Synergy of modern English word-formation system

The article focuses on the study of synergetic approach to the principles of Modern English word-formation system structural organization and development. Word-formation is regarded as a complex open non-equilibrium system with non-linear scenarios of development. The structural organization of the English language in general and word-formation endo-system in particular ensures their ability to self-organize via accepting and adapting new language units, meanings and functions (in terms of synergetic – innovative substance, energy and information) or their dissipation. Special attention is paid to the phenomenon of language units’ functional trans orientation which contributes to the enrichment of word-forming devices and leads to the improvement of verb creative mechanisms.

(H,H)-Isomerism of cis- and trans-di[benzo]porphyrazines: Quantum chemical modeling within the framework of the DFT method

Quantum-chemical calculation of the molecular structures of potential isomeric (NNNN)- donoratomic macrocyclic tetradentate ligands, cis- and trans-di[benzo]porphyrazines, was carried out using the density functional theory (DFT) B3PW91/TZVP. It is noted that the first of these compounds can exist in four forms [so-called ([Formula: see text]-isomers], differing from each other by the mutual orientation of hydrogen atoms bonded to the nitrogen atoms, while the second compounds take the form of two similar isomers. The values of the most important bond lengths, bond and non-bond angles in each of these ([Formula: see text] -isomeric compounds, as well as the values of their relative energy, standard enthalpy, entropy, and Gibbs energy of formation are presented. It was found that the most stable among both cis- and trans-di[benzo]porphyrazines is the ([Formula: see text]-isomer with the trans-orientation of hydrogen atoms bonded to nitrogen atoms, while the ([Formula: see text] -isomers with cis-oriented hydrogen atoms for both of these compounds had significantly higher relative energies.

The cis- and trans-orientation of benzo[1,2-b:4,5-b′]dithiophene-based isomers in organic solar cells

This work provides new insight into the backbone configurations of A-D-A-type acceptors. Two isomers have significant difference in optical and electric properties, resulting in a major impact on the current density and fill factor of the devices.

A Computational Study of a Prebiotic Synthesis of the Steroid Progesterone (A and B Rings)

The magnesium ion metalloporphyrin complex is shown to bind the ligands propyne (p) and ethyne (e) on the metal or nitrogen pyrrole sites as a two site catalyst in their copolymerization. The order of addition of the monomers is (pepeeepee). The steroid ring D (pep) is formed first from the propyne adduct bound to the metal site and the but-diene adduct bound to the N-site. The optimal orientation of these adducts determines the β-orientation of the 17-substituent. Further reaction with hydroxyl radicals allows this to be a 17 β- acetyl substituent. Further addition of three ethyne monomers forms a N-tri-ene cyclopentene derivative able to cyclise to form the steroid ring C (pee) with a trans conformation and a 13-β methyl substituent.. Further binding of propyne on the metal site together with the N-indenyl bound adduct enables the B-ring (eep) to form with a trans orientation and a 10-β-methyl substituent. Further addition of two ethyne monomers to the Mg.porphin.N-phenanthrenyl bound adduct allows cyclisation to form the A-ring (pee). The polymerization is curtailed by reaction with hydroxyl radical to form the 3-keto substituent. The cleavage of the Mg.porphin catalyst produces the double bond of pregnane-4,5-diene-3,20-dione. The reactions have been shown to be feasible from the overall enthalpy changes in the ZKE approximation at the HF and MP2 /6-31G* level, and with acceptable activation energies.

Genome Mining of Marine-Derived Streptomyces sp. SCSIO 40010 Leads to Cytotoxic New Polycyclic Tetramate Macrolactams

Polycyclic tetramate macrolactams (PTMs) biosynthetic gene cluster are widely distributed in different bacterial types, especially in Streptomyces species. The mining of the genomic data of marine-derived Streptomyces sp. SCSIO 40010 reveals the presence of a putative PTM-encoding biosynthetic gene cluster (ptm′ BGC) that features a genetic organization for potentially producing 5/5/6 type of carbocyclic ring-containing PTMs. A fermentation of Streptomyces sp. SCSIO 40010 led to the isolation and characterization of six new PTMs 1–6. Comprehensive spectroscopic analysis assigned their planar structures and relative configurations, and their absolute configurations were deduced by comparing the experimental electronic circular dichroism (ECD) spectra with the reported spectra of the known PTMs. Intriguingly, compounds 1–6 were determined to have a trans-orientation of H-10/H-11 at the first 5-membered ring, being distinct from the cis-orientation in their known PTM congeners. PTMs 1–5 displayed cytotoxicity against several cancer cell lines, with IC50 values that ranged from 2.47 to 17.68 µM.

