Supramolecular iridium(III) assemblies

Abstract

Iridium(III) complexes exhibit remarkable photophysical properties such as high photoluminescence quantum yields, wide color tunability and high chemical stability. They have featured prominently in diverse applications such as sensing, bio-imaging, photoredox catalysis, solar fuels and solid-state lighting. In the vast majority of these reports the iridium complex is mononuclear in nature. The use of iridium complexes as components of selfassembled systems has garnered increasing attention and this review aims to comprehensively document the advances made in this area. Special emphasis will be devoted to describing the photophysical properties and applications of such photo-active supramolecular materials. Soft materials such as soft salts, liquid crystals, gels, colloids incorporating iridium are described as are hydrogen bonding-and π-π staking-directed assemblies, coordination-driven selfassembled materials such as coordination polymers and metal organic frameworks, macrocycles, capsules and cages. Finally, guest Ir(III) complexes encapsulated within the cavities of cage-type structures are presented. Contents

Marigold Flower‐Like Assemblies of Phosphorescent Iridium–Silver Coordination Polymers

“…Herein, we report chiral phosphorescent coordination polymers, rac ‐, Λ‐, and Δ‐ IrAg , formed, respectively, through the self‐assembly between the iridium metalloligand rac ‐, Λ‐, and Δ‐ Ir of composition rac ‐, Λ‐, and Δ‐[Ir(mesppy) 2 (qpy)]PF 6 ( Figure ) and Ag + ions through N py –Ag linear coordination. Although in recent years the use of iridium(III) complexes as luminescent components in 3D assemblies such as metal–organic frameworks (MOFs) and coordination polymers (CP) has become increasingly popular, to the best of our knowledge, these are the first examples of coordination polymers formed through the assembly between an iridium metalloligand and silver ions. Phosphorescent silver(I) coordination polymers themselves are rare and limited to silver‐triazolates, such as those found by Zhou and coworkers, a,b consisting of cyanide‐containing Ag + polymers that exhibit broad green emissions located at λ PL between 500 and 520 nm.…”

A Pd3L6 supramolecular cage incorporating photoactive [2.2]paracyclophane units

“…10 These 1D assemblies often exhibit a high electron delocalization across the entire supramolecular chains as a result of strong intermolecular p-stacking interactions between adjacent pCp units that produce materials with low-energy optical gaps, infrared emission, and high conductivity. 10 There exist examples of 3D-photoactive cage assemblies that have been synthesized through integration of phosphorescent metal complexes, [11][12] porphyrins 13 or fluorescent aromatic compounds [14][15][16] into the ligand backbone of the metallosupramolecular architectures.…”

Phosphorescent iridium(iii) complexes capable of imaging and distinguishing between exogenous and endogenous analytes in living cells

“…Living HeLa cells incubated with the complexes (5 μM, 20 min, 37 °C) revealed intense cellular luminescence. Compared to many other iridium( iii ) complexes that show efficient cellular internalization 21 – 25 or specific organelle staining, 31 – 36 complexes 1–4 were partially retained in the cell membrane. The internalized complexes were localized in the cytoplasm surrounding the cell nuclei ( Fig.…”

“…1 ). Phosphorescent iridium( iii ) polypyridine complexes are selected for this study because of their advantageous photophysical properties 21 – 25 including intense phosphorescence and large Stokes shift. Their long luminescence lifetimes and high photostability facilitate photoluminescence lifetime imaging.…”