N1-Arylsulfonyl-3-piperazinyl indole derivatives were designed and identified as a novel class of 5-HT6 receptors ligands. All the compounds have high affinity and antagonist activity towards 5-HT6 receptor. The compound 7a (Ki= 3.4 nM, functional assay IC50= 310nM) shows enhanced cognitive effect when tested in NORT and Morris water maze models. Synthesis, SAR and PK profile of these novel compounds constitute the subject ...