High throughput plasma N-glycome profiling using multiplexed labelling and UPLC with fluorescence detection

A rapid glycomic profiling method is described wherein N-glycans from plasma samples individually labelled with aniline, 2-aminobenzamide and 2-aminoacridone are mixed, co-injected and separated in the same HILIC-fluorescence run. Transfer of the multiplexed method to UPLC-fluorescence permits an increase in sample throughput from 24 to 864 plasma samples per day.     

A polarizable ion model for the structure of molten CuI

The results are reported of the molecular dynamics simulations of the coherent static structure factor of molten CuI at 938 K using a polarizable ion model. This model is based on a rigid ion potential to which the many body interactions due to the anions induced polarization are added. The calculated structure factor reproduces the clear sharp prepeak observed in neutron diffraction data. The corresponding partial structure factors and the related radial distribution functions calculated by molecular dynamics are compared with those found in the literature derived from a combination of neutron and x-ray diffraction data with the aid of the reverse Monte Carlo simulation technique, as well as those calculated by ab initio MD simulations.     

The effect of rotational and translational energy exchange on tracer diffusion in rough hard sphere fluids

A study is presented of tracer diffusion in a rough hard sphere fluid. Unlike smooth hard spheres, collisions between rough hard spheres can exchange rotational and translational energy and momentum. It is expected that as tracer particles become larger, their diffusion constants will tend toward the Stokes-Einstein hydrodynamic result. It has already been shown that in this limit, smooth hard spheres adopt "slip" boundary conditions. The current results show that rough hard spheres adopt boundary conditions proportional to the degree of translational-rotational energy exchange. Spheres for which this exchange is the largest adopt "stick" boundary conditions while those with more intermediate exchange adopt values between the "slip" and "stick" limits. This dependence is found to be almost linear. As well, changes in the diffusion constants as a function of this exchange are examined and it is found that the dependence is stronger than that suggested by the low-density, Boltzmann result. Compared with smooth hard spheres, real molecules undergo inelastic collisions and have attractive wells. Rough hard spheres model the effect of inelasticity and show that even without the presence of attractive forces, the boundary conditions for large particles can deviate from "slip" and approach "stick."     

Improved Synthesis of Monoprotected 5- and 6-Amino-2-azanorbornanes

An improved synthesis of Boc-monoprotected 5- and 6-amino-2-azanorbornanes is reported. The synthetic scheme consists of five steps and allows multigram quantities of the title compounds to be obtained. The regio- and stereochemistries of the products are established by two-dimensional NMR experiments.

Dynamic capillary diffusion system for monoterpene and sesquiterpene calibration: quantitative measurement and determination of physical properties

This article describes a method for preparation of low concentration gas standard mixtures of biogenic volatile organic compounds (BVOCs) emitted primarily by plants. A set of 10 plant volatiles including α-pinene, β-pinene, 3-carene, linalool, methyl salicylate, α-cedrene, β-caryophyllene, β-farnesene, aromadendrene and α-humulene was used in the study. Gas standard mixture of these compounds was generated using a capillary diffusion system (CDS). Diffusion coefficient (D) and saturation vapour pressure (p _s) data of these compounds were calculated from experimentally determined gas chromatographic retention indices (RI) and empirical relationships between D and p _s versus RI. A comparison of the calculated and measured concentrations of investigated compounds has proved that designed CDS can be successfully used for the proper quantification of BVOCs.     

Fullerene “Superhalogen” Radicals: the Substituent Effect on Electronic Properties of 1,7,11,24,27‐C60X5

Hexasubstituted fullerenes with the skew pentagonal pyramid (SPP) addition pattern are predominantly formed in many types of reactions and represent important and versatile building blocks for supramolecular chemistry, biomedical and optoelectronic applications. Regioselective synthesis and characterization of the new SPP derivative, C₆₀(CF₃)₄(CN)H, in this work led to the experimental identification of the new family of “superhalogen fullerene radicals”, species with the gas‐phase electron affinity higher than that of the most electronegative halogens, F and Cl. Low‐temperature photoelectron spectroscopy and DFT studies of different C₆₀X₅ radicals reveal a profound effect of X groups on their electron affinities (EA), which vary from 2.76 eV (X=CH₃) to 4.47 eV (X=CN). The measured gas‐phase EA of the newly synthesized C₆₀(CF₃)₄CN equals 4.28 (1) eV, which is about 1 eV higher than the EA of Cl atom. An observed remarkable stability of C₆₀(CF₃)₄CN^? in solution under ambient conditions opens new venues for design of air‐stable molecular complexes and salts for supramolecular structures of electroactive functional materials.     

