Long-lived nuclear spin states in the solution NMR of four-spin systems.
نویسندگان
چکیده
The existence of long-lived nuclear spin states in four-spin systems is explored by solution-state NMR experiments. Long-lived states are proved to exist in three different natural product molecules, each containing either a AA'BB' or a AA'XX' proton spin system. The measured state lifetimes are between four and eight times the spin-lattice relaxation time constants.
منابع مشابه
Long-lived nuclear spin states far from magnetic equivalence.
Clusters of coupled nuclear spins may form long-lived nuclear spin states, which interact weakly with the environment, compared to ordinary nuclear magnetization. All experimental demonstrations of long-lived states have so far involved spin systems which are close to the condition of magnetic equivalence, in which the network of spin-spin couplings is conserved under all pair exchanges of symm...
متن کاملLong-lived Nuclear Spin States in Multiple-Spin Systems
a ) 400 MHz 1H-NMR spectrum at 300 K of citric acid; b) typical singlet state pattern obtained for t = 1 ms; c) singlet state pattern obtained for t = 3.5 s. The sequence, originally written for the AX case, was applied to the citric acid, an AA’BB’ four spin system. The CW decoupling was set to 3.5 kHz while the timing optimized to obtain the maximum population of the singlet state at the time...
متن کاملHyperpolarized long-lived nuclear spin states in monodeuterated methyl groups.
Monodeuterated methyl groups may support a long-lived nuclear spin state, with a relaxation time exceeding the conventional spin-lattice relaxation time T1. Dissolution-DNP (dynamic nuclear polarization) may be used to hyperpolarize such a long-lived spin state. This is demonstrated for the CH2D groups of a piperidine derivative. The polarized sample is manipulated in the ambient magnetic field...
متن کاملA Nuclear Singlet Lifetime of More than One Hour in Room‐Temperature Solution†
Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are supremely important techniques with numerous applications in almost all branches of science. However, until recently, NMR methodology was limited by the time constant T1 for the decay of nuclear spin magnetization through contact with the thermal molecular environment. Long-lived states, which are correlated quantum state...
متن کاملcis Versus trans-Azobenzene: Precise Determination of NMR Parameters and Analysis of Long-Lived States of 15N Spin Pairs
We provide a detailed evaluation of nuclear magnetic resonance (NMR) parameters of the cis- and trans-isomers of azobenzene (AB). For determining the NMR parameters, such as proton-proton and proton-nitrogen J-couplings and chemical shifts, we compared NMR spectra of three different isotopomers of AB: the doubly 15N labeled azobenzene, 15N,15N'-AB, and two partially deuterated AB isotopomers wi...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of magnetic resonance
دوره 182 2 شماره
صفحات -
تاریخ انتشار 2006