Microporosity of a Guanidinium Organodisulfonate Hydrogen‐Bonded Framework

Guanidinium organosulfonates (GSs) are a large and well‐explored archetypal family of hydrogen‐bonded organic host frameworks that have, over the past 25 years, been regarded as nonporous. Reported here is the only example to date of a conventionally microporous GS host phase, namely guanidinium 1,4‐benzenedisulfonate ( p ‐G₂BDS ). p ‐G₂BDS is obtained from its acetone solvate, AcMe@ G₂BDS , by single‐crystal‐to‐single‐crystal (SC‐SC) desolvation, and exhibits a Type I low‐temperature/pressure N₂ sorption isotherm (SA_BET=408.7(2) m² g^?1, 77 K). SC‐SC sorption of N₂, CO₂, Xe, and AcMe by p ‐G₂BDS is explored under various conditions and X‐ray diffraction provides a measurement of the high‐pressure, room temperature Xe and CO₂ sorption isotherms. Though p ‐G₂BDS is formally metastable relative to the “collapsed”, nonporous polymorph, np ‐G₂BDS , a sample of p ‐G₂BDS survived for almost two decades under ambient conditions. np ‐G₂BDS reverts to zCO₂@ p ‐G₂BDS or yXe@ p ‐G₂BDS (y,z=variable) when pressure of CO₂ or Xe, respectively, is applied.     

Versatile post-functionalisation strategy for the formation of modular organic–inorganic polyoxometalate hybrids

Hybrid structures incorporating different organic and inorganic constituents are emerging as a very promising class of materials since they synergistically combine the complementary and diverse properties of the individual components. Hybrid materials based on polyoxometalate clusters (POMs) are particularly interesting due to their versatile catalytic, redox, electronic, and magnetic properties, yet the controlled incorporation of different clusters into a hybrid structure is challenging and has been scarcely reported. Herein we propose a novel and general strategy for combining multiple types of metal-oxo clusters in a single hybrid molecule. Two novel hybrid POM structures (HPOMs) bis-functionalised with dipentaerythritol (R–POM₁–R; R = (OCH₂)₃CCH₂OCH₂C(CH₂OH)) were synthesised as building-blocks for the formation of heterometallic hybrid triads (POM₂–R–POM₁–R–POM₂). Such a modular approach resulted in the formation of four novel heterometallic hybrids combing the Lindqvist {V₆}, Anderson–Evans {XMo₆} (X = Cr or Al) and trisubstituted Wells–Dawson {P₂V₃W₁₅} POM structures. Their formation was confirmed by multinuclear Nuclear Magnetic Resonance (NMR), infrared (IR) and UV-Vis spectroscopy, as well as Mass Spectrometry, Diffusion Ordered Spectroscopy (DOSY) and elemental analysis. The thermal stability of the hybrids was also examined by Thermogravimetric Analysis (TGA), which showed that the HPOM triads exhibit higher thermal stability than comparable hybrid structures containing only one type of POM. The one-pot synthesis of these novel compounds was achieved in high yields in aqueous and organic media under simple reflux conditions, without the need of any additives, and could be translated to create other hybrid materials based on a variety of metal-oxo cluster building-blocks.

A versatile modular approach has been developed for incorporating different metal-oxo nanoclusters with characteristic structures into a single hybrid molecule by covalently linking them with polyol ligands.     

Fast simultaneous LC/MS/MS determination of 10 active compounds in human serum for therapeutic drug monitoring in psychiatric medication

A UPLC/MS/MS method with simple protein precipitation has been validated for the fast simultaneous analysis of agomelatine, asenapine, amisulpride, iloperidone, zotepine, melperone, ziprasidone, vilazodone, aripiprazole and its metabolite dehydro‐aripiprazole in human serum. Alprenolol was applied as an internal standard. A BEH C₁₈ (2.1 × 50 mm, 1.7 µm) column provided chromatographic separation of analytes using a binary mobile phase gradient (A, 2 mmol/L ammonium acetate, 0.1% formic acid in 5% acetonitrile, v/v/v; B, 2 mmol/L ammonium acetate, 0.1% formic acid in 95% acetonitrile, v/v/v). Mass spectrometric detection was performed in the positive electrospray ionization mode and ion suppression owing to matrix effects was evaluated. The validation criteria were determined: linearity, precision, accuracy, recovery, limit of detection, limit of quantification, reproducibility and matrix effect. The concentration range was as follows: 0.25–1000 ng/mL for agomelatine; 0.25–100 ng/mL for asenapine and iloperidone; 2.5–1000 ng/mL for amisulpride, aripiprazole, vilazodone and zotepine; 2.3–924.6 ng/mL for dehydroaripiprazole; 2.2–878.4 ng/mL for melperone; and 2.2–883.5 ng/mL for ziprasidone. Limits of quantitation below a therapeutic reference range were achieved for all analytes. Intra‐run precision of 0.4–5.5 %, inter‐run precision of 0.6–8.2% and overall recovery of 87.9–114.1% were obtained. The validated method was successfully implemented into routine practice for therapeutic drug monitoring in our hospital. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and properties of cationic polyelectrolyte with regioregular polyalkylthiophene backbone and ionic‐liquid like side groups

