Solid-state spin-echo Fourier transform NMR of 39K and 67Zn salts at high field

Solid-state NMR characterisation of the thermal transformation of a Hungarian white illite

“…An echo sequence was used with two 5 μs (sub-90 o ) pulses separated by 200 μs with a recycle delay of 0.05 s. Extended phase cycling was used to suppress direct magnetisation and any ringing [36]. 39 K spectra were referenced against a static sample of solid KBr at 55.1 ppm.…”

Solid-State 25Mg NMR Spectroscopic and Computational Studies of Organic Compounds. Square-Pyramidal Magnesium(II) Ions in Aqua(magnesium) Phthalocyanine and Chlorophyll a

“…13 The Mg(II) ion in this compound is coordinated to six nitrogen atoms in a distorted octahedral geometry where the 25 Mg quadrupole coupling constant (C Q ) exceeds 15 MHz, the largest so far being observed for all Mg-(II) compounds. Frydman and co-workers studied solid-state 25 Mg NMR spectra for a Mg(II) salt of adenosine 5′-triphosphate (ATP). 7 Hung and Schurko reported solid-state 25 Mg NMR spectra for bis(cyclopentadienyl)magnesium(II).…”

“…1,2 A particularly important trend is that solid-state NMR has emerged as a viable technique to study metal binding sites involving low-γ quadrupolar nuclei with half-integer spins such as 39 K (spin-3/2), 67 Zn (spin-5/2), and 25 Mg (spin-5/2) in organic and biological compounds. [3][4][5][6][7][8][9][10][11][12][13][14][15][16] These metal ions are biologically important, but technically difficult to study by NMR spectroscopy.…”

“…18 Wu and co-workers 14 have demonstrated that solidstate 39 K NMR can be used as a new probe for studying K + binding in DNA-related G-quadruplexes. In the context of 25 Mg NMR, several research groups have recently extended solidstate 25 Mg NMR to organic systems. Sham and Wu 6 reported solid-state 25 Mg NMR spectra of several Mg(II) complexes including the first 25 Mg multiple-quantum magic-angle spinning (MQMAS) spectrum for organic Mg(II) salts.…”

“…Because Mg(II) ions play pivotal roles in biological structures and functions (e.g., enzyme activity and RNA folding), [19][20][21] it is important to establish a baseline for the utility of solid-state 25 Mg NMR as an effective technique. To this end, it is necessary to characterize 25 Mg NMR parameters (tensors) for all known modes of Mg(II) ion binding in organic compounds. In this study, we report solid-state 25 Mg NMR characterization for an important class of Mg(II) ions: Mg(II) ions in a squarepyramidal geometry.…”