Triple-quantum dynamics in multiple-spin systems undergoing magic-angle spinning: application to 13C homonuclear correlation spectroscopy.
We analyze the multiple-quantum dynamics governed by a new homonuclear recoupling strategy effecting an average dipolar Hamiltonian comprising three-spin triple-quantum operators (e.g., S(p)+S(q)+S(r)+) under magic-angle spinning conditions. Analytical expressions are presented for polarization transfer processes in systems of three and four coupled spins-1/2 subject to triple-quantum filtration (3QF), and high-order multiple-quantum excitation is investigated numerically in moderately large clusters, comprising up to seven spins. This recoupling approach gives highly efficient excitation of triple-quantum coherences: ideally, up to 67% of the initial polarization may be recovered by 3QF in three-spin systems in polycrystalline powders. Two homonuclear 2D correlation strategies are demonstrated experimentally on powders of uniformly 13C-labeled alanine and tyrosine: the first correlates the single-quantum spectrum in the first dimension with the corresponding 3QF spectrum along the other. The second protocol correlates triple-quantum coherences with their corresponding single-quantum coherences within triplets of coupled spins.
Edén
Mattias
M
Physical Chemistry Division, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden. mattias@physc.su.se
Brinkmann
Andreas
A
D000409:Alanine / Q000737:chemistry*; D002247:Carbon Isotopes; D008962:Models, Theoretical; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D014443:Tyrosine / Q000737:chemistry*
D002247:Carbon Isotopes; D014443:Tyrosine; D000409:Alanine