The present invention provides novel trimethylammonium compounds of the formula: methods of making these compounds, methods of using the compounds for preparation of tau imaging agents, and preparation of tau imaging agent formulations.本發明提供下式之新穎三甲基銨化合物,製造此等化合物之方法,使用該等化合物製備TAU造影劑之方法,及TAU造影劑調配物之製備。