“Degrees of equivalence” for chemical measurement capabilities: primary pH

The key comparison (KC) studies of the Consultative Committee for Amount of Substance—Metrology in Chemistry help ensure the reliability of chemical and biochemical measurements relevant to international trade and environmental-, health-, and safety-related decision making. The traditional final evaluation of each measurement result reported by a KC participant is a “degree of equivalence” (DEq) that quantitatively specifies how consistent each individual result is relative to a reference value. Recognizing the impossibility of conducting separate KCs for all important analytes in all important sample matrices at all important analyte levels, emphasis is now shifting to documenting broadly applicable critical or “core” measurement competencies elicited through a series of studies. To better accomplish the necessary synthesis of results, data analysis and display tools must be developed for objectively and quantitatively combining individual DEqs. The information detailed in the 11 KCs of primary method pH measurements publically available as of 2013 provides an excellent “best case” prototype for such analysis. We here propose tools that enable documenting the expected primary pH measurement performance of individual participants between pH 1 and pH 11 and from 15 °C to 37 °C. These tools may prove useful for other areas where the uncertainty of measurement is a predictable function of the measured quantity, such as the stable gases. That results for relatively simple measurement processes can be combined using relatively simple analysis and display methods does not ensure that similarly meaningful summaries can be devised for less well understood and controlled systems, but it provides the incentive to attempt to do so.     

Reversible Single‐Crystal‐to‐Single‐Crystal Photochemical Formation and Thermal Cleavage of a Cyclobutane Ring

A [2+2] cycloaddition reaction has been observed in a number of solids. The cyclobutane ring in a photodimerized material can be cleaved into olefins by UV light and heat. The high thermal stability of the metal–organic salt K₂SDC (H₂SDC=4,4’‐stilbenedicarboxylic acid) has been successfully utilized to investigate the reversible cleavage of a cyclobutane ring. The two polymorphs of K₂SDC undergo reversible cyclobutane formation by UV light and cleavage by heat in cycles. Of these, one polymorph retains its single‐crystal nature during the reversible processes. Polymorphs are known to show different physical properties and chemical reactivities. This work reveals that the retention of single‐crystal nature is strongly associated with the packing of molecules, which is controlled by kinetics and thermodynamics. The photoemissive nature of the products makes this as a promising material for photoswitches and optical data storage devices.     

Matrix-assisted laser desorption/ionization imaging mass spectrometry revealed traces of dental problem associated with dental structure

Periodontal disease is a serious dental problem because it does not heal naturally and leads to tooth loss. In periodontal disease, inflammation at periodontal tissue is thought as predominant, and its effect against tooth itself remains unclear. In this study, we applied matrix-assisted laser desorption/ionization imaging mass spectrometry (IMS) to teeth for the first time. By comparing anatomical structure of tooth affected with periodontal disease with normal ones, we analyzed traces of the disease on tooth. We found signals characteristic of enamel, dentin, and dental pulp, respectively, in mass spectra obtained from normal teeth. Ion images reconstructed using these signals showed anatomical structures of the tooth clearly. Next, we performed IMS upon teeth of periodontal disease. Overall characteristic of the mass spectrum appeared similar to normal ones. However, ion images reconstructed using signals from the tooth of periodontal disease revealed loss of periodontal ligament visualized together with dental pulp in normal teeth. Moreover, ion image clearly depicted an accumulation of signal at m/z 496.3 at root surface. Such an accumulation that cannot be examined only from mass spectrum was revealed by utilization of IMS. Recent studies about inflammation revealed that the signal at m/z 496.3 reflects lyso-phosphatidylcholine (LPC). Infiltration of the signal is statistically significant, and its intensity profile exhibited the influence has reached deeply into the tooth. This suggests that influence of periodontal disease is not only inflammation of periodontal tissue but also infiltration of LPC to root surface, and therefore, anti-inflammatory treatment is required besides conventional treatments.     

Atom transfer radical polymerization on the interior of the P22 capsid and incorporation of photocatalytic monomer crosslinks

We have successfully used atom transfer radical polymerization (ATRP) to form linear and crosslinked polyacrylamide and polyacrylate polymers, constrained within the virus like particle (VLP) derived from the bacteriophage P22. Polymerization of Tris(hydroxymethyl)methylacrylamide was initiated, in a spatially controlled manner, using macroinitiators derived from two different mutants of P22, S39C and K118C. Initiation from the S39C mutant results in spatially confined polymer growth on the interior of P22 while initiation from the K118C site results in a polymerized VLP in which some of the polymer is partially exposed on the outside of the capsid. Using the S39C macroinitiator we have demonstrated polymerization of aminoethyl methacrylate (AEMA) monomers, crosslinked by co-polymerization with the multifunctional monomer [Ru(5-methacrylamido-phenanthroline)₃]²⁺ resulting in an active photocatalytic P22 capsid particle.     

Recyclable and Ligandless Suzuki Coupling Catalyzed by Carbon Nanotube‐Supported Palladium Nanoparticles Synthesized in Supercritical Fluid

Carbon nanotube–supported palladium nanoparticles prepared by a supercritical fluid deposition method show high activities for catalyzing Suzuki coupling reactions, and the catalysts can be recycled and reused at least six times without losing activity.     

