Structures of MMPI. Structures of the different compounds used in our studies. PY-2 and 1,2-HOPO-2 represent novel semiselective MMPI. PY-2 is a hydroxypyrone and 1,2-HOPO-2 is a hydroxypyridinone. PICO-2, the negative control, is a hydroxypyridine molecule bearing a nonfunctional ZBG. CGS27023A is a hydroxamate-based broad-spectrum MMPI, and PD166793 is a carboxylate-based broad-spectrum MMPI.