The compositions of the present invention include anthraquinone compounds of formula (1) wherein the groups R7, R8, R9, and R10 can be hydrogen or an electron withdrawing group; the groups R1, R14, and R15 can be hydrogen or electron donating groups; R6 can be any group other than acetyl that can covalently bind to the nitrogen; X can include a solid support, a biologically relevant molecule, or a