Funding by the University of East Anglia, the EPSRC (EP/L012855/1) and the EU (H2020-MSCA-IF-2014-EF-ST-658172) is gratefully acknowledged (MTQ).

<ol>
	<li>Bain, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+Exchange+in+NMR.">Chemical Exchange in NMR.</a> Prog. Nuc. Mag. Res. Spect. 43, 63-103 (2003).</li><li>Bain, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+Exchange.">Chemical Exchange.</a> Modern Magnetic Resonance. , 421-427 (2006).</li><li>Bain, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+2+-+Chemical+Exchange.">Chapter 2 - Chemical Exchange.</a> Ann. Rep. NMR Spect. 63, 23-48 (2008).</li><li>Reeves, L., Shaddick, R., Shaw, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nuclear+Magnetic+Resonance+Studies+of+Multi-site+Chemical+Exchange.+III.+Hindered+Rotation+in+Dimethylacetamide,+Dimethyl+Trifluoro-acetamide,+and+Dimethyl+Benzamide.">Nuclear Magnetic Resonance Studies of Multi-site Chemical Exchange. III. Hindered Rotation in Dimethylacetamide, Dimethyl Trifluoro-acetamide, and Dimethyl Benzamide.</a> Can. J. Chem. 49, 3683-3691 (1971).</li><li>Drakenberg, T., Dahlqvist, K., Forsen, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Barrier+to+Internal+Rotation+in+Amides.+IV.+N,N-Dimethylamides.+Substituent+and+Solvent+Effects.">Barrier to Internal Rotation in Amides. IV. N,N-Dimethylamides. Substituent and Solvent Effects.</a> J. Phys. Chem. 76, 2178-2183 (1972).</li><li>Fujiwara, F., Airoldi, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon-13+NMR+Study+of+the+Barrier+to+Internal+Rotation+of+N,N-Dimethylacetamide+in+the+Adduct+with+Antimony(III)+Chloride.">Carbon-13 NMR Study of the Barrier to Internal Rotation of N,N-Dimethylacetamide in the Adduct with Antimony(III) Chloride.</a> J. Phys. Chem. 88, 1640-1642 (1984).</li><li>Gutowsky, H. S., Holm, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rate+Processes+and+Nuclear+Magnetic+Resonance+Spectra.+II.+Hindered+Internal+Rotation+of+Amides.">Rate Processes and Nuclear Magnetic Resonance Spectra. II. Hindered Internal Rotation of Amides.</a> J. Chem. Phys. 25, 1228-1234 (1956).</li><li>Forsen, S., Hoffman, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+New+Method+for+the+Study+of+Moderately+Rapid+Chemical+Exchange+Rates+Employing+Nuclear+Magnetic+Double+Resonance.">A New Method for the Study of Moderately Rapid Chemical Exchange Rates Employing Nuclear Magnetic Double Resonance.</a> Acta Chem. Scand. 17, 1787-1788 (1963).</li><li>Forsen, S., Hoffman, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+of+Moderately+Rapid+Chemical+Exchange+Reactions+by+Means+of+Nuclear+Magnetic+Double+Resonance.">Study of Moderately Rapid Chemical Exchange Reactions by Means of Nuclear Magnetic Double Resonance.</a> J. Chem. Phys. 39, 2892-2901 (1963).</li><li>Williams, T. J., Kershaw, A. D., Li, V., Wu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Inversion+Recovery+NMR+Kinetics+Experiment.">An Inversion Recovery NMR Kinetics Experiment.</a> J. Chem. Educ. 88, 665-669 (2011).</li><li>Bain, A. D., Cramer, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Slow+Chemical+Exchange+in+an+Eight-Coordinated+Bicentered+Ruthenium+Complex+Studied+by+One-Dimensional+Methods.+Data+Fitting+and+Error+Analysis.">Slow Chemical Exchange in an Eight-Coordinated Bicentered Ruthenium Complex Studied by One-Dimensional Methods. Data Fitting and Error Analysis.</a> J. Magn. Res., Series A. 118, 21-27 (1996).</li><li>Sandstrom, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Dynamic NMR Spectroscopy. , (1982).</li><li>Castanar, L., Nolis, P., Virgili, A., Parella, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+T1/T2+Relaxation+Times+in+Overlapped+Regions+from+Homodecoupled+1H+Singlet+Signals.">Measurement of T1/T2 Relaxation Times in Overlapped Regions from Homodecoupled 1H Singlet Signals.</a> J. Magn. Reson. 244, 30-35 (2014).</li><li>Mu&#241;oz, M. P., de la Torre, M. C., Sierra, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+Platinum-Catalysed+Dihydroalkoxylation+of+Allenes.">New Platinum-Catalysed Dihydroalkoxylation of Allenes.</a> Adv. Synth. Catal. 352, 2189-2194 (2010).</li><li>Mu&#241;oz, M. P., de la Torre, M. C., Sierra, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platinum-Catalysed+Bisindolylation+of+Allenes:+A+Complementary+Alternative+to+Gold+Catalysis.">Platinum-Catalysed Bisindolylation of Allenes: A Complementary Alternative to Gold Catalysis.</a> Chem. Eur. J. 18, 4499-4504 (2012).</li><li>Hurtado-Rodrigo, C., Hoehne, S., Mu&#241;oz, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+New+Gold-Catalysed+Azidation+of+Allenes.">A New Gold-Catalysed Azidation of Allenes.</a> Chem. Comm. 50, 1494-1496 (2014).