A new poly-dentate double Schiff base ligand 1,10-phenanthroline-2,9-dicarboxaldehyde-di-2-hydroxybenzoylhydrazone (H 2 L) was synthesized and structurally characterized. Two Cd II and Mn II dimers of this ligand were also synthesized, and their crystal structures and photoelectronic spectra were characterized. In the two dimers, ligand L acts as a bridge in the interesting mono–poly-dentate bridging mode. The ligand and its Cd II complex strongly emit at 525nm and 570nm, respectively, and thus can be utilized as potential fluorescent materials. Furthermore, magnetization measurements for its Mn II dimer in the range 5–300K indicate two magnetic orderings, at high temperature (T>230K) a ferromagnetic ordering is observed, and below this temperature, an antiferromagnetic behavior takes place.