An Investigation of 1:1 Adducts of Gallium Trihalides with Triarylphosphines by Solid‐State 69/71Ga and 31P NMR Spectroscopy

Several 1:1 adducts of gallium trihalides with triarylphosphines, X₃Ga(PR₃) (X=Cl, Br, and I; PR₃=triarylphosphine ligand), were investigated by using solid‐state ^69/71Ga and ³¹P NMR spectroscopy at different magnetic‐field strengths. The ^69/71Ga nuclear quadrupolar coupling parameters, as well as the gallium and phosphorus magnetic shielding tensors, were determined. The magnitude of the ⁷¹Ga quadrupolar coupling constants (C_Q(⁷¹Ga)) range from approximately 0.9 to 11.0 MHz . The spans of the gallium magnetic shielding tensors for these complexes, δ₁₁?δ₃₃, range from approximately 30 to 380 ppm; those determined for phosphorus range from 10 to 40 ppm. For any given phosphine ligand, the gallium nuclei are most shielded for X=I and least shielded for X=Cl, a trend previously observed for In^III–phosphine complexes. This experimental trend, attributed to spin‐orbit effects of the halogen ligands, is reproduced by DFT calculations. The signs of C_Q(^69/71Ga) for some of the adducts were determined from the analysis of the ³¹P NMR spectra acquired with magic angle spinning (MAS). The ¹J(^69/71Ga,³¹P) and ΔJ(^69/71Ga, ³¹P) values, as well as their signs, were also determined; values of ¹J(⁷¹Ga,³¹P) range from approximately 380 to 1590 Hz. Values of ¹J(^69/71Ga,³¹P) and ΔJ(^69/71Ga,³¹P) calculated by using DFT have comparable magnitudes and generally reproduce experimental trends. Both the Fermi‐contact and spin‐dipolar Fermi‐contact mechanisms make important contributions to the ¹J(^69/71Ga,³¹P) tensors. The ³¹P NMR spectra of several adducts in solution, obtained as a function of temperature, are contrasted with those obtained in the solid state. Finally, to complement the analysis of NMR spectra for these adducts, single‐crystal X‐ray diffraction data for Br₃Ga[P(p‐Anis)₃] and I₃Ga[P(p‐Anis)₃] were obtained.     

Divergent and Overlapping Roles for Selected Phytochemicals in the Regulation of Pathological Cardiac Hypertrophy

Plant-based foods, like fruits, vegetables, whole grains, legumes, nuts, seeds and other foodstuffs, have been deemed as heart healthy. The chemicals within these plant-based foods, i.e., phytochemicals, are credited with protecting the heart. However, the mechanistic actions of phytochemicals, which prevent clinical endpoints, such as pathological cardiac hypertrophy, are still being elucidated. We sought to characterize the overlapping and divergent mechanisms by which 18 selected phytochemicals prevent phenylephrine- and phorbol 12-myristate 13-acetate-mediated cardiomyocyte enlargement. Of the tested 18 compounds, six attenuated PE- and PMA-mediated enlargement of neonatal rat ventricular myocytes. Cell viability assays showed that apigenin, baicalein, berberine hydrochloride, emodin, luteolin and quercetin dihydrate did not reduce cell size through cytotoxicity. Four of the six phytochemicals, apigenin, baicalein, berberine hydrochloride and emodin, robustly inhibited stress-induced hypertrophy and were analyzed further against intracellular signaling and genome-wide changes in mRNA expression. The four phytochemicals differentially regulated mitogen-activated protein kinases and protein kinase D. RNA-sequencing further showed divergence in gene regulation, while pathway analysis demonstrated overlap in the regulation of inflammatory pathways. Combined, this study provided a comprehensive analysis of cardioprotective phytochemicals. These data highlight two defining observations: (1) that these compounds predominantly target divergent gene pathways within cardiac myocytes and (2) that regulation of overlapping signaling and gene pathways may be of particular importance for the anti-hypertrophic actions of these phytochemicals. Despite these new findings, future works investigating rodent models of heart failure are still needed to understand the roles for these compounds in the heart.     

Investigation of N‐Heterocyclic Carbene‐Supported Group 12 Triflates as Pre‐catalysts for Hydrosilylation/Borylation

N‐Heterocyclic carbene (NHC) complexes of Cd and Hg triflates (OTf) were prepared and their attempted conversion into rare cadmium and mercury hydrides was explored. In contrast to zinc, which forms stable [ZnH]⁺ complexes with NHCs, the heavier Cd and Hg congeners could not be formed; the increased instability of Cd‐H and Hg‐H units was rationalized with the aid of computations. It was also discovered that the dimeric adduct [IPr?Cd(μ‐OTf)₂]₂ (IPr=[(HCNDipp)₂C:]; Dipp=2,6‐iPr₂C₆H₃) is an active precatalyst for the hydrosilylation and hydroborylation of hindered aldehydes and ketones. The related zinc congener was inactive as a catalyst highlighting a distinct advantage of using heavy Group 12 metals to promote catalytic hydrosilylation/borylation.     

Dalitz analysis of D0-->K(0)(S)pi(+)pi(-)

In e(+)e(-) collisions using the CLEO detector, we have studied the decay of the D0 to the final state K(0)(S)pi(+)pi(-) with the initial flavor of the D0 tagged by the decay D(*+)-->D0pi(+). We use the Dalitz technique to measure the resonant substructure in this final state and clearly observe ten different contributions by fitting for their amplitudes and relative phases. We observe a K(*)(892)(+)pi(-) component which arises from doubly Cabibbo suppressed decays or D0-D0; mixing.     

