Naphthyridine pseudobases

The extremely electron-deficient heteroaromatic dications produced by quatemization of both ring nitrogen atoms of the naphthyridines very readily form pseudobases in aqueous solution. The data of Table I indicate that pKR+ values for N.AT-dimethylnaphthyridinium dications are 7-10 units lower than for the corresponding N-methylnaphthyridinium monocations. The N,N -bridged 1,10-phenanthrolinium dications 17 and 18 also have considerably lower pK values than the N-methyl-1,10-phenanthrol in ium... 

---