</li><li>Vrieze, K., Volger, H. C., Gronert, M., Praat, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intramolecular+Rearrangements+in+Platinum--Tetramethylallene+Compounds+as+Influenced+by+Ligands+Trans+to+the+Allene+Group.">Intramolecular Rearrangements in Platinum--Tetramethylallene Compounds as Influenced by Ligands Trans to the Allene Group.</a> J. Organometal. Chem. 16, 19-22 (1969).</li><li>Vrieze, K., Volger, H. C., Praat, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complexes+of+Allenes+with+Platinum+(II)+and+Rhodium+(I).">Complexes of Allenes with Platinum (II) and Rhodium (I).</a> J. Organometal. Chem. 21, 467-475 (1970).</li><li>Brown, T. J., Sugie, A., Leed, M. G. D., Widenhoefer, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structures+and+Dynamic+Solution+Behavior+of+Cationic,+Two-Coordinate+Gold(I)-&#960;-Allene+Complexes.">Structures and Dynamic Solution Behavior of Cationic, Two-Coordinate Gold(I)-&#960;-Allene Complexes.</a> Chem. Eur. J. 18, 6959-6971 (2012).</li><li>Yang, W., Hashmi, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanistic+Insights+into+the+Gold+Chemistry+of+Allenes.">Mechanistic Insights into the Gold Chemistry of Allenes.</a> Chem. Soc. Rev. 43, 2941-2955 (2014).</li><li>Quiros, M. T., Angulo, J., Munoz, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetics+of+Intramolecular+Chemical+Exchange+by+Initial+Growth+Rates+of+Spin+Saturation+Transfer+Difference+Experiments+(SSTD+NMR).">Kinetics of Intramolecular Chemical Exchange by Initial Growth Rates of Spin Saturation Transfer Difference Experiments (SSTD NMR).</a> Chem. Commun. 51, 10222-10225 (2015).</li><li>Mayer, M., Meyer, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+Ligand+Binding+by+Saturation+Transfer+Difference+NMR+Spectroscopy.">Characterization of Ligand Binding by Saturation Transfer Difference NMR Spectroscopy.</a> Ang. Chem. Int. Ed. 38, 1784-1788 (1999).</li><li>Angulo, J., Nieto, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=STD-NMR:+Application+to+Transient+Interactions+Between+Biomolecules+-+A+Quantitative+Approach.">STD-NMR: Application to Transient Interactions Between Biomolecules - A Quantitative Approach.</a> Eur. Biophys. J. 40, 1357-1369 (2011).</li><li>Kemper, S., Patel, M. K., Errey, J. C., Davis, B. G., Jones, J. A., Claridge, T. D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Group+Epitope+Mapping+Considering+Relaxation+of+the+Ligand+(GEM-CRL):+Including+Longitudinal+Relaxation+Rates+in+the+Analysis+of+Saturation+Transfer+Difference+(STD)+Experiments.">Group Epitope Mapping Considering Relaxation of the Ligand (GEM-CRL): Including Longitudinal Relaxation Rates in the Analysis of Saturation Transfer Difference (STD) Experiments.</a> J. Magn. Reson. 203, 1-10 (2010).</li><li>Berger, S., Braun, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> 200 and More NMR Experiments: A Practical Course. , (2004).</li><li>Cutting, B., Shelke, S. V., Dragic, Z., Wagner, B., Gathje, H., Kelm, S., Ernst, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitivity+Enhancement+in+Saturation+Transfer+Difference+(STD)+Experiments+Through+Optimized+Excitation+Schemes.">Sensitivity Enhancement in Saturation Transfer Difference (STD) Experiments Through Optimized Excitation Schemes.</a> Magn Reson Chem. 45, 720-724 (2007).</li><li>Ley, N. B., Rowe, M. L., Williamson, R. A., Howard, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimising+Selective+Excitation+Pulses+To+Maximize+Saturation+Transfer+Difference+NMR+Spectroscopy.">Optimising Selective Excitation Pulses To Maximize Saturation Transfer Difference NMR Spectroscopy.</a> RSC Adv. 4, 7347-7351 (2014).</li><li>Antanasijevic, A., Ramirez, B., Caffrey, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+the+Sensitivities+of+WaterLOGSY+and+Saturation+Transfer+Difference+NMR+Experiments.">Comparison of the Sensitivities of WaterLOGSY and Saturation Transfer Difference NMR Experiments.</a> J. Biomol. NMR. 60 (1), 37-44 (2014).</li><li>Jarek, R. L., Flesher, R. J., Shin, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetics+of+Internal+Rotation+of+N,N-Dimethylacetamide:+A+Spin-Saturation+Transfer+Experiment.">Kinetics of Internal Rotation of N,N-Dimethylacetamide: A Spin-Saturation Transfer Experiment.</a> J. Chem. Ed. 74, 978-982 (1997).</li><li>Forsen, S., Hoffman, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exchange+Rates+by+Nuclear+Magnetic+Multiple+Resonance.+III.+Exchange+Reactions+in+Systems+with+Several+Nonequivalent+Sites.">Exchange Rates by Nuclear Magnetic Multiple Resonance. III. Exchange Reactions in Systems with Several Nonequivalent Sites.</a> J. Chem. Phys. 40, 1189-1196 (1964).</li></ol>

