Improved Synthesis of Oligodeoxyribonucleotides by Solid-Phase Phosphotriester Method Utilizing O6-[2-(p-Nitrophenyl)ethyl]-2′-deoxyguanosine Derivatives

The synthesis of oligodeoxyribonucleotides on a cross-linked polystyrene solid support utilizing stable mono- and dinucleotide phosphotriester building blocks is presented. The use of O⁶[2-(p-nitrophenyl)ethyl]-2′-deoxyguanosine derivatives yields cleaner DNA fragments by suppressing side reactions. Modifications improving the phosphotriester methodology are presented. The purification methods and analysis of synthetic oligodeoxyribonucleotides are described.     

One-step electroblotting of 2- to 100-kDa proteins onto a PVDF membrane

This article describes a method for electroblotting peptides and small proteins (< 100 kDa) from tricine gels onto a PVDF membrane. The major potential problem with these types of procedures is that proteins tend to stay in the gel under conditions where peptides are effectively eluted. The suggested protocol allows the complete transfer and binding of proteins and peptides in the range of 2–97 kDa.     

Geminal bis-ureas as gelators for organic solvents: gelation properties and structural studies in solution and in the gel state

Several geminal bis-urea compounds were synthesised by means of an acid-catalysed condensation of various benzaldehydes with different monoalkylureas. Many of these compounds form thermoreversible gels with a number of organic solvents at very low concentrations (<3mM) and which are stable to temperatures higher than 100 degrees C. Electron microscopy revealed a three-dimensional (3D) network of intertwined fibres, which are several tens of micrometers long and have a width ranging from approximately 30 to 300 nm. The possible aggregate forms and aggregate symmetries were evaluated by means of molecular mechanics calculations. 1H NMR, 2D NMR, 13C NMR and 13C-CP/MAS NMR techniques were used to obtain information about the aggregation and possible aggregate symmetry of geminal bis-ureas in solution, in the gel state, and in the solid state.     

Long-range sigma-pi interactions in tetrahydro-4H-thiopyran end-capped oligo(cyclohexylidenes). Photo-electron spectroscopy, ab initio SCF MO calculations, and natural bond orbital analyses

Long-range sigma-pi interactions in tetrahydro4H-thiopyran end-capped oligo(cyclohexylidenes) were identified by He(I) photoelectron spectroscopy (PES) and ab initio RHF/6-31G* calculations. The vertical ionization energies Ivj of the highest occupied molecular orbitals (MO's) were assigned using Koopmans' theorem (Iv,j = -epsilonj) and by correlation with the ionizations of related reference compounds. The experimental (PES) and theoretical (RHF/6-31G*) results are in good agreement. For tercyclohexylidene derivatives which contain two nonconjugated pi-bonds splittings deltaIv,j of the pi-bands in the range from approximately 0.5 to 0.7 eV (delta-epsilonj approximately 0.6 to 0.9 eV). For the bi- and tercyclohexylidene compounds containing two sulfur atoms at their alpha- and omega-end positions the pi-type sulfur lone pair bands [Lppi(S)] split significantly by deltaIvj approximately 0.3 to 0.4 eV (delta-epsilonj approximately 0.3 to 0.4 eV), i.e. sigma-pi interactions over distances of ca. 8 and 12 A, respectively, occur. The magnitude of the interactions and the observed splittings are independent of the anti and syn conformations of the oligo(cyclohexylidene) hydrocarbon skeletons. RHF/6-31G* Natural Bond Orbital analyses reveal that the Hax-C-C-Hax precanonical MO's (PCMO's) centered on the cyclohexyl-type rings are paramount for the relay of the through-bond sigma-pi interactions; no through-space sigma-pi interactions were identified.     

Organotin compounds : X. Organotin hydride addition to methyl cyclohexene-1-carboxylate and methyl indene-3-carboxylate

Free radical hydrostannation of methyl cyclohexene-1-carboxylate (I) and methyl indene-3-carboxylate (III) with trialkyltin hydrides, R₃SnH (R = Me, n-Bu, Ph) gives the energetically unfavourable cis products, 2-trialkylstannyl cyclohexanecarboxylate (II) and 2-trialkylstannyl indane-1-carboxylate (IV) in high yields, via a trans addition of the tin hydrides. The hydride abstractions by the intermediate trialkylstannylcyclohexanyl (VIII) and trialkylstannylindanyl (IX) intermediate radicals take place stereospecifically, and exclusively from the less hindered ring side. The structures of the isomers II and IV were established by (a) their transformation into the corresponding chlorodialkylstannyl derivatives V and VI, which were shown spectroscopically to have cis stereochemistries by intramolecular complexation of the ester group, and (b) their NMR data. Full ¹H, ¹³C, and ¹¹⁹Sn NMR data are given.     

Structural and spectroscopic characterization of the macrocyclic complex: [Tb(CrO4)(H2O)(C22H26N6)] ·0.5(Cr2O7)·(H2O)

The title complex was obtained by anion metathesis from [Tb(CH₃COO)₂(C₂₂H₂₆N₆)] (CH₃COO)·4H₂O and K₂CrO₄ in aqueous solution. The compound crystallizes in the triclinic space group witha=8.384(2),b=10.425(2)c=15.752(2)Å, =98.82(2), =93.52(2), =97.22(2)°, andZ=2. The structure is ionic and consists of a (+1) complex cation balanced in a 21 ratio by a disordered dichromate ion. The 9-coordinate Tb(III) is linked to the six nitrogen atoms of the macrocyclic ligand L=C₂₂H₂₆N₆, as well as to a water molecule and a bidentate chelating chromate situated on opposite sides of the macrocycle. The infrared spectrum shows, in addition to the pattern of the macrocyclic ligand, the absorptions arising from the stretching modes of the bidentate chelating CrO₄ ^2– ligand and of the Cr₂O₇ ^2– counterion.     

Simulation models to support the preliminary electoral results program for the Mexican Electoral Institute

On July 1st, 2018, federal elections for president, senators and deputies took place in Mexico. In most states, elections for state governors and representatives took also place in the same polling booths. The Technical Unit for Information Services (UNICOM) of the National Electoral Institute (INE) of Mexico has the responsibility for planning and implementation of the Preliminary Electoral Results Program (PREP) for federal elections. For the 2018 elections UNICOM developed forecasting models for the performance of PREP based on simulation models that were developed using a special purpose simulation software and C++ subroutines for fast simulation of queues. These simulation models were a valuable tool for planning, scheduling and allocation of the main resources that participated in the operational process of the PREP. In this article we report the main features, applications and results obtained by using these simulation models.