1 NT8 (1-azanyl-1-phosphono-decyl)phosphonic acid 1.000 2 252 (1-hydroxynonane-1,1-diyl)bis(phosphonic acid) 0.850 3 H23 (1-hydroxydodecane-1,1-diyl)bis(phosphonic acid) 0.818 4 028 (1-hydroxyheptane-1,1-diyl)bis(phosphonic acid) 0.750