Interaction of an Iridium(III)–Bibenzimidazole Complex with Anions – Implications for Luminescent Sensing

Abstract

Iridium(III) complex [Ir(ppy) 2 (tmBBI-H 2 )](PF 6 ) (IrBBI-H 2 ) has been exploited as an anion receptor. In this complex, the cis-diamine function of the bibenzimidazole is coupled in such a way to the photophysics of the iridium metal core that the photophysics is influenced by hydrogen bonds in the ligand periphery. Systematic studies on the complex reveal that IrBBI-H 2 is a convenient sensor for various anions under aerobic conditions and interacts with Cl -, Br -, I -, and HSO 4 by forming hydrogen bonds. Whereas H 2 PO 4 is only capable of mono-deprotonating IrBBI-H 2 , a stepwise process is operative when F - [a]

Luminescent chemosensors by using cyclometalated iridium(iii) complexes and their applications

“…Rau and co-workers recently reported improved IrBBI–H 2 -based complexes by using a DNBA-free strategy, in which the high acidity of the N–H protons allows the complex to be more easily deprotonated in the presence of strongly basic anions or to form hydrogen bonds with weakly basic anions with distinct emission responses. 55 The exploration of this interesting type of mechanism, including the pocket effect on anion binding affinity, deserves further attention.…”

Homogeneous and Heterogeneous Anion Sensing by a Molecular Cobalt–Vanadium Oxide

“…Theoretical calculations : Density functional theory calculations were performed using the B3LYP exchange‐correlation functional with unrestricted Kohn–Sham wave functions as implemented in the Jaguar electronic structure program . Metal and halide atoms are described using effective core potentials with LACVP‐type basis sets, oxygen atoms are described using the 6‐31G++ basis set.…”

“…For successful qualitative and/or quantitative anion sensing, a colorimetric, luminescent, electrochemical, or other response is required . Based on these prerequisites, coordination compounds are ideal candidates for the development of homogeneous anion sensors . Because the ligands of coordination compounds can be structurally tuned, size‐ and shape‐exclusive anion binding can be achieved .…”

Optical Sensing of Anions via Supramolecular Recognition with Biimidazole Complexes

“…In principal, this offers luminescence as a probe channel for intermolecular interactions utilizing H‐bond interaction and may further enable sensing also in high pH media . The following section will focus on the anion recognition features of ruthenium(II) and iridium(III) based imidazole type sensors in particular.…”