The structure of I consists of linkages between LaO9 tricapped trigonal prisms and SO4 tetrahedral units.
The LaO9 units are connected through three coordinated oxygen atoms [O(3),O(5), and O(6)] forming an infinite two-dimensional La-OLa network (Figure 1a).
The two sulfate tetrahedral units, S(1)O4 and S(2)O4, are connected to the La-O-La twodimensional layers in such a way that they connects with 4 and 3 La atoms respectively, and each possess one terminal SdO bond [S(1)-O(7) and S(2)-S(8)] (Figure 1b).
The layers are arranged in a ABABAB 3 3 3 fashion and are stabilized by the NH3 3 3O interaction between the protonated bipyridinium cation and the framework oxygen [N(1)-H(1) 3 3 3 O(7), N-O = 2.72 Å, angle = 143] (Figure 1c).