[2,2'-Bipyridine]-5,5'-dicarboxylic acid2,2′-Bipyridine-5,5′-dicarboxylic acid2,2′-联吡啶-5,5′-二羧酸2,2'-Bipyridyl-5,5'-dicarboxylic Acid2,2'-Bipyridine-5,5'-dicarboxylic acid5,5'-Dicarboxy-2,2'-bipyridine6,6'-Binicotinic Acid [2,2'-Bipyridine]-5,5'-dicarboxylic Acid