Crystal structure of thioflavin-T and its binding to amyloid fibrils: insights and implications at the molecular level

1. Experimental details All reagents were purchased from Aldrich, the commercial ThT(Cl) was recrystallized in acetonitrile. The slow addition of an aqueous saturated solution of KI (5 ml) to an aqueous solution (20 ml) of (ThT)Cl (0.600 g, 1.88 mmol) resulted in the formation of a yellow solid that was filtered off, washed with cold water (10 ml) and dried in vacuo. MS(+ESI-MS) showed the presence of ThT exclusively. m/z (relative intensity): 283.1 ([ThT], 100). A saturated CHCl3 solution of this solid was allowed to evaporate slowly at room temperature under open atmosphere. Reddish crystals, (ThT)2I4·2CHCl3 (1), were obtained after 24 h and yellow crystals, (ThT)I·CHCl3 (2), after ca. one week, both types of crystals being suitable for X-ray diffraction.