One step microelectroelution concentration method for efficient coupling of sodium dodecylsulfate gel electrophoresis and matrix-assisted laser desorption time-of-flight mass spectrometry for protein analysis

The coupling of the widely used separation technique of conventional sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) with the mass accuracy measurement capability of mass Spectrometry (MS) provides a very powerful analytical technique. However, at present, there is no simple, definitive method for coupling the two methods. Typically, separated proteins are extracted from the gel, either as the native protein or as a peptide mixture after in-gel proteolytic digestion, and then analyzed by mass Spectrometry. However, the various extraction techniques described previously have been labor intensive and require a large number of steps. The mass Spectrometry analysis of very low concentrations of in vivo derived proteins requires minimum sample handling and on-line concentration. Therefore, we have developed an efficient microelectroelution technique that is applied in a single step manner and contains an on-line concentration device. Initial results from this system have shown a high efficiency of analyte elution from the gel and a simple, robust technique for the coupling of SDS-containing gels with MALDI-TOF-MS analysis and a capability of analyzing proteins at the subpicomole level.     

Carbazole compounds as host materials for triplet emitters in organic light-emitting diodes: polymer hosts for high-efficiency light-emitting diodes

A carbazole homopolymer and carbazole copolymers based on 9,9'-dialkyl-[3,3']-bicarbazolyl, 2,5-diphenyl-[1,3,4]-oxadiazole and 9,9-bis(4-[3,7-dimethyloctyloxy]phenyl)fluorene were synthesized and their electrical and photophysical properties were characterized with respect to their application as host in phosphorescent polymer light-emitting diodes. It is shown that the triplet energy of a polymer depends on the specific connections between its building blocks. Without changing the composition of the polymer, its triplet energy can be increased from 2.3 to 2.6 eV by changing the way in which the different building blocks are coupled together. For poly(9-vinylcarbazole) (PVK), a carbazole polymer often used as host for high-energy triplet emitters in polymer light-emitting diodes, a large hole-injection barrier of about 1 eV exists due to the low-lying HOMO level of PVK. For all carbazole polymers presented here, the HOMO levels are much closer to the Fermi level of a commonly used anode such as ITO and/or a commonly used hole-injection layer such as PEDOT:PSS. This makes high current densities and consequently high luminance levels possible at moderate applied voltages in polymer light-emitting diodes. A double-layer polymer light-emitting diode is constructed comprising a PEDOT:PSS layer as hole-injection layer and a carbazole-oxadiazole copolymer doped with a green triplet emitter as emissive layer that shows an efficacy of 23 cd/A independent of current density and light output.     

Synthesis,structure, and thermal decomposition of a novel one-dimensional chain complex of manganese(II) with 2,2-diphenic acid and 1,10-phenanthroline

A novel one-dimensional (1D) chain coordination polymer [Mn₂(2,2′-dipha)₂(phen)]_n has been synthesized by hydrothermal reaction, and characterized by elemental analysis, IR spectroscopy, TGA, and X-ray diffraction. Orange crystals crystallized in the monoclinic system, space group C2/c with a = 19.393(7) Å, b = 19.183(7) Å, c = 19.729(7) Å, β = 90.826(6)°, V = 7338(5) ų, Z = 8. In the crystal structure, one manganese atom is six-coordinated with four carboxylate oxygen atoms from one pentadentate 2,2′-dipha ligand and two tetradentate 2,2′-dipha ligands, and with two nitrogen atoms of one phen ligand, giving a slightly distorted octahedral geometry. The other manganese atom is five-coordinated with five oxygen atoms from two tetradentate 2,2′-dipha ligands and two pentadentate 2,2′-dipha ligands and has a trigonal bipyramidal environment. The TGA curve shows that the compound is stable below 310°.     