The authors declare that they have no competing financial interests.

One of the more obvious advantages of this methodology is that the rate constants and the relaxation time for a given temperature can be obtained with a single set of experiments, with a robust pulse sequence (the same used for STD experiments to study protein-ligand interactions, which is typically found within the available set of experiments from the spectrometer manufacturer). This simplifies the experimental setup since there is no need to measure T1 or reach steady state saturation. Besides, it is remarkable that this method does not depend on the magnet strength, as coalescence methods. On the other hand, the main limitation is that this technique cannot be applied to chemical exchange processes too fast or too slow, which would depend on the temperature range of the NMR machine or the solvents used.
This new technique for the calculation of kinetic parameters can be applied to a great variety of substrates and its applicability has already been demonstrated with some interesting molecules.21 The kinetic parameters of the 4-N,N-dimethylamido[2.2]paracyclophane, a challenging substrate in which the signal of one of the methyl groups of interest is overlapped with other signals from the molecule, were successfully calculated using SSTD NMR. Interestingly, this methodology can be applied as long as one of the signals of study is isolated. SSTD NMR is also a useful protocol for the calculation of kinetic parameters in molecules in which the coalescence temperature is so high that the molecule decomposes before reaching it. This is the case with PtCl2(dimethylallene)(pyridine), in which the methodology was successfully applied without the need of reaching coalescence. The choice of solvents and temperatures is critical to obtain good results, since the chemical exchange rates can vary significantly with these parameters. Moreover, in addition to the criteria in a normal NMR experiment, key steps in a SSTD NMR experiment are the selectivity of the irradiation as well as the temperature control. Both factors have to be precise to guarantee the success of the experiment.
The representative results presented here are for the kinetics of intramolecular chemical exchange, but the technique can also be applied to study the kinetics of intermolecular chemical exchange and also ligand exchange, common processes in the dynamic behavior of transition metal complexes. 
Finally, providing a proper modification of the equations is made,32 this method could be extended to deal with multi-site exchange and unequal populations, as it has been done in former double resonance experiments,8-9 increasing the usefulness of this technique for the study of chemical exchange processes in challenging compounds.

