MOLECULAR-COMPLEXES OF EXPLOSIVES WITH CYCLODEXTRINS .1. CHARACTERIZATION OF COMPLEXES WITH THE NITRAMINES RDX, HMX AND TNAZ IN SOLUTION BYH-1-NMR SPIN-LATTICE RELAXATION-TIME MEASUREMENTS

Inclusion complex formation between the explosive molecules of the nit ramine type, RDX, HMX and TNAZ, and cyclodextrins (alpha, beta and gam ma) was studied in aqueous solution by means of H-1 spin-lattice relax ation time (T1) measurements. The results show that nitramines bind to cyclodextrins in solution; RDX and HMX bind most strongly to gamma-cy clodextrin whereas TNAZ binds most strongly to beta-cyclodextrin. The dynamic coupling coefficient and dissociation constant were determined for the complex of TNAZ with beta-cyclodextrin. The values obtained s uggest that TNAZ forms a relatively weak complex with beta-cyclodextri n (K(d) = 1.8 x 10(-2) M) that displays considerable motion in the com plex with respect to cyclodextrin (coupling coefficient = 0.23). This method of using H-1 T1 measurements for characterizing complex formati on in solution, while limited to guest molecules containing a pair of protons having a fixed internuclear distance, is shown to be useful wh en complexation-induced chemical shifts are too small to be significan t.