A compound of the formula (I): wherein R is selected from the group consisting of H, alkyl, alkenyl, alkynyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl and acyl, each of which may be optionally substituted; R1 is an organic moiety that is capable of being converted into a charged group; each X and Y is independently selected from the group consisting of H, halogen, —CN, —NO2, —CF3, —OCF3, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, heteroalkyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkylalkyl, arylalkyl, heteroarylalkyl, arylalkenyl, cycloalkylheteroalkyl, arylheteroalkyl, heterocycloalkylheteroalkyl, heteroarylheteroalkyl, hydroxy, hydroxyalkyl, alkoxy, alkoxyalkyl, alkoxyaryl, alkenyloxy, alkynyloxy, cycloalkyloxy, heterocycloalkyloxy, aryloxy, heteroaryloxy, arylalkyloxy, phenoxy, benzyloxy, amino, alkylamino, aminoalkyl, acylamino, arylamino, sulfonylamino, sulfinylamino, —COOH, —COR2, —COOR2, —CONHR2, —NHCOR2, —NHCOOR2, —NHCONHR2, C(═NOH)R2, alkoxycarbonyl, alkylaminocarbonyl, sulfonyl, alkylsulfonyl, alkylsulfinyl, arylsulfonyl, arylsulfinyl, aminosulfonyl, SR2 and acyl, each of which may be optionally substituted; each R2 is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, haloalkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkylalkyl, arylalkyl, heteroarylalkyl, and acyl, each of which may be optionally substituted; m is an integer selected from the group consisting of 0, 1, 2, 3, 4 and 5; p is an integer selected from 0, 1, 2 and 3; or a pharmaceutically acceptable salt or prodrug thereof.