Compositions and methods for modifying one or more biologic targets are provided. Suitable targets include cells, DNA, proteins, enzymes, and/or a subject in need thereof. The compositions may exist as a monomer or multimer and are active in a biologic environment with enhanced activity in hypoxic environments and, thus, exhibit improved specificity for hypoxic biologic targets (e.g., tumorigenic cells and those undergoing uncontrolled cell growth). A composition typically comprises a complex with an overall charge of 2+ or greater having at least one ruthenium atom attached to a redox active ligand. The redox active ligand helps maintain separation of more than one ruthenium atom. Suitable compositions may further include a terminal ligand comprising a heterocyclic aromatic compound. When provided to a biologic target, the composition modifies the biologic target and no additional compounds need be provided. Suitable compositions are typically catalytic and regenerative in the presence of a reducing agent.