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
S. Cahill et S. Bulusu, 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, Magnetic resonance in chemistry, 31(8), 1993, pp. 731-735
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.