A compound selected from the group consisting of G6, G7, G8, and G9 with the following structures: and wherein each R is independently substituted or unsubstituted-(C 1 -C 6 )alkyl-, substituted or unsubstituted -(CH 2 ) n O(C 1 -C 6 )alkyl-, substituted or unsubstituted-(CH 2 ) n C(O)-, substituted or unsubstituted-(CH 2 ) n C(O)(C 1 -C 6 )alkyl-, substituted or unsubstituted- (CH 2 ) n C(O)O(C 1 -C 6 )alkyl-, substituted or unsubstituted -(CH 2 ) n NH(C 1 -C 6 )alkyl-, substituted or unsubstituted-(CH 2 ) n C(O)NH(C 1 -C 6 )alkyl-, substituted or unsubstituted- (CH 2 ) n S(C 1 -C 6 )alkyl-, substituted or unsubstituted-(CH 2 ) n C(O)(CH 2 ) n S(C 1 -C 6 )alkyl-, substituted or unsubstituted-(C 2 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n O(C 2 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n C(O)(C 2 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n C(O)O(C 2 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n NH(C 1 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n C(O)NH(C 2 -C 6 )alkenyl-, substituted or unsubstituted -(CH 2 ) n S(C 2 -C 6 )alkenyl-, substituted or unsubstituted -(CH 2 ) n C(O)(CH 2 ) n S(C 2 -C 6 )alkenyl-, substituted or unsubstituted -(C 2 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n O(C 2 -C 6 )alkynyl-, substituted or unsubstituted- (CH 2 ) n C(O)(C 2 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n C(O)O(C 2 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n NH(C 1 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n C(O)NH(C 2 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n S(C 2 -C 6 )alkynyl-, substituted or unsubstituted -(CH 2 ) n C(O)(CH 2 ) n S(C 2 -C 6 )alkyynyl-, wherein each alkyl, alkenyl and alkynyl group is optionally substituted with alkyl, alkoxy, amino, carboxyl, cyano, nitro, or trifluoromethyl, and each n is independently an integer selected from 0, 1, 2, 3, 4, 5, and 6. wherein each R is independently substituted or unsubstituted-(C 1 -C 6 )alkyl-, substituted or unsubstituted -(CH 2 ) n O(C 1 -C 6 )alkyl-, substituted or unsubstituted-(CH 2 ) n C(O)-, substituted or unsubstituted-(CH 2 ) n C(O)(C 1 -C 6 )alkyl-, substituted or unsubstituted- (CH 2 ) n C(O)O(C 1 -C 6 )alkyl-, substituted or unsubstituted -(CH 2 ) n NH(C 1 -C 6 )alkyl-, substituted or unsubstituted-(CH 2 ) n C(O)NH(C 1 -C 6 )alkyl-, substituted or unsubstituted- (CH 2 ) n S(C 1 -C 6 )alkyl-, substituted or unsubstituted-(CH 2 ) n C(O)(CH 2 ) n S(C 1 -C 6 )alkyl-, substituted or unsubstituted-(C 2 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n O(C 2 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n C(O)(C 2 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n C(O)O(C 2 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n NH(C 1 -C 6 )alkenyl-, substituted or unsubstituted-(CH 2 ) n C(O)NH(C 2 -C 6 )alkenyl-, substituted or unsubstituted -(CH 2 ) n S(C 2 -C 6 )alkenyl-, substituted or unsubstituted -(CH 2 ) n C(O)(CH 2 ) n S(C 2 -C 6 )alkenyl-, substituted or unsubstituted -(C 2 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n O(C 2 -C 6 )alkynyl-, substituted or unsubstituted- (CH 2 ) n C(O)(C 2 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n C(O)O(C 2 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n NH(C 1 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n C(O)NH(C 2 -C 6 )alkynyl-, substituted or unsubstituted-(CH 2 ) n S(C 2 -C 6 )alkynyl-, substituted or unsubstituted -(CH 2 ) n C(O)(CH 2 ) n S(C 2 -C 6 )alkyynyl-, wherein each alkyl, alkenyl and alkynyl group is optionally substituted with alkyl, alkoxy, amino, carboxyl, cyano, nitro, or trifluoromethyl, and each n is independently an integer selected from 0, 1, 2, 3, 4, 5, and 6. <EOS>