يشير التبادل الكيميائي عادة إلى أي عملية الجزيئات أو ضمجزيئي عامل ضمن الجزيئ الذي نواة تتحرك من بيئة إلى أخرى التي المعلمات NMR لها (التحول الكيميائي، واقتران العددية، واقتران ثنائي القطب، ومعدل الاسترخاء) تختلف. وهناك أمثلة عديدة للتبادل الكيميائية في الجزيئات العضوية والفلزية العضوية (على سبيل المثال، والحواجز التناوب في biaryls، عصابة الحواجز التقليب والتوازن بتكوين والنيتروجين انعكاس، يجند ملزمة، تتدهور الصرف يجند وtautomerization) 1-3 ويرتبط معدل التبادل الكيميائي ل الديناميكا الحرارية من حاجز عملية التبادل، وبالتالي دراستها يتسم بأهمية حاسمة لفهم ديناميات الجزيئية لهذه الأنظمة. علامة الكلاسيكي الصرف الديناميكي في NMR هو تغيير جذري في خط شكل إشارات NMR كما التغيرات في درجات الحرارة. في درجات حرارة منخفضة، عملية بطيئة واثنين من التحولات الكيميائية متميزة وobserفيد. في درجات حرارة عالية، دمج إشارات اثنين في إشارة واحدة، والذي يعرف باسم &quot;التحام&quot;. في درجات الحرارة المتوسطة، وإشارات أصبحت واسعة جدا. هذه الحساسية من الطيف الرنين المغناطيسي لصرف الكيميائي يجعل NMR وسيلة قوية جدا لدراسة ديناميكية الجزيئات في الحل. وقد استخدمت طريقتين أساسا في دراسة العمليات الدينامية في حل: تحليل خط الشكل، 4-7 والتشبع تدور التجارب نقل 8-9 وعلاوة على ذلك، فمن الجدير بالذكر أيضا أن طريقة (10) وCIFIT برنامج نقل انقلاب 11 ل استخراج المباشر من ثوابت المعدل، التي هي نهج فعال نسبيا لقياس الصرف في أنظمة بسيطة. على الرغم من أن هذه الطرق تعطي نتائج جيدة جدا في معظم الحالات، ولكن، لديك عدد من السلبيات. العيب الرئيسي للتحليل خط الشكل هو درجات الحرارة العالية اللازمة للوصول إلى التحام في بعض العينات. 12 والقضايا الرئيسية التي يجب مراعاتها عند كاليفورنياrrying خارج تدور التجارب نقل التشبع هي: العصر التشبع طويلة جدا المطلوبة للوصول إلى مطرد نقل التشبع الدولة بين مواقع تبادل، وضرورة تحديد وقت الاسترخاء الطولي المستمر، تي 1، والذي يمكن أن يكون صعبا إذا كان هناك تداخل مختلفة إشارات في منطقة الدراسة. 13 كجزء من تحقيقاتنا في آليات الفلزية العضوية، 14-16 مجموعتنا تدرس سلوك fluxional المجمعات البلاتين allene في الحل. وهذه مهمة معقدة تنطوي على الأقل ثلاث عمليات مختلفة، واحد منهم تبادل π وجه أو دوران المعدنية حول واحدة من محور allene. واجهنا أن التجارب VT وتقنيات تحليل خط الشكل التي استخدمت من قبل في أنظمة مشابهة وضعها الطبيعي، وكانت 17-19 يست مناسبة في دراستنا، وذلك بسبب دوران بطيء جدا في منطقتنا مجمع البلاتين allene التي جعلت درجة الحرارة تجمع لل سيجNALS من فائدة أعلى من درجة حرارة التحلل من المجمع. ومن أجل التغلب على هذا القيد، وضعنا وذكرت مؤخرا بروتوكول NMR الجديد (SSTD NMR) لدراسة عمليات التبادل الكيميائي المتبادل الموقع. 20 وكما يوحي اسم هذا الأسلوب يجمع بين أسلوب سبين التشبع نقل تستخدم لجزيئات صغيرة، مع نقل التشبع الفرق طريقة الرنين المغناطيسي يعمل لدراسة التفاعلات البروتين يجند، 21-24 عن طريق قياس عابرة تدور نقل التشبع جنبا إلى جنب زيادة مرات التشبع (منحنيات بناء متابعة) في جزيئات صغيرة تمر التبادل الكيميائي. مع هذا الأسلوب الجديد (SSTD NMR) لقد أظهرنا أننا نستطيع الحصول على المعلمات الحركية التبادل الكيميائي ضمجزيئي في الجزيئات العضوية والعضوية الفلزية صغيرة مع بعض المزايا الإضافية على الأساليب التقليدية: ليست هناك حاجة تجمع للإشارات، وذلك على مدى درجة الحرارة أكثر مرونة ممكن استخدامهفي الدراسة؛ إشارة التداخل لا تتدخل، على الرغم من واحد على الأقل من الأصداء تبادل يجب أن تكون معزولة. ليست هناك حاجة لقياس تي 1 أو الوصول إلى الإشباع حالة مستقرة. يتم قياس معدل قيم ثابتة مباشرة ويتم الحصول عليها تي 1 القيم في نفس التجربة، وذلك باستخدام مجموعة واحدة فقط من التجارب. ميزة رائعة أخرى لمنهجية SSTD NMR هي أنه، على النقيض من lineshape التحليل، وتحديد الثوابت معدل حركية لا يحد من الزيادة في درجات الحرارة التحام المرتبطة المجالات المغناطيسية العالية. وبالتالي، لدينا منهجية وثم خصصت بشكل جيد للغاية لكلا المجالات المغناطيسية العالية والمنخفضة. يهدف هذا المقال إلى مساعدة المستخدمين الجدد تطبيق هذا الأسلوب الجديد لأنظمتها الخاصة تمر التبادل الكيميائي، ويصف إعداد العينات، مجموعة تجريبية تصل، والحصول على البيانات، ومثال على معالجة البيانات وتحليلها في جزيء عضوي بسيط.

