A series of diazabicyclo [3.3. 0] octane substituted pyridines and pyrazines was synthesized and characterized at the α4β2 neuronal nicotinic acetylcholine receptor (nAChR). The compounds were designed to mimic the profile of ABT-089, high affinity binding ligand for the α4β2 nAChR, with limited agonist activity. Carboxamide derivatives of 3-(diazabicyclo [3.3. 0] octane)-substituted pyridines or 2-(diazabicyclo [3.3. 0] octane)-substituted ...