Patent ID: 8916513

Claim:
A compound represented by Formula I or a salt thereof; wherein: R 1 is a C 4 -C 24 alkyl; R 2 is selected from the group consisting of —N + R 4 R 5 R 6 , NO 2 , CN, C(O)R 7 , CO 2 R 7 , SOR 7 , or SO 2 R 7 ; R 4 is H or alkyl; R 5 is H or alkyl; R 6 is H or alkyl; any two of R 4 , R 5 , and R 6 can optionally join to form a heterocyclyl group; R 7 is H, alkyl, polyalkoxy, aryl, heteroaryl, or heterocyclyl group; and R 1 and R 2 can optionally join to form a cycloalkyl group.