X₁ and X₂ are independently selected from the group consisting of O, S, Se, Te, and NR₁, wherein R₁, is selected from the group consisting of H, alkyl, substituted alkyl, cycloalkyl, aryl, and substituted aryl;

p is an integer from 0 to 1;

each q is independently an integer from 0 to 2;

each R₂ is independently selected from the group consisting of alkyl, substituted alkyl, aryl, substituted aryl, halo, hydroxyl, alkoxyl, aryloxyl, and aralkyloxyl;

Ar₁ and Ar₂ are independently selected from the group consisting of phenyl, pyridine, and benzimidazole;

Am₁ and Am₂ are each

wherein:

each R₃ is independently selected from the group consisting of H, hydroxyl, acyloxyl, and alkoxyl;

each R₄, R₅, R₆, and R₇ is independently selected from the group consisting of H, alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl; or

R₃ and R₄ together represent a C₂ to C₁₀ alkyl, C₂ to C₁₀ hydroxyalkyl, or C₂ to C₁₀ alkylene; or

R₃ and R₄ together are:

wherein s is a number from 1 to 4, and R₈ is H or —CONHR₉NR₁₀R₁₁, wherein R₉ is alkyl, and R₁₀ and R₁₁ are each independently selected from the group consisting of H and alkyl;

or a pharmaceutically acceptable salt thereof.