Self-assembly of highly luminescent heteronuclear coordination cages

Abstract

Exo-functionalized Pd2L4 cage compounds with attached Ru(ii) pyridine complexes were prepared via coordination-driven self-assembly. Unlike most of the previously reported palladium(ii) cages, one of these metallocages exhibits an exceptionally high quantum yield of 66%. The presented approach is promising to obtain luminescent coordination complexes for various applications.

Highly luminescent metallacages featuring bispyridyl ligands functionalised with BODIPY for imaging in cancer cells

“…This could be formed either via amide bond formation or by copper catalysed azide-alkynyl cycloaddition (CuAAC) reaction depending on the functional groups of the fluorophore and ligand. Thus, an amine exo-functionalised ligand was synthesised via Sonogashira cross coupling between dibromoaniline and two equivalents of 3-ethynyl pyridine, according to a previously reported procedure, [14] to afford the amine functionalised ligand (L1). Afterwards, L1 could be converted to the corresponding azide exo-functionalised ligand by in situ substitution of the amine for a reactive nitro group, followed by substitution of the nitro group to afford the corresponding azide functionalised ligand (L2) (Scheme S1).…”

“…Previously, we have reported on a number of Pd2L4 cages exo-functionalised with luminescent moieties, including anthracenyl groups [13] and Ru(II) polypyridyl ligands. [14] However, while the former did not display sufficient luminescence due to the lowered probability of π -π* excitation upon conjugation of the fluorophore to the ligand scaffold, [13] the latter achieved strong emission only upon excitation in the UV region, [14] which is not ideal for conventional microscopy analysis.…”

Anticancer Activity and Cisplatin Binding Ability of Bis-Quinoline and Bis-Isoquinoline Derived [Pd2L4]4+ Metallosupramolecular Cages

“…Thus, in order to exploit these [Pd 2 ( L ) 4 ] 4+ cages as cisplatin delivery vehicles these issues need to be addressed. We and others have examined a range of modifications to the parent [Pd 2 ( L ) 4 ] 4+ cage system in order to improve the solubility (Lewis and Crowley, 2014 ; Preston et al, 2015 ; Han et al, 2017 ) and other properties (Lewis et al, 2013 , 2014 ; Kaiser et al, 2016 ; Schmidt et al, 2016a ) of the cage. Efforts have also been made to enhance the strength of the host-guest interaction (Kim et al, 2015 ) and the stability of the cages in the presence of biologically revelant nucleophiles (Preston et al, 2016 ).…”

Heterometallic Cluster‐Capped Tetrahedral Assemblies with Postsynthetic Modification of the Metal Cores

“…[3g,5] As has been recently noted, [6] thee mployment of metal-based phosphorescent blocks,which can expand optical functionality of the self-assembled supramolecular compounds,r emains ap oorly investigated approach in the design of SCCs.T he limited cases of phosphorescent metallo-cycles/cages comprise af ew Pd II -assembled 3D compounds decorated with pendant Re I [7] or Ru II [8] diimine chromophores.A lternatively,t he complexes incorporating luminescent organometallic motifs as a) linkers represented by Pt II -dialkynyl [6a, 9] and Ir III cyclometataled metalloligands, [10] or b) coordinating centers (acceptor tectons) based on Ir III , [11] Pt II , 12] Ru II , [6b] and Re I [13] metals,h ave been employed in supramolecular construction of the photofunctional SCCs. [3g,5] As has been recently noted, [6] thee mployment of metal-based phosphorescent blocks,which can expand optical functionality of the self-assembled supramolecular compounds,r emains ap oorly investigated approach in the design of SCCs.T he limited cases of phosphorescent metallo-cycles/cages comprise af ew Pd II -assembled 3D compounds decorated with pendant Re I [7] or Ru II [8] diimine chromophores.A lternatively,t he complexes incorporating luminescent organometallic motifs as a) linkers represented by Pt II -dialkynyl [6a, 9] and Ir III cyclometataled metalloligands, [10] or b) coordinating centers (acceptor tectons) based on Ir III , [11] Pt II , 12] Ru II , [6b] and Re I [13] metals,h ave been employed in supramolecular construction of the photofunctional SCCs.…”

“…Unsurprisingly,t he majority of luminescent SCCs show intra-ligand fluorescence due to the utilization of organic linkers with extended conjugated systems,which additionally can be modified by appending an external fluorophore motif. [3g,5] As has been recently noted, [6] thee mployment of metal-based phosphorescent blocks,which can expand optical functionality of the self-assembled supramolecular compounds,r emains ap oorly investigated approach in the design of SCCs.T he limited cases of phosphorescent metallo-cycles/cages comprise af ew Pd II -assembled 3D compounds decorated with pendant Re I [7] or Ru II [8] diimine chromophores.A lternatively,t he complexes incorporating luminescent organometallic motifs as a) linkers represented by Pt II -dialkynyl [6a, 9] and Ir III cyclometataled metalloligands, [10] or b) coordinating centers (acceptor tectons) based on Ir III , [11] Pt II , 12] Ru II , [6b] and Re I [13] metals,h ave been employed in supramolecular construction of the photofunctional SCCs.…”