DOSY diffusion ordered NMR spectroscopy

Detection of n-n interactions has largely relied on NMR-based techniques, such as chemical shifts variations,and Nuclear Overhauser Effect Spectroscopy (NOESY) or Rotating-Erame NOE Spectroscopy (ROESY)7 Diffusion-ordered NMR spectroscopy (DOSY) has also been used to detect n-n stacked complexes. ... 

This can convieniently be achieved by applying diffusion-ordered NMR spectroscopy (DOSY) [23, 24],... 

Various new techniques suitable for estimating D are now available fluorescence correlation spectroscopy (FCS) [5], fluorescence recovery after photobleaching (FRAP) [6], pulsed field gradient nuclear magnetic resonance (PFG-NMR) [7], diffusion ordered NMR spectroscopy (DOSY) [8], and others. Among these, FCS and FRAP are popular in biological studies because they are often installed on a commercial LSM system and conveniently coupled with it. 

W. J. Lough, Alternative Analytical Techniques for Determination or Isolation of Drug Enantiomers , in Drugs and the Pharmaceutical Sciences, eds. K. Jozwiak, W. J. Lough and I. W. Warner, Informa Healthcare, 2012, Vol. 211, Drug Stereochemistry, Analytical Methods and Pharmacology, p. 167. A. Macchioni, G. Ciancaleoni, C. Zuccacda and D. Zuccaccia, Diffusion Ordered NMR Spectroscopy (DOSY) , in Supramolecular Chemistry From Molecules to Nanomaterials, eds. P. A. Gale and J. W. Steed, John Wiley Sons Ltd., Chichester, UK, 2012, Vol. 2, p. 319. 

Voltammetric and other electrochemical techniques can be used to determine D values of redox-active species. For instance, in CV experiments the slope of a plot of peak current versus scan rate depends on (D) / according to (9). However, in the last few years the popularity of NMR methods to determine D values has increased almost exponentially. NMR spectroscopy offers some advantages for this purpose, as the determination relies on the rate of signal intensity decay as a function of applied field gradient and does not require previous knowledge of the concentration of the diffusing species (see Diffusion Ordered NMR Spectroscopy (DOSY), Techniques). Unlike with electrochemical methods, the diffusing species do not have to be... 

D. Li, I. Keresztes, R. Hopson and P. G. Wdliard, Characterization of Reactive Intermediates by Multinuclear Diffusion-Ordered NMR Spectroscopy (DOSY) , Acc. Chem. Res., 2009, 42, 270. 

Diffusion-ordered NMR spectroscopy (DOSY) is a powerful tool for structural studies of molecular aggregates in solution. Translational diffusion coefficients (D) determined by DOSY correlate directly with the sizes and dimensions of aggregates. The diffusion coefficients of 18 and a 1 1 mixture of 18 and 19 at a low concentration in chloroform-(ij are 4.09 x 10and 2.57 x 10 ° m S", respectively. The ratio of D1S.19/D19 of 0.63 was reasonably close to the theoretical range of 0.59 to 0.60 expected for a linear trimer. These results confirmed the formation of oligomeric assemblies even at low concentrations. 

In addition to supramolecular polymers constructed from 9, bifunctional monomer 10 (Scheme 10.3), incorporating a less-flexible trimethylhexyl linker, exists in an equilibrium between cyclic and linear aggregates in solution as evidenced by viscosity studies and diffusion-ordered NMR spectroscopy (DOSY). These results are in line with the proposal of equilibrium between linear polymeric and oligomeric cyclic structures (i.e., ring-chain equilibrium). Because of its restricted conformational freedom, 10 is more prone to the formation of rings than 9. 

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