Synthesis and solid-state characterization of platinum complexes with hexadentate amino- and iminophosphine ligands

Hexadentate ligands cis,cis-C6H9(N[double bond, length as m-dash]CHC6H4(PPh2))3 (1) and cis,cis-C6H9(NHCH2C6H4(PPh2))3 (2) were synthesized starting from cis,cis-1,3,5-triaminocyclohexane, and characterized using NMR spectroscopy and single-crystal X-ray diffraction. These ligands can bind both Pt(0) and Pt(II) metal centers using either or both of the soft phosphine moieties and the hard amine/imine moieties. In many cases the resulting complexes are negligibly soluble; hence, 31P and 195Pt solid-state NMR (SSNMR) spectroscopy was applied to analyse the bonding modes of the hexadentate ligands. The 195Pt SSNMR spectroscopy of these complexes is particularly challenging, since 1H–195Pt cross polarization is extremely inefficient, the 195Pt longitudinal relaxation times are extremely long and the 195Pt powder patterns are expected to be quite broad due to platinum chemical shift anisotropy. It is demonstrated that the ultra-wideline 195Pt SSNMR spectra can be efficiently acquired with a combination of frequency-stepped piecewise acquisitions and cross-polarization/Carr–Purcell Meiboom–Gill (CP/CPMG) NMR experiments. The 195Pt and 31P SSNMR data are correlated to important structural features in both Pt(0) and Pt(II) specie

Portable Heart Rate Monitor

We at Heart Guard Technologies propose to design a portable heart rate monitor, which is capable  of measuring the number of heart beats per minute and displaying the heart rate information in a  clear and simple way to avoid any confusion in chaotic situations.  This device is composed of a  small ear clip, which is similar to those used in hospitals and exercise equipments.  In order to  increase noise immunity, infrared light is used to for pulse rate measurements.  Furthermore, the  completion cost of this project will be kept low, since the use of pulse sensing equipment used for  exercise means is widespread.  &nbsp

Comprehensive Solid-State Characterization of Rare Earth Flouride Nanoparticles

The combination of multinuclear solid-state NMR spectroscopy and powder X-ray diffraction has been applied to characterize the octahedron-shaped crystalline nanoparticle products resulting from an inverse micelle synthesis. Rietveld refinements of the powder X-ray diffraction data from the nanoparticles revealed their general formula to be (H3O)Y3F10·xH2O. 1H magic-angle spinning (MAS) NMR experiments provided information on sample purity and served as an excellent probe of the zeolithic incorporation of atmospheric water. 19F MAS NMR experiments on a series of monodisperse nanoparticle samples of various sizes yielded spectra featuring three unique 19F resonances arising from three different fluorine sites within the (H3O)Y3F10·xH2O crystal structure. Partial removal of zeolithic water from the internal cavities and tunnels of the nanoparticles led to changes in the integrated peak intensities in the 19F MAS NMR spectra; the origin of this behavior is discussed in terms of 19F longitudinal relaxation. 19F–89Y variable-amplitude cross-polarization (VACP) NMR experiments on both stationary samples and samples under MAS conditions indicated that two distinct yttrium environments are present, and on the basis of the relative peak intensities, the population of one of the two sites is closely linked to the nanoparticle size. Both 19F MAS and 19F–89Y VACP/MAS experiments indicated small amounts of an impurity present in certain nanoparticles; these are postulated to be spherical amorphous YF3 nanoparticles. We discuss the importance of probing molecular-level structure in addition to microscopic structure and how the combination of these characterization methods is crucial for understanding nanoparticle design, synthesis, and application

