New computer program to calculate the symmetry of molecules

In this paper we, present some MATLAB and GAP programs and use them to find the automorphism group of the Euclidean graph of the C₈₀ fullerence with connectivity and geometry of I _h symmetry point group. It is proved that this group has order 120 and is isomorphic to I _h ≊Z₂×A₅, where Z₂ is, a cyclic group of order 2 and A₅ is the alternating group on five symbols.     

Stereoselective 1,2-cis glycosylation of 2-O-allyl protected thioglycosides

The technique of intramolecular aglycon delivery (IAD), whereby a glycosyl acceptor is temporarily appended to a hydroxyl group of a glycosyl donor is an attractive method that can allow the synthesis of 1,2-cis glycosides in an entirely stereoselective fashion. 2-O-Allyl protected thioglycoside donors are excellent substrates for IAD, and may be glycosylated stereoselectively through a three-step reaction sequence. This sequence consists of quantitative yielding allyl bond isomerisation, to produce vinyl ethers that can then undergo N-iodosuccinimide mediated tethering of the desired glycosyl acceptor, and subsequent intramolecular glycosylation, to yield either alpha-glucosides or beta-mannosides accordingly. Although attempted one-pot tethering and glycosylation is hampered by competitive intermolecular reaction with excess glycosyl acceptor, this problem can be simply overcome by the use of excess glycosyl donor. Allyl mediated IAD is a widely applicable practical alternative to other IAD approaches for the synthesis of beta-mannosides, that is equally applicable for alpha-gluco linkages. It is advantageous in terms of both simplicity of application and yield, and in addition has no requirement for cyclic 4,6-protection of the glycosyl donor.     

Die Reaktion von Tellurhexafluorid mit Trimethylamin,Strukturen der TeF5−- und SeF5−-Anionen

Reaction of Telluriumhexafluoride and Trimethylamine, Structures of the TeF₅^? and SeF₅^? Anions The reaction of TeF₆ and (CH₃)₃N is of the redox kind, resulting in reduction of tellurium: X-ray single crystal analysis reveals the compounds (CH₃)₂N? CH₂? N(CH₃)₂⁺TeF₅^? and [(CH₃)₃NH⁺]₅(TeF₅^?)₃(HF₂^?)₂. By comparison with published data it can be shown that this mixture is identical to previously published [(CH₃)₃N]₂TeF₆. The latter was supposed to be one of the few examples of tellurium in a coordination state of eight. (CH₃)₄N⁺TeF₅^? and (CH₃)₄N⁴SeF₅^? are obtained and their structure is investigated by single crystal x-ray methods also. The anions SF₅^?, SeF₅^? and TeF₅^? are discussed in terms of weak interactions.     

A novel one-pot synthesis of some new interesting pyrrole derivatives

[reaction: see text] 11-(1H-Pyrrol-1-yl)-11H-indeno[1,2-b]quinoxaline and 3-(1H-pyrrol-1-yl)indolin-2-one derivatives have been synthesized in good yields in a novel, one-pot, and efficient process by condensation of 11H-indeno[1,2-b]quinoxalin-11-one or isatin derivatives with 4-hydroxyproline on solid-support montmorillonite K10 under microwave irradiation.     

Absorption spectra of 2-styryl-4-phenyl-thiazole ethiodides in organic solvents of varying polarities and determination of the formation constant of the charge transfer complex formed

The electronic absorption spectra of some 2-styryl-4-phenyl-thiazole ethiodides are studied in organic solvents of different polarities. The shorter wavelength band appearing in the visible region is assigned to an intramolecular charge transfer (CT)-transition originating from the phenyl moiety to the positively charged hetero ring, while the longer wavelength one is due to an intermolecular CT-transition from the iodide ion to the 2-styryl-4-phenyl-thiazolinium cation. These assignments are based on the nature of the aldehydic residue and effects of solvent, concentration, and temperature on both the position and absorptivity of the CT complex-band. It is concluded that the CT complex formed will be highly solvated inDMF, DMSO, ethanol and methanol relative to in CHCl₃, dioxane and acetone. The formation constant of the CT complex in solutions of different polarities is determined at different temperatures. Furthermore, the thermodynamic parameters H ^o, G ^o and S ^o for complex formation are calculated and discussed.

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Absorptionsspektren von 2-Styryl-4-phenyl-thiazol-ethiodiden in verschiedenen Lösungsmitteln und Bestimmung der Bildungskonstanten der Charge-Transfer-Komplexe

Zusammenfassung Die Elektronenanregungsspektren einiger substituierter 2-Styryl-4-phenyl-thiazol-ethiodide wurden in einigen Lösungsmitteln unterschiedlicher Polarität untersucht. Die Absorption bei kürzerer Wellenlänge wird einem intramolekularen Charge-Transfer (CT)-Übergang zugeordnet, die langwellige Bande einem intermolekularen CT-Übergang (Jodid—organ. Kation). Die Diskussion erfolgt basierend auf Substitutions-, Lösungsmittel-, Konzentrations-, und Temperatur-Effekten. Die Komplexbildungskonstanten und die thermodynamischen Parameter H ^o, G ^o und S ^o werden angegeben.

