Cyclization of 4,5‐Diamino Pyrazole Derivatives and Their Antibacterial Activities

A convenient synthesis of intermediate 4,5‐diamino‐3‐aryl‐1‐phenylpyrazoles 4a – 4c was reported. The different cyclization reactions were carried out with chalcone, 2‐mercaptoacetic acid and p‐anisialdehyde, ethyl chloroformate, glyoxal and thiourea to afford different N and S containing heterocycles. The reaction conditions were compared by conventional heating and microwave irradiation. The structures of the cyclization products were determined by analytical and spectroscopic data. All the synthesized compounds were screened for antibacterial activities in vitro.     

Solution studies of dinuclear polyamine-linked platinum-based antitumour complexes

The aquation profiles of two novel dinuclear polyamine-linked, platinum-based antitumour complexes [{trans-PtCl((15)NH(3))(2)}(2){μ-((15)NH(2)(CH(2))(6)(15)NH(2)(CH(2))(6)(15)NH(2))}](3+) (BBR3007, 1,1/t,t-6,6, 1) and [{trans-PtCl((15)NH(3))(2)}(2){μ-((15)NH(2)(CH(2))(6)(15)NH(2)(CH(2))(2)(15)NH(2)(CH(2))(6)(15)NH(2))}](4+) (BBR3610, 1,1/t,t-6,2,6, 1') have been probed using 2D [(1)H, (15)N] HSQC NMR spectroscopy. Reported herein are the rate constants for the hydrolysis of 1 and 1', as well as the acid dissociation constants of the coordinated aqua ligands in their aquated derivatives. The aquation and anation rate constants for the single step aquation model in 15 mM NaClO(4) (pH 5.4) at 298 K are, for 1, k(1) = 7.2 ± 0.1 ×10(-5) s(-1), k(-1) = 0.096 ± 0.002 M(-1) s(-1) and, for 1', k(1) = 4.0 ± 0.2 × 10(-5) s(-1), k(-1) = 1.4 ± 0.1 M(-1) s(-1). The effect of the linker backbone (Pt(tetra(m)mine vs. polyamine) was evaluated by comparison with previous data for the trinuclear complex [{trans-PtCl(NH(3))(2)}(2)(μ-trans-Pt(NH(3))(2){NH(2)(CH(2))(6)NH(2)}(2))](4+) (1,0,1/t,t,t or BBR3464). The pK(1) for 1,0,1/t,t,t (3.44) is closest to that of 1 (3.12), while the pronounced difference for 1' (4.54), means that 1' is the least aquated of the three complexes at equilibrium. pK(a) values of 5.92 were calculated for the aquated forms of both 1 and 1', which are 0.3 pK units higher than for either 1,0,1/t,t,t, or the dinuclear 1,1/t,t. The higher pK(a) values for both polyamine-linked compounds may be attributed to the formation of macrochelates between the central NH(2) groups and the {PtN(3)O} coordination sphere of the aquated species.     

The Behavior of Certain Coumarins and Furocoumarins Toward Sulfur Reagents

The behavior of 4-hydroxycoumarin (1), 7-hydroxycoumarin (2), 4-hydroxy-bergapten (3), and 4-hydroxyisopimpinellin (4) toward sulfur reagents, namely, thionyl chloride, phosphorus pentasulfide, thiolacetic acid, and Lawesson's reagent (5), was studied. The nature of products in each case depended upon the type of reactants and reaction conditions. Possible reaction mechanisms were considered, and structural elucidations of the new products were based upon compatible elementary and spectroscopic evidences.     

