Compounds having affinity for amyloid

A compound represented by the following formula (4) or a salt thereof:

• wherein A13, A14, A15 and A16 represent a carbon,
• R7 is a group selected from the group consisting of a non-radioactive halogen substituent, a nitro substituent, a trialkylammonium group having alkyl chains with 1 to 4 carbon atoms, a trialkylstannyl substituent having alkyl chains with 1 to 4 carbon atoms and a triphenylstannyl group,
• R8 is a group selected from the group consisting of a hydroxyl group, a methoxy group, a carboxyl group, an N-methylamino group, and a cyano group, and
• q is an integer of 0 to 2, and
• provided that R7 binds to a carbon represented by A13, A14, A15 and A16.

A diagnostic agent for Alzheimer's disease, which comprises a compound represented by the following formula (3), or a salt thereof:

• wherein A9, A10, A11, and A12 represent a carbon,
• R5 is a radioactive halogen substituent,
• R6 is a group selected from the group consisting of a hydroxy group, a methoxy group, a carboxyl group, an N-methylamino group, and a cyano group, and
• P is an integer of 0 to 2, and
• provided that R5 binds to a carbon represented by A9, A10, A11 and A12.