Pd (II)‐catalyzed vinyl addition polymerization of novel functionalized norbornene bearing dimethyl carboxylate groups

Three novel functionalized polynorbornenes (PNB) with pendant dimethyl carboxylate group (carboxylates—acetate, propionate, and butyrate) are synthesized as a vinyl‐type with a palladium (II) catalyst in high yield. The effects of size of substitutents, molar ratio of monomer to catalyst, solvent polarity, reaction time, and temperature on the polymerization of exo‐norbornene dimethyl propionate were systematically investigated. The low molar ratio and temperature, as well as high polarity of solvent, and long reaction time, are favorable for the enhancement of the monomer conversion, especially, the solvent have an obvious effect on the catalyst activity. The resulting poly(cis‐norbornene‐exo‐2,3‐dimethyl carboxylates) (PNB‐dimethyl carboxylates) show good solubility in common organic solvent and high thermal stability up to 360 °C. The glass transition temperature was detected by DMA at 331, 324, and 318 °C for acetate, propionate, and butyrate, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3391–3399, 2007     

Anticancer agent development: X-ray crystal structure and keto-enol tautomerism of dimethyl 1-hydroxy-6,7-methylenedioxy-4-(3′,4′,5′-trimethoxyphenyl-trans-3,4-dihydronaphthalene-2,3-dicarboxylate

Structural and conformational information obtained from the crystal structure and solution¹H nmr investigations of the title compound are compared. The 4-aryltetralone, C₂₄H₂₄O₁₀, crystallizes as a chloroform solvate in the monoclinic space group, P2₁/n, witha=12.519(4),b=17.938(6),c=12.534(9)Å,=111.90(5)°, and D_calc=1.51 g cm^–3 forZ=4. The data for this compound were collected at –150°C. Least-squares refinement of 2796 observed [F _o5(F _o)] reflections led to the final agreement index ofR=0.062. A threefold static disorder was observed for one of the carboxyl groups. The second carboxyl group participates in an intramolecular hydrogen bond and is thus ordered. The¹H nmr spectrum revealed the title compound to exist as a keto-enol tautomeric mixture in solution. Vicinal hydrogen coupling constant analysis proved reliable in ascertaining B-ring stereochemistry of 2,3-disubstituted-4-aryltetralones.     

Synthesis of molecular sieve AlPO4-12

A member of the novel family of crystalline microporous aluminophosphates, AlPO₄-12, was synthesized by hydrothermal crystallization using different aluminum-containing compounds. Three new crystalline phases were obtained by varying the composition of the reaction mixture. The effect of the synthesis conditions on the hudrothermal process and the kinetics of crystallization are discussed. The apparent activation energies obtained for AlPO₄-12 are 20.9 and 14.6 kcal/mol for nucleation and crystallization, respectively. The adsorption isotherms of one AlPO₄-12 product were measured.     

FT–IR spectroscopic study on the photo- and photooxidative degradation of nylons

The progress of photo- and photooxidative degradation of nylon films were studied by FT–IR spectroscopy. The gases evolved from the photolysis of various nylons and their model amides were also analyzed. The formation of double bonds, changes of crystallinity, and the effect of amino and carboxyl end groups has been studied and discussed. The band shapes of the IR spectra pertaining to the carbonyl groups formed by thermal oxidation or photooxidation were found to be very similar, suggesting that the two oxidation mechanisms might be similar. The broadness of these bands indicates that the carbonyl groups may belong to more than one species. The photodegradation of nylons containing purposely inserted carbonyl groups formed ? CH?CH₂ groups. Carbonyl groups formed during oxidation, and present either as keto groups or part of N-acylamide units make nylons susceptible to degradation reactions entailing mainly a Norrish type II mechanism.     

Natural abundance 13C - 13C coupling constants observed via double quantum coherence. Structural elucidation by the one- and the two-dimensional NMR experiements of velloziolone,a new seco-diterpene.

With the help of Natural Abundance ¹³C - ¹³C Coupling Constants, observed via double quantum coherence, the structural determination of VELLOZIOLONE (1), a new diterpene, has been carried out.     

Antimicrobial activity studies of the binuclear metal complexes derived from tridentate Schiff base ligands

Three novel tridentate Schiff base ligands derived fromthe 3-hydroxysalicylaldehyde (H₂L¹), 4-hydroxysalicylaldehyde (H₂L²) and 5-bromosalicylaldehyde (H₂L³) with a new amine N-(pyridyl)-2-hydroxy-3-methoxy-5-aminobenzylamine (2) have been prepared. The ligands and their metal complexes have been characterized by elemental analyses, conductivity and magnetic susceptibility measurements, i.r., electronic absorption and ¹H and ¹³C n.m.r. spectroscopy. All complexes are binuclear and, in some, the H₂O molecules are coordinated to the metal ion. Antimicrobial activities of the ligands and their complexes have been tested against to the Bacillus subtilis IMG 22 (bacteria), Micrococcus luteus LA 2971 (bacteria) Saccharamyces cerevisiae WET 136 (yeast), and Candida albicans CCM 314 (yeast). Thermal properties of all complexes have been studied by t.g. and d.t.a techniques.     