Diazido Mixed‐Amine Platinum(IV) Anticancer Complexes Activatable by Visible‐Light Form Novel DNA Adducts

Platinum diam(m)ine complexes, such as cisplatin, are successful anticancer drugs, but suffer from problems of resistance and side‐effects. Photoactivatable Pt^IV prodrugs offer the potential of targeted drug release and new mechanisms of action. We report the synthesis, X‐ray crystallographic and spectroscopic properties of photoactivatable diazido complexes trans,trans,trans‐[Pt(N₃)₂(OH)₂(MA)(Py)] ( 1 ; MA=methylamine, Py=pyridine) and trans,trans,trans‐[Pt(N₃)₂(OH)₂(MA)(Tz)] ( 2 ; Tz=thiazole), and interpret their photophysical properties by TD‐DFT modelling. The orientation of the azido groups is highly dependent on H bonding and crystal packing, as shown by polymorphs 1 p and 1 q . Complexes 1 and 2 are stable in the dark towards hydrolysis and glutathione reduction, but undergo rapid photoreduction with UVA or blue light with minimal amine photodissociation. They are over an order of magnitude more potent towards HaCaT keratinocytes, A2780 ovarian, and OE19 oesophageal carcinoma cells than cisplatin and show particular potency towards cisplatin‐resistant human ovarian cancer cells (A2780cis). Analysis of binding to calf‐thymus (CT), plasmids, oligonucleotide DNA and individual nucleotides reveals that photoactivated 1 and 2 form both mono‐ and bifunctional DNA lesions, with preference for G and C, similar to transplatin, but with significantly larger unwinding angles and a higher percentage of interstrand cross‐links, with evidence for DNA strand cross‐linking further supported by a comet assay. DNA lesions of 1 and 2 on a 50 bp duplex were not recognised by HMGB1 protein, in contrast to cisplatin‐type lesions. The photo‐induced platination reactions of DNA by 1 and 2 show similarities with the products of the dark reactions of the Pt^II compounds trans‐[PtCl₂(MA)(Py)] ( 5 ) and trans‐[PtCl₂(MA)(Tz)] ( 6 ). Following photoactivation, complex 2 reacted most rapidly with CT DNA, followed by 1 , whereas the dark reactions of 5 and 6 with DNA were comparatively slow. Complexes 1 and 2 can therefore give rapid potent photocytotoxicity and novel DNA lesions in cancer cells, with no activity in the absence of irradiation.     

Calorimetric study of the copolymers on basis perfluorinated germanium hydrides with different structures

The temperature dependences of heat capacity of copolymers on the basis of perfluorinated germanium hydrides have been measured using an adiabatic vacuum calorimeter over the temperature range from 6 K to the final temperature of their stability for the first time. Thus, the physical transformations were detected and their thermodynamic characteristics were estimated. The experimental results were used to calculate the standard thermodynamic functions, namely heat capacity, enthalpy, entropy and Gibbs function over the range from T → 0 to the final temperature stability of copolymers. The standard entropy of formation of the under study copolymers at T = 298.15 K was calculated. The obtained results were compared with corresponding data for hyperbranching perfluor polyphenylenegermaniums with other structures. Some conclusions about dependences of the thermodynamic polymers properties versus their structures were made.     

Molecular structure and relative stability of trans and cis isomers of formanilide: gas-phase electron diffraction and quantum chemical studies

Molecular structure of formanilide is determined by gas-phase electron diffraction (GED) augmented by quantum chemical calculations (B3LYP/cc-pVTZ and MP2/cc-pVTZ) and literature microwave (MW) data. The combined GED and MW data are well reproduced for the mixture of trans and cis isomers with the relative abundance of 59 ± 5 and 41 ± 5 %, respectively, at T = 410 K. The trans isomer (C _s symmetry) is planar, while the cis isomer (C ₁ symmetry) has the twisted structure with the amide group rotated by 36.7 ± 2.7° with respect to the phenyl ring. In accord with theoretical calculations, the amide bond –NH–C(O)– is planar in trans formanilide and a somewhat nonplanar in cis isomer. Accurate structural parameters were obtained by a simultaneous fit of the rotational constants reported in the literature and GED intensities obtained in this study. The N–C(O) and N–C_Ph bond dissociation energies in formanilide are calculated using Gaussian-4 method. It is revealed that the strength of N–C(O) bond in formanilide is 50 kJ/mol less than that in benzamide. On the contrary, the strength of adjacent bond (N–C_Ph) increases by 35 kJ/mol compared to aniline. It is rather unexpectedly that the bond strength weakening does not result in the bond elongating, and vice versa.