We report the design and synthesis of a new class of piperazine-pyridazinone analogues. The arylpiperazine moiety, the length of the spacer, and the terminal molecular fragment were varied to evaluate their influence in determining the affinity of the new compounds toward the α1-adrenergic receptor (α1-AR), α2-adrenergic receptor (α2-AR), and the 5-HT1A serotoninergic receptor (5-HT1AR). Biological data showed that most of the compounds ...