Abstract: The invention provides compounds of formula (I) and compositions comprising compounds of formula (I). The invention further provides uses of the compounds of formula (I) and compositions comprising compounds of formula (I), including the use of such compounds for the detection of tau deposits, and the use of such compounds and compositions as diagnostic agents in the diagnosis or monitoring of the progression of a disease or disorder such as Alzheimer's disease or corticobasal degeneration, or for the prevention or treatment of a disease or disorder such as Alzheimer's disease or corticobasal degeneration.