E. Graf et al., SIMULTANEOUS BINDING OF BORON AND AMMONIUM CATION BY A PSEUDOCRYPTAND- SYNTHESIS, X-RAY-ANALYSIS AND SOLUTION STUDIES BY NMR-SPECTROSCOPY, Journal of the Chemical Society, Chemical Communications, (15), 1995, pp. 1505-1506
Treatment of the macrocyclic compound 1 bearing two catecholate moieti
es with equimolar amounts of B(OH)(3) and aqueous NH3 in a H2O-EtOH mi
xture gave exclusively the ammonium inclusion complex 2 which was then
studied both in solution and in the solid state; the selectivity sequ
ence NH4+ > Na+ > Cs+ in CD3OD solution was obtained and the ammonium
ion complex 2 was found to be more stable than the ([222], NH4+) compl
ex by at least 3 orders of magnitude.