<table border="0" cellpadding="0" cellspacing="0" width="1616">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:639px;">N,N-dimethylacetamide</td>
			<td style="width:691px;">Aldrich</td>
			<td style="width:119px;">38840</td>
			<td style="width:167px;">Acute toxicity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:639px;">Toluene-d8</td>
			<td style="width:691px;">Fluorochem</td>
			<td style="width:119px;">D-005</td>
			<td>Flammable and toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:639px;">500MHz 7&#34; Select Series NMR Tubes</td>
			<td style="width:691px;">GPE LTD</td>
			<td style="width:119px;">S-5-500-7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:639px;">TopSpin 2.1</td>
			<td>TopSpin program, Bruker Corp., http://www.bruker.com/products/mr/nmr/nmr-software/software/topspin/ (2015).</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:639px;">Origin 6.0</td>
			<td>Origin 6.0 software, OriginLab Corp., http://originlab.com.</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bruker Avance III 500 MHz fitted with 5mm broadband observed BBFOplus Z-gradient SmartProbeTM probe</td>
			<td style="width:691px;">&#160;Bruker Corp., http://www.bruker.com</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bruker Avance I 500 MHz Inverse Triple Resonance NMR spectrometer fitted with a 5mm TXI Z-gradient probe</td>
			<td style="width:691px;">&#160;Bruker Corp., http://www.bruker.com</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:639px;">Ceramic Spinner standardbore shimsystems (5 mm)</td>
			<td>&#160;Bruker Corp., http://www.bruker.com</td>
			<td style="width:119px;">H00804</td>
			<td></td>
		</tr>
	</tbody>
</table>

spin saturation transfer difference nmr (sstd nmr): a new tool to obtain kinetic parameters of chemical exchange processes

يصف هذا البروتوكول مفصل الجديد نقل سبين التشبع الفرق النووية بروتوكول الرنين المغناطيسي (NMR SSTD)، التي وضعت مؤخرا في مجموعتنا لدراسة عمليات التبادل الكيميائي المتبادل الموقع التي يصعب تحليلها بالطرق التقليدية. وكما يوحي اسمها، وهذا الأسلوب يجمع بين أسلوب سبين التشبع نقل تستخدم لجزيئات صغيرة، مع نقل التشبع الفرق طريقة (STD) NMR المستخدمة لدراسة التفاعلات البروتين يجند، عن طريق قياس عابرة نقل تدور التشبع جنبا إلى جنب زيادة مرات التشبع (بناء منحنيات الهاتفي) في الجزيئات العضوية والعضوية الفلزية صغيرة تمر التبادل الكيميائي. مزايا هذه الطريقة أكثر من تلك القائمة هي: ليست هناك حاجة للوصول إلى تجمع للإشارات تبادل. ويمكن تطبيق هذا الأسلوب طالما إشارة واحدة من مواقع تبادل معزولة. ليست هناك حاجة لقياس تي 1 أو الوصول إلى الإشباع حالة مستقرة. معدل فا المستمريتم قياس الزهرى مباشرة، ويتم الحصول عليها تي 1 القيم في نفس التجربة، وذلك باستخدام مجموعة واحدة فقط من التجارب. لاختبار طريقة، درسنا ديناميات دوران حال دون من -dimethylamides N، N، والتي هي الكثير من البيانات المتاحة للمقارنة. المعلمات الحرارية التي تم الحصول عليها باستخدام SSTD هي مشابهة جدا لتلك التي ذكرت (تقنيات نقل تدور التشبع وتحليل خط الشكل). ويمكن تطبيق هذه الطريقة لركائز أكثر الصعبة التي لا يمكن دراستها بالطرق السابقة. ونحن نتوقع أن تجريبية بسيطة أقامت وسوف تطبيق واسع من أسلوب إلى مجموعة كبيرة ومتنوعة من ركائز جعل هذا أسلوب شائع بين علماء الكيمياء العضوية والعضويه دون خبرة واسعة في NMR.

Watch this Scientific Journal Video about Spin Saturation Transfer Difference NMR SSTD NMR: A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes at JoVE.com

Spin Saturation Transfer Difference NMR SSTD NMR: A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

A detailed protocol describing the SSTD NMR method is presented here to help new users apply this new method to obtain the kinetic parameters of their own systems undergoing chemical exchange.

تدور نقل التشبع الفرق NMR (SSTD NMR): أداة جديدة الحصول الحركية معلمات من عمليات التبادل الكيميائي

This detailed protocol describes the new Spin Saturation Transfer Difference Nuclear Magnetic Resonance protocol (SSTD NMR), recently developed in our ...

spin-saturation-transfer-difference-nmr-sstd-nmr-new-tool-to-obtain

Research

Education

JoVE Core

JoVE Journal

Analytical Chemistry

Chemistry

Unit 1

Spin Saturation Transfer Difference NMR (SSTD NMR): A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

Advanced Nuclear Magnetic Resonance Spectroscopy

SCIENTISTS IN ACTION

17.6K Views.  University of East Anglia. A detailed protocol describing the SSTD NMR method is presented here to help new users apply this new method to obtain the kinetic parameters of their own systems undergoing chemical exchange.

