Disclosed is a phenyl or pyridine acetylene compound of formula (I) where the substituents are as disclosed in the description. The compound must contain a halogen or halogen isotope. Also disclosed is a composition comprising a compound of formula (I) a diagnostic composition for imaging amyloid deposits comprising a radio labelled compound of formula (I) and the use of a compound of formula (I) for manufacturing a diagnostic composition. Amyloid detection is often used as a diagnosis for Alzheimers disease.