Cyclometallated 1,2,3-triazol-5-ylidene iridium(III) complexes: synthesis,structure, and photoluminescence properties

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Distribution of benzo-substituted crown-ethers between chloroform and water: effects of macrocycle ring size and lithium chloride

Small size benzo-substituted crown ethers are attractive complexing agents for lithium isotope separation by solvent extraction. Low transfer of the crown ethers from solvent to water is a key point for applicability of the extractants. In the present study, 9- and 12-membered crown ethers were synthesized, and their distribution between chloroform and water was studied. Polyether ring size, benzene substituents and addition of LiCl to water were found to effect on distribution constants. Low losses of the macrocycles were observed at single-stage contact with aqueous phase. However, these losses should be taken into account in the design of multistage processes for the preparation of highly enriched lithium isotopes.     

Addition Polymerization of 5-Ethylidene-2-Norbornene in the Presence of Pd N-Heterocyclic Carbene Complexes

New high-performance catalytic systems based on Pd N-heterocyclic carbene complexes for the selective addition polymerization of 5-ethylidene-2-norbornene (ENB) were proposed. With these catalysts, polymerization can be conducted at unprecedentedly high monomer/catalyst ratio (up to 5 × 10⁵/1) and gives high-molecular-weight soluble polymers with good film-forming properties. Varying the polymerization conditions (reaction temperature, monomer and catalyst concentrations, monomer/Pd ratio) makes it possible to prepare soluble ENB-based addition polymers with specified molecular weights in reasonable yields.     

Insights into the reaction paths of copper(i) acetylides with dichloroglyoxime leading to 3,3′-biisoxazoles

Russian Chemical Bulletin - Base-free reaction of dichloroglyoxime with copper(i) acetylides gave 3,3′-biisoxazoles via a nucleophilic substitution of the chlorine atom of dichloroglyoxime...     

Solvent-free telomerization of isoprene with alcohols catalyzed by palladium(ɪɪ) carbene complexes

Russian Chemical Bulletin - The effect of various factors on the activity and selectivity of palladium N-heterocyclic carbene (NHC) complexes in the telomerization of isoprene with alcohols has...     

Characterization of the dehydration products due to thermal decomposition of peptides by liquid chromatography‐tandem mass spectrometry

Thermal decomposition (TD) of proteins is being investigated as a rapid digestion step for bottom‐up proteomics. Mass spectrometry (MS) analyses of the TD products of simple peptides and intact proteins have revealed several nonvolatile products at masses lower than the precursor biomolecule (M). In addition to products stemming from site‐specific cleavages, many signals are also observed at a corresponding M‐18, most likely because of dehydration (M‐H₂O) during the heating process. Understanding the structural nature of the water loss product is important in establishing the utility of their tandem mass spectra (collision‐induced dissociation) in determining the precursor ion amino acid sequence in a bottom‐up proteomic workflow. Dehydration of a peptide can take place from a variety of sources including side chain groups, C‐terminus, and/or intramolecular cyclization (C to N‐terminus cyclization). In this work, liquid chromatography‐tandem MS (LC‐MS/MS) and a series of standard peptides (angiotensin II, DRVYIHPF and its cyclic analog) are implemented to decipher the structure of the TD dehydration product. In addition, a derivatization strategy incorporating N‐terminus acetylation was developed that allowed the direct comparison of tandem mass spectra of standard cyclic peptides with those resulting from the TD process, thus eliminating any ambiguity from the direct comparison of their mass spectra (due to gas‐phase cyclization of b‐ions, which can result in sequence scrambling of the precursor ion). Results from these investigations indicated that peptide dehydrated TD products were mostly linear in nature, and water loss was favored from the C‐terminus carboxyl group or, when present, the aspartic acid side chain. Given the predictable nature of the formation of TD dehydration products, their MS/MS analysis can be of utility in providing complementary and confirmatory sequence information of the precursor peptide. Copyright © 2015 John Wiley & Sons, Ltd.     

Addition homo- and copolymerization of 3-triethoxysilyltricyclo[4.2.1.0<Superscript>2,5</Superscript>]non-7-ene

New norbornene type monomer bearing reactive triethoxysilyl group was synthesized, and its addition homo- and copolymerization with 3-trimethylsilyltricyclonon-7-ene was studied. The target monomer was obtained using regio- and stereospecific [2σ+2σ+2π] cyclo-addition of quadricyclane with vinyltrichlorosilane followed by the reaction of the formed cycloadduct with ethanol in the presence of triethylamine. Addition polymerization was investigated over the three-component Pd-containing catalytic system (Pd complex, Na+[B(3,5-(CF₃)₂C₆H₃)₄]–(cocatalyst) and tricyclohexylphosphine). The N-heterocyclic carbene Pd complex (SIPrPd(cinn)Cl) with high activity and tolerance to the Si—O—C moieties was used as a catalyst. The yields of the homo- and copolymers were 24—68% depending on the monomer (comonomer): Pd: B: PCy₃ ratio. The obtained addition polymers are high-molecular-weight amorphous products, the glass transition temperature of which exceeds 300 °C. The presence of reactive Si(OC₂H₅)₃ groups in the homo- and copolymers made it possible to carry out a hard-to-realize cross-linking involving side substituents and followed by the formation of insoluble polymers.     

Numerical Simulation Optimization of Selective Heating of Blood Vessels in “Port-Wine Stains” under Laser Irradiation in Various Modes

Numerical simulation of blood vessel heating is used to select the most efficient and safe methods of laser treatment of “port-wine stains”. Selective heating under radiation is calculated for a 980-nm diode laser, a Nd:YAG laser, a copper vapor laser (CVL), and a pulsed dye laser (PDL). The energy exposure range (fluence), the diameter and depth of vessels, at which their selective heating to the coagulation temperature is possible, are determined.     

Arylation of nitromethane with sterically hindered aryl halides

Efficient conditions for Pd-catalyzed cross-coupling of sterically hindered aryl halides with nitromethane were developed to give corresponding aryl nitromethanes. The opportunity to carry out the reaction of polynitromethylation under these conditions was demonstrated, as well as to use the obtained products in the synthesis of bisnitrile oxides.