Video: Spin Saturation Transfer Difference NMR SSTD NMR: A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

Methods to Identify the NMR Resonances of the 13C-Dimethyl N-terminal Amine on Reductively Methylated Proteins

Nuclear magnetic resonance (NMR) spectroscopy is a proven technique for protein structure and dynamic studies. To study proteins with NMR, stable magnetic isotopes are typically incorporated metabolically to improve the sensitivity and allow for sequential resonance assignment. Reductive 13C-methylation is an alternative labeling method for proteins that are not amenable to bacterial host over-expression, the most common method of isotope incorporation. Reductive 13C-methylation is a chemical reaction performed under mild conditions that modifies a protein&#39;s primary amino groups (lysine &#949;-amino groups and the N-terminal &#945;-amino group) to 13C-dimethylamino groups. The structure and function of most proteins are not altered by the modification, making it a viable alternative to metabolic labeling. Because reductive 13C-methylation adds sparse, isotopic labels, traditional methods of assigning the NMR signals are not applicable. An alternative assignment method using mass spectrometry (MS) to aid in the assignment of protein 13C-dimethylamine NMR signals has been developed. The method relies on partial and different amounts of 13C-labeling at each primary amino group. One limitation of the method arises when the protein&#39;s N-terminal residue is a lysine because the &#945;- and &#949;-dimethylamino groups of Lys1 cannot be individually measured with MS. To circumvent this limitation, two methods are described to identify the NMR resonance of the 13C-dimethylamines associated with both the N-terminal &#945;-amine and the side chain &#949;-amine. The NMR signals of the N-terminal &#945;-dimethylamine and the side chain &#949;-dimethylamine of hen egg white lysozyme, Lys1, are identified in 1H-13C heteronuclear single-quantum coherence spectra.

Methods to Identify the NMR Resonances of the 13C-Dimethyl N-terminal Amine on Reductively Methylated Proteins

Two methods for assigning the &#945;- and &#949;-dimethylamine nuclear magnetic resonance signals of a reductively 13C-methylated N-terminal lysine are described. One method utilizes the pH-induced selectivity of the reductive methylation reaction, and the other uses aminopeptidase to selectively remove the N-terminal lysine.

Nuclear magnetic resonance (NMR) spectroscopy is a proven technique for protein structure and dynamic studies. To study proteins with NMR, stable magnetic ...

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel &#945;-diimine ethylene polymerization catalyst. Initial polymerizations with the catalyst lead to optimized reaction conditions, including catalyst concentration, ethylene pressure and reaction time. Using gas-uptake data for these reactions, a procedure to calculate the initial rate of propagation (kp) is presented. Using the optimized conditions, the ability of the nickel &#945;-diimine polymerization catalyst to undergo chain transfer with diethylzinc (ZnEt2) during ethylene polymerization was investigated. A procedure to assess the ability of the catalyst to undergo chain transfer (from molecular weight and 13C NMR data), calculate the degree of chain transfer, and calculate chain transfer rates (ke) is presented.

A protocol for the high-throughput analysis of polymerization catalyst, chain transfer polymerizations, polyethylene characterization, and reaction kinetic analysis is presented.

Polymerizations الإثيلين عن طريق المفاعلات الضغط الموازية وتحليل الحركية من سلسلة البلمرة نقل

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel ...

Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form catalytically active N-Heterocyclic Carbenes (NHCs). Here we have used ILs as precatalysts in the addition of &#945;,&#946;-unsaturated aldehydes to chalcones to form 1,6-ketoesters, incorporating an anti-diphenyl moiety in a highly stereoselective fashion. The reaction has a broad substrate scope and several functional groups and heteroaromatics can be integrated into the ketoester backbone in generally good yields with maintained stereoselectivity. The reaction protocol is robust and scalable. The starting materials are inexpensive and the products can be obtained after simple filtration, avoiding solvent-demanding chromatography. Furthermore, the IL can be recycled up to 5 times without any loss of reactivity. Moreover, the 1,6-ketoester end product is a potent gelator in several hydrocarbon based solvents. The method enables rapid access to and evaluation of a new class of low molecular weight gelators (LMWGs) from recyclable and inexpensive starting materials.

Ionic liquids (ILs) mediate fast, simple and cheap access to 1,6-ketoesters in high diastereoselectivities and good yields. The reaction protocol is robust and the 1,6-ketoesters can be obtained in gram scale after a simple filtration protocol. Moreover, the 1,6-ketoesters are potent gelators in hydrocarbon solvents.

