An Iridium Complex as Bidentate Halogen Bond-Based Anion Receptor Featuring an IncreasedOptical Response

We present a luminescent Ir(III) complex featuring a bidentate halogen bond donor site capable of strong anion binding. The tailor-made Ir(III)(L)2 moiety offers a significantly higher emission quantum yield (8.4 %) compared to previous Ir(III)-based chemo-sensors (2.5 %). The successful binding of chloride, bromide and acetate is demonstrated using emission titrations. These experiments reveal association constants of up to 1.6x105 M-1. Furthermore, a new approach to evaluate the association constant by utilizing the shift of the emission was used for the first time. The experimentally observed characteristics are supported by quantum chemical simulations. We present a luminescent Ir(III) complex featuring strong halogen bonding of anions as a chemo-sensor. The strong binding of anions is determined using the shift of the emission energy as a reliable readout parameter for evaluation of association constants. Those results were additionally corroborated by quantum chemical calculations. image