Deep-blue luminescent [{Ir(C^N)2}3(L)2]3+ coordination cages with structurally integral pyridyl-azo-phenyl groups can be reversibly photo-isomerised with no compositional change.

The racemic ligands (±)‐tris(isonicotinoyl)‐cyclotriguaiacylene (L1), or (±)‐tris(4‐pyridyl‐methyl)‐cyclotriguaiacylene (L2) assemble with racemic (Λ,Δ)‐[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]⋅3BF4 has MM‐ΛΛΛ and PP‐ΔΔΔ 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+.

Zirconium and hafnium metallocene dihalides based on simple polyphenyl cyclopentadienes are stable room-temperature lumophores with large Stokes shifts, emitting from states with substantial LMCT character. Their synthesis is described, including by a rapid solvent-free approach compatible with the lifetime of PET-active isotopes (89Zr). Preliminary experiments indicate the viability of these species as lumophores for fluorescence cell-imaging microscopy.

No abstract

Mononuclear and trinuclear bis‐cyclometallated IrIII complexes of the host ligands tris(4‐[4′‐methyl‐2,2′‐bipyridyl]methyl)cyclotriguaiacylene (L1) and tris(4‐(4′‐methyl‐2,2′‐ bipyridyl)carboxy)cyclotriguaiacylene (L2) have been prepared. Complexes [{Ir(ppy)2}3(L1)](PF6)3 (1.1), [{Ir(ppy)2}(L1)](PF6)3 (1.2), [{Ir(ppy)2}3(L2)](PF6)3 (2.1) and [{Ir(ppy)2}(L2)](PF6)3 (2.2) (where ppy=phenylpyridinato) showed distinct photophysical properties depending on the L ligand. Complexes featuring the L1 ligand were comparatively blue‐shifted in solution, with longer lifetimes and higher quantum yields. The mixed bis‐cyclometallated IrIII complexes [{Ir(ppy)2}{Ir(dFppy)2}2(L1)](PF6)3 (1.3), [{Ir(ppy)2}{Ir(dFppy)2}2(L2)](PF6)3 (2.3), [{Ir(ppy)2}2{Ir(dFppy)2}(L1)](PF6)3 (1.4) and [{Ir(ppy)2}2{Ir(dFppy)2}(L2)](PF6)3 (2.4) (where dFppy=2,4‐difluorophenylpyrinato) were also synthesised. Steady‐state and time‐resolved spectroscopy, along with electrochemical investigations, show that the Ir(III) chromophores within these mixed Ir‐environment species behave as isolated centres, with no energy transfer or electronic communication between them.

Quadruply bonded metal complexes of rhenium and molybdenum have been prepared with tetrachlorocatechol. Structural characterization on the [Re(2)(Cl(4)Cat)(4)](2-) anion has shown that it consists of distorted square-planar Re(Cl(4)Cat)(2) units linked by a short (2.2067 A) quadruple Re-Re bond. The addition of tetrachlorocatechol to molybdenum acetate was used to prepare the isoelectronic molybdenum analogue "[Mo(2)(Cl(4)Cat)(4)](4-)". This complex was found to be far more reactive than the rhenium dimer. A dimer containing a Mo-Mo double bond, [(Cl(4)Cat)(2)Mo(mu-O)(mu-OCH(3))Mo(Cl(4)Cat)(2)](3-), was obtained as the methanolysis product of the complex formed initially, and the oxomolybdenum(V) monomer [MoO(Cl(4)Cat)(2)](-) was formed under more oxidative conditions. Both complexes are oxygen-sensitive, giving [MoO(2)(Cl(4)Cat)(2)](2-) as the final air-stable complex product.

Luminescent mono‐metallic and tri‐metallic complexes with Ir(III)‐chromophores have been synthesised using tripodal ligands with a host‐type scaffold. Mono‐metallic complexes can be further reacted to give multi‐metallic species with different types of Ir‐based chromophores. The distinct chromophores do not show energy transfer nor electronic communication between them, hence this platform moves towards tuning of emissive properties through a predictable additive strategy. For more details, see the Full Paper by E. Zysman‐Colman, M. J. Hardie et al. on page 8839 ff.