Abstract: 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, —N