The effect of the pyridyl nitrogen position in pyridylpiperazine sigma ligands

A series of pyridylpiperazines was synthesized and analyzed for sigma receptor binding affinity to determine the optimal pyridyl nitrogen position and chain length for the σ1 and σ2 receptor recognition. The (3-pyridyl)piperazines and (4-pyridyl)piperazines favor σ1 receptors, while previously studied (2-pyridyl)piperazines favor σ2 receptors.