توليف فراغي للغاية من 1،6-Ketoesters وساطة من قبل أيوني السوائل: رد فعل ثلاثي مكون تمكين الوصول السريع إلى فئة جديدة من الاسعار المنخفضة الوزن الجزيئي Gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form ...

Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO4)2&#183;H2O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C4H9)4NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior.

A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.

التوليف وتقشير من Discotic الزركونيوم الفوسفات للحصول على بلورات الغروية السائل

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and ...

NMR Spectroscopy as a Robust Tool for the Rapid Evaluation of the Lipid Profile of Fish Oil Supplements

The western diet is poor in n-3 fatty acids, therefore the consumption of fish oil supplements is recommended to increase the intake of these essential nutrients. The objective of this work is to demonstrate the qualitative and quantitative analysis of encapsulated fish oil supplements using high-resolution 1H and 13C NMR spectroscopy utilizing two different NMR instruments; a 500 MHz and an 850 MHz instrument. Both proton (1H) and carbon (13C) NMR spectra can be used for the quantitative determination of the major constituents of fish oil supplements. Quantification of the lipids in fish oil supplements is achieved through integration of the appropriate NMR signals in the relevant 1D spectra. Results obtained by 1H and 13C NMR are in good agreement with each other, despite the difference in resolution and sensitivity between the two nuclei and the two instruments. 1H NMR offers a more rapid analysis compared to 13C NMR, as the spectrum can be recorded in less than 1 min, in contrast to 13C NMR analysis, which lasts from 10 min to one hour. The 13C NMR spectrum, however, is much more informative. It can provide quantitative data for a greater number of individual fatty acids and can be used for determining the positional distribution of fatty acids on the glycerol backbone. Both nuclei can provide quantitative information in just one experiment without the need of purification or separation steps. The strength of the magnetic field mostly affects the 1H NMR spectra due to its lower resolution with respect to 13C NMR, however, even lower cost NMR instruments can be efficiently applied as a standard method by the food industry and quality control laboratories.

Here, high-resolution 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy was used as a rapid and reliable tool for quantitative and qualitative analysis of encapsulated fish oil supplements.

NMR الطيفي كأداة قوية لتقييم السريع من الدهون الملف من السمك ملاحق النفط

The western diet is poor in n-3 fatty acids, therefore the consumption of fish oil supplements is recommended to increase the intake of these essential ...

Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products

Here, we describe a protocol developed by our group that uses low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) to measure the average content of fluorinated drugs in their formulated drug product forms: tablets or capsules. This method is specific to fluorinated drugs because it detects only the content of fluorine, avoiding interference from the excipients that lack fluorine. The advantages of measuring the active content of fluorinated drugs using low-field 19F TD-NMR versus high-field 19F solid-state (SS) NMR are the simplicity of the method; the low cost; and the non-destructive nature of the technique, with all samples recoverable in intact forms (e.g., powders, tablets, and capsules), making this technique affordable for any laboratory.
We have tested the method with three fluorinated drug products available on the market - cinacalcet, lansoprazole, and ciprofloxacin - with doses ranging from 15 to 500 mg. The results of the analyses, measured by low-field 19F TD-NMR, supported the reported label claims for the average drug content.
Based on the simplicity and reproducibility of the analysis, we envision this methodology being implemented in any laboratory, including manufacturing plants, as a process analytical technology (PAT) tool in the pharmaceutical industry.

Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products

A simple and non-destructive technique that measures the average content of drug substances in formulated drug products containing fluorine using low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) is presented here. The technique can be applied to the development and manufacturing of drugs in the pharmaceutical industry.

التطبيق ومنهجية تقنية الرنين المغناطيسي المجال الوقت غير مدمرة 19و لقياس المحتوى الموجود في المنتجات الدوائية التي تحتوي على الفلور

Here, we describe a protocol developed by our group that uses low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) to measure the ...

A New Straightforward Method for Lipophilicity (logP) Measurement using 19F NMR Spectroscopy

Fluorination has become an effective tool to optimize physicochemical properties of bioactive compounds. One of the applications of fluorine introduction is to modulate the lipophilicity of the compound. In our group, we are interested in the study of the impact of fluorination on lipophilicity of aliphatic fluorohydrins and fluorinated carbohydrates. These are not UV-active, resulting in a challenging lipophilicity determination. Here, we present a straightforward method for the measurement of lipophilicity of fluorinated compounds by 19F NMR spectroscopy. This method requires no UV-activity. Accurate solute mass, solvent and aliquot volume are also not required to be measured. Using this method, we measured the lipophilicities of a large number of fluorinated alkanols and carbohydrates.

