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13C Dynamic Nuclear Polarization Using a Trimeric Gd3+ Complex as an Additive
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2017-06-28 00:00:00 , DOI: 10.1021/acs.jpca.7b03869 Peter Niedbalski 1 , Christopher Parish 1 , Qing Wang 1 , Andhika Kiswandhi 1 , Zahra Hayati 2 , Likai Song 2 , Lloyd Lumata 1
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2017-06-28 00:00:00 , DOI: 10.1021/acs.jpca.7b03869 Peter Niedbalski 1 , Christopher Parish 1 , Qing Wang 1 , Andhika Kiswandhi 1 , Zahra Hayati 2 , Likai Song 2 , Lloyd Lumata 1
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Dissolution dynamic nuclear polarization (DNP) is one of the most successful techniques that resolves the insensitivity problem in liquid-state nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) by amplifying the signal by several thousand-fold. One way to further improve the DNP signal is the inclusion of trace amounts of lanthanides in DNP samples doped with trityl OX063 free radical as the polarizing agent. In practice, stable monomeric gadolinium complexes such as Gd-DOTA or Gd-HP-DO3A are used as beneficial additives in DNP samples, further boosting the DNP-enhanced solid-state 13C polarization by a factor of 2 or 3. Herein, we report on the use of a trimeric gadolinium complex as a dopant in 13C DNP samples to improve the 13C DNP signals in the solid-state at 3.35 T and 1.2 K and consequently, in the liquid-state at 9.4 T and 298 K after dissolution. Our results have shown that doping the 13C DNP sample with a complex which holds three Gd3+ ions led to an improvement of DNP-enhanced 13C polarization by a factor of 3.4 in the solid-state, on par with those achieved using monomeric Gd3+ complexes but only requires about one-fifth of the concentration. Upon dissolution, liquid-state 13C NMR signal enhancements close to 20 000-fold, approximately 3-fold the enhancement of the control samples, were recorded in the nearby 9.4 T high resolution NMR magnet at room temperature. Comparable reduction of 13C spin–lattice T1 relaxation time was observed in the liquid-state after dissolution for both the monomeric and trimeric Gd3+ complexes. Moreover, W-band electron paramagnetic resonance (EPR) data have revealed that 3-Gd doping significantly reduces the electron T1 of the trityl OX063 free radical, but produces negligible changes in the EPR spectrum, reminiscent of the results with monomeric Gd3+-complex doping. Our data suggest that the trimeric Gd3+ complex is a highly beneficial additive in 13C DNP samples and that its effect on DNP efficiency can be described in the context of the thermal mixing mechanism.
中文翻译：
使用三聚体Gd 3+配合物作为添加剂的13 C动态核极化
溶解动态核极化（DNP）是最成功的技术之一，它通过将信号放大数千倍来解决液态核磁共振（NMR）光谱学和成像（MRI）中的不敏感性问题。进一步改善DNP信号的一种方法是在掺杂了三苯甲基OX063自由基作为偏振剂的DNP样品中包含痕量的镧系元素。实际上，稳定的单体g络合物（例如Gd-DOTA或Gd-HP-DO3A）在DNP样品中用作有益的添加剂，从而将DNP增强的固态13 C极化进一步提高了2或3倍。关于在13 C DNP样品中使用三聚g络合物作为掺杂剂以改善13溶解后，C DNP在固态时处于3.35 T和1.2 K信号，因此在液态时处于9.4 T和298 K信号。我们的结果表明，用一种固持三个Gd 3+离子的复合物掺杂13 C DNP样品，在固态下，DNP增强的13 C极化提高了3.4倍，这与使用单体法获得的结果相当。 Gd 3+复合物只需要浓度的五分之一左右。溶解后，在室温下，在附近的9.4 T高分辨率NMR磁体中记录到液态13 C NMR信号增强接近2万倍，是对照样品的增强约3倍。可比的减少13单体和三聚体Gd 3+配合物溶解后，在液态下观察到C自旋晶格T 1弛豫时间。此外，W波段电子顺磁共振（EPR）数据表明，3-Gd掺杂显着降低了三苯甲基OX063自由基的电子T 1，但在EPR谱中产生的变化可忽略不计，这令人想起单体Gd 3+的结果。-复杂的掺杂。我们的数据表明，三聚体Gd 3+复合物在13 C DNP样品中是非常有益的添加剂，其对DNP效率的影响可以在热混合机理的背景下进行描述。
更新日期：2017-06-29
中文翻译：
使用三聚体Gd 3+配合物作为添加剂的13 C动态核极化
溶解动态核极化（DNP）是最成功的技术之一，它通过将信号放大数千倍来解决液态核磁共振（NMR）光谱学和成像（MRI）中的不敏感性问题。进一步改善DNP信号的一种方法是在掺杂了三苯甲基OX063自由基作为偏振剂的DNP样品中包含痕量的镧系元素。实际上，稳定的单体g络合物（例如Gd-DOTA或Gd-HP-DO3A）在DNP样品中用作有益的添加剂，从而将DNP增强的固态13 C极化进一步提高了2或3倍。关于在13 C DNP样品中使用三聚g络合物作为掺杂剂以改善13溶解后，C DNP在固态时处于3.35 T和1.2 K信号，因此在液态时处于9.4 T和298 K信号。我们的结果表明，用一种固持三个Gd 3+离子的复合物掺杂13 C DNP样品，在固态下，DNP增强的13 C极化提高了3.4倍，这与使用单体法获得的结果相当。 Gd 3+复合物只需要浓度的五分之一左右。溶解后，在室温下，在附近的9.4 T高分辨率NMR磁体中记录到液态13 C NMR信号增强接近2万倍，是对照样品的增强约3倍。可比的减少13单体和三聚体Gd 3+配合物溶解后，在液态下观察到C自旋晶格T 1弛豫时间。此外，W波段电子顺磁共振（EPR）数据表明，3-Gd掺杂显着降低了三苯甲基OX063自由基的电子T 1，但在EPR谱中产生的变化可忽略不计，这令人想起单体Gd 3+的结果。-复杂的掺杂。我们的数据表明，三聚体Gd 3+复合物在13 C DNP样品中是非常有益的添加剂，其对DNP效率的影响可以在热混合机理的背景下进行描述。
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