Chloride substitution of [CpRu(dppf)Cl] with sulfur-containing ligands

The reactions of CpRu(dppf)Cl (1) with the sulfur-containing ligands, thiophenol HSPh, 2-mercaptopyridine C₅H₄N(SH), thiourea SC(NH₂)₂, vinylene trithiocarbonate SCS(CH)₂S and ethylene trithiocarbonate SCS(CH₂)₂S, yielded chloro-substituted derivatives, viz. the mono-ruthenium(II) complexes CpRu(dppf)(SPh) (2), [CpRu(dppf)(SC₅H₄NH)]BPh₄ (3)BPh₄, [CpRu(dppf)(SC(NH₂)₂]PF₆ (4)PF₆, [CpRu(dppf)(SCS(CH)₂S)]Cl (5)Cl and [CpRu(dppf)(SCS(CH₂)₂S)]Cl (6)Cl, respectively. Treatment of 1 with AuCl(SMe₂) in the presence of NH₄PF₆ gave [(CpRu(dppf)(SMe₂)]PF₆ (7)PF₆. The reaction of 1 or 6 with SnCl₂ resulted in cleavage of chloro and dithiocarbonate ligands, respectively, to give CpRu(dppf)SnCl₃ (8). All complexes were spectroscopically characterized and the structures of 2 and cationic complexes 4-7 were determined by single-crystal diffraction analyses.     

Synthesis and heterocyclizations of 3‐alkynyl‐6,8‐dimethylpyrimido‐[4,5‐c]pyridazine‐5,7(6H,8H)‐diones and their lumazine analogues

Synthesis of some condensed pyrrolo‐, thieno‐, furo‐, pyrido‐ and pyranopteridines as well as isomeric pyrrolo‐ and thienopyrimido[4,5‐c]pyridazines from alkynyl derivatives of 6,8‐dimethylpyrimido[4,5‐c]pyridazine‐5,7(6H,8H)‐dione and 1,3‐dimethyllumazine is represented.     

n-Hexane dehydrocyclization over Pt?Ni supported on alumina catalysts

Pt–Ni/-Al₂O₃ catalysts have been prepared and studied in n-hexane dehydrocyclization. The selectivity for benzene and toluene, a chain lengthening product formation was improved by Ni and correlated with its content.

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Pt–Ni/-Al₂O₃ -. Ni . Ni , .

     

Role of tin in a PtSb alloy and a Pt-Sn/Al2O3 reforming catalyst

The conversion of n-hexane was studied on a Pt-Sn/Al₂O₃ catalyst, a PtSn alloy and on the corresponding Pt catalysts. The results indicate the same catalytic effect of tin in supported and unsupported catalysts. It is concluded that the role of tin is connected with alloy formation.

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- Pt-Sn/Al₂O₃, PtSn Pt-. . , .

     

Purification of a synthetic myristylated peptide by counter-current chromatography

A preparative purification of myristyl-Gly-Asn-Ile-Phe-Ala-Asn-Leu-Phe-Lys-Gly-Leu-Phe-Gly-Lys-Lys-Glu -NH2 was accomplished using the multi-coil counter-current chromatograph. A partition coefficient was determined in the n-butanol-acetic acid-water (4:1:5) system. Chromatographic runs were made in this system and one modified with ethyl acetate. The peptide material showed anomalous elution behavior due to its surfactant properties. It was found that by loading the sample exclusively in the stationary phase, satisfactory retention of the compound occurred. Finally, conditions utilizing the upper phase as the mobile phase successfully separated the impurities.     

Engineering reactions in crystalline solids: predicting photochemical decarbonylation from calculated thermochemical parameters

A detailed thermochemical analysis of the alpha-cleavage and decarbonylation reactions of acetone and several ketodiesters was carried out with the B3LYP/6-31G* density functional method. The heats of formation of several ground-state ketones and radicals were calculated at 298 K to determine bond dissociation energies (BDE) and radical stabilization energies (RSE) as a function of substituents. Results show that the radical-stabilizing abilities of the ketone substituents play a very important role on the thermodynamics of the alpha-cleavage and decarbonylation steps. An excellent correlation between calculated values and previous experimental observations suggests that photochemical alpha-cleavage and decarbonylation in crystals should be predictable from knowledge of excitation energies and the RSE of the substituent.