A compound, or a pharmaceutically acceptable salt or ester thereof, having a structure of: wherein X is a divalent linking moiety; and R1-R10 are each individually H, optionally-substituted alkyl, optionally-substituted alkoxy, optionally-substituted aryl, optionally-substituted cycloalkyl, optionally-substituted heterocyclic, halogen, amino, or hydroxy, provided that at least one of R3 or R8 is an optionally-substituted alkyl, a substituted alkoxy, optionally-substituted aryl, optionally-substituted cycloalkyl, optionally-substituted heterocyclic, or halogen.