Electronic modulation of hyperpolarizable (porphinato)zinc(II) chromophores featuring ethynylphenyl-, ethynylthiophenyl-, ethynylthiazolyl-, and ethynylbenzothiazolyl-based electron-donating and -accepting moieties

A series of conjugated (porphinato)zinc(II)-based chromophores structurally related to [5-(4-dimethylaminophenylethynyl)-15-(5-nitrothienyl-2-ethynyl)-10,20-bis(3,5-bis(3,3-dimethyl-1-butyloxy)phenyl)]zinc(II) were synthesized using metal-catalyzed cross-coupling reactions involving [5-bromo-15-triisopropylsilylethynyl-10,20-diarylporphinato]zinc(II), [5-bromo-15-(4-dimethylaminophenylethynyl)-10,20-diarylporphinato]zinc(II), [5-(4-dimethylaminophenylethynyl)-15-ethynyl-10,20-diarylporphinato]zinc(II), and [5-(4-nitrophenylethynyl)-15-ethynyl-10,20-diarylporphinato]zinc(II), along with appropriately functionalized aryl, thienyl (or thiophenyl), thiazolyl, benzothiazolyl, and carbazolyl precursors. The linear and nonlinear optical properties of these asymmetrically 5,15-substitued-(10,20-diarylporphinato)zinc(II) chromophores that bear either 2-(9H-carbazol-9-yl)-thiophen-5-yl-ethynyl, 4-dimethylaminophenylethynyl, or 2-(N,N-diphenylamino)thiophen-5-yl-ethynyl electron-releasing groups and an electron-withdrawing group selected from 2-formyl-thiophen-5-yl-ethynyl, 2-(2,2-dicyanovinyl)-thiophen-5-yl-ethynyl, 4-nitrophenylethynyl, 6-nitrobenzothiazol-2-yl-ethynyl, or 5-nitrothiazol-2-yl-ethynyl are reported. The dynamic hyperpolarizabilities of these compounds were determined from hyper-Rayleigh light scattering measurements carried out at a fundamental incident irradiation wavelength (lambda(inc)) of 1300 nm; these measured beta1300 values ranged from 690 --> 1400 x 10(-30) esu. These data (i) show that these neutral dipolar molecules express substantial beta1300 values, (ii) highlight that reductions in the magnitude of the aromatic stabilization energy of (porphinato)metal-pendant arylethynyl groups have a significant impact upon the magnitude of the molecular hyperpolarizability, and (iii) provide insights into advantageous design modifications for closely related structures having potential utility in long-wavelength electrooptic applications.     

Catalytic asymmetric synthesis of acyclic arrays by tandem 1,4-addition-aldol reactions

Herein, we report efficient acyclic stereocontrol in tandem 1,4-addition-aldol reactions triggered by catalytic asymmetric organometallic addition. Grignard reagents add to alpha,beta-unsaturated thioesters in a 1,4-fashion and the resulting magnesium enolates are trapped with aromatic or aliphatic aldehydes. The process provides a range of tandem products bearing three contiguous stereocenters with excellent control of relative and absolute stereochemistry. The various diastereomeric products have been fully characterized using single-crystal X-ray analysis and the origins of stereocontrol in this tandem protocol are discussed. The versatility and efficiency of this methodology are demonstrated in the first catalytic asymmetric synthesis of (-)-phaseolinic acid with 54% overall yield via a short and concise route.     

Visible-light-sensitized near-infrared luminescence from rare-earth complexes of the 9-hydroxyphenalen-1-one ligand

The unique absorption properties of the 9-hydroxyphenalen-1-one (HPHN) ligand have been exploited to obtain visible-light-sensitizable rare-earth complexes in 1:3 and 1:4 metal-to-ligand ratios. In both stoichiometries (1:3, tris, Ln(PHN)3; 1:4, tetrakis, A[Ln(PHN)4], with Ln being a trivalent rare-earth ion and A being a monovalent cation), the complexes of Nd(III), Er(III), and Yb(III) show typical near-infrared luminescence upon excitation with visible light with wavelengths up to 475 nm. The X-ray crystal structures of the tris complexes show solvent coordination to the central rare-earth ion, whereas in the tetrakis complexes, the four PHN- ligands form a protective shield around the central ion, preventing small solvent molecules from coordinating to the rare-earth ion, at least in the solid state.     

Base-base interactions in the minor groove of double-stranded DNA

A method has been developed for the synthesis of bisheaded nucleosides with thymine and adenine base moieties. We have demonstrated that, when incorporated in oligonucleotides, extrahelical A-T base interactions are possible when the bisheaded nucleosides are positioned in opposite strands of the duplex and are separated from each other by one regular base pair.     

