A compound of formula: or a pharmaceutically acceptable salt or ester thereof, wherein: Q is piperazine-1,4-diyl; 2,5-diazabicyclo[2.2.1]heptane-2,5-diyl; 2,5-diazabicyclo[2.2.2]octane-2,5-diyl; 1,4-diazepane-1,4-diyl; benzene-1,4-diamine-N 1 ,N 4 -diyl; ethane-1,2-diamine-N 1 ,N 2 -diyl; N 1 ,N 2 -dialkylethane-1,2-diamine-N 1 ,N 2 -diyl; propane-1,3-diamine-N 1 ,N 3 -diyl; N 1 ,N 3 -dialkylpropane-1,3-diamine-N 1 ,N 3 -diyl; 1,4-diaminoanthracene-9,10-dione-1,4-diyl; C 6 arene-1,4-diamine-N 1 ,N 4 -diyl wherein the arene is substituted with one to four substituents in the 2, 3, 5, or 6 positions and wherein the substituents are independently selected from the group consisting of -C(O)O(C 1 to C 6 )alkyl, OH, O(C 1 to C 6 )alkyl, (C 1 to C 6 )alkyl, CF 3 , F, Cl, and Br; or substituted piperazine-1,4-diyl wherein the piperazine is substituted with one to eight substituents in the 2, 3, 5, or 6 positions and wherein the substituents are independently selected from the group consisting of (C 1 to C 6 )alkyl, aryl, aryl(C 1 to C 6 )alkyl, C(O)OH, and C(O)O(C 1 to C 6 )alkyl; A 1 and A 1 ' are each independently N or CR 6 ; A 2 and A 2 ' are each independently N or CR 7 ; A 3 is NR 8 ; A 3 ' is NR 8 , O, or S; A 4 and A 4 ' are each independently N or CR 9 ; A 5 and A 5 ' are each independently N or CR 10 ; A 6 and A 6 ' are each independently N or CR 11 ; and R 1 , R 1' , R 2 , R 2' , R 3 , R 3' , R 4 , R 4' , R 6 , R 7 , R 8 , R 9 , R 10 , and R 11 , if present, are in each instance independently selected from the group consisting of hydrogen, alkyl, halo, trifluoromethyl, dialkylamino wherein each alkyl is the same or different, -NH 2 , alkylamino, and arylalkyl. Q is piperazine-1,4-diyl; 2,5-diazabicyclo[2.2.1]heptane-2,5-diyl; 2,5-diazabicyclo[2.2.2]octane-2,5-diyl; 1,4-diazepane-1,4-diyl; benzene-1,4-diamine-N 1 ,N 4 -diyl; ethane-1,2-diamine-N 1 ,N 2 -diyl; N 1 ,N 2 -dialkylethane-1,2-diamine-N 1 ,N 2 -diyl; propane-1,3-diamine-N 1 ,N 3 -diyl; N 1 ,N 3 -dialkylpropane-1,3-diamine-N 1 ,N 3 -diyl; 1,4-diaminoanthracene-9,10-dione-1,4-diyl; C 6 arene-1,4-diamine-N 1 ,N 4 -diyl wherein the arene is substituted with one to four substituents in the 2, 3, 5, or 6 positions and wherein the substituents are independently selected from the group consisting of -C(O)O(C 1 to C 6 )alkyl, OH, O(C 1 to C 6 )alkyl, (C 1 to C 6 )alkyl, CF 3 , F, Cl, and Br; or substituted piperazine-1,4-diyl wherein the piperazine is substituted with one to eight substituents in the 2, 3, 5, or 6 positions and wherein the substituents are independently selected from the group consisting of (C 1 to C 6 )alkyl, aryl, aryl(C 1 to C 6 )alkyl, C(O)OH, and C(O)O(C 1 to C 6 )alkyl; A 1 and A 1 ' are each independently N or CR 6 ; A 2 and A 2 ' are each independently N or CR 7 ; A 3 is NR 8 ; A 3 ' is NR 8 , O, or S; A 4 and A 4 ' are each independently N or CR 9 ; A 5 and A 5 ' are each independently N or CR 10 ; A 6 and A 6 ' are each independently N or CR 11 ; and R 1 , R 1' , R 2 , R 2' , R 3 , R 3' , R 4 , R 4' , R 6 , R 7 , R 8 , R 9 , R 10 , and R 11 , if present, are in each instance independently selected from the group consisting of hydrogen, alkyl, halo, trifluoromethyl, dialkylamino wherein each alkyl is the same or different, -NH 2 , alkylamino, and arylalkyl. <EOS>