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 sigma(1) and sigma(2) receptor recognition. The (3-pyridyl)piperazines and (4-pyridyl)piperazines favor sigma(1) receptors, while previously studied (2-pyridyl)piperazines favor sigma(2) receptors.