Addition of AlkylHalide toward a Tungsten-Phosphorus Double Bond

The terminal phosphide complex of tungsten Cp(CO) 3 W{PN(Me)CH 2 CH 2 PNMe} ( 3 ) prepared from Cp(Sn n Bu 3 )(CO) 2 W{PN(Me)CH 2 CH 2 NMe(OMe)}, BF 3 ;OEt 2 , and NaBPh 4 in situ reacts with PhCH 2 Cl to give cis -Cp(CO 2 )ClW{PN(Me)CH 2 CH 2 NMe(CH 2 Ph)} ( cis-4 ). During the reaction, C--Cl bond addition takes place toward a tungsten-phosphorus double bond. In contrast, isolated 3 does not react with PhCH 2 Cl. Isolated 3 , however, reacts with PhCH 2 Cl in the presence of BPh 3 and BF 3 to give trans-4 and cis-4 , respectively.     

Amyloid‐like Nanofibrillation of Metal‐Organic Complex Arrays Ruled by Their Precisely Designed Metal Sequences

Self‐assembly of a series of dimetallic sequences constructed on a backbone with two successive tyrosine moieties ( Fmoc‐M ¹ ‐M ² ‐CO₂H ) revealed that the resultant morphology is clearly dependent on the metal sequence, where Re‐containing sequences such as homometallic Fmoc‐Re‐Re‐CO₂H specifically afforded amyloid‐like nanofibers. These findings further allowed to achieve the fibrillation of a longer metal sequence containing three different metals ( Fmoc‐Rh‐Pt‐Re‐Re‐CO₂H ). Cyclic voltammetry of the fibrillated Fmoc‐Re‐Re‐CO₂H demonstrated that the redox activity of the metal complexes in the sequence is preserved in the nanofibrous forms.     

Utilization of a Crown Ether/Amine‐Type Rotaxane as a Probe for the Versatile Detection of Anions and Acids by Thin‐Layer Chromatography

A crown ether/amine‐type [2]rotaxane was synthesized and utilized as a probe for the detection of acids and anions. The addition of acids to the amine‐type [2]rotaxane solution generated corresponding crown ether/ammonium‐type [2]rotaxanes, which were purified by silica gel column chromatography as ammonium salts. The isolated yields of the [2]rotaxanes, possessing a variety of anions, depended on the acidity and polarity of the counter anions. The behaviours of the ammonium‐type [2]rotaxanes on thin‐layer chromatography (TLC) silica gel reflected the properties of the counter anions. The treatment of the amine‐type [2]rotaxane with acids afforded the corresponding ammonium‐type [2]rotaxanes bearing several different anions. The ammonium‐type [2]rotaxanes behaved similarly to the purified [2]rotaxanes on the TLC silica gel. Furthermore, we succeeded in the analysis of anions using mixtures of the amine‐type [2]rotaxane and salts in an appropriate solvent. We demonstrated the detection of anions by the combination of TLC and the utilization of the [2]rotaxane probe.     

The Thermal Rearrangement of an NHC‐Ligated 3‐Benzoborepin to an NHC‐Boranorcaradiene

An N‐heterocyclic‐carbene‐ligated 3‐benzoborepin with a bridged structure has been synthesized by double radical trans‐hydroboration of benzo[3,4]cycloundec‐3‐ene‐1,5‐diyne with an N‐heterocyclic carbene borane. The thermal reaction of the NHC‐ligated borepin at 150 °C gives an isolable NHC‐boranorcaradiene. Experiments and density functional theory calculations support a mechanism whereby the borepin initially rearranges to a boranorcaradiene by a thermal 6π‐electrocyclic reaction. This is followed by 1,5‐boron shift to give a rearranged boranorcaradiene. This shift occurs with stereoinversion at boron through a transition state with open‐shell diradical character. This is the first example of the isolation of a boranorcaradiene from a thermal reaction of a borepin.     

A simplified method for therapeutic drug monitoring of mitotane by gas chromatography-electron ionization-mass spectrometry

Mitotane is a key drug for the treatment of adrenal cortical carcinoma. Due to its narrow therapeutic window, 14–20 μg/mL, monitoring its concentration is crucially important. In this study, a simplified method for measuring mitotane in plasma using gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) was developed. Through deproteination and liquid–liquid extraction, mitotane and an internal standard (IS) were extracted from plasma samples. GC-EI-MS yielded retention times of 8.2 and 8.7 min, for mitotane and the IS, respectively, with a total run time of 12 min. Selectivity and intra-/inter-batch accuracy and precision analyses provided a lower limit of quantification of 0.25 μg/mL, and a calibration curve between 0.25 and 40 μg/mL had good linearity (coefficient of determination = 0.992). The matrix effect factor and percent recovery of the method had good precision. Additionally, long-term sample stability was observed below 4°C. In a clinical setting, mitotane levels in plasma from an adrenal cortical carcinoma patient were within calibration range. Therefore, this simplified method can be applied to routine therapeutic drug monitoring of mitotane, which may contribute to improved treatment of adrenal cortical carcinoma.