Compounds 3-8 were tested at 10.0, 5.0, 2.5 μM concentrations against 5.0 μM solutions of WT TTR□ and A108G mutant TTR■. According to our design hypothesis, we predicted 4 would bind A108G TTR■ to enable keto emission. Unfortunately, this was not the case, as 4 displayed little change in emission characteristics in the presence of the TTR proteins (Fig. ). Gratifyingly, however, 5 showed selectivity for the A108G TTR■ mutant interface (Fig. ) in preference to WT TTR□. Both in buffer and in the presence of WT TTR, 5 displayed the expected signal for enol emission at 450 nm indicating that it was excluded into bulk solution. In the presence of A108G, however, 5 exhibits pronounced keto emission at 520 nm and the original 450 nm band diminishes.