Ferroelectric properties of a series of core-fluorinated dopants containing the 2,3-difluoroalkoxy tail

Abstract

Previous reports from these laboratories [1] have discussed the synthesis and properties of core-fluorinated phenylpyridines with an attached difluoroalkoxy tail. This paper discusses core-fluorinated phenylpyridine difluoroalkoxides and compares their properties to those of the corresponding phenylpyrimidines. The pyridine and pyrimidine series are found to be remarkably similar in properties. They have similar high polarizations and fast rise times, attractive in surfacestabilized ferroelectric liquid crystal (SSFLC) applications, and in high concentration have pitch properties compatible with deformable helix FLC applications.     

Substituted tertiary phosphine Ru(II) organometallics: catalytic utility on the hydrolysis of etofibrate in pharmaceuticals

Some new organometallics of ruthenium(II) of the type [RuCl(2)(COD)(CO)L] (1a-f) and [RuCl(2)(COD)L(2)] (2a-f) (where L is substituted tertiary phosphines), have been synthesized by using precursors [RuCl(2)(COD)(CO)(CH(3)CN)] (1) and [RuCl(2)(COD)(CH(3)CN)(2)] (2) with the substituted tertiary phosphine ligands in 1:1 and 1:2 molar ratio. The organometallics (2a-f) have been further reacted with carbonmonoxide to produce compounds of the type [RuCl(2)(CO)L(2)] (3a-f). These compounds were characterized by elemental analysis, IR, NMR ((1)H, (13)C and (31)P), mass and electronic spectral data. The catalytic activity of all these organometallics were studied and found that they are efficient catalysts for hydrolysis of etofibrate. The hydrolyzed product was separated by column chromatography and the percent yields are found in the range of 98.6-99.1%.     

Study of Ba3M(II)M(IV)WO9 (M(II) = Ca, Zn; M(IV) = Ti, Zr) perovskite oxides: competition between 3C and 6H perovskite structures

We describe an investigation of Ba3MIIMIVWO9 oxides for MII = Ca, Zn, and other divalent metals and MIV = Ti, Zr. In general, a 1:2-ordered 6H (hexagonal, P63/mmc) perovskite structure is stabilized at high temperatures (1300 degrees C) for all of the Ba3MIITiWO9 oxides investigated. An intermediate phase possessing a partially ordered 1:1 double perovskite (3C) structure with the cation distribution, Ba2(Zn2/3Ti1/3)(W2/3Ti1/3)O6, is obtained at 1200 degrees C for Ba3ZnTiWO9. Sr substitution for Ba in the latter stabilizes the cubic 3C structure instead of the 6H structure. A metastable Ba3CaZrWO9 that adopts the 3C (cubic, Fmm) structure has also been synthesized by a low-temperature metathesis route. Besides yielding several new perovskite oxides that may be useful as dielectric ceramics, the present investigation provides new insights into the complex interplay of crystal chemistry (tolerance factor) and chemical bonding (anion polarization and d0-induced distortion of metal-oxygen octahedra) in the stabilization of 6H versus 3C perovskite structures for the Ba3MIIMIVWO9 series.     

Orbital-optimized opposite-spin scaled second-order correlation: an economical method to improve the description of open-shell molecules

Coupled-cluster methods based on Brueckner orbitals are well known to resolve the problems of symmetry breaking and spin contamination that are often associated with Hartree-Fock orbitals. However, their computational cost is large enough to prevent application to large molecules. Here the authors present a simple approximation where the orbitals are optimized with the mean-field energy plus a correlation energy taken as the opposite-spin component of the second-order many-body correlation energy, scaled by an empirically chosen parameter (recommended as 1.2 for general applications). This "optimized second-order opposite-spin" (abbreviated as O2) method requires fourth-order computation on each orbital iteration. O2 is shown to yield predictions of structure and frequencies for closed-shell molecules that are very similar to scaled second-order Moller-Plesset methods. However, it yields substantial improvements for open-shell molecules, where problems with spin contamination and symmetry breaking are shown to be greatly reduced.     

Probing CP-violating Higgs contributions in γγ → f$$ \bar f $$

We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson ϕ in γγ → f , f = τ/t, from that of the QED continuum. This can help in getting information on the γγϕ coupling in case ϕ is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case ϕ has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well as its CP properties over a wide range of MSSM parameters.      

Palladium-catalyzed C-CN activation for intramolecular cyanoesterification of alkynes

Conditions for the C-CN activation and intramolecular cyanoesterification of alkynes to provide butenolides in good to excellent yields are presented. Pd catalysts, high temperatures/short reaction times (microwave irradiation), and Lewis basic solvents minimized competitive decarbonylation. Less sterically encumbered, electron-rich alkynes underwent cyanoesterification with greater ease compared to sterically encumbered, electron-deficient alkynes. The results led to the hypothesis that migratory insertion of the alkyne, rather than C-CN activation, might be the product-determining step.     

Ferroelectric properties of a series of core-fluorinated dopants containing the 2,3-difluoroalkoxy tail

Previous reports from these laboratories [1] have discussed the synthesis and properties of core-fluorinated phenylpyridines with an attached difluoroalkoxy tail. This paper discusses core-fluorinated phenylpyridine difluoroalkoxides and compares their properties to those of the corresponding phenylpyrimidines. The pyridine and pyrimidine series are found to be remarkably similar in properties. They have similar high polarizations and fast rise times, attractive in surfacestabilized ferroelectric liquid crystal (SSFLC) applications, and in high concentration have pitch properties compatible with deformable helix FLC applications.     

Engineering Design,Implementation, and Sensing Mechanisms of Wearable Bioelectronic Sensors in Clinical Settings

Wearable sensing devices have transformed the hourly analysis of events such as body signals and environmental risks into real-time monitoring in minutes or seconds. Wearable sensors have facilitated the ability to obtain useful data by monitoring the physiological parameters and activities of an aided and a healthy individual. Wearable devices employ detectable biomarkers in the human body, such as in tears, saliva, interstitial fluid, sweat, and so on. These can deliver relevant information on human health, online activity monitoring, and therapeutic treatments. This section outlines the significance of sample types and associated biomarkers as indicators in the development and manufacturing of wearable biosensors. We have emphasized the most recent advances of wearables based on skin-like and textile, giving attention to personalized health monitoring to record signals of motion and physiological and body fluid investigation. Furthermore, this review categorizes wearable biosensors based on the sensing mechanism, electrochemical, optical, and mechanical. Additionally, the recent wearables related to the detection of the newly havoc-causing pandemic, COVID-19, and the future perspective for the development of much more advanced and potent wearable biosensors have been highlighted. The final section highlights unmet difficulties and gaps in wearable sensors in personalized therapy.