Fig. 1. Diagram showing the structure of PTI·LiBr. (a) A charge balanced structure of PTI·LiBr showing the position of the Br^– anions located between the layers and the (assumed) positions of Li⁺ cations, that either partially replace H⁺ bound to the bridging imide units or between two adjacent triazine rings.26 In the present study the Br site occupancy was found to be approximately 50%. (b) A diagram of PTI·LiBr showing the layer stacking arrangement, with Br^– ions intercalated between the layers. The layers are arranged such that the triazine rings in successive layers are directly aligned above each other, but with bridging amine groups on alternating sides of the triazine ring in adjacent layers. This is termed the AA′ stacking motif.