4-[omega-[4-arylpiperazin-1-yl]alkoxy]phenyl)imidazo[1,2-a]pyridine derivatives: fluorescent high-affinity dopamine D3 receptor ligands as potential probes for receptor visualization.

Sixteen long-chain arylpiperazines bearing the fluorescent moiety 2-phenylimidazo[1,2-a]pyridine were synthesized as fluorescent dopamine D3 receptors ligands (385 nM < Ki < 0.72 nM). The most potent D3 compounds 15a and 19a (Ki = 1.6 and 0.72 nM, respectively) showed good Stokes shift and high quantum yield in ethanol (Phi = 0.74 and 0.66, respectively). In the first attempt, 15a was unable to visualize D3 receptors expressed in CHO cells by epifluorescence microscopy.