On the physical adsorption of gases on carbon materials from molecular simulation

In this paper we present a series of work covering a range of aspects relating molecular simulation to experiment. The importance of surface mediation type effects to the adsorption of simple and complex gases is demonstrated. Coupled with the adsorption of simple gases is their projection area when used for surface area determination. The pressure dependence of a projection area is demonstrated for argon at 77 and 87.3 K. A simple model is used to account for the degree of graphitisation of a surface is demonstrated and used to account for the isosteric heat behaviour of non-graphitised carbon blacks. Turning from surfaces to porous solids, an alternative treatment of experiment data (either sub or super critical) is presented that avoids the ambiguity of excess amounts adsorbed. Using this method one is able to obtain pore size distributions and amounts adsorbed without relying on such things as helium expansion volumes. Since this type of method is usually applied to composite solids we also demonstrate the correct method for calculating the heat of adsorption using independent sets of simulations. The final topic covered in this paper is an example of the information that can be gained from the heat capacity of an adsorbed phase.     

Global Forcing Number of Benzenoid Graphs

A global forcing set in a simple connected graph G with a perfect matching is any subset S of E(G) such that the restriction of the characteristic function of perfect matchings of G on S is an injection. The number of edges in a global forcing set of the smallest cardinality is called the global forcing number of G. In this paper we prove several results concerning global forcing sets and numbers of benzenoid graphs. In particular, we prove that all catacondensed benzenoids and catafused coronoids with n hexagons have the global forcing number equal to n, and that for pericondensed benzenoids the global forcing number is always strictly smaller than the number of hexagons.     

Nonequilibrium synthesis and assembly of hybrid inorganic-protein nanostructures using an engineered DNA binding protein

We show that a protein with no intrinsic inorganic synthesis activity can be endowed with the ability to control the formation of inorganic nanostructures under thermodynamically unfavorable (nonequilibrium) conditions, reproducing a key feature of biological hard-tissue growth and assembly. The nonequilibrium synthesis of Cu(2)O nanoparticles is accomplished using an engineered derivative of the DNA-binding protein TraI in a room-temperature precursor electrolyte. The functional TraI derivative (TraIi1753::CN225) is engineered to possess a cysteine-constrained 12-residue Cu(2)O binding sequence, designated CN225, that is inserted into a permissive site in TraI. When TraIi1753::CN225 is included in the precursor electrolyte, stable Cu(2)O nanoparticles form, even though the concentrations of [Cu(+)] and [OH(-)] are at 5% of the solubility product (K(sp,Cu2O)). Negative control experiments verify that Cu(2)O formation is controlled by inclusion of the CN225 binding sequence. Transmission electron microscopy and electron diffraction reveal a core-shell structure for the nonequilibrium nanoparticles: a 2 nm Cu(2)O core is surrounded by an adsorbed protein shell. Quantitative protein adsorption studies show that the unexpected stability of Cu(2)O is imparted by the nanomolar surface binding affinity of TraIi1753::CN225 for Cu(2)O (K(d) = 1.2 x 10(-)(8) M), which provides favorable interfacial energetics (-45 kJ/mol) for the core-shell configuration. The protein shell retains the DNA-binding traits of TraI, as evidenced by the spontaneous organization of nanoparticles onto circular double-stranded DNA.     

Review of time lag permeation technique as a method for characterisation of porous media and membranes

The time lag permeation technique has proven to bean effective method for characterisation. Because of the simple nature of the permeation experiment, transport parameters can be directly obtained from experimental data hence avoiding the intensive mathematical treatment required by other techniques. The method has historically been applied to diffusion and adsorption in porous membranes and diffusion in polymer membranes. Since its origins in 1920, interest in the time lag method has expanded because of its value in characterising simple permeation processes and also complex systems of diffusion with simultaneous adsorption and surface diffusion. This review focuses on presenting the asymptotic solution of the mass balance diffusion equations and includes applications of time lag analysis, in order to give a critical and broad perspective of this method as a tool for characterisation. It includes much of the previously published literature in order to show that for most cases the asymptotic solution of the transport equations is simple, and for more complex cases that an analytical solution is possible hence avoiding cumbersome numerical techniques.