A benzodiazepine dimer having a structure represented by formula wherein X is selected from the group consisting of and R 1 is according to formula (Ia) or formula (Ib): each G and G' is C or N, with the proviso that no more than two Gs or two G's are N; each R 2 is independently H or C 1 -C 5 alkyl; each R 3 and R 4 is independently H, F, Cl, Br, OH, C 1 -C 3 alkyl, O(C 1 -C 3 alkyl), cyano, (CH 2) 0-5 NH 2, or NO 2; each double line ----- in a diazepine ring system independently represents a single bond or a double bond; each R 5 is H if the double line ----- to the N to which it is attached is a single bond and is absent if the double line is a double bond; each R 6 is H, OH, SO 3 Na, or SO 3 K if the double line ----- to the C to which it is attached is a single bond and is absent if the double line is a double bond; each R 7, R 8, R 9, and R 10 is independently H, C 1 -C 5 alkyl, C≡C(CH 2) 1-5 X 2, OH, O(C 1 -C 5 alkyl), cyano, NO 2, F, Cl, Br, O(CH 2 CH 2 O) 1-8 (C 1-3 alkyl), (CH 2) 0-5 X 2, O(CH 2) 2-5 X 2, 3- to 7-membered cycloalkyl or heterocycloalkyl unsubstituted or substituted with (CH 2) 0-5 X 2 or O(CH 2) 2-5 X 2, 5- to 6-membered aryl or heteroaryl unsubstituted or substituted with (CH 2) 0-5 X 2 or O(CH 2) 2-5 X 2, or or where a R 7, R 8, R 9, or R 10 is attached to a G or G' that is N, such R 7, R 8, R 9, or R 10 is absent; the dotted lines in ring C of formula (Ib) indicate the optional presence of a C1-C2, C2-C3, or C2-R 11 double bond; R 11 is H, =O, =CH 2, =CH(C 1 -C 5 alkyl), CH=CH(CH 2) 1-5 X 2, C≡C(CH 2) 1-5 X 2, C 1 -C 5 alkyl, OH, O(C 1 -C 5 alkyl), cyano, NO 2, F, Cl, Br, O(CH 2 CH 2 O) 1-8 (C 1-3 alkyl), (CH 2) 0-5 X 2, 4- to 7-membered aryl, heteroaryl, cycloalkyl, or heterocycloalkyl unsubstituted or substituted with (CH 2) 0-5 X 2, O(CH 2) 2-5 X 2, 3- to 7-membered cycloalkyl or heterocycloalkyl unsubstituted or substituted with (CH 2) 0-5 X 2 or O(CH 2) 2-5 X 2, 5- to 6-membered aryl or heteroaryl unsubstituted or substituted with (CH 2) 0-5 X 2 or O(CH 2) 2-5 X 2; R 11' is absent if a C1-C2, C2-C3, or C2-R 11 double bond is present and otherwise is H; each X 2 is independently H, F, Cl, Br, OH, O(C 1 -C 3 alkyl), O(C 1 -C 3 alkylene), CO 2 H, N 3, CN, NO 2, CO 2 (C 1 -C 3 alkyl), NH 2, NH(C 1 -C 5 alkyl), N(C 1 -C 5 alkyl) 2, SH, CHO, N(CH 2 CH 2) 2 N(C 1 -C 3 alkyl), NHNH 2, or C(=O)NHNH 2; each Y is independently CH 2, C=O, or CHR 12; wherein each R 12 is independently F, Cl, Br, or C 1 -C 3 alkyl; and Y' and Y" are independently CH 2, C=O, or CHR 12; wherein each R 12 is independently F, Cl, Br, or C 1 -C 3 alkyl, with the proviso that at least one of Y' and Y" is present; or a pharmaceutically acceptable salt thereof. X is selected from the group consisting of and R 1 is according to formula (Ia) or formula (Ib): each G and G' is C or N, with the proviso that no more than two Gs or two G's are N; each R 2 is independently H or C 1 -C 5 alkyl; each R 3 and R 4 is independently H, F, Cl, Br, OH, C 1 -C 3 alkyl, O(C 1 -C 3 alkyl), cyano, (CH 2) 0-5 NH 2, or NO 2; each double line ----- in a diazepine ring system independently represents a single bond or a double bond; each R 5 is H if the double line ----- to the N to which it is attached is a single bond and is absent if the double line is a double bond; each R 6 is H, OH, SO 3 Na, or SO 3 K if the double line ----- to the C to which it is attached is a single bond and is absent if the double line is a double bond; each R 7, R 8, R 9, and R 10 is independently H, C 1 -C 5 alkyl, C≡C(CH 2) 1-5 X 2, OH, O(C 1 -C 5 alkyl), cyano, NO 2, F, Cl, Br, O(CH 2 CH 2 O) 1-8 (C 1-3 alkyl), (CH 2) 0-5 X 2, O(CH 2) 2-5 X 2, 3- to 7-membered cycloalkyl or heterocycloalkyl unsubstituted or substituted with (CH 2) 0-5 X 2 or O(CH 2) 2-5 X 2, 5- to 6-membered aryl or heteroaryl unsubstituted or substituted with (CH 2) 0-5 X 2 or O(CH 2) 2-5 X 2, or or where a R 7, R 8, R 9, or R 10 is attached to a G or G' that is N, such R 7, R 8, R 9, or R 10 is absent; the dotted lines in ring C of formula (Ib) indicate the optional presence of a C1-C2, C2-C3, or C2-R 11 double bond; R 11 is H, =O, =CH 2, =CH(C 1 -C 5 alkyl), CH=CH(CH 2) 1-5 X 2, C≡C(CH 2) 1-5 X 2, C 1 -C 5 alkyl, OH, O(C 1 -C 5 alkyl), cyano, NO 2, F, Cl, Br, O(CH 2 CH 2 O) 1-8 (C 1-3 alkyl), (CH 2) 0-5 X 2, 4- to 7-membered aryl, heteroaryl, cycloalkyl, or heterocycloalkyl unsubstituted or substituted with (CH 2) 0-5 X 2, O(CH 2) 2-5 X 2, 3- to 7-membered cycloalkyl or heterocycloalkyl unsubstituted or substituted with (CH 2) 0-5 X 2 or O(CH 2) 2-5 X 2, 5- to 6-membered aryl or heteroaryl unsubstituted or substituted with (CH 2) 0-5 X 2 or O(CH 2) 2-5 X 2; R 11' is absent if a C1-C2, C2-C3, or C2-R 11 double bond is present and otherwise is H; each X 2 is independently H, F, Cl, Br, OH, O(C 1 -C 3 alkyl), O(C 1 -C 3 alkylene), CO 2 H, N 3, CN, NO 2, CO 2 (C 1 -C 3 alkyl), NH 2, NH(C 1 -C 5 alkyl), N(C 1 -C 5 alkyl) 2, SH, CHO, N(CH 2 CH 2) 2 N(C 1 -C 3 alkyl), NHNH 2, or C(=O)NHNH 2; each Y is independently CH 2, C=O, or CHR 12; wherein each R 12 is independently F, Cl, Br, or C 1 -C 3 alkyl; and Y' and Y" are independently CH 2, C=O, or CHR 12; wherein each R 12 is independently F, Cl, Br, or C 1 -C 3 alkyl, with the proviso that at least one of Y' and Y" is present;