Little Live Pets 28847 Cozy DOZYS, Multi-Colour

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L. L. Fillbrook, M. D. Nothling, M. H. Stenzel, W. S. Price and J. E. Beves, ACS Macro Lett., 2022, 11, 166 CrossRef CAS PubMed . A. G. Slater, P. H. Beton and N. R. Champness, Comprehensive Supramolecular Chemistry II, Elsevier, 2nd edn, 2011, vol. 2, pp. 1440–1448 Search PubMed. I. Fernandez, M. E. Fernandez-Valle, R. Martinez-Alvarez, D. Molero-Vilchez, Z. D. Pardo, E. Saez-Barajas, A. Sanchez and A. Herrera, J. Org. Chem., 2014, 79, 8086 CrossRef CAS PubMed . S. Balayssac, S. Trefi, V. Gilard, M. Malet-Martino, R. Martino and M. A. Delsuc, J. Pharm. Biomed. Anal., 2009, 50, 602 CrossRef CAS PubMed .

Jean-Nicolas Dumez is a CNRS researcher (Centre National de la Recherche Scientifique) currently working at Nantes Université. He received his PhD in 2011 from Ecole Normale Supérieure de Lyon, and carried out post-doctoral research at the Weizmann Institute of Science and Southampton University, before moving in 2014 to Université Paris-Saclay as a CNRS researcher, then to Nantes in 2018. His research interests include the development of methods for the analysis of mixtures, NMR pulse sequences, and spin dynamics. I. Timari, C. Wang, A. L. Hansen, G. Costa Dos Santos, S. O. Yoon, L. Bruschweiler-Li and R. Bruschweiler, Anal. Chem., 2019, 91, 2304 CrossRef CAS PubMed .

Research

I. Reile, N. Eshuis, N. K. Hermkens, B. J. van Weerdenburg, M. C. Feiters, F. P. Rutjes and M. Tessari, Analyst, 2016, 141, 4001 RSC . Complexity The most commonly used NMR experiment for mixture analysis is the 1D 1H pulse-acquire experiment. Protons have a spin I = 1/2, over 99% natural abundance, and the largest gyromagnetic ratio among stable nuclei, resulting in favourable sensitivity from an NMR point of view. However, the chemical-shift dispersion in 1H spectra is limited to 10–15 ppm. In addition, the large abundance of 1H nuclei result in the ubiquitous presence of 1H– 1H couplings, that yield diverse multiplet structures and broaden NMR signals. Overall, the spectra of all but the simplest mixtures are usually complex. L. Paudel, R. W. Adams, P. Kiraly, J. A. Aguilar, M. Foroozandeh, M. J. Cliff, M. Nilsson, P. Sandor, J. P. Waltho and G. A. Morris, Angew. Chem., Int. Ed., 2013, 52, 11616 CrossRef CAS PubMed . A. Dawn, M. Mirzamani, C. D. Jones, D. S. Yufit, S. Qian, J. W. Steed and H. Kumari, Soft Matter, 2018, 14, 9489–9497 RSC. Y. Cohen, L. Avram, T. Evan-Salem, S. Slovak, N. Shemesh and L. Frish, Analytical Methods in Supramolecular Chemistry, Wiley, 2nd edn, 2012, pp. 197–285 Search PubMed.

Fig. 8 SPEN 3D DOSY of a mixture of 3 alcohols (methanol, ethanol, propanol) and an amino-acid ( L-valine), at a concentration of ∼100 mM in D 2O. (a–e) COSY-type spectra obtained as slabs of the 3D ( D, δ direct, δ indirect) dataset resulting from DOSY processing. The selected range in D is shown in each panel. The slice of the ( z, δ direct, δ indirect) dataset with the lowest diffusion gradient area is shown in (f). The experiment was carried out with a 600 MHz spectrometer equipped with a triple-axis gradient high-resolution probe, and lasted 12 min. Adapted from ref. 161 with permission from the Royal Society of Chemistry. P. Lameiras, S. Patis, J. Jakhlal, S. Castex, P. Clivio and J. M. Nuzillard, Chemistry, 2017, 23, 4923 CrossRef CAS PubMed .A. L. Hansen, E. R. Kupce, D. W. Li, L. Bruschweiler-Li, C. Wang and R. Bruschweiler, Anal. Chem., 2021, 93, 6112 CrossRef CAS PubMed . H. Kumari, S. R. Kline, S. R. Kennedy, C. Garvey, C. L. Raston, J. L. Atwood and J. W. Steed, Chem. Commun., 2016, 52, 4513–4516 RSC.