A New Straightforward Method for Lipophilicity logP Measurement using 19F NMR Spectroscopy

A novel and straightforward variation of the shake-flask method was developed for accurate lipophilicity measurement of fluorinated compounds by 19F NMR spectroscopy.

أسلوب مباشر جديد لقياس أجسام (logP) باستخدام 19"و مطيافية الرنين المغناطيسي النووي"

Fluorination has become an effective tool to optimize physicochemical properties of bioactive compounds. One of the applications of fluorine introduction ...

A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

أسلوب اصطناعية سهلة للحصول على البزموت أوكسييوديدي الجزئي المجالات الخرز الصغير وظيفية عالية على بهوتوكاتاليتيك عمليات التنقية المياه

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...

Quantitative 31P NMR Analysis of Lignins and Tannins

The development of sustainable biorefinery products is confronted, among others, with the challenge of lignin and tannin valorization. These abundant, renewable aromatic biopolymers have not been widely exploited due to their inherent structural complexity and high degrees of variability and species diversity. The lack of a defined primary structure for these polyphenols is further compounded with complex chemical alterations induced during processing, eventually imparting a large variety of structural features of extreme significance for any further utilization efforts.
Consequently, a protocol for the rapid, simple, and unequivocal identification and quantification of the various functional groups present in natural polyphenols, is a fundamental prerequisite for understanding and accordingly tailor their reactivity and eventual utility.
Quantitative 31P NMR offers the opportunity to rapidly and reliably identify unsubstituted, o-mono substituted, and o-disubstituted phenols, aliphatic OHs, and carboxylic acid moieties in lignins and tannins with broad application potential.
The methodology consists of an in situ quantitative lignin or tannin labeling procedure using a suitable 31P containing probe, followed by the acquisition of a quantitative 31P NMR spectrum in the presence of an internal standard. The high natural abundance of the 31P nucleus allows for small amounts of the sample (~30 mg) and short NMR acquisition times (~30-120 min) with well-resolved 31P signals that are highly dependent on the surrounding chemical environment of the labeled OH groups.

Quantitative 31P NMR Analysis of Lignins and Tannins

31P NMR is a powerful tool for the structural elucidation of polyphenols. This fast, easy, precise, quantitative, and highly reproducible analytical procedure, that allows for the quantification and differentiation of the different types of hydroxy, phenolic, and carboxylic groups in lignins and tannins has now become a routine analytical tool.

تحليل الكم 31P NMR من التينين والعفص

The development of sustainable biorefinery products is confronted, among others, with the challenge of lignin and tannin valorization. These abundant, ...

3D Printing and In Situ Surface Modification via Type I Photoinitiated Reversible Addition-Fragmentation Chain Transfer Polymerization

3D printing provides facile access to geometrically complex materials. However, these materials have intrinsically linked bulk and interfacial properties dependent on the chemical composition of the resin. In the current work, 3D printed materials are post-functionalized using the 3D printer hardware via a secondary surface-initiated polymerization process, thus providing independent control over the bulk and interfacial material properties. This process begins with preparing liquid resins, which contain a monofunctional monomer, a crosslinking multifunctional monomer, a photochemically labile species that enables initiation of polymerization, and critically, a thiocarbonylthio compound which facilitates reversible addition-fragmentation chain transfer (RAFT) polymerization. The thiocarbonylthio compound, known commonly as a RAFT agent, mediates the chain growth polymerization process and provides polymeric materials with more homogeneous network structures. The liquid resin is cured in a layer-by-layer fashion using a commercially available digital light processing 3D printer to give three-dimensional materials having spatially controlled geometries. The initial resin is removed and replaced with a new mixture containing functional monomers and photoinitiating species. The 3D printed material is then exposed to light from the 3D printer in the presence of the new functional monomer mixture. This allows photoinduced surface-initiated polymerization to occur from the latent RAFT agent groups on the surface of the 3D printed material. Given the chemical flexibility of both resins, this process allows a wide range of 3D printed materials to be produced with tailorable bulk and interfacial properties.

3D Printing and In Situ Surface Modification via Type I Photoinitiated Reversible Addition-Fragmentation Chain Transfer Polymerization

The present protocol describes the digital light processing-based 3D printing of polymeric materials using type I photoinitiated reversible addition-fragmentation chain transfer polymerization and the subsequent in situ material post-functionalization via surface-mediated polymerization. Photoinduced 3D printing provides materials with independently tailored and spatially controlled bulk and interfacial properties.

الطباعة 3D وتعديل السطح في الموقع عبر النوع الأول من الصور الضوئية عكسها إضافة تجزئة سلسلة نقل البلمرة

3D printing provides facile access to geometrically complex materials. However, these materials have intrinsically linked bulk and interfacial properties ...