Sensitivity considerations in polarization transfer and filtering using dipole-dipole couplings: implications for biomineral systems.
The robustness and sensitivities of different polarization-transfer methods that exploit heteronuclear dipole-dipole couplings are compared for a series of heterogeneous solid systems, including polycrystalline tetrakis(trimethylsilyl)silane (TKS), adamantane, a physical mixture of doubly (13)C,(15)N-enriched and singly (13)C-enriched polycrystalline glycine, and a powder sample of siliceous marine diatoms, Thalossiosira pseudonana. The methods were analyzed according to their respective frequency-matching spectra or resultant signal intensities. For a series of (13)C{(1)H} cross-polarization experiments, adiabatic passage Hartmann-Hahn cross-polarization (APHH-CP) was shown to have several advantages over other methods, including Hartmann-Hahn cross-polarization (HHCP), variable-amplitude cross-polarization (VACP), and ramped-amplitude cross-polarization (RACP). For X-Y systems, such as (13)C{(15)N}, high and comparable sensitivities were obtained by using APHH-CP with Lee-Goldburg decoupling or by using the transferred-echo double resonance (TEDOR) experiment. The findings were applied to multinuclear (1)H, (13)C, (15)N, and (29)Si CP MAS characterization of a powder diatom sample, a challenging inorganic-organic hybrid solid that places high demands on NMR signal sensitivity.
Christiansen
Sean C
SC
Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, USA.
Hedin
Niklas
N
Epping
Jan D
JD
Janicke
Michael T
MT
del Amo
Yolanda
Y
Demarest
Mark
M
Brzezinski
Mark
M
Chmelka
Bradley F
BF
D001704:Biopolymers / Q000032:analysis* / Q000737:chemistry*; D002247:Carbon Isotopes; D005374:Filtration / Q000379:methods; D008903:Minerals / Q000032:analysis* / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D001704:Biopolymers; D002247:Carbon Isotopes; D008903:Minerals; D011522:Protons