Patent ID: 7446196

Claim:
A compound having a structure according to formula Ia wherein m is 0, 1, 2, 3, 4, or 5; R 1 is H, C 1 -C 5 alkyl, C 2 -C 5 alkenyl, or C 2 -C 5 alkynyl; and R 2 is H, aryl, cycloalkyl, a heterocyclic moiety, wherein R 3 is H, C 1 -C 5 alkyl, C 2 -C 5 alkenyl, or C 2 -C 5 alkynyl, provided that R 3 is not H where m is 0; R 4 is H, C 1 -C 5 alkyl, C 2 -C 5 alkenyl, C 2 -C 5 alkynyl, aryl, cycloalkyl, or a heterocyclic moiety; R 5 is H, C 1 -C 5 alkyl, C 2 -C 5 alkenyl, C 2 -C 5 alkynyl, aryl, cycloalkyl, a heterocyclic moiety, or C(═O)O(C 1 -C 5 alkyl); and R 6 is H, C 1 -C 5 alkyl, C 2 -C 5 alkenyl, C 2 -C 5 alkynyl, cycloalkyl or a fluorescent moiety; or R 5 and R 6 and the nitrogen to which they are commonly bonded combine to form a 4, 5, 6, or 7 membered nitrogen-containing heterocyclic ring structure.