Understanding the complexation of AlCl3 with beta-cyclodextrin. A 27Al NMR study”

VELASCO, M. I.; ROSSI, L.I.

Alta Gracia, Cordoba

Congreso; Magnetic Resonance in a Cordubensis Perspective; 2011

Sugars are the building blocks for a large number of biological molecules. Our approach consists of using transition metals with their different assembling properties (depending on the metal and its oxidation state, coordination number, counterion, etc.) for the creation of novel architectures in coordination chemistry. These molecules may provide (i) chiral metals (acids, bases, free radicals), (ii) chiral cavities, (iii) chiral precursors for aggregates via weak interactions, (iv) novel fragments in organometallic chemistry or (v) oxygenrich cavities for transition metal salts. These novel complexes have potential application as catalyst in several organic reactions, since the corresponding metallic salts have showed to be very efficient, but their poor stability under atmospheric conditions is a disadvantage for its use. An alternative to improve the physicochemical properties of these salts without loosing their activity is the formation of complexes with cyclodextrins (CD)1. Cyclodextrins are cyclic oligomers of glucose with 6,7 or 8 glucose units for a, b and g cyclodextrin respectively. We have previously synthesized more than 60 complexes between several transition metals and different CD. The synthetic procedure is simple and leads to reproducible resoults for most of the studied complexes. When AlCl3 was used as salt, different complexes where obtaind with minimal variations on the procedure. We atribute this to the particular coordination chemistry that Al envolves. In this opportinity we will show an 27Al NMR study of this complexes in solution and how it helped us to elucitdate the structure of this complexes and provide us a better undesrtansding of the complexation reaction between cyclodextrin and AlCl3.