Unravelling the Structure of Magnus' Pink Salt

A combination of multinuclear ultra-wideline solid-state NMR, powder X-ray diffraction (pXRD), X-ray absorption fine structure experiments, and first principles calculations of platinum magnetic shielding tensors has been employed to reveal the previously unknown crystal structure of Magnus’ pink salt (MPS), [Pt(NH3)4][PtCl4], study the isomeric Magnus’ green salt (MGS), [Pt(NH3)4][PtCl4], and examine their synthetic precursors K2PtCl4 and Pt(NH3)4Cl2·H2O. A simple synthesis of MPS is detailed which produces relatively pure product in good yield. Broad 195Pt, 14N, and 35Cl SSNMR powder patterns have been acquired using the WURST-CPMG and BRAIN-CP/WURST-CPMG pulse sequences. Experimentally measured and theoretically calculated platinum magnetic shielding tensors are shown to be very sensitive to the types and arrangements of coordinating ligands as well as intermolecular Pt–Pt metallophilic interactions. High-resolution 195Pt NMR spectra of select regions of the broad 195Pt powder patterns, in conjunction with an array of 14N and 35Cl spectra, reveal clear structural differences between all compounds. Rietveld refinements of synchrotron pXRD patterns, guided by first principles geometry optimization calculations, yield the space group, unit cell parameters, and atomic positions of MPS. The crystal structure has P-1 symmetry and resides in a pseudotetragonal unit cell with a distance of >5.5 Å between Pt sites in the square-planar Pt units. The long Pt–Pt distances and nonparallel orientation of Pt square planes prohibit metallophilic interactions within MPS. The combination of ultra-wideline NMR, pXRD, and computational methods offers much promise for future investigation and characterization of Pt-containing systems

Application of static microcoils and WURST pulses for solid-state ultra-wideline NMR spectroscopy of quadrupolar nuclei

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Comprehensive Solid-State Characterization of Rare Earth Fluoride Nanoparticles

The combination of multinuclear solid-state NMR spectroscopy and powder X-ray diffraction has been applied to characterize the octahedron-shaped crystalline nanoparticle products resulting from an inverse micelle synthesis. Rietveld refinements of the powder X-ray diffraction data from the nanoparticles revealed their general formula to be (H₃O)­Y₃F₁₀·<i>x</i>H₂O. ¹H magic-angle spinning (MAS) NMR experiments provided information on sample purity and served as an excellent probe of the zeolithic incorporation of atmospheric water. ¹⁹F MAS NMR experiments on a series of monodisperse nanoparticle samples of various sizes yielded spectra featuring three unique ¹⁹F resonances arising from three different fluorine sites within the (H₃O)­Y₃F₁₀·<i>x</i>H₂O crystal structure. Partial removal of zeolithic water from the internal cavities and tunnels of the nanoparticles led to changes in the integrated peak intensities in the ¹⁹F MAS NMR spectra; the origin of this behavior is discussed in terms of ¹⁹F longitudinal relaxation. ¹⁹F–⁸⁹Y variable-amplitude cross-polarization (VACP) NMR experiments on both stationary samples and samples under MAS conditions indicated that two distinct yttrium environments are present, and on the basis of the relative peak intensities, the population of one of the two sites is closely linked to the nanoparticle size. Both ¹⁹F MAS and ¹⁹F–⁸⁹Y VACP/MAS experiments indicated small amounts of an impurity present in certain nanoparticles; these are postulated to be spherical amorphous YF₃ nanoparticles. We discuss the importance of probing molecular-level structure in addition to microscopic structure and how the combination of these characterization methods is crucial for understanding nanoparticle design, synthesis, and application

New Insights into the Short-Range Structures of Microporous Titanosilicates As Revealed by Ti-47/49, Na-23, K-39, and Si-29 Solid-State NMR Spectroscopy

Seven prototypical microporous titanosilicates have been studied by multinuclear solid-state NMR (SSNMR) spectroscopy, representing four typical Ti environments: square-pyramidal TiO5 units (natisite, AM-1, ETS-4), edge-shared brookite-type TiO6 chains (AM-4), cubane-type Ti4O16 clusters (sitinakite, GTS-1), and corner-shared TiO6 chains (ETS-10, ETS-4). Ti-47/49 SSNMR spectra at 21.1 T are related to the coordination, crystal symmetry, and local environment of Ti. Distortions in TiO bond lengths and OTiO coordination angles are reflected via C-Q(Ti-47/49) values that range from 8 to 16 MHz. Several titanosilicates feature axially symmetric Ti-47/49 electric field gradient (EFG) tensors that permit facile spectral assignment and detection of deviations in local symmetry. This study uses Si-29 NMR experiments to assess phase purity and crystallinity. Na-23 NMR is used to probe the location and mobility of the sodium ions in the framework. The potential of K-39 SSNMR for investigation of extra-framework counter cations is demonstrated by ETS-10, with increased spectral resolution and enhanced sensitivity to changes in local environment versus Na-23 experiments. Plane-wave DFT calculations predicted Ti-47/49 NMR parameters assisting in spectral assignments and help correlate Na-23 and Si-29 NMR resonances to crystallographic sites. The approach described in this work should promote further SSNMR investigations of microporous solids, such as titanosilicates, with unknown or poorly defined structures