Microwave-Assisted Solid-Phase Synthesis of Cephalosporin Derivatives with Antibacterial Activity

Summary.  The reaction of heterocyclic acids with 7-amino-cephalosporanic acid adsorbed on basic alumina under microwave irradiation afforded the N-acylated cephalosporin analogues in satisfactory yield. All compounds were tested for their antibacterial activity; some of them showed significant antibacterial properties. Cefotaxime and cephalothin were used as reference drugs. Received February 23, 2000. Accepted March 28, 2000     

Synthesis,antibacterial, anticancer and molecular docking studies of macrocyclic metal complexes of dihydrazide and diketone

The complexes of Co(II), Ni(II), Cu(II) and Zn(II) metal ions has been synthesized through template method by the condensation of succinic acid dihydrazide with 5-chloroisatin in alcoholic medium. Complexes were characterized by C H N analysis, molar conductance, thermal analysis, magnetic susceptibility, mass spectrometry, FTIR, EPR, ¹H NMR, UV–Visible spectroscopy. These studies suggest an octahedral geometry for all the complexes. The compounds were found active against B. subtilis and S. aureus and P. aeruginosa and E. coli bacteria. The Zn(II) complex showed significant anticancer activity against Squamous Cell Carcinoma cells tested by the MTT assay method. Molecular docking studies with EGFR tyrosine kinase were also carried out. All these results show that some of the synthesized compounds have remarkable antibacterial and anticancer property.     

Identification of Non‐Carbonaceous Cathodes in Al Batteries: Potential Applicability of Black and Blue Phosphorene Monolayers

In the present era of growing energy demands, low‐dimensional materials are emerging as the suitable choices for energy storage due to their excellent ion transport properties, improved reversible capacity, fine rate performance and good cycling stability. In this context, we have investigated the applicability of black and blue phosphorene monolayers as potential cathodes for Al batteries. Both black and blue phosphorene monolayers show similar electrochemical behavior as that of experimentally reported graphite with a charge transfer from the surface in order to bind the tetrahedral geometry of AlCl₄ during the charging process. The adsorption of AlCl₄ drives semiconductor‐to‐metallic transformation of black/blue phosphorene, which ensures constant conductivity in Al batteries. Following the systematic adsorption of AlCl₄, the voltage for black and blue phosphorene is calculated to be ≈1.50 V and ≈1.80 V with storage capacities of 144 mAh g^?1 and 108 mAh g^?1, respectively. Besides, low diffusion barriers of 0.11 eV and 0.14 eV are predicted for AlCl₄ on the respective systems of black and blue phosphorene monolayers. Our work suggests that both black and blue phosphorene monolayers can be potential cathodes for Al batteries with delivery of high storage capacity and high voltage, respectively.     

Microwave-Assisted Solid-Phase Synthesis of Cephalosporin Derivatives with Antibacterial Activity

 The reaction of heterocyclic acids with 7-amino-cephalosporanic acid adsorbed on basic alumina under microwave irradiation afforded the N-acylated cephalosporin analogues in satisfactory yield. All compounds were tested for their antibacterial activity; some of them showed significant antibacterial properties. Cefotaxime and cephalothin were used as reference drugs.     

Shifted Witt groups of semi-local rings

We show that the odd-indexed derived Witt groups of a semi-local ring with trivial involution vanish. We show that this is wrong when the involution is not trivial and we provide examples.The first author was supported by the Swiss National Science Foundation, grant 620-66065. The second author would like to thank the ETH-Zurich for its generous support.     

Hasse principle for classical groups over function fields of curves over number fields

In (Letter to J.-P. Serre, 12 June 1991) Colliot-Thélène conjectures the following: Let F be a function field in one variable over a number field, with field of constants k and G be a semisimple simply connected linear algebraic group defined over F. Then the map has trivial kernel, denoting the set of places of k.The conjecture is true if G is of type 1A∗, i.e., isomorphic to SL₁(A) for a central simple algebra A over F of square free index, as pointed out by Colliot-Thélène, being an immediate consequence of the theorems of Merkurjev-Suslin [S1] and Kato [K]. Gille [G] proves the conjecture if G is defined over k and F=k(t), the rational function field in one variable over k. We prove that the conjecture is true for groups G defined over k of the types 2A∗, B_n, C_n, D_n (D₄ nontrialitarian), G₂ or F₄; a group is said to be of type 2A∗, if it is isomorphic to SU(B,τ) for a central simple algebra B of square free index over a quadratic extension k′ of k with a unitary k′|k involution τ.     

Spectrophotometric determination of beryllium with carminic acid

Summary A new reagent has been proposed for the determination of beryllium. The method is based on the reaction between beryllium and carminic acid, forming a Be-carminic acid complex at pH 4. The absorption is measured at 580 nm. The molar absorptivity is 2.25×10³ mol^–1 cm^–1. Beer's law is obeyed from 0.4 ppm to 1.6 ppm of beryllium. The effects of pH, reagent concentration and interferences from foreign ions have been studied. The method has been applied to the determination of beryllium in polluted water and blood samples.

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Spektralphotometrische Bestimmung von Beryllium mit CarminsÄure

     

Phase Diagram Study of Succinonitrile-Vanillin Organic Alloy System

Phase diagram studies of succinonitrile-vanillin system show the formation of 2:1 congruent melting type compound. Crystallization velocities of pure components, succinonitrile-vanillin complex, and two eutectics have been determined at different undercoolings. On the basis of heat of fusion measurements, excess thermodynamic functions have been calculated. Microstructural studies revealed that impurities modify the morphology. FTIR spectral studies and computer simulation have shown the existence of hydrogen bonding in the eutectics and the congruent melting compound. On the basis of experimental results, the mechanism of formation of eutectics and its solidification behavior are discussed.     

Solvent free reactions

Reactions of nitrophenols have been studied in the eutectic melt of 8-hydroxyquinoline–benzoic acid, where it reacted with 8-hydroxyquinoline. The reactions were also carried out in solution. The reaction products obtained from both the methods were characterized by FT-IR, differential scanning calorimetry, X-ray diffraction technique and microstructural investigations. The reaction products obtained from eutectic melt were analyzed for C, H, N. The results showed that reaction products obtained from both the methods are same. An attempt has been made to propose the overall mechanism of the reaction in the eutectic melt.     

Molecular mechanism-based network-like similarity graphs reveal relationships between different types of receptor ligands and structural changes that determine agonistic, inverse-agonistic, and antagonistic effects

Receptor ligands might act as agonists, partial agonists, inverse agonists, or antagonists and it is often difficult to understand structural modifications that alter the mechanism of action. In order to compare ligands that are active against a given receptor but have different mechanisms of action, we have designed molecular networks that mirror similarity relationships and incorporate both mechanism of action information and mechanism-specific SAR features. These network representations make it possible to systematically evaluate relationships between different types of receptor ligands and identify communities of structurally very similar ligands with different mechanisms. From a series of such ligands, structural modifications can often be deduced that lead to "mechanism hops".