Improved measurement of Vub with inclusive semileptonic B decays

We report a new measurement of the Cabibbo-Kobayashi-Maskawa parameter Vub made with a sample of 9.7 x 10(6) BB- events collected with the CLEO II detector. Using heavy quark theory, we combine the observed yield of leptons from semileptonic B decay in the end-point momentum interval 2.2-2.6 GeV/c with recent CLEO II data on B-->X(s)gamma to find Vub = (4.08+/-0.34+/-0.44+/-0.16+/-0.24)x10(-3), where the first two uncertainties are experimental and the last two are from theory.     

T-ray computed tomography

We demonstrate a tomographic imaging modality that uses pulsed terahertz (THz) radiation to probe the optical properties of three-dimensional (3D) structures in the far-infrared. This THz-wave computed tomography (T-ray CT) system provides sectional images of objects in a manner analogous to conventional CT techniques such as x-ray CT. The transmitted amplitude and phase of broadband pulses of THz radiation are measured at multiple projection angles. The filtered backprojection algorithm is then used to reconstruct the target object, including both its 3D structure and its frequency-dependent far-infrared optical properties.     

Studies on the nature and significance of macromolecular complexes in the rheology of synovial fluid from normal and diseased human joints

Summary The rheological characteristics of synovial fluid have been examined with aWeissenberg Rheogoniometer.Rheological evidence for the existence of a macromolecular complex in normal but not in inflammatory joint fluids has been deduced from experiments with hydrogen bond breaking agents.Further flow experiments with measurements of relaxation time and activation energy for viscous flow appear to support the contention that macromolecular complexes do exist in normal fluid and that dilution alone does not account for their dissolution in inflammatory joint diseases.Proteolytic enzyme extracts from inflammatory synovial fluid appear to have no effect on the flow characteristics of normal synovial fluid.Attempts to identify the nature of the macromolecular complex by analytical ultracentrifugation were not successful.It is concluded that rheological techniques offer a way of investigating macromolecular interactions when classical chemical methods may not be appropriate.

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Zusammenfassung Es ist gut bekannt, daß Synovialflüssigkeit von rheumatisch-veränderten Gelenken eine geringere Viskosität hat, weniger Nicht-Newtonsches Verhalten zeigt und weniger elastisch ist als Synovialflüssigkeit von normalen Gelenken. Thixotropie, die normale Synovialflüssigkeit charakterisiert, ist in Synovialflüssigkeit von kranken Gelenken verringert oder nicht vorhanden. In dieser Veröffentlichung werden rheologische Experimente beschrieben, die mit normaler und rheumatisch veränderter Synovialflüssigkeit durchgeführt worden sind, um diese Veränderungen in Theologischen Besonderheiten zu erklären.Das Fließverhalten wurde mit einemWeissenberg-Rheogoniometer (Typ R 16) unter kontinuierlicher Schubbelastung untersucht.Andere Forscher haben gezeigt, daß in rheumatischer Synovialflüssigkeit die Hyaluronsäure abgebaut und daß die Konzentration an Hyaluronsäure-Eiweißkomplex reduziert wird. In-vitro-Experimente haben in unserem Labor auch gezeigt, daß Zugabe von wasserstoffbrückenzerstörenden Reagenzien zu normaler Synovialflüssigkeit das Fließverhalten von dieser der rheumatischen Synovialflüssigkeit sehr ähnlich machen. Rheologische Daten, die in Detail gegeben werden, zeigen, daß in normaler Synovialflüssigkeit ein makromolekularer Komplex vorhanden ist, der in rheumatischer Flüssigkeit dissoziiert.Die Art und Bedeutung dieses makromolekularen Komplexes sind weiter untersucht worden, besonders durch Bestimmung der Aktivierungsenergien für laminares Fließen von mehreren Synovialflüssigkeiten. Diese Daten wurden gestützt durch Ergebnisse von analytischen Ultrazentrifugen-Experimenten und durch weitere rheologische Experimente mit Extrakten von proteolytischen Enzymen.

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Paper presented to the British Society of Rheology Conference on Rheology in Medicine and Pharmacy, London, April 14–15, 1970.     

Anisotropy of NMR relaxation,and diffusion,of penetrants in stretched cis-polyisoprene

We have measured ¹H and ¹⁹F NMR relaxation times T₁, T_1ρ, and T₂, and diffusion constants, in trace penetrants hexafluorobenzene and n-hexadecane dissolved in stretched cis-polyisoprene, as function of temperature, rubber elongation, and angle with respect to the stretch direction. Values of T₁ and T₂ in the rubber were also measured. At all temperatures (—40 ≤ T ≤ 85°C), T₁ in rubber and penetrants is isotropic and independent of elongation; the differences between rubber and penetrants are related to penetrant diffusion. All T₂ above—15°C are anisotropic and elongation dependent, and follow a motional narrowing model. For the penetrants, averaging the dipolar interactions implies averaging over a diffusion path; this correctly reproduces the observed much higher T₂ anisotropy in the penetrants. Penetrant diffusion rates, however, are essentially isotropic and elongation independent. These effects depend only weakly on the shape of the penetrant molecules.