The preparation of hydrophilic 2,9-diatkyl-1,10-phenanthrolines, inclu
ding phenanthroline-5-sulfonic acids and phenanthrolines with side cha
in functionality is described. Nucleophilic aromatic substitution chem
istry is used to obtain regiochemically defined phenanthroline sulfoni
c acids by much simpler means than have been available in the past.