High‐regioregular poly{3‐[6‐(1‐methylimidazolium‐3‐yl)hexyl]thiophene‐2,5‐diyl bromide}, PMHT‐Br, has been prepared by reaction of high‐regioregular (above 92%) poly[3‐(6‐bromohexyl)thiophene‐2,5‐diyl] with 1‐methylimidazole. PMHT‐Br is soluble in water and water miscible solvents such as methanol, DMSO and shows solvatochromism; λ_max (nm): 423 (H₂O); 435 (MeOH); 452 (DMSO). Increased absorption band broadening observed for aqueous solution as well as NMR spectra in D₂O suggests a micelle‐like structure of PMHT‐Br molecules in these solutions: poly(3‐hexylthiophene) core and 1‐methylimidazolium bromide shell. Despite the disturbing effect of ionic groups, the solid‐state PMHT‐Br shows absorption maximum at 520 nm, the band edge at 660 nm (ca. 1.9 eV), and fluorescence emission with maximum at 635 nm, in a good agreement with the polymer regioregularity. Fluorescence emission maxima: λ_em (nm): 598 (H₂O); 562 (MeOH); 574 (DMSO), occur in a vicinity of corresponding adsorption band edges. Plot of electrical conductivity of PMHT‐Br (measured under the dynamic vacuum conditions, 5 × 10^?5 Pa) versus 1/T shows a break at about 70 °C same as the temperature dependence of λ_max of the solid PMHT‐Br. These breaks indicate an increase in the mobility of polymer segments and ions within PMHT‐Br; however, a thermal analysis did not provide solid evidence for it. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3073–3081, 2010     

Thermodynamic stability of clusters of molybdenum oxide

We show that a single geometrical rule underlies the stability of "polyoxomolybdates", the variety of clusters of molybdenum(VI) oxide in (acidified) aqueous solution that are found experimentally. We predict that upon increasing the proton or total molybdenum oxide concentration, the average size of the clusters increases. We compare our predictions with results from ultracentrifugation experiments and with data in the literature. Finally, it is shown that the formation of metal oxide clusters is thermodynamically equivalent to the formation of surfactant micelles.     

On The Maximum Friction Law for Rigid/Plastic,Hardening Materials

For a rigid/plastic, hardening material model, it is shown that the velocity fields adjacent to surfaces of maximum friction must satisfy the sticking condition. This means that the stress boundary condition, the maximum friction law, may be replaced by the velocity boundary condition. Axisymmetric flows without rotation and planar flows are considered.     

Development and Validation of an LC–ESI-MS Ion-Trap Method for Analysis of Impurities in Transkarbam 12, a Novel Transdermal Accelerant

A new, sensitive LC–MS method for evaluation of the purity of Transkarbam 12 (T12), a novel and highly effective accelerant of transdermal penetration, has been developed and validated. T12 and its impurities (6-aminohexanoic acid, AH, ε-caprolactam, CA, and dodecyl 6-(6-aminohexanamido)hexanoate, DAH) were characterized by MS and MS–MS analysis. Separation was achieved on a 150 mm × 3 mm, 5-μm particle, phenyl–hexyl column. The mobile phase was a gradient prepared from water, formic acid, and acetonitrile. The method was validated within the concentration range 50–250 ng mL^?1; correlation coefficients were >0.998. The accuracy of the method was from 98.6–105.0% for AH, 102.6–104.8% for CA, and 97.9–100.9% for DAH. Precision was in the range 3.19–4.42% for AH, 3.22–5.81% for CA, and 4.8–8.78% for DAH. The selectivity of the method and sample stability were also confirmed. The practical applicability of the method was proven by analysis of T12 bulk substance.