Synthesis and characterization of new homologous series of unsymmetrical liquid crystalline compounds based on chalcones and 3, 5-disubstituted isoxazoles

Two homologous series of unsymmetrical alkylated chalcones and 3,5-diaryl isoxazoles, consisting of 20 members, with various n-alkyl bromides (n=2−7, 10, 12, 14, 16) have been synthesized and studied for their liquid crystalline property. Simple strategy was employed to achieve the target materials. Flexibilityin the synthesized molecules is provided by attaching straight alkoxy chains, where one terminal group is fixed and other terminal group is varied. The synthesized compounds were characterized on the basis of Mass, IR and NMR spectroscopy. The stability and the range of the mesophases increased with the length of the chain on the isoxazoles. The melting point, transition temperatures and enantiotropic liquid crystal morphologies were determined by polarizing optical microscopy (POM) in conjunction with a hot stage and by differential scanning calorimetry (DSC)

One pot synthesis of dihydroisoxazoles via 1,3-dipolar cycloaddition of nitrile oxides to allyl chloride

Nitrile oxides derived from oxidative dehydrogenation of aldoximes by chloramine-T react with allyl chloride to afford 5-(chloromethyl)-3-aryl-4,5-dihydroisoxazoles in good yields. All compounds were characterized by IR, 1 H-NMR, and MS studies

One pot synthesis of dihydroisoxazoles via 1,3-dipolar cycloaddition of nitrile oxides to allyl chloride

Nitrile oxides derived from oxidative dehydrogenation of aldoximes by chloramine-T react with allyl chloride to afford 5-(chloromethyl)-3-aryl-4,5-dihydroisoxazoles in good yields. All compounds were characterized by IR, 1 H-NMR, and MS studies

Synthesis and pharmacological evaluation of 1,3,4-oxadiazole bearing bis(heterocycle) derivatives as anti-inflammatory and analgesic agents

A series of novel ether-linked bis(heterocycle)s have been synthesized via 3 + 2]-cycloaddition reaction of nitrile oxide with allyl alcohol followed by intramolecular 1,3-diploar cycloaddition reaction of nitrite imine with carbonyl group. All the newly synthesized compounds were screened for their anti-inflammatory and analgesic activities. Among the list of compounds (7a-k) studied, 7d, 7g, 7j, and 7k exhibited excellent activity comparable to ibuprofen and aspirin at the similar dosages. (C) 2009 Elsevier Masson SAS. All rights reserved

The first crystal structure of NAD-dependent 3-dehydro-2-deoxy-d-gluconate dehydrogenase from Thermus thermophilus HB8

2-Keto-3-deoxygluconate (KDG) is one of the important intermediates in pectin metabolism. An enzyme involved in this pathway, 3-dehydro-3-deoxy-d- gluconate 5-dehydrogenase (DDGDH), has been identified which converts 2,5-diketo-3-deoxygluconate to KDG. The enzyme is a member of the short-chain dehydrogenase (SDR) family. To gain insight into the function of this enzyme at the molecular level, the first crystal structure of DDGDH from Thermus thermophilus HB8 has been determined in the apo form, as well as in complexes with the cofactor and with citrate, by X-ray diffraction methods. The crystal structures reveal a tight tetrameric oligomerization. The secondary-structural elements and catalytically important residues of the enzyme were highly conserved amongst the proteins of the NAD(P)-dependent SDR family. The DDGDH protomer contains a dinucleotide-binding fold which binds the coenzyme NAD + in an intersubunit cleft; hence, the observed oligomeric state might be important for the catalytic function. This enzyme prefers NAD(H) rather than NADP(H) as the physiological cofactor. A structural comparison of DDGDH with mouse lung carbonyl reductase suggests that a significant difference in the α-loop-α region of this enzyme is associated with the coenzyme specificity. The structural data allow a detailed understanding of the functional role of the conserved catalytic triad (Ser129-Tyr144-Lys148) in cofactor and substrate recognition, thus providing substantial insights into DDGDH catalysis. From analysis of the three-dimensional structure, intersubunit hydrophobic interactions were found to be important for enzyme oligomerization and thermostability

Effect of ionic conductivity in aluminophosphates with different organic structure directing templates

The ionic conductivity has been measured for different organic templates in aluminophosphate gels. After crystallization of aluminophosphates under hydrothermal conditions, the conductivity exhibited by these materials arises from the migration of cations through the anion framework cages. The thermodynamic parameters have been evaluated