     

Divalent transition metal ion mixed ligand complexes with aliphatic dicarboxylic acids and imidazoles

Summary Mixed ligand metal complexes of Co^II, Ni^II and Cu^II with dicarboxylic aliphatic acids, H₂L (succinic, malic and tartaric) as primary ligands and with imidazoles, L (imidazole and 2-methylimidazole) as secondary ligands were prepared and characterized. MLL₂ and ML₄ molecular formulae were suggested for these complexes were Formation constants of the different complexes were determined pH-metrically at T = 25 ± 0.1°C and = 0.1 mol dm^–3 (NaClO₄). The stability of the mixed ligand complexes increased as the effective basicity of the dicarboxylic aliphatic acid anion increased, namely, tartarate < malate < succinate acid.     

Factors Contributing to Solubility Synergism of Some Basic Drugs with β-Cyclodextrin in Ternary Molecular Complexes

Ternary complexes exploiting solubility synergism (SSn) between basic drugs and β-cyclodextrin (β-CD) in the presence of an organic hydoxy acid have been reported to provide the pharmaceutical technology with highly soluble ternary complexes, even with the least soluble β-CD. In this work, phase solubility techniques were used to study factors affecting SSn in aqueous solution, which may help in understanding the mechanism involved in ternary complex formation in solution, under equilibrium conditions. The equilibrium solubility of both β-CD and each of 8 structurally unrelated drugs were measured in tandem in the presence of different acid types at low and high pHs, and at different time intervals over a period of 1–40 days. The results indicate that SSn is evident regardless of acid type (organic and inorganic) at low pH, but the extent of SSn is acid type dependant and is limited by the drug salt solubility product constant (pK _sp). Among different drugs, no apparent trend exists between drug salt solubility and the extent of SSn, but lowering drug salt solubility by increasing pH depresses SSn. The results also reveal no apparent trend between the magnitude of the complex formation constant (K _ij) and SSn. For example, drugs of low K _ij values such as astemizole, cisapride and sildenafil do not show any SSn, yet ketotifen and pizotifen, which also have low K _ij values, exhibit substantial SSn. However, the solublizing power of β-CD represented by the slope of phase solubility diagram can be used as a marker for SSn (slopes exceeding 0.4 induce SSn).     

Chelate Compounds of a Selected Non-Transition and Transition Metal Ions with Some Salicylic Acid Derivatives

A series of binary complexes of Zn(II), Hg(II), Pb(II), La(III), Ce(III), Th(IV) and UO₂(II) with 3,5-dinitrosalicylic acid and 5-sulphosalicylic acid have been isolated and characterized. The solution equilibria of these complexes have been studied pH-metrically. The formation constants (log K) at 25±1°C and ionic strength of 0.2M NaClC₄ have been calculated. Stability of the complexes formed in relation to ligand molecular structure and nature of the metal ion has been examined and discussed.     

Spectroscopic characterization of human and mouse primary cells,cell lines and malignant cells

Fourier transform infrared (FTIR) spectroscopy is currently being developed as a new optical approach to the diagnosis and characterization of cell or tissue pathology. The advantage of FTIR microspectroscopy over conventional FTIR spectroscopy in the diagnosis of malignancies is that it facilitates inspection of restricted regions of the cell culture or tissue. In this study, we set out to evaluate FTIR microspectroscopy as a diagnostic tool for identifying retrovirus-induced malignancies. Our study showed significant and consistent differences between cultures of different types of cells of both mouse and human origin, i.e. primary fibroblast cells (one to two passages in cell culture), fibroblast cell lines and malignant cells transformed by murine sarcoma virus. An impressive decrease in the levels of phosphate and other metabolites was seen in malignant cells compared with primary cells. The levels of these metabolites in the cell lines were significantly lower than in the primary cells but higher than in the malignant cells. In addition, the peak attributed to the PO2- symmetric stretching mode at 1082 cm(-1) in primary cells shifted significantly to 1085 cm(-1) for the cell line and to 1087 cm(-1) for the malignant cells. These differences taken together with differences in the shapes of various bands throughout the spectrum strongly support the possibility of developing FTIR microspectroscopy for the detection and study of malignant--and possibly premalignant--cells.     

Dendrimer‐encapsulated Cu(Π) nanoparticles immobilized on superparamagnetic Fe3O4@SiO2 nanoparticles as a novel recyclable catalyst for N‐arylation of nitrogen heterocycles and green synthesis of 5‐substituted 1H‐tetrazoles

In this study, dendrimer‐encapsulated Cu(Π) nanoparticles immobilized on superparamagnetic Fe₃O₄@SiO₂ nanoparticles were prepared via a multistep‐synthesis. Then, the synthesized composite was fully characterized by various techniques such as fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), dynamic light scattering (DLS), UV‐vis spectroscopy, energy dispersive X‐ray analysis (EDX), thermogravimetric analysis (TGA) and vibration sample magnetometer (VSM). From the information gained by FE‐SEM and TEM studies it can be inferred that the particles are mostly spherical in shape and have an average size of 50 nm. Also, the amount of Cu is determined to be 0.51 mmol/g in the catalyst by inductively coupled plasma (ICP) analyzer. This magnetic nano‐compound has been successfully applied as a highly efficient, magnetically recoverable and stable catalyst for N‐arylation of nitrogen heterocycles with aryl halides (I, Br) and arylboronic acids without using external ligands or additives. The catalyst was also employed in a one‐pot, three‐component reaction for the efficient and green synthesis of 5‐substituted 1H‐tetrazoles using various aldehydes, hydroxylamine hydrochloride and sodium azide in water. The magnetic catalyst can be easily separated by an external magnet bar and is recycled seven times without significant loss of its activity.