When comparing the 1H-NMR spectra of resorcin[4]arene 1 with and without glutaric acid 2, different guest signals of 2 are found upfield-shifted. Additionally, integration yielded a host–guest stoichiometry of around 1 : 1, indicating six enclosed guest molecules. The extend of the encapsulation process was shown to increase with higher concentrations of glutaric acid and longer reaction times, which was readily observable due to the high sensitivity of the host aryl peak at 6.1 ppm. This supported the proposed encapsulation mechanism and additionally indicated a slowly occurring exchange mechanism at the expense of solvent molecules, in this case chloroform.A. Fernandez, J. Ferrando-Soria, E. M. Pineda, F. Tuna, I. J. Vitorica-Yrezabal, C. Knappke, J. Ujma, C. A. Muryn, G. A. Timco, P. E. Barran, A. Ardavan and R. E. P. Winpenny, Nat. Commun., 2016, 7, 1–6 Search PubMed. Homonuclear decoupling is also possible for 2D experiments. BIRD-based decoupling can notably be incorporated into 2D HSQC experiments, with no sensitivity penalty for experiments at natural 13C abundance. 18 This was exploited for the quantitative analysis of biological mixtures. 21,22

K. Kristinaityte, A. Mames, M. Pietrzak, F. F. Westermair, W. Silva, R. M. Gschwind, T. Ratajczyk and M. Urbańczyk, J. Am. Chem. Soc., 2022, 144, 13945 CrossRef PubMed . L. Guduff, P. Berthault, C. van Heijenoort, J.-N. Dumez and G. Huber, Chem. Phys. Chem., 2019, 20, 392 CrossRef CAS PubMed . G. D. Enright, S. Takeya and J. A. Ripmeester, Supramolecular Chemistry: From Molecules to Nanomaterials, John Wiley & Sons, Ltd, 2012 Search PubMed. G. Dal Poggetto, L. Castanar, M. Foroozandeh, P. Kiraly, R. W. Adams, G. A. Morris and M. Nilsson, Anal. Chem., 2018, 90, 13695 CrossRef CAS PubMed . E. Abbasi, S. F. Aval, A. Akbarzadeh, M. Milani, H. T. Nasrabadi, S. W. Joo, Y. Hanifehpour, K. Nejati-Koshki and R. Pashaei-Asl, Nanoscale Res. Lett., 2014, 9, 1–10 CrossRef CAS PubMed.J. Kim, Y. Kim, Q. S. Luu, J. Kim, C. Qi, C. Hilty and Y. Lee, Chem. Commun., 2020, 56, 15000 RSC . Z. D. Pardo, G. L. Olsen, M. E. Fernandez-Valle, L. Frydman, R. Martinez-Alvarez and A. Herrera, J. Am. Chem. Soc., 2012, 134, 2706 CrossRef CAS PubMed . The power of NMR spectroscopy also results from the vast space of possible experiments that can be carried out, with a given instrument and a given sample, through the use of different pulse sequences. This makes it possible, through the controlled manipulations of nuclear spins, to access chemical information that would otherwise remain invisible or inaccessible. The process of developing NMR pulse sequences has sometimes been referred to as “spin choreography” or “spin alchemy”. 3 After discussing the most relevant techniques for the structural characterisation of supramolecular molecules, we move to present three examples where supramolecular systems were successfully characterised by multi-technique approaches. In particular, we highlight the powerful interplay of the already discussed techniques while also mentioning the impact of other methods. 7 Host–guest complex formation of pyridine[4]arenes Molecular recognition describes the specific binding between two molecules via non-covalent interactions, for example between a host and a guest molecule. 80,81 This concept represents a major challenge in supramolecular chemistry because it is particularly important for catalytic processes and molecular sensors. In this context, binding preferences of macrocycles towards cationic, neutral or anionic guests are a critical aspect of fundamental supramolecular research. Intramolecular self-inclusion was another possible interpretation of the data, but this could be discounted with the use of DOSY NMR. In case of this hypothetical event, the diffusion coefficients of 3 in acidic solution would have remained similar compared to the monomer, whereas the experimental data shows a strong decrease of this value. This observation could only be explained with oligomers (or polymers).