N-Containing bidentate/tridentate ligands, such as series of symmetric/unsymmetric substituted 2,2'-bipyridine, 1,10-phenanthroline and 2,2':6',2"-terpyridine derivatives, have been useful precausors for metal complexes, application for homogeneous and heterogeneous catalytic reactions, ion detection, organic photoelectric conversion materials, etc. UCHEM is main supplier on the world for the above ligands, and most of them are available from warehosue, some of them has been supplying over kilorgrams or commercially.