Screening for anabolic steroids in doping analysis by liquid chromatography/electrospray ion trap mass spectrometry

A fast and selective LC/MS/MS method for the screening of four anabolic steroids in human urine has been developed and validated. Liquid-liquid extraction with diethyl ether was applied after enzymatic hydrolysis. Analyses were performed on an ion trap mass spectrometer equipped with electrospray ionisation. MS/MS was applied for all compounds. The analytical run time was 11 min. The LOD for all compounds varied between 1 and 10 ng/mL. Left-over A samples, which were declared positive by GC/MS for the presence of 3'-hydroxystanozolol, were assessed using the described method.     

Three-level phase modulator based on orthoconic antiferroelectric liquid crystals

Surface-stabilized orthoconic antiferroelectric liquid crystals (OAFLCs) have a director tilt of theta = 45 degrees and are, with no field applied, negatively uniaxial with the optic axis perpendicular to the cell substrates. We demonstrate that OAFLCs can be utilized to achieve lossless phase modulation with three almost equidistant phase levels. This turns out to be true also for polymer-stabilized OAFLCs, where the polymer network increases the switching speed of the device without affecting the phase modulation appreciably.     

Modelling overall particle motion in fluidised beds for top-spray coating processes

A mathematical model predicting the overall particle motion in liquid-sprayed gas–solid fluidised beds has been developed. The proposed model is a superposition of bubble-induced particle motion and particle random walk. The model was validated using experimental particle residence times from literature. Good agreement between experimental and model-predicted residence times was obtained for those cases where atomisation air was absent and on the condition of the inclusion of a so-called “dead zone”. The “dead zone”, being a region of stagnant particles in the annular bottom part of the bed, has also been previously reported in literature. In case atomisation air was present, a less favourable agreement was seen between the model and the experiment. As the atomisation air has been shown to significantly alter the ejection distance of particles in the freeboard, recalibration of the ejection height parameter has been demonstrated to obtain an acceptable agreement between model-predicted and experimental data.     

Efficient approach for the detection and identification of new androgenic metabolites by applying SRM GC‐CI‐MS/MS: a methandienone case study

Identification of anabolic androgenic steroids (AAS) is a vital issue in doping control and toxicology, and searching for metabolites with longer detection times remains an important task. Recently, a gas chromatography chemical ionization triple quadrupole mass spectrometry (GC‐CI‐MS/MS) method was introduced, and CI, in comparison with electron ionization (EI), proved to be capable of increasing the sensitivity significantly. In addition, correlations between AAS structure and fragmentation behavior could be revealed. This enables the search for previously unknown but expected metabolites by selection of their predicted transitions. The combination of both factors allows the setup of an efficient approach to search for new metabolites. The approach uses selected reaction monitoring which is inherently more sensitive than full scan or precursor ion scan. Additionally, structural information obtained from the structure specific CI fragmentation pattern facilitates metabolite identification. The procedure was demonstrated by a methandienone case study. Its metabolites have been studied extensively in the past, and this allowed an adequate evaluation of the efficiency of the approach. Thirty three metabolites were detected, including all relevant previously discovered metabolites. In our study, the previously reported long‐term metabolite (18‐nor‐17β‐hydroxymethyl,17α‐methyl‐androst‐1,4,13‐trien‐3‐one) could be detected up to 26 days by using GC‐CI‐MS/MS. The study proves the validity of the approach to search for metabolites of new synthetic AAS and new long‐term metabolites of less studied AAS and illustrates the increase in sensitivity by using CI. Copyright © 2016 John Wiley & Sons, Ltd.     

A novel ultrasonic strain gauge for single-sided measurement of a local 3D strain field

A novel method is introduced for the measurement of a 3D strain field by exploiting the interaction between ultrasound waves and geometrical characteristics of the insonified specimen. First, the response of obliquely incident harmonic waves to a deterministic surface roughness is utilized. Analysis of backscattered amplitudes in Bragg diffraction geometry then yields a measure for the in-plane strain field by mapping any shift in angular dependency. Secondly, the analysis of the reflection characteristics of normal incident pulsed waves in frequency domain provides a measure of the out-of-plane normal strain field component, simply by tracking any change in the stimulation condition for a thickness resonance. As such, the developed ultrasonic strain gauge yields an absolute, contactless and single-sided mapping of a local 3D strain field, in which both sample preparation and alignment procedure are needless. Results are presented for cold-rolled DC06 steel samples onto which skin passing of the work rolls is applied. The samples have been mechanically loaded, introducing plastic strain levels ranging from 2 % up to 35 %. The ultrasonically measured strains have been validated with various other strain measurement techniques, including manual micrometer, longitudinal and transverse mechanical extensometer and optical mono- and stereovision digital image correlation. Good agreement has been obtained between the ultrasonically determined strain values and the results of the conventional methods. As the ultrasonic strain gauge provides all three normal strain field components, it has been employed for the extraction of Lankford ratios at different applied longitudinal plastic strain levels, revealing a strain dependent plastic anisotropy of the investigated DC06 steel sheet.