Detecting intermolecular NOEs by means of a novel DPFGSE pulse sequence. Application to the solvation of carbohydrates in binary mixtures.
We present a pulse sequence based on solute-to-solvent NOE enhancement and aimed at the detection of intermolecular NOE's. Thus, a W3 pulse cluster is used to selectively filter the solvent signals in a DPFGSE sequence. The sequence has been tested on a sample of glucose dissolved in two binary aqueous mixtures (water-acetonitrile and water-DMSO). We show how the resulting enhancements may derive from intermolecular cross-relaxation or, in the water-DMSO sample, also from chemical exchange. In each case, a quantitative interpretation of the data is also supplied, both in terms of local enrichment in one specific solvent (preferential solvation), and by means of a kinetic model for a two-site chemical exchange.
Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131 Padua, Italy. alessandro.bagno@unipd.it
Alessandro
A
Bagno
Federico
F
Rastrelli
Gianfranco
G
Scorrano
D000097:Acetonitriles / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry*; D045424:Complex Mixtures / Q000032:analysis / Q000737:chemistry*; D003198:Computer Simulation; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D012815:Signal Processing, Computer-Assisted; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D000097:Acetonitriles; D002241:Carbohydrates; D045424:Complex Mixtures; D046911:Macromolecular Substances; D012997:Solvents; D014867:Water; D005947:Glucose; D004121:Dimethyl Sulfoxide; C032159:acetonitrile