<unk> s form a family of chemical compounds with the formula (C5H4N)2.  They are derived by the coupling of two pyridine rings.  Six isomers of<unk>  exist.  Two isomers are prominent: 2,2'-bipyridine is a popular ligand in coordination chemistry and 4,4'-bipyridine is a precursor to the herbicide paraquat.  The<unk> s are colourless solids, which are soluble in organic solvents and slightly soluble in water.
Inamrinone and Milrinone are used occasionally for short term. They inhibit phosphodiesterase by increasing cAMP, exerting positive inotropy and causing vasodilation. Amrinone causes thrombocytopenia; Milrinone decreases survival in heart failure.
Bipyridine
Amsacrine
Iotroxic acid
Ampyrone
Bumadizone
Periciazine
Chenodiol
Guaiazulene