Transformation of [EMIm][BPB] into a Cationic Luminescent Ln‐Coordination Polymer with the Bis(phthalato)borate Anion

Starting from phthalic acid and Na[BH4], the low‐melting salt [EMIm+][BPB] [EMIm+ = 1‐ethyl‐3‐methylimidazolium; BPB– = bis(phthalato)borate] was synthesized and further reacted with Tb(NO3)3·6H2O to yield the one‐dimensional coordination polymer 1∞[Tb(o‐HBDC)(H2O)6][BPB]2. Product formation is a result of the formation of the ortho‐phthalato mono acid (o‐HBDC) from [BPB]– anions in the process and leads to linkage of adjacent Tb3+ ions resulting in the cationic strand 1∞[Tb(o‐HBDC)]2+. The cationic charge of the coordination polymer is compensated by the [BPB]– anions in the crystal structure. Furthermore, the one‐dimensional coordination polymer 1∞[Tb(o‐HBDC)(H2O)6][BPB]2 shows characteristic luminescence based on the 4f–4f transitions of the Tb3+ ions upon excitation with UV light.