POLYMERIC SURFACTANTS BASED ON OLEIC ACID III. Copolymerization of Sodium Acrylamidostearate and Oleic Acid in a Lamellar Liquid Crystal

Copolymerization of sodium acrylamidostearate (NaAAS) and oleic acid was performed in the lamellar liquid crystal (LLC) formed by NaAAS, oleic acid and water, in the absence of N.N’-methylenebisacrylamide (MBAA) and in the presence of MBAA, respectively. In the absence of MBAA, after the polymerization the lamellar structure remained, and the disorder of the lamellar liquid crystal was, to some extent, enhanced. Surface tension, small-angle X-ray diffraction, viscosity, and fluorescence methods were used to study the properties of the linear copolymer. The linear polymeric surfactant behaves like     

Physicochemical studies of a new series of aryloxide complexes,Na2[Co(OAr)4].nTHF

Summary By the interaction of anhydrous CoBr₂ or CoBr₂·2THF with different sodium aryloxides, a new series of complexes of general formula Na₂[Co(OAr)₄]·nTHF (OAr =o-nitro,o-chloro,o-bromo,m-chloro,p-bromo, 2,4-dichloro, 2,6-dichloro, or 2,4-dimethylphenoxide;n = 1, 3, 4 or 5) were prepared and characterized by physicochemical means. The electronic spectra and magnetic measurements suggest a tetrahedral geometry for cobalt(II). Heating the complexes led to reversible loss of THF with an accompanying colour change.     

STUDIES ON THE INTERACTION OF EPOXY POLYMERS WITH HOMOPOLYUREAS

INTRODUCTION Epoxy resins are reactive polymers which when cured with a variety of chemicals lead to a host of useful thermosets. Since the epoxide is a strained ring, it readily undergoes addition and homopolymerization. The homopolymerization is a process catalysed by acids, bases, Lewis acids, t-amines as well as by inorganic salts.     

Mixed-Isotope Labeling with LC-IMS-MS for Characterization of Protein–Protein Interactions by Chemical Cross-Linking

Chemical cross-linking of proteins followed by proteolysis and mass spectrometric analysis of the resulting cross-linked peptides provides powerful insight into the quaternary structure of protein complexes. Mixed-isotope cross-linking (a method for distinguishing intermolecular cross-links) was coupled with liquid chromatography, ion mobility spectrometry and mass spectrometry (LC-IMS-MS) to provide an additional separation dimension to the traditional cross-linking approach. This method produced multiplet m/z peaks that are aligned in the IMS drift time dimension and serve as signatures of intermolecular cross-linked peptides. We developed an informatics tool to use the amino acid sequence information inherent in the multiplet spacing for accurate identification of the cross-linked peptides. Because of the separation of cross-linked and non-cross-linked peptides in drift time, our LC-IMS-MS approach was able to confidently detect more intermolecular cross-linked peptides than LC-MS alone.      

trans‐Diaquabis(3‐hydroxybenzoato‐κO1)bis(nicotinamide‐κN1)copper(II)

The title compound, [Cu(C₇H₅O₃)₂(C₆H₆N₂O)₂(H₂O)₂], is a two‐dimensional hydrogen‐bonded supramolecular complex. The Cu^II ion resides on a centre of symmetry and is in an octahedral coordination environment comprising two pyridine N atoms, two carboxylate O atoms and two O atoms from water molecules. Intermolecular N—H...O and O—H...O hydrogen bonds produce R₂²(4), R₂²(8) and R₂²(15) rings which lead to one‐dimensional polymeric chains. An extensive two‐dimensional network of N—H...O and O—H...O hydrogen bonds and C—H...π interactions are responsible for crystal stabilization.     

Iron Oxide Supported on Al2O3 Catalyst for Methane Decomposition Reaction: Effect of MgO Additive and Calcination Temperature

Production of hydrogen is a challenging task and have significant impact in the recent scenario. The alumina supported iron oxide nanoparticle synthesized using non‐ionic surfactant Triton‐X was found very effective for steady production of hydrogen through methane decomposition reaction. The high surface area, easily reducible catalyst calcined at 500 °C and 800 °C temperature showed steady activity towards methane decomposition reaction. At a higher reaction temperature there was catalyst deactivation. The doping of MgO facilitated particle growth rendering the poor catalytic activity. The TPR study showed that reducibility of TPR was difficult in presence of MgO additive. The formation of Fe? Mg? Al solid solution confirmed by XRD study was found mainly responsible for the lower catalytic activity. The bamboo‐shaped carbon nanotube formed from 20 % Fe/Al₂O₃ catalyst which is mainly because of the poor wetting property of quasi‐liquid metal and carbon nanotube.