Homochiral Self-Sorted and Emissive IrIII Metallo-Cryptophanes

The racemic ligands (+/-)-tris(isonicotinoyl)-cyclotriguaiacylene (L1), or (+/-)-tris(4-pyridyl-methyl)-cyclotriguaiacylene (L2) assemble with racemic (,)-[Ir(ppy)(2)(MeCN)(2)](+), in which ppy=2-phenylpyridinato, to form [{Ir(ppy)(2)}(3)(L)(2)](3+) metallo-cryptophane cages. The crystal structure of [{Ir(ppy)(2)}(3)(L1)(2)]3BF(4) has MM- and PP- isomers, and homochiral self-sorting occurs in solution, a process accelerated by a chiral guest. Self-recognition between L1 and L2 within cages does not occur, and cages show very slow ligand exchange. Both cages are phosphorescent, with [{Ir(ppy)(2)}(3)(L2)(2)](3+) having enhanced and blue-shifted emission when compared with [{Ir(ppy)(2)}(3)(L1)(2)](3+).