square-pyramidal 16e bis-carbonyl complex [Mn(PNP^NH-tBu)(CO)₂]⁺ was obtained. In contrast, in the case of rhenium, the 18e complex [Re(PNP^NH-tBu)(CO)₃]⁺ was formed. The dissociation of CO was studied by means of DFT calculation revealing in agreement with experimental findings that CO release from [M(κ³ P,N,P-PNP)(CO)₃]⁺ is in general endergonic, while for [Mn(κ³ P,N,P-PNP^NH-tBu)(CO)₃]⁺, this process is thermodynamically favored. X-ray structures of representative complexes are provided.

Graphical abstract:

Abstract: Here, we present a robust synthetic route to a 2'-amino-2'-deoxyadenosine phosphoramidite building block for automated RNA solid-phase synthesis. The thus accessible 2'-amino-modified RNA finds applications in the evaluation of hydrogen-bond networks in folded RNA, such as riboswitches or ribozymes. In this context, we previously implemented the here described 2'-amino-2'-deoxyadenosine building block in a comparative study on self-cleaving pistol ribozymes to shed light on structural versus catalytic roles of active-site 2'-OH groups in the reaction mechanism.

Graphical abstract:

Abstract: The novel iron-substituted Krebs-type polyoxotungstate (C₁₂N₄H₁₁)₄Na₂H₅[(Fe(H₂O)₃)₂((FeO₂)_0.5(WO₂)_0.5)₂(β-SbW₉O₃₃)₂] (Fe-1) has been synthesized using ortho-phenylenediamine (opda) as a precursor for the in situ formation of the counter cation 2,3-diaminophenazinium (C₁₂N₄H₁₁)⁺ (2,3-DAP). Fe-1 has been thoroughly characterized in the solid state by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), IR spectroscopy, and elemental analysis as well as in solution by UV-Vis spectroscopy. The crystal structure of Fe-1 reveals π-π-interactions between the aromatic systems of the unconventional 2,3-DAP counter cation. POM-protein interaction studies using SDS-PAGE revealed a non-proteolytic behavior of Fe-1 towards Human Serum Albumin (HSA) as a model protein.

Graphical abstract: