In vivo imaging compounds

A compound of formula (I)

• or a salt or solvate thereof, wherein:
• R1 is selected from hydrogen, C1-6alkyl, C2-6alkenyl, C2-6alkynyl, C5-12aryl, C5-12hetaryl, and hydroxy;
• R2 is selected from hydrogen, C1-6alkyl, C2-6alkenyl, C2-6alkynyl, C5-12aryl, and C5-12hetaryl;
• L is C1-6alkylene;
• one or two of the groups R3 to R7 are independently selected from halo, C1-6alkyl, C1-6haloalkyl, C1-6alkoxy, C1-6haloalkoxy, phenyl, phenylC1-4alkyl, and halophenylC1-4alkenyl, and the remaining groups R3 to R7 are hydrogen;
• one, two, three, or four of the groups R8 to R12 are independently selected from halo, C1-6alkyl, C1-6haloalkyl, C1-6alkoxy, C1-6haloalkoxy and the remaining groups R8 to R12 are hydrogen;
• provided that
• (i) when R5 is C1-6alkoxy or C1-6haloalkoxy and R3, R4, R6, and R7 are hydrogen two, three, or four of the groups R8 to R12 are independently selected from halo, C1-6alkyl, C1-6haloalkyl, C1-6alkoxy, C1-6haloalkoxy;
• (ii) at least one of the groups R1 to R12 comprises a radiolabel selected from 11C, 18F, 123I, 124I, and 122I.