Phosphonate compounds

A phosphonate compound having the structure:

• wherein:
• R1 and R1′ are independently —H, optionally substituted —O(C1-C24)alkyl, —O(C1-C24)alkenyl, —O(C1-C24)acyl, —S(C1-C24)alkyl, —S(C1-C24)alkenyl, or —S(C1-C24)acyl, wherein at least one of R1 and R1′ are not —H, and wherein said alkenyl or acyl optionally have 1 to about 6 double bonds,
• R2 and R2′ are independently —H, optionally substituted —O(C1-C7)alkyl, —O(C1-C7)alkenyl, —S(C1-C7)alkyl, —S(C1-C7)alkenyl, —O(C1-C7)acyl, —S(C1-C7)acyl, —N(C1-C7)acyl, —NH(C1-C7)alkyl, —N((C1-C7)alkyl)2, oxo, halogen, —NH2, —OH, or —SH;
• R3 is a phosphonate derivative of a pharmacologically active compound linked to a functional group on optional linker L or to an available oxygen atom on Cα;
• X, when present, is:
• L is a valence bond or a bifunctional linking molecule of the formula —J—(CR2)t—G—, wherein t is an integer from 1 to 24, J and G are independently —O—, —S—, —C(O)O—, or —NH—, and R is —H, substituted or unsubstituted alkyl, or alkenyl;
• m is an integer from 0 to 6;
• and
• n is 0 or 1.