Synthesis of Cyclobutane Analogue 4: Preparation of Purine and Pyrimidine Carbocyclic Nucleoside Derivatives

The coupling of 2-bromo-3-benzoyloxycyclobutanone with purine under basic conditions produces two regioisomers consisting of the N-7 and N-9 alkylated products in equal amounts in their racemic forms. The distribution of the isomers is consistent with the charge delocalization between the N-7 and N-9 positions of the purinyl anion. The structural assignments and relative stereochemistry of each regioisomer were based on 1 and 2D NMR techniques. The relative stereochemistry of the C-2 and C-3 substituents in each regioisomer was the trans orientation consistent with steric factors in the coupling step. The N-9 regioisomer was reduced with sodium borohydride to give the all trans cyclobutanol as the major product in a stereoselective manner. The alcohol was debenzoylated with sodium methoxide in a transesterification step to give the nucleoside analogue. The regioisomeric pyrimidine nucleosides were prepared by Vorbrüggen coupling of the 3-hydroxymethylcyclobutanone triflate with either thymine or uracil followed by stereoselective hydride addition. Regiospecificity of the coupling at the N-1 position was observed and stereoselective reduction to the trans-disubstituted cyclobutanol structure assignments was based on NMR data.

Crystal structures and conformers of CyMe4-BTBP

The crystal structure of new conformation of the CyMe4-BTBP ligand (ttc) has been presented. The ttt conformer of this compound in a form of THF solvate has been also crystallized. The geometries of six possible conformations (ttt, ttc, tct, tcc, ctc and ccc) of the CyMe4-BTBP ligand have been modeled in the gas phase and in solutions (MeOH and H2O) by DFT calculations using B3LYP/6-31G(d,p) method. According to the calculations, in the three different media the conformers with trans orientation of the N atoms in the bipyridyl moiety are the most stable.

Synthesis, Solution Behavior, Molecular and Supramolecular Structures of the Water-soluble Gold(I) Saccharinate Complexes M[Au(Sac)2] (M = Na, K, NH4)

Three gold(I) saccharinate complexes of the type M[Au(Sac)2] (M = Na, K and NH4) have been prepared by treatment of Au(tht)Cl (tht = tetrahydrothiophene) with saccharine and MOH in MeOHacetone. The compounds are very stable in the solid state but moderately soluble and of limited stability in water. Single crystal X-ray diffraction analysis of the three compounds revealed a linear coordination of the gold atom by the two N-bonded saccharinato ligands. For M = Na, the two heterobicyclic ligands are roughly coplanar with a cis orientation of the two carbonyl groups which allows for a chelation of the sodium cation. For M = K, NH4, the ligands form large dihedral angles with a trans orientation of the donor sites out of which the potassium cations are coordinated in bridging positions between neighboring anions, and the ammonium ions are hydrogen-bonded, respectively.

Structure of artificial and natural VE-cadherinbased adherens junctions

In vascular endothelium, adherens junctions between endothelial cells are composed of VE-cadherin (vascular endothelial cadherin), an adhesive receptor that is crucial for the proper assembly of vascular structures and the maintenance of vascular integrity. As a classical cadherin, VE-cadherin links endothelial cells together by homophilic interactions mediated by its extracellular part and associates intracellularly with the actin cytoskeleton via catenins. Although, from structural crystallographic data, a dimeric structure arranged in a trans orientation has emerged as a potential mechanism of cell–cell adhesion, the cadherin organization within adherens junctions remains controversial. Concerning VE-cadherin, its extracellular part possesses the capacity to self-associate in solution as hexamers consisting of three antiparallel cadherin dimers. VE-cadherin-based adherens junctions were reconstituted in vitro by assembly of a VE-cadherin EC (extracellular repeat) 1–EC4 hexamer at the surfaces of liposomes. The artificial adherens junctions revealed by cryoelectron microscopy appear as a two-dimensional self-assembly of hexameric structures. This cadherin organization is reminiscent of that found in native desmosomal junctions. Further structural studies performed on native VE-cadherin junctions would provide a better understanding of the cadherin organization within adherens junctions. Homophilic interactions between cadherins are strengthened intracellularly by connection to the actin cytoskeleton. Recently, we have discovered that annexin 2, an actin-binding protein connects the VE-cadherin–catenin complex to the actin cytoskeleton. This novel link is labile and promotes the endothelial cell switch from a quiescent to an angiogenic state.

Studies of Dihydropyridines by X-Ray Diffraction and Solid State 13C NMR

Fourteen dimethyl 4-aryl-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylates (DHPs) were evaluated by means of single crystal X-ray diffraction in order to investigate the effects of the structure in the crystals on the solid state 13C NMR chemical shifts. These include the analysis of three DHPs containing two molecules per asymmetric unit. The chiral rotamer unit generated by the s-cis/s-trans orientation of the carbonyl groups, as well as by rotation of the 4-phenyl ring out of the bisecting plane containing the N1, C4, C7 atoms, resulted in a significant magnetic non-equivalence for the C2-CH3/C6-CH3 and the COOCH3 pairs of signals. The solid state 13C NMR data reveal that the substitution pattern of the phenyl ring has a marked effect on the extent to which the signals of the carbonyl carbon atoms and those of C-2/C-6 peaks are split.