Complexes with a Metal Phosphorus Triple Bond

Herein we report the synthesis of different phosphido-complexes and -intermediates with WLE-triple bond. These compounds reveal different reactivity patterns. Details of reactivity as well as spectroscopic and theoretical aspects will be discussed in detail.     

Triple Helix Formation in a Topologically Controlled DNA Nanosystem

In the present study, we demonstrate single‐molecule imaging of triple helix formation in DNA nanostructures. The binding of the single‐molecule third strand to double‐stranded DNA in a DNA origami frame was examined using two different types of triplet base pairs. The target DNA strand and the third strand were incorporated into the DNA frame, and the binding of the third strand was controlled by the formation of Watson–Crick base pairing. Triple helix formation was monitored by observing the structural changes in the incorporated DNA strands. It was also examined using a photocaged third strand wherein the binding of the third strand was directly observed using high‐speed atomic force microscopy during photoirradiation. We found that the binding of the third strand could be controlled by regulating duplex formation and the uncaging of the photocaged strands in the designed nanospace.     

Mercuration of a Terminal Triple Bond of Substituted Azoles

Russian Journal of Organic Chemistry - Mercuration of a terminal triple bond in pirazoles and triazoles derivatives in the presence of acetylacetone followed by demercuration of intermediates by...     

Thermodynamics of a 24-Mer Triple Helix Formation and Stability

In this work we report a thermodynamic characterization of stability and melting behaviour of two 24-mer DNA triplexes. The third strand, that binds the Watson-Crick double helix with Hoogsteen hydrogen bonds, contains 3′-3′ phosphodiester junction that determines the polarity inversion. The target double helix is composed of adjacent and alternate fragments of oligopurine-oligopyrimidine tracts. The two helices differ from the substitution of the cytosine, involved in the junction, with the thymine. Calorimetric data reported here provide a quantitative measure of the influence of pH and base modification on the stability of a DNA triplex. This revised version was published online in August 2006 with corrections to the Cover Date.     

An Alternative Generation of a 13.14-Carbon-Carbon Triple Bond in Prostanoids

A novel HBr elimination method for the introduction of a 13.14-triple bond into the prostanoid framework starting from readily available vinyl bromides is described. The transformation can be performed even on sensitive compounds in the presence of various functional groups in synthetically useful yields.     

Novel DNA-Polysaccharide Triple Helixes and Their Application to a Gene Carrier

Schizophyllan is a polysaccharide that belongs to the β-(1 → 3)-glucanfamily and has been known to activate the immunity system. This paper reviews our recent finding that schizophyllan can form a macromolecular complex with single-stranded polynucleotides and this complex is applicable to a new class of gene carriers.     

Nucleophilic Addition to a Triple Bond; Preliminary ab initio study

Preliminary ab initio, calculations (minimal basis set STO-3 G) suggest that the preferred direction of approach of a nucleophilic centre towards a CC triple bond makes an obtuse angle (～120°) with this bond. The stereoelectronic requirements for nucleophilic addition to triple bonds and to ketones are thus rather similar.     

Triple Frustrated Lewis Pair-Type Reactivity on a Single Rare-Earth Metal Center

Rare-earth metal cations have been used rarely as Lewis-acidic components in the chemistry of frustrated Lewis pairs (FLPs). Herein, we report the first cerium/phosphorus system ( 2 ) employing a heptadentate N₄P₃ ligand, which exhibits triple FLP-type reactivity towards a series of organic substrates, including isocyanates, isothiocyanates, diazomethane, and azides on a single rare-earth Lewis acidic Ce center. This result shows that the Ce center and three P atoms in 2 could simultaneously activate three equivalents of small molecules under mild conditions. This study broadens the diversity of FLPs and demonstrates that rare earth based FLP exhibit unique properties compared with other FLP systems.     

A pH-Switchable Triple Hydrogen-Bonding Motif

A stimuli responsive linear hydrogen bonding motif, capable of in situ protonation and deprotonation, has been investigated. The interactions of the responsive hydrogen bonding motif with complementary partners were examined through a series of ¹H NMR experiments, revealing that the recognition preference of the responsive hydrogen bonding motif in a mixture can be switched between two states.     

Triple points and plutonium equilibrium

Summary Equilibrium prevails at all points in plutonium predominance region diagrams. Triple points combine equilibrium with equal fractions of three Pu oxidation states. A rearrangement equation can be used to describe plutonium at a triple point. Two-reaction-product disproportionation equations are not satisfactory for that purpose.     

Factors in the Single-Step Bulk Process Preparation of a Triple Janus Emulsion

Some factors in the preparation of triple Janus emulsions in a single-step bulk process were investigated using optical microscopy. The emulsions consisted of water, O.097 weight fraction, a commercial surfactant, Tween 80, 0.03 weight fraction, a vegetable oil (VO), 0.18 weight fraction, and a silicone oil (SO), 0.72 weight fraction. A surprising connection was found between the state of the compounds prior to mixing and the final morphology as well as stability of the emulsion. Separately adding the compounds or with the surfactant dissolved in the vegetable oil, prior to mixing, did not result in a Janus emulsion. Instead, simpler emulsions with limited stability were attained even with prolonged mixing. Storing the compounds together without mixing for two days followed by mixing resulted in a Janus emulsion in which the (VO + SO)/W/VO drops were more sparsely populated with Janus drops, and emulsion stability was limited. Finally, preparing the emulsion from the aqueous surfactant solution and the two oils gave a (VO + SO)/W/VO/SO emulsion with the W drops heavily populated by Janus drops and with improved stability.      

Triple ring contraction of a [2+2] macrocyclic ligand

Schiff base condensation of 2,6‐diformylpyridine and 1,3‐diaminopropan‐2‐ol in the presence of a Ba^II template ion yields a complex containing a [2+2] macrocycle, [Ba₂(μ_1,2‐ClO₄)₂(H₂L1)₂], where H₂L1 is 3,7,15,19,25,26‐hexaazatricyclo[19.3.1.1^9,13]hexacosa‐1(25),2,7,9(26),10,12,14,19,21,23‐decaene‐5,17‐diol. On transmetallation with Cu^II cations, the macrocycle undergoes three successive ring contractions, yielding crystals of (acetato‐κO)[26,28‐dioxa‐3,7,15,19,25,27‐hexaazahexacyclo[19.3.1.1^2,5.1^9,13.1^17,10.0^3,8]octacosa‐1(25),9(27),10,12,14,21,23‐heptaene‐κ⁵N]copper(II) perchlorate, [Cu(CH₃COO)(C₂₀H₂₂N₆O₂)]ClO₄ or [Cu(CH₃COO)(L2)]ClO₄, in which the macrocycle ring size has been reduced from 20 members in H₂L1 to 16 in L2.     

Characterization of the Converging Jet Region in a Triple Torch Plasma Reactor

Enthalpy probe measurements were taken of the converging plasma plume in a triple torch plasma reactor and related to substrate heat flux measurements. Results show excellent entrainment of process gases injected into the converging plasma plume by way of the central injection probe. At lower pressures (40 kPa), the plasma volume is equivalent to at least a 3 cm diameter, 4 cm long cylinder, with relatively uniform temperature, velocity, and substrate heat flux profiles when compared to a typical dc arc jet. Converging plasma plume size, substrate heat flux, and enthalpy profiles are also shown to be a strong function of applied system power. Substrate heat flux measurements show smaller radial gradients than enthalpy probe measurements, because of the high radial velocity component of gases above the substrate boundary layer. Enthalpy probe measurements were also conducted for diamond deposition conditions and approximate temperature and velocity profiles obtained. Problems with the uniform gas mixture assumption prohibited more accurate measurements. Reproducibility of enthalpy measurement results was shown with an average standard deviation of 11.8% for the velocity and 7.6% for the temperature measurements.     

ECD of Tyrosine Phosphorylation in a Triple Quadrupole Mass Spectrometer with a Radio-Frequency-Free Electromagnetostatic Cell

A radio frequency-free electromagnetostatic (EMS) cell devised for electron-capture dissociation (ECD) of ions has been retrofitted into the collision-induced dissociation (CID) section of a triple quadrupole mass spectrometer to enable recording of ECD product-ion mass spectra and simultaneous recording of ECD-CID product-ion mass spectra. This modified instrument can be used to produce easily interpretable ECD and ECD-CID product-ion mass spectra of tyrosine-phosphorylated peptides that cover over 50% of their respective amino-acid sequences and readily identify their respective sites of phosphorylation. ECD fragmentation of doubly protonated, tyrosine-phosphorylated peptides, which was difficult to observe with FT-ICR instruments, occurs efficiently in the EMS cell. Figure

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Triple point measurements for alternative refrigerants

Triple point data are important in the refrigerating industry, defining the lowest temperature limit at which a refrigerant may circulate in a fluid state. For several refrigerants, triple point data present in the literature are extremely scarce or inaccurate. A recently developed Solid–Liquid Equilibria (SLE) apparatus was used to measure the triple point temperature of 16 of the most widely applied alternative refrigerants, namely three methane derivatives (fluoromethane, R41; difluoromethane, R32; trifluoromethane, R23), four ethane derivatives (pentafluoroethane, R125; 1,1,1,2-tetrafluoroethane, R134a; 1,1,1-trifluoroethane, R143a; 1,1-difluoroethane, R152a), five propane derivatives [1,1,1,2,3,3,3-heptafluoropropane, R227ea; 1,1,2,3,3,3-hexafluoropropane, R236ea; 1,1,1,3,3-Pentafluoropropane, R245fa; 1,1,2,2,3-pentafluoropropane, R245ca; 1,1,1,3,3,3-hexafluoropropane, R236fa), and four hydrofluoro-olefines (2,3,3,3-tetrafluoroprop-1-ene, R1234yf; trans-1,3,3,3 tetrafluoropropene, R1234ze(E); 3,3,3-trifluoropropene, R1243zf; 1,2,3,3,3-pentafluoropropene, 1225ye(Z)]. The experimental setup, that was recently adopted for the SLE estimation of binary systems containing carbon dioxide (J Therm Anal Calorim 105:489–493, 2011), comprises a measuring cell and a system for drawing the liquid nitrogen directly from its insulated tank with the aid of compressed air: the carrier fluid circulating in the circuit is thus the refrigerant itself. The measurements were performed both in the heating and in the cooling mode. In order to confirm the functional efficiency and fine adjustment of the apparatus, the already available triple point literature data for carbon dioxide, dimethyl ether, and nitrous oxide were also compared with the ones measured by the present setup, confirming the validity of the setup. The measured triple point data for the refrigerants revealed generally good agreement with the literature, excepting a few fluids that revealed some discrepancies.