A compound, or a pharmaceutically acceptable salt thereof, having a formula I of: wherein Ar is an arylene or heteroarylene; R1 has a structure of: wherein W is an alkanediyl, alkenediyl, a carbonyl, or a combination thereof; X is —NR5—, wherein R5 is H or an alkyl, or —O—; and Y is optionally-substituted cycloalkyl, optionally-substituted cycloalkyl-substituted alkyl, optionally-substituted heterocycloalkyl, or optionally-substituted heterocycloalkyl-substituted alkyl; each R2 is the same or different and has a structure of: wherein Z is —NR6—, wherein R6 is H or an alkyl, —O—, —S—, or —CH2—; Z1 is (—CH2—)m wherein m is 0 to 5, or an alkenediyl having 2 to 6 carbon atoms; Cy is a 3-8-membered cycloalkyl, heterocycloalkyl, aryl or heteroaryl ring; and each R4 is the same or different and is selected from hydroxy, halogen, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, or amino; and c is 0 to 5; and each R3 is the same or different and is selected from hydroxy, halogen, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, amino, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or a nitro, wherein a is 